The scale of the problem is expanding rapidly. As cellular therapies and B-cell-depleting agents become standard care for hematologic malignancies, the number of patients with prolonged hypogammaglobulinemia, meaning abnormally low levels of immunoglobulin G, is expected to rise substantially. These patients suffer recurrent bacterial infections, frequent hospitalizations and a marked decline in health-related quality of life. The immune dysfunction is not uniform: B-cell-depleting drugs primarily damage humoral immunity, while stem cell transplantation and CAR-T therapy can produce broader defects that also impair cellular immune defenses and delay immune reconstitution for months or even years. Because diagnostic criteria developed for primary antibody deficiencies do not translate cleanly to these acquired conditions, clinicians must tailor immunoglobulin replacement to each patient’s infection history, immune status and treatment regimen.

The evidence that replacement therapy works is robust. Real-world data and clinical studies consistently show substantial reductions in infections, emergency department visits and hospital admissions once therapy begins. In the Ontario Immunoglobulin Treatment Case Registry, treatment was associated with an 82.6 percent reduction in annual infections, an 84.6 percent reduction in emergency department visits and an 83.3 percent reduction in hospitalizations. A Japanese retrospective cohort of patients with hematologic malignancy-associated hypogammaglobulinemia found that 20 percent subcutaneous immunoglobulin cut infection rates from 3.67 to 1.32 infections per patient-year. Post-marketing data for the subcutaneous product IgPro20 showed similar reductions in infections and serious bacterial events. Randomized trials and consensus guidelines support both routes for infection prevention in chronic lymphocytic leukemia, lymphoma and post-transplant populations.

The two delivery routes differ fundamentally in their pharmacokinetic behavior. Intravenous immunoglobulin is typically given every three to four weeks in a hospital or infusion center, producing a sharp peak in serum IgG followed by a gradual decline toward a trough before the next infusion. Subcutaneous immunoglobulin, by contrast, is administered more frequently, often weekly or biweekly, and sometimes monthly with facilitated formulations, yielding near-steady-state IgG concentrations with minimal peak-to-trough fluctuation. This smoother exposure profile matters clinically, because trough levels are a central pharmacokinetic goal of long-term management. Notably, a retrospective comparison of 131 patients with secondary antibody deficiency and 102 with primary antibody deficiency found that the secondary group achieved comparable reductions in infection burden despite receiving lower doses and reaching lower steady-state IgG trough concentrations, suggesting that dosing requirements differ between the two populations.

Safety profiles also diverge in clinically meaningful ways. Intravenous immunoglobulin carries a higher incidence of systemic adverse reactions, including headache, fever, nausea, thromboembolic events, aseptic meningitis, hemolysis and, less commonly, renal dysfunction or anaphylaxis. Systemic reactions occur in roughly 20 to 50 percent of patients and in 5 to 15 percent of infusions, although most are mild to moderate. Subcutaneous administration produces far fewer systemic events but more frequent local injection-site reactions such as erythema, swelling and rash, which are typically mild and self-limited. Facilitated subcutaneous immunoglobulin, which includes an added enzyme that allows larger volumes to be infused, may further improve tolerability while reducing hospital burden, according to emerging evidence reviewed by the authors.

Beyond infection control, the review highlights patient-reported outcomes as an increasingly important dimension of treatment success. Real-world studies show that subcutaneous therapy is associated with greater treatment convenience, improved autonomy and better quality-of-life scores, largely because patients can self-administer at home rather than traveling to infusion centers. Patients who switch from intravenous to subcutaneous treatment frequently report higher satisfaction and a reduced treatment burden. These gains in daily living are not merely cosmetic: they translate into measurable differences in how immunocompromised cancer survivors experience long-term supportive care.

Health economics reinforce the case for the subcutaneous route. A ten-year cost-utility analysis comparing hospital-based intravenous therapy with home-based subcutaneous therapy found that the subcutaneous approach yielded more quality-adjusted life years, 3.51 versus 3.07, at lower cumulative healthcare cost, making it the dominant strategy from a healthcare system perspective. Home-based administration reduces infusion-center utilization and hospital visits while maintaining clinical effectiveness, and registry data demonstrate durable treatment persistence during long-term subcutaneous therapy in routine practice. As global demand for plasma-derived immunoglobulin continues to climb, the review argues that responsible stewardship of this finite resource requires evidence-informed patient selection, periodic reassessment and timely discontinuation when immune recovery makes replacement unnecessary.

Guidance from major international bodies, including the American Academy of Allergy, Asthma, and Immunology, the British Committee for Standards in Hematology, the National Comprehensive Cancer Network and the European Society for Immunodeficiencies, supports either route for patients with documented hypogammaglobulinemia and recurrent or severe infections. The AAAAI recommends an individualized intravenous dosing range of 0.4 to 0.8 grams per kilogram every 28 days when clinically indicated. In practice, therapy is generally considered for patients with chronic lymphocytic leukemia or multiple myeloma whose IgG levels fall below roughly 400 to 500 milligrams per deciliter and who experience recurrent or severe infections despite appropriate antimicrobial management. Inadequate vaccine responses to diphtheria, tetanus or pneumococcal antigens can further support initiation in selected patients. For stem cell transplant recipients, routine prophylactic intravenous immunoglobulin is not recommended, but either route may be considered when IgG remains below 400 milligrams per deciliter with recurrent or severe infections. After CAR-T therapy, baseline immune assessment and individualized replacement strategies are increasingly advised.

The review emphasizes that there is no universally accepted IgG trough target for this population. Decisions to start, continue, modify or stop therapy should integrate serum IgG concentrations with infection history, underlying disease activity, ongoing immunosuppression and evidence of B-cell reconstitution rather than relying on a single numeric threshold. Monitoring should track infection frequency and severity, adverse events, treatment tolerability and, following B-cell-directed therapy, peripheral B-cell recovery assessed by flow cytometry when appropriate. Patients who remain infection-free and show immune recovery may interrupt or discontinue therapy, with reinitiation if infections recur, although validated biomarker thresholds for stopping treatment have not been established. The primary objective, the authors stress, is prevention of recurrent and severe infections, not achievement of a universal serum IgG number.

Significant gaps remain. Comparative prospective data on subcutaneous versus intravenous therapy in hematologic malignancy populations, particularly among CAR-T and transplant recipients, are scarce, and evidence on survival benefits is limited because most studies were not powered to detect mortality differences. Replacement therapy also addresses only humoral deficiency and cannot correct the broader cellular immune dysfunction that follows transplantation or CAR-T treatment. Several ongoing trials, including registries of facilitated subcutaneous immunoglobulin in multiple myeloma and a dedicated study of immunoglobulin for hypogammaglobulinemia after CAR-T therapy, should help refine dosing, monitoring and discontinuation criteria. For now, the message for clinicians is clear: both routes work, but for patients facing years of antibody replacement, the steadier pharmacokinetics, fewer systemic reactions and home-based convenience of the subcutaneous route make it an increasingly attractive first choice.

Subject of Research: Immunoglobulin replacement therapy via subcutaneous and intravenous routes for secondary immunodeficiency in hematologic malignancy patients

Article Title: Immunoglobulin replacement therapy in hematologic malignancy–associated secondary immunodeficiency: roles of SCIG and IVIG

Article References: Seaquist, E., Majapuro-Hirvonen, A., Van Wagoner, R., & Rutland, B. (2026). Immunoglobulin replacement therapy in hematologic malignancy–associated secondary immunodeficiency: roles of SCIG and IVIG. Frontiers in Hematology, 5, Article 1904290. https://doi.org/10.3389/frhem.2026.1904290

Image Credits: AI Generated

DOI: 10.3389/frhem.2026.1904290

Keywords: immunoglobulin replacement therapy, secondary immunodeficiency, hematologic malignancies, SCIG, IVIG, CAR-T therapy, hypogammaglobulinemia, immune reconstitution, infection prevention, pharmacokinetics, patient-reported outcomes, healthcare cost-effectiveness

The review, conducted by researchers at the University of Winchester and published in March 2026, followed the PRISMA 2020 reporting standard and searched seven bibliographic sources for randomised controlled trials published between January 2019 and February 2026. To qualify, trials had to compare structured exercise-based rehabilitation against usual care or a control condition in adult transplant recipients, with outcomes measured at least three months after transplant or after the intervention ended. The screening process whittled 1,212 records down to seven trials comprising 529 participants across seven countries, spanning inpatient, outpatient, home-based and telehealth delivery. Two trials enrolled exclusively allogeneic recipients, who receive donor stem cells and typically remain on immunosuppressive drugs; two enrolled exclusively autologous recipients, who receive their own cells; and three enrolled mixed cohorts. Because the trials differed so much in modality, timing, population and outcome instruments, the authors abandoned meta-analysis and synthesised the findings narratively, rating certainty with the GRADE framework.

The clearest signal concerned walking ability. In the largest trial, an Australian telehealth-delivered programme of exercise and mindfulness reported in the Journal of Clinical Oncology, patients who exercised improved their six-minute walk distance by 51.4 metres more than controls at three months, an effect that persisted at 59.3 metres at twelve months. That is a substantial mechanical difference: a published threshold for clinically meaningful deterioration in the six-minute walk, borrowed from lung cancer research, sits between 22 and 42 metres, so the observed gains meet or exceed it, though the review authors are careful to note that no such threshold has been formally established in transplant survivors. A United States prehabilitation trial reported a non-significant between-group difference of 62.8 metres at day 100 post-transplant, and a Spanish telehealth trial found that the exercise group recovered to its pre-admission walking distance while controls remained 41 metres below baseline.

Lower-body strength told an even more consistent story. Across four trials that measured sit-to-stand or chair-stand performance, exercise groups gained roughly 2.5 to 3.8 extra repetitions in thirty seconds compared with controls, and no trial reported findings contradicting the direction of benefit. In the German whole-body vibration trial, which had patients training on a vibrating platform for about twenty minutes five times a week during their transplant admission, chair-rising power improved significantly in the intervention group. Grip strength, by contrast, showed no consistent between-group advantage anywhere, suggesting that the benefits of exercise after transplant concentrate in the large muscle groups of the legs rather than the hands.

The picture darkens for the outcomes patients often care about most. Effects on cardiorespiratory fitness, measured directly as peak oxygen uptake, were inconsistent: the German trial found a within-group gain in the exercisers, while the large Dutch EXIST trial, which tested an eighteen-week supervised programme in autologous recipients, found no between-group difference immediately after the programme or twelve months later, and the intervention was not cost-effective. Fatigue results were similarly mixed, with benefits reported in trials that began during or close to the transplant period but null findings in late-survivorship cohorts. Global quality of life was largely unchanged across trials, although physical functioning and daily-activity domains did improve in several. The GRADE ratings reflect this patchwork: low certainty for strength and walking benefits, very low certainty for everything else.

Perhaps the most provocative pattern in the review is the split between transplant types. Autologous recipients, whose immune systems typically engraft without long-term immunosuppression and whose main late risk is relapse, showed essentially no durable benefit in the only fully powered trial, EXIST. Allogeneic recipients, by contrast, face chronic graft-versus-host disease, steroid-related bone loss, late infections and years of deconditioning, and it is precisely in these patients that exercise appeared to deliver the most. The Spanish trial’s allogeneic subgroup showed a 77-metre between-group walking difference, and the allogeneic peri-transplant trials preserved strength, fatigue levels and even body cell mass while controls declined. The biology makes sense: patients with more deconditioning have more room to recover. The practical implication is that exercise referrals and future trials should be designed differently for the two populations rather than pooling them, as most mixed-cohort studies have done.

Two trials dipped a toe into immunometabolism, the least-studied domain and arguably the most tantalising. The Australian trial measured 27 serum cytokines and found, in an exploratory analysis of 69 of its 139 participants, a significant between-group reduction in soluble intercellular adhesion molecule-1, a marker of vascular inflammation and endothelial activation, at three months. No other cytokine differed, and samples were collected only at baseline and three months, so the finding is a hypothesis rather than a conclusion. The German trial reported that body cell mass, a proxy for metabolically active lean tissue, fell significantly in controls over the six months after transplant while exercisers regained their baseline values. Strikingly, no trial measured lymphocyte subset reconstitution, T-cell receptor diversity, vaccination responses, lipid profiles or glycaemic control, leaving the question of whether exercise can actually reshape immune recovery after transplant entirely open.

Safety, at least, is settled. No serious exercise-related adverse events were reported in any of the seven trials. Whole-body vibration was performed at platelet counts as low as 10,000 per microlitre without bleeding complications, the American prehabilitation trial reported zero exercise-related adverse events with 92 percent adherence, and the only serious event in any trial, a fall during a baseline walking test that caused a subarachnoid haemorrhage, occurred in a participant who had not been randomised and was unrelated to exercise.

Methodological honesty tempers all of these findings. Using the Cochrane Risk of Bias 2.0 tool, the reviewers judged six of the seven trials at high risk overall, mostly because of large and often health-related losses to follow-up: the Canadian feasibility trial retained roughly a third of its participants by one year, and the German trial analysed 44 of 71 randomised patients. Because exercise cannot be blinded, every trial was open-label, and none used blinded outcome assessment. Trials at higher risk of bias tend to report larger effects, which means the conservative null results from the largest study, EXIST, may in some respects represent the more realistic estimate of what exercise achieves in unselected survivors.

The review’s authors conclude that structured exercise appears safe and may improve objective physical function after transplant, with the greatest benefit in allogeneic and more impaired recipients, but that cardiorespiratory fitness, fatigue and quality-of-life effects remain uncertain and immunometabolic evidence is preliminary. Their prescriptions for the field are specific: future trials should report outcomes separately by transplant type, adopt harmonised core outcome sets, pre-specify immunological endpoints such as lymphocyte subsets and inflammatory panels alongside metabolic measures like fasting lipids and HbA1c, and follow patients well beyond twelve months to test effects on cardiometabolic risk, immune reconstitution and survival. For now, the practical message for the growing population of transplant survivors is measured but real: if you are still rebuilding strength and walking distance months after your transplant, structured exercise, particularly through telehealth models that reach patients at home, is a reasonable and safe bet, and the sooner after treatment it starts, the more deconditioning there may be to reverse.

Subject of Research: Exercise-based rehabilitation outcomes and immunometabolic parameters in adult haematopoietic stem cell transplant recipients

Article Title: Long‐Term Outcomes of Exercise‐Based Rehabilitation and Immunometabolic Parameters in Adult Haematopoietic Stem Cell Transplant Recipients: An Updated Systematic Review of Randomised Controlled Trials

Article References: Bayquen, D. D., & Narasimhan, P. (2026). Long‐Term Outcomes of Exercise‐Based Rehabilitation and Immunometabolic Parameters in Adult Haematopoietic Stem Cell Transplant Recipients: An Updated Systematic Review of Randomised Controlled Trials. eJHaem, 7(5), Article e70420. https://doi.org/10.1002/jha2.70420

Image Credits: AI Generated

DOI: 10.1002/jha2.70420

Keywords: haematopoietic stem cell transplantation, exercise rehabilitation, systematic review, randomised controlled trials, allogeneic transplant, autologous transplant, physical function, six-minute walk distance, fatigue, quality of life, immune reconstitution, sICAM-1

X-linked hyper-IgM syndrome, abbreviated XHIM, is caused by mutations in the gene encoding CD40 ligand, a surface molecule on helper T cells that is essential for instructing B cells to switch antibody classes. Without a functional CD40 ligand, B cells remain frozen at the IgM stage, leaving patients unable to produce IgG, IgA, and IgE antibodies. The name of the disease reflects the paradoxical laboratory finding: IgM levels are normal or even elevated, while the rest of the antibody repertoire is missing. But the defect reaches further than humoral immunity. CD40 ligand signaling is also required for macrophage activation and for effective T cell communication with antigen-presenting cells, so patients suffer from a combined cellular and humoral immunodeficiency. The clinical consequences are devastating: recurrent and severe infections with bacteria, fungi, and above all opportunistic pathogens that healthy immune systems dispatch without notice.

Among these opportunistic threats, few are as characteristic or as consequential as Cryptosporidium parvum, a waterborne intestinal parasite that is merely an inconvenience for immunocompetent people but a relentless adversary in XHIM. The parasite colonizes the biliary tract, where it drives a progressive, scarring inflammation of the bile ducts known as sclerosing cholangitis. Over time the ducts are destroyed, bile flow is obstructed, and the liver fails. There is no reliably effective antimicrobial therapy for cryptosporidial cholangitis once it takes hold; the only definitive cure for the underlying immune defect is allogeneic hematopoietic stem cell transplantation, or HSCT, which replaces the patient’s defective hematopoietic system with donor stem cells capable of generating functional T cells and class-switched antibodies. The critical caveat, well recognized in the field, is that outcomes of HSCT deteriorate sharply once advanced liver disease has developed, creating a race against time that many patients lose.

The Bergamo patient illustrates exactly why that race matters. By age 19, his sclerosing cholangitis was progressive, and the team proceeded with HSCT from an unrelated donor matched at 8 of 10 HLA loci, a partially mismatched graft that carries heightened risks of rejection and graft-versus-host disease but was necessitated by the lack of a fully matched donor. Early after the infusion, he developed severe cholestasis and persistent fever. Diagnostic workup identified active Cryptosporidium parvum infection that responded poorly to antimicrobial agents. What ultimately turned the tide was not a new drug but the withdrawal of immunosuppression: as the team tapered the medications given to prevent graft rejection, the patient’s donor-derived T cells recovered, and with that immune reconstitution the cryptosporidial infection finally resolved. The observation underscores a central principle of transplant immunology in immunodeficiency: antimicrobial therapy can suppress pathogens, but only a reconstituted cellular immune system can truly clear them.

Engraftment, however, was not enough to save his native liver. The cholangiopathy, already advanced before transplantation, continued its downward course, and six months after the stem cell transplant the patient underwent liver transplantation. This sequential strategy, HSCT followed by solid organ transplantation, is exceptionally rare and exceptionally demanding. Each procedure imposes its own burden of immunosuppression, and the two must be balanced against each other: too little immunosuppression invites graft rejection and opportunistic infection, while too much suppresses the very T cell recovery that the bone marrow transplant was meant to achieve and that the patient’s survival against Cryptosporidium depended upon.

Superimposed on this balancing act was a second viral threat: cytomegalovirus, or CMV. CMV is among the most common and dangerous infections after transplantation, capable of causing pneumonia, hepatitis, colitis, and bone marrow suppression, and of amplifying the risk of rejection and secondary infections. Patients who are CMV-seropositive themselves, or who receive organs or stem cells from seropositive donors, are classified as high risk for reactivation once immunosuppression begins. For this patient, whose CMV risk profile was unfavorable and whose blood counts were severely depressed, the team selected letermovir, a relatively recent antiviral that inhibits the CMV terminase complex, an enzyme the virus needs to package its DNA into newly formed viral particles. Because the terminase complex has no human counterpart, letermovir is highly specific, sparing the mitochondrial and renal toxicity that complicates older CMV drugs such as ganciclovir and foscarnet, an advantage of particular importance in a patient already battling cytopenias and liver dysfunction.

The team administered letermovir prophylaxis for 100 days after transplantation, a duration consistent with the evidence base established in studies of CMV-seropositive recipients of hematopoietic stem cell transplants, where the drug has dramatically reduced clinically significant CMV infection during the early post-transplant period. During prophylaxis the patient remained protected. But when letermovir was discontinued, recurrent CMV reactivations emerged, a pattern well described in the literature as late CMV disease occurring after prophylaxis ends. Once again, the decisive intervention was not an escalation of antiviral therapy alone but the careful tapering of immunosuppression, which allowed further T cell immune reconstitution to take place. With each round of tapering, the patient’s donor-derived cellular immunity matured, and the CMV episodes resolved.

At three years of follow-up, the outcome is striking. The patient is clinically well, with full donor chimerism, meaning that every measurable hematopoietic cell in his blood now originates from the donor’s stem cells. His liver function is stable, a testament to the success of the sequential transplant strategy. Most remarkably, his immune recovery has been sufficient to allow discontinuation of the lifelong immunoglobulin replacement therapy that XHIM patients typically require, indicating that his donor-derived B cells, now receiving proper CD40 ligand signals from functional donor T cells, are producing their own antibodies of the correct classes. In effect, the two transplants together replaced both the cellular and the humoral arms of his immune system, and the liver transplant replaced the organ that the defective immune system had destroyed.

The authors draw several lessons from this course that extend beyond the single patient. First, the case reinforces the argument for early HSCT in XHIM, before Cryptosporidium-associated liver disease becomes irreversible, because the window in which stem cell transplantation can be performed safely closes as cholangiopathy advances. Second, it highlights the central role of immune reconstitution in controlling opportunistic infections, with both cryptosporidiosis and CMV reactivation resolving only as donor T cells recovered and immunosuppression was withdrawn. Third, it suggests that extended letermovir prophylaxis may have a useful role in high-risk liver transplant recipients, a population in whom the drug’s evidence base is still being defined, and that clinicians should anticipate late CMV reactivation when prophylaxis is stopped before immune recovery is complete. For a disease as rare as XHIM, individual cases carry disproportionate weight, and this one, documented with open access and full transparency, adds a valuable data point to the small but growing literature on managing combined immune and solid organ transplantation in the era of targeted antiviral prophylaxis.

Subject of Research: Sequential hematopoietic stem cell and liver transplantation with letermovir CMV prophylaxis in X-linked hyper-IgM syndrome

Article Title: Sequential transplantation of allogeneic hematopoietic stem cells and liver in x-linked hyper-IgM syndrome: the role of CMV prophylaxis with letermovir

Article References: Murgia, D., Algarotti, A., Micò, M. C., D’Antiga, L., Luca, M., Del Carro, F., Lussana, F., Rambaldi, A., & Grassi, A. (2026). Sequential transplantation of allogeneic hematopoietic stem cells and liver in x-linked hyper-IgM syndrome: the role of CMV prophylaxis with letermovir. Annals of Hematology. https://doi.org/10.1007/s00277-026-07261-0

Image Credits: AI Generated

DOI: 10.1007/s00277-026-07261-0

Keywords: X-linked hyper-IgM syndrome, CD40 ligand deficiency, hematopoietic stem cell transplantation, liver transplantation, sclerosing cholangitis, Cryptosporidium parvum, cytomegalovirus, letermovir, immune reconstitution, donor chimerism, inborn errors of immunity, CMV prophylaxis

The team, led by Carl C. Crodel and Inken Hilgendorf, enrolled 114 patients between July and September 2022 and followed them up one year later. The cohort had a median age of 62 years, with ages ranging from 27 to 70, and included 55 women, or 48.2 percent of participants. Rather than relying solely on hospital records, the investigators combined retrospective chart review with a questionnaire that captured each patient’s vaccination status, any side effects experienced, and the course of any COVID-19 illness that occurred. This dual approach allowed them to assess not just laboratory measures of immunity but also the real-world tolerability of vaccination in a group whose immune systems are still rebuilding after transplantation.

Vaccine uptake in the cohort was high but not universal. Overall, 89.4 percent of patients had received at least two doses of a SARS-CoV-2 vaccine, and 66.7 percent had completed three vaccinations. A notable minority, 10.5 percent, refused vaccination altogether, a finding that underscores lingering hesitancy even among patients at elevated risk of severe disease. The mRNA vaccines dominated the vaccination landscape in this cohort, consistent with their widespread use across Germany during the pandemic. Because mRNA vaccines deliver the genetic instructions for the viral spike protein directly into host cells, they depend on the recipient’s own cellular machinery to produce antigen and on intact antigen-presenting cell function to prime T cells, both of which can be compromised in the months following transplantation.

The central immunological finding was encouraging. Most patients responded to vaccination, with 81.8 percent reaching detectable SARS-CoV-2 spike IgG titers after the second dose and 96.1 percent achieving seroconversion after the third. The spike protein, the surface molecule the virus uses to enter cells via the ACE2 receptor, is the principal target of neutralizing antibodies induced by all currently licensed vaccines, so anti-spike IgG levels serve as a widely used proxy for protective humoral immunity. The jump in response rates between the second and third doses suggests that a two-dose primary series is insufficient for many transplant recipients, and that a booster dose plays a genuine immunological role rather than being merely a formality.

One of the most clinically actionable results concerns timing. Patients who were vaccinated within 24 months of their transplant had significantly lower anti-spike IgG levels than those vaccinated later, a difference that reached statistical significance with a p-value of 0.017. This finding aligns with the known kinetics of immune reconstitution after allogeneic transplantation, in which B cell recovery and the re-establishment of functional B cell repertoires can take one to two years or longer. During this window, newly generated B cells are still learning to respond to new antigens, and the donor-derived immune system may not yet have fully replaced the recipient’s lymphocytes. Delaying vaccination, when clinically feasible, may therefore allow the immune system to mature enough to generate a stronger antibody response.

Safety data from the study were similarly reassuring. The most common side effect was pain at the injection site, reported by 34 percent of patients, followed by limb pain in 17 percent and swelling in 14 percent. These rates are broadly comparable to those seen in the general population and in other immunocompromised groups, and no alarming safety signals emerged. For clinicians counseling transplant recipients who may worry that vaccination could trigger graft-versus-host disease flares or other complications, these data provide a concrete evidence base for recommending vaccination as feasible and well tolerated. The authors concluded that vaccination in this population is both safe and effective, with the timing of administration relative to transplantation emerging as the key modifiable factor influencing immune response.

The study’s design has both strengths and limitations worth noting. By combining hospital records with patient questionnaires, the investigators captured a fuller picture of the vaccination experience than either source alone would provide, including self-reported side effects that might never appear in clinical documentation. The one-year follow-up also allowed assessment of longer-term outcomes rather than just immediate post-vaccination antibody titers. On the other hand, the cohort size of 114 patients, while respectable for a single-center transplant study, limits the statistical power to detect subtle subgroup effects, such as differences by donor type, conditioning regimen, or the degree of immunosuppression. The observational design also means that the association between vaccination timing and antibody levels, however biologically plausible, cannot be taken as proof of causation without randomized or prospective confirmation.

The findings arrive at a time when COVID-19 vaccination policy for immunocompromised populations continues to evolve. Many national guidelines already recommend additional vaccine doses for severely immunocompromised individuals, and this study provides direct evidence supporting that approach specifically for allogeneic transplant recipients. The near-universal seroconversion after three doses, reaching 96.1 percent, argues for ensuring that transplant recipients complete at least a three-dose series, while the timing effect suggests that clinicians and patients may reasonably weigh the benefits of earlier protection against the prospect of a stronger response if vaccination can be deferred until more than two years after transplantation. In practice, the risk of SARS-CoV-2 exposure during the waiting period will often tip the balance toward earlier vaccination, but the study gives clinicians a quantitative basis for that conversation.

Beyond its immediate clinical implications, the study contributes to a broader understanding of how the reconstructed immune system of a transplant recipient handles novel antigens. Allogeneic transplantation effectively resets the adaptive immune system, replacing it with donor-derived lymphocytes that must re-educate themselves in a new host environment. How quickly this new immune system can respond to vaccination reflects the pace of thymic output, B cell lymphopoiesis, and the establishment of functional immune cell communication. The Jena team’s observation that responses improve with time since transplant and with additional doses fits neatly into this framework and suggests that the same principles may apply to other vaccines, from influenza to newer respiratory syncytial virus immunizations, in this growing population of long-term transplant survivors.

As the number of allogeneic stem cell transplant survivors continues to grow worldwide, evidence-based vaccination strategies tailored to their unique immunology become increasingly important. This study, conducted without external funding and published open access, adds a valuable European dataset to the literature, confirming that mRNA vaccination against SARS-CoV-2 is feasible, well tolerated, and largely effective in transplant recipients, while highlighting that the third dose and the interval since transplantation are the factors that matter most. For the patients themselves, the message is one of cautious optimism: their rebuilt immune systems can indeed learn to recognize and respond to a virus they had never encountered, provided the vaccine is given the time and the doses it needs to do its work.

Subject of Research: Long-term humoral immune response and safety of SARS-CoV-2 mRNA vaccination in allogeneic haematopoietic stem cell transplant recipients

Article Title: Longer-term response to SARS-CoV-2 vaccination after allogeneic blood stem cell transplantation

Article References: Crodel, C. C., Gork, L., Göpel, W., Linke, P., Sinn, K., Miethke, J., Hochhaus, A., & Hilgendorf, I. (2026). Longer-term response to SARS-CoV-2 vaccination after allogeneic blood stem cell transplantation. Journal of Cancer Research and Clinical Oncology. https://doi.org/10.1007/s00432-026-06632-4

Image Credits: AI Generated

DOI: 10.1007/s00432-026-06632-4

Keywords: allogeneic stem cell transplantation, SARS-CoV-2, vaccination, mRNA vaccines, antibody response, immunogenicity, immunocompromised patients, COVID-19, immune reconstitution, booster dose, haematology, oncology

The study, known as SPIZ — short for the German phrase describing cross-sector care for patients with hematological diseases following innovative cell therapy — is a randomized controlled trial led from University Hospital Carl Gustav Carus at TUD Dresden University of Technology, with participating centers in Dresden, Leipzig and Chemnitz. Its protocol, published in the Annals of Hematology, describes a comprehensive post-treatment care program built on an interdisciplinary, digitally supported, cross-regional and cross-sectoral model. Rather than treating the hospital, the community hematologist and the patient’s home as separate silos, SPIZ attempts to weave them into a single continuum of care, with technology acting as the connective tissue.

The clinical rationale is stark. Both allogeneic stem cell transplantation and CAR T-cell therapy are associated with substantial morbidity, high healthcare costs and a considerable risk of severe complications, including death. Patients face non-relapse mortality driven by infections, graft-versus-host disease and secondary organ dysfunction, often surfacing weeks or months after they have left the transplant unit. Current aftercare, the authors note, is insufficiently standardized and still delivered largely through in-person, non-integrated processes. For patients living far from specialized centers — a common situation in a country where cellular therapy is concentrated in a limited number of hospitals — this means long journeys for routine monitoring, delayed recognition of deteriorating symptoms and a heavy coordination burden placed on patients and families who are often least equipped to carry it.

SPIZ’s answer is a care model with human and digital components working in tandem. Each patient in the intervention arm is supported by dedicated case managers who coordinate care across institutional boundaries, and by oncology nurses who conduct home visits. Layered on top of this personal infrastructure is a digital monitoring system: patients report vital signs and symptoms through a mobile application, enabling continuous, patient-reported surveillance between clinical encounters. Video consultations replace some travel-intensive check-ins, and virtual case conferences bring community-based hematologists into direct contact with the specialists at the transplant and cellular therapy centers, so that treatment decisions are made with the full picture rather than through slow, paper-based referrals.

The digital architecture is more than a convenience feature. Patient-reported outcome monitoring has emerged in recent years as a powerful tool in oncology, with studies in other cancer settings showing that systematic symptom tracking can catch complications earlier and, in some cases, improve survival. By pairing app-based symptom and vital sign reporting with professional case management and home nursing, SPIZ essentially extends the vigilance of the transplant ward into the patient’s living room. The model also draws on lessons from earlier eHealth initiatives in the transplant field, including the SMILe program, which explored how electronic health tools can support patients through the risky early phase after stem cell transplantation.

Evaluation of the intervention is deliberately two-pronged. On the quantitative side, the trial tracks hard clinical endpoints, including mortality and rehospitalization rates, alongside measures of quality of life assessed with instruments from the European Organization for Research and Treatment of Cancer and patient satisfaction with cancer care. On the qualitative side, semi-structured interviews probe how patients and providers experience the model — what works, what feels burdensome and where the digital tools help or hinder. This mixed-methods design reflects a growing recognition in implementation science that a care model can only spread if it is not only effective but also acceptable to the people who must live and work inside it.

The scale and pace of the trial are notable. After ethics approvals were secured, the three study centers were successfully initiated in 2024, and the trial was registered in the German Clinical Trials Register in January 2025. By January 2026, recruitment was complete: a total of 306 patients had been enrolled and randomized in a 1:1 ratio to receive either the SPIZ intervention or routine care. That pace — filling a complex, multi-center randomized trial of a care-model intervention in roughly two years — speaks both to the urgency of the unmet need and to the engagement of the patient community, which the investigators explicitly thank for their trust and contribution.

What happens next could have consequences well beyond Saxony. SPIZ is funded by the Innovation Fund of the Federal Joint Committee, the German body known as the G-BA that evaluates and steers healthcare provision in the statutory system, with administrative support from the health insurer AOK PLUS, which helped develop a selective contract for the model. This positioning matters: a positive evaluation could facilitate the integration of the care model into routine clinical practice across Germany, converting a research protocol into standard care. In other words, the trial is designed not merely to generate a publication but to inform a policy decision about how aftercare for cellular therapy patients should be organized and reimbursed nationwide.

The study also arrives at a moment when the population needing such care is expanding rapidly. CAR T-cell therapy has moved from experimental novelty to established treatment for selected hematologic malignancies, and transplant activity continues to grow, which means the number of survivors navigating the fragile post-treatment period is rising year by year. Health systems that were built around episodic, in-person hospital care are straining to provide the continuous, specialized surveillance these patients require. If SPIZ demonstrates that a digitally supported, cross-sectoral model reduces deaths and readmissions while improving quality of life, it would offer one of the clearest templates yet for how oncology systems can adapt — pairing the extraordinary power of cellular therapies with an aftercare infrastructure worthy of them.

For now, the patients have been randomized, the data are accumulating, and the hematology community is watching. The protocol paper itself makes no efficacy claims; it lays out the rationale, the architecture and the endpoints of an experiment still in progress. But its publication marks a shift in how the field frames the problem: survival after cellular therapy is no longer treated as an individual patient’s private challenge of coordination and travel, but as a system-level design question that can be tested, measured and — if the evidence holds — fixed at scale.

Subject of Research: A randomized controlled trial of digitally supported cross-sectoral aftercare for patients following allogeneic hematopoietic cell transplantation and CAR T-cell therapy

Article Title: The SPIZ study: rationale and protocol of a randomized controlled trial to optimize interdisciplinary care of patients following cellular therapy through a digitally supported, cross-regional and cross-sectoral care model

Article References: Schneider, M. M. K., Müller, G., Herbst, S., Slesaczeck, J., Schmädig, R., Schmidt, F., Illmer, T., Leppla, L., Valenta, S., De Geest, S., Teynor, A., Wolfien, M., Ernst, A., Bischof, L., Schmitt, J., Hänel, M., Metzeler, K. H., Platzbecker, U., Vučinić, V., … Egger-Heidrich, K. (2026). The SPIZ study: rationale and protocol of a randomized controlled trial to optimize interdisciplinary care of patients following cellular therapy through a digitally supported, cross-regional and cross-sectoral care model. Annals of Hematology, 105(10), Article 429. https://doi.org/10.1007/s00277-026-07290-9

Image Credits: AI Generated

DOI: 10.1007/s00277-026-07290-9

Keywords: allogeneic hematopoietic cell transplantation, CAR T-cell therapy, post-treatment care, digital health, randomized controlled trial, patient-reported outcomes, telemedicine, case management, graft-versus-host disease, hematologic malignancies, health services research, Germany

The study, published in eClinicalMedicine, brought together 111 adults with chronic disseminated candidiasis from 19 countries, diagnosed between January 2007 and December 2025. The condition, also known as hepatosplenic candidiasis, typically strikes patients with blood cancers such as acute myeloid leukaemia as their white blood cell counts recover after prolonged chemotherapy-induced neutropenia. It produces persistent fever, abdominal pain, cholestasis and characteristic abscesses in the liver and spleen, and it can force delays in cancer treatment that may ultimately matter more than the infection itself.

Almost all patients in the cohort had an underlying haematological malignancy. Acute myeloid leukaemia accounted for 48.6 percent of cases and acute lymphoblastic leukaemia for 24.7 percent, with lymphoma making up a further 15.6 percent. Notably, 24.8 percent of patients developed the infection despite receiving systemic antifungal prophylaxis in the days before diagnosis, so-called breakthrough disease, a figure that underscores the limits of current preventive strategies in the era of widespread mould-active azole prophylaxis.

The researchers applied a sophisticated statistical approach rarely used in this field: marginal structural models with inverse probability of treatment weighting, designed to account for time-varying confounders such as neutropenia and corticosteroid exposure that shift over the course of illness and can distort simple treatment comparisons. After this adjustment, neither the class of first-line antifungal, whether echinocandins, liposomal amphotericin B or azoles, nor the choice between fluconazole and other azoles for long-term oral step-down therapy was significantly associated with treatment response or overall survival.

This is a striking result given that international guidelines currently recommend echinocandins or liposomal amphotericin B as initial therapy, followed by an oral azole. Echinocandins were indeed the most common first-line choice in the cohort, used in 58.6 percent of patients, reflecting alignment with contemporary guidance. But the new data suggest clinicians may have greater flexibility than guidelines imply, particularly for patients with prior azole exposure or resistant organisms, where alternatives to fluconazole have previously rested on thin evidence.

Perhaps the most practice-changing observation concerns treatment duration. The median total course of targeted antifungal therapy was 107 days, substantially shorter than the four to seven months reported in earlier cohorts, and no relapses were documented after treatment was stopped during a median post-discontinuation follow-up of 92 days. Because conventional CT abnormalities can persist for many months after the infection has been controlled, with resolution rates of only 30 to 34 percent at three months in prior studies, the findings support the idea that extending therapy until complete radiological resolution may be unnecessary in selected patients.

Advanced imaging may hold the key to individualising that decision. Positron emission tomography combined with CT was performed in 26.1 percent of patients, and in 12 of them, regression of PET/CT findings was explicitly cited as the reason for stopping antifungal therapy. These patients had markedly longer treatment courses than those without PET-guided decisions, a median of 219 versus 88 days. The results complement the earlier French CANHPARI pilot study, which suggested that PET/CT normalisation at three months may better reflect resolution of active inflammation than conventional imaging, and they point toward PET/CT-guided assessment as a promising tool for distinguishing residual infection from immune reconstitution inflammatory syndrome, the paradoxical worsening that occurs as neutrophils recover.

The study also documented under-recognised manifestations of the disease. Nine patients showed central nervous system involvement, with multifocal punctate or ring-enhancing lesions on neuroimaging and, in some cases, positive cerebrospinal fluid beta-D-glucan testing. Skin and soft tissue involvement occurred in nine patients, six of whom had Candida tropicalis infection, a species known for cutaneous dissemination. The authors suggest that clinicians should consider CNS imaging in patients with neurological symptoms or refractory disease, since cerebral spread may be more common than previously appreciated.

Microbiological findings carried their own geographic and therapeutic signals. Candida albicans accounted for 32.4 percent of identified isolates and C. tropicalis for 24.3 percent, with the latter clustering markedly in Taiwan and Colombia. Fluconazole resistance was found in 11 isolates and was far more frequent in C. tropicalis than in other species, affecting 29.6 percent versus 3.6 percent, and nearly two-thirds of resistant cases occurred in the context of breakthrough infection. Yet resistance did not translate into worse survival, and beta-D-glucan, a fungal cell-wall marker measured at baseline in 35 patients, was positive in 88.6 percent, suggesting it may serve as a useful diagnostic adjunct.

Ultimately, the numbers tell a story about host biology rather than pharmacology. Only 4.5 percent of deaths were attributable to the fungal infection itself, even though all-cause mortality reached 33.3 percent, and patients with breakthrough disease actually survived more often than those without, likely because their underlying cancers were in a more favourable state. The authors caution that their comparative treatment analyses were exploratory and not powered to exclude clinically meaningful differences, and they call for prospective studies incorporating immune biomarkers such as cytokine profiles and Candida-specific T-cell responses alongside PET/CT. But for a disease that has been managed largely by tradition and caution, the message is clear: immune recovery, not drug selection, may be the true engine of cure, and shorter, individually tailored treatment could spare vulnerable patients months of toxicity, cost and delayed cancer therapy.

Subject of Research: Treatment strategies and outcomes of chronic disseminated candidiasis in patients with haematological malignancies in the era of antifungal prophylaxis

Article Title: Treatment and outcome of chronic disseminated candidiasis in the era of antifungal prophylaxis: a retrospective multicentre cohort of 111 patients

Article References: Reinhold, I., Ramirez-Sanchez, I. C., Chen, P.-Y., Chen, Y.-C., Dhariwal, A., Lambourne, J., Agrawal, S., Bastida, M., Gudiol, C., Alfandari, S., Di Pilla, A., Khostelidi, S., Aguilar-Zapata, D., Barac, A., Cipriano, A., Ehrlich, S., Grothe, J., Illarramendi, J., Jennrich, S., … Zager, L. (2026). Treatment and outcome of chronic disseminated candidiasis in the era of antifungal prophylaxis: a retrospective multicentre cohort of 111 patients. eClinicalMedicine, 100, Article 104194. https://doi.org/10.1016/j.eclinm.2026.104194

Image Credits: AI Generated

DOI: 10.1016/j.eclinm.2026.104194

Keywords: chronic disseminated candidiasis, hepatosplenic candidiasis, haematological malignancies, antifungal therapy, echinocandins, azoles, Candida tropicalis, fluconazole resistance, PET/CT imaging, immune reconstitution, neutropenia, beta-D-glucan

The report, published as an open-access case series in Annals of Hematology by a team from the Department of Paediatric Haematology and Bone Marrow Transplant at Manchester University NHS Foundation Trust, describes three children who developed non-haematological alloimmune disease after transplantation. Led by corresponding author Hilary Cahill, with co-authors including Ramya Hanasoge-Nataraj, Oana Mirci-Danicar, Omima Mustafa, Robert F. Wynn and Srividhya Senthil, the team emphasises that although these manifestations are rare, they contribute significant morbidity and mortality in paediatric transplant recipients. The literature to date consists almost entirely of isolated case reports of individual patients, which makes pattern recognition difficult and leaves clinicians without a clear framework for diagnosis or treatment. By presenting three cases together, the Manchester group demonstrates the remarkable breadth of alloimmunity that can emerge in children after a transplant, ranging from disease confined to a single organ to a systemic illness so severe that it required a second haematopoietic stem cell transplant.

To understand why these complications matter, it helps to consider what happens immunologically after a stem cell transplant. The donor’s stem cells gradually rebuild the recipient’s immune system, a process known as immune reconstitution. In theory, the newly generated donor-derived immune cells should learn tolerance to the recipient’s tissues. In practice, particularly when the donor is unrelated or only partially matched, the developing immune repertoire can include cells that react against recipient antigens. When these self-perpetuating donor cells attack host tissues, the result can look strikingly like an autoimmune disease in a genetically susceptible child: organ-specific inflammation, autoantibody-like phenomena and chronic damage that does not respond to the standard immunosuppressive regimens used for graft-versus-host disease. Because these syndromes are rare and their presentations overlap with infections, drug toxicities and other post-transplant complications, diagnosis is often delayed, sometimes for months, during which time irreversible organ injury can accumulate.

The Manchester cases illustrate this diagnostic challenge vividly. In one of the children, the alloimmune process was confined to a single organ, requiring targeted local and systemic therapy to bring the inflammatory attack under control. In another, the disease manifested in a different organ system entirely, underscoring that there is no single clinical picture that should alert clinicians to alloimmunity; instead, the unifying feature is a new inflammatory syndrome arising after engraftment that behaves like autoimmunity rather than infection or conventional graft-versus-host disease. The third case represents the most dramatic end of the spectrum: a widespread systemic alloimmune disease that proved refractory to multiple lines of therapy and ultimately necessitated a second haematopoietic stem cell transplant as the only way to reset the aberrant immune system. That such an intervention was required highlights both the severity these conditions can reach and the fact that, in the most severe cases, replacing the rogue immune system may be the definitive cure.

The authors stress that diagnosis is frequently the greatest hurdle. Symptoms can be nonspecific, and the differential diagnosis in a post-transplant child is broad, encompassing opportunistic infections, medication side effects, thrombotic microangiopathy, disease relapse and organ toxicity from prior chemotherapy or radiation. Distinguishing alloimmune injury from these mimics often requires tissue biopsies, specialist serology and careful correlation of clinical course with laboratory findings. In the published report, the team acknowledges the contribution of Dr Chinna Thambi Narayanan Sai Shalini from the Department of Pathology at Manchester University NHS Foundation Trust, who provided the renal biopsy images used in the manuscript, an indication of the multi-disciplinary work-up that these cases demand. Verbal informed consent was obtained from the children’s legal guardians, and the authors declare no competing interests.

Treatment, too, is far from standardised. Because the evidence base consists of scattered case reports, clinicians resort to a patchwork of approaches: escalation of corticosteroids, calcineurin inhibitors and other broad immunosuppressants, followed by biological agents targeting specific immune pathways when first-line measures fail. The Manchester series notes that these conditions often require multiple lines of therapy before remission is achieved, and in the systemic case, even aggressive sequential immunosuppression could not substitute for eliminating the dysregulated immune system itself. This therapeutic pessimism is precisely why the authors argue for earlier consideration of non-haematologic alloimmune manifestations. The earlier the diagnosis is made, the earlier targeted therapy can begin, and the greater the chance of preventing permanent organ damage or the need for heroic interventions such as a second transplant.

For the wider transplant community, the significance of this series lies less in its size, three patients, than in its conceptual framing. It consolidates a scattered literature into a coherent message: alloimmunity after transplantation exists on a spectrum, and its non-haematologic manifestations deserve recognition as a distinct clinical entity rather than being dismissed as atypical graft-versus-host disease or unexplained organ dysfunction. Paediatric patients may be particularly vulnerable because their immune systems are still developing at the time of transplant, and because the donor-derived cells that repopulate them will circulate for decades. A child cured of leukaemia at age five who then develops a chronic alloimmune attack on the kidneys, lungs, liver or endocrine organs faces a lifetime of secondary morbidity that families and clinicians may not have anticipated when consenting to the transplant.

The report also carries implications for how transplant centres counsel families and design follow-up. Parents are routinely warned about infection, graft failure and graft-versus-host disease, but alloimmune single-organ and systemic syndromes are rarely part of the conversation. Building awareness among paediatric haematologists, transplant physicians and the allied specialties that manage post-transplant organ complications could shorten the diagnostic odyssey for future patients. The authors suggest that early consideration of these manifestations, supported by a low threshold for specialist referral and tissue diagnosis, is essential to facilitate appropriate diagnosis and initiation of targeted therapies to improve patient outcomes. In an era when biologics can precisely neutralise individual cytokines and immune cell populations, the difference between a late, organ-destroying diagnosis and an early, targeted intervention may be substantial.

Published on 7 September 2026 after being received on 16 December 2025 and accepted on 19 August 2026, the article is available under a Creative Commons Attribution 4.0 licence, reflecting the growing movement toward open access to clinically relevant research. The study received no external funding. As a case series, it cannot establish incidence rates or identify risk factors definitively; those questions will require multi-centre registries and larger cohorts. But as an early contribution to that effort, it provides a valuable anchor: concrete, well-documented examples of the clinical spectrum that non-haematologic alloimmunity can produce in children after stem cell transplantation, documented at a major UK transplant centre with the pathological and laboratory detail that other clinicians can use as a reference point.

For families facing a paediatric stem cell transplant, the message is one of vigilance rather than alarm. These complications remain rare, and most transplants proceed without them. But the Manchester experience demonstrates that when a child develops unexplained organ inflammation or systemic inflammatory disease after engraftment, alloimmunity belongs on the differential diagnosis from the outset. Recognising the possibility early, pursuing the appropriate investigations and escalating to targeted therapy promptly may spare children months of debility and, in the most severe cases, the trauma of a second transplant. In transplant medicine, where the cure for one disease can inadvertently seed another, the cases reported here are a reminder that the new immune system is a powerful ally that must be watched as carefully as it is welcomed.

Subject of Research: Non-haematologic alloimmune manifestations following paediatric haematopoietic stem cell transplantation

Article Title: Non-haematologic alloimmune manifestations following paediatric haematopoietic stem cell transplantation: a case series

Article References: Cahill, H., Hanasoge-Nataraj, R., Mirci-Danicar, O., Mustafa, O., F. Wynn, R., & Senthil, S. (2026). Non-haematologic alloimmune manifestations following paediatric haematopoietic stem cell transplantation: a case series. Annals of Hematology. https://doi.org/10.1007/s00277-026-07252-1

Image Credits: AI Generated

DOI: 10.1007/s00277-026-07252-1

Keywords: haematopoietic stem cell transplantation, alloimmunity, paediatric transplant, graft-versus-host disease, immune reconstitution, autoimmune-like disease, organ inflammation, immunosuppression, second transplant, case series, Manchester, Annals of Hematology