RB-1355 is distinguished by its unique mechanism of action which centers on the use of a patient’s own macrophages, a type of immune cell often residing in the tumor milieu. These macrophages are extracted and then subjected to an ex vivo hyperactivation process using proprietary methodologies designed to induce a robust pro-inflammatory and immune-supportive phenotype. This reprogramming effectively converts macrophages from potentially tumor-promoting actors to powerful anti-tumor effectors. Upon reintroduction into the patient’s lesions via direct intratumoral injections, these engineered macrophages reshape the tumor microenvironment by igniting a cascade of immune responses that encompass activation of neoantigen-specific T cells and B cells, thereby orchestrating a comprehensive immune assault on lymphoma cells.

One of the most compelling advantages of RB-1355 therapy is the rapid manufacturing pipeline, which allows for treatment readiness in approximately one week. This expedited timeline stands in stark contrast to other cell therapies which often require extended preparation periods, thereby making RB-1355 a more accessible option that can be deployed in a timely manner. Additionally, the therapy circumvents the need for lymphodepleting chemotherapy, a common preconditioning regimen that can cause considerable toxicity. This attribute not only enhances safety but also broadens the eligibility of patients who can receive the therapy irrespective of tumor mutational status, positioning RB-1355 as a versatile therapeutic across a spectrum of B-cell and T-cell lymphomas.

The initial clinical findings have been presented at the prestigious 2026 Tandem Meetings of the American Society for Transplantation and Cellular Therapy (ASTCT) and Center for International Blood and Marrow Transplant Research (CIBMTR), showcasing promising efficacy signals. Among thirteen heavily pretreated patients enrolled in the trial, two individuals with diffuse large B-cell lymphoma (DLBCL) achieved complete remission, notably including those who had previously failed CAR T cell therapy—a population with extremely limited treatment options. These responses, including durability beyond 100 days for one patient, underscore the potential of RB-1355 to address aggressive, refractory disease in a clinical setting.

In addition to complete remissions, partial responses were also observed in patients suffering from peripheral T-cell lymphoma and mycosis fungoides, malignancies traditionally resistant to standard therapies. This breadth of activity exemplifies RB-1355’s capacity to generate meaningful clinical benefit across heterogeneous lymphoma subtypes. Equally important is the favorable safety profile reported from the trial; no dose-limiting toxicities were encountered, and only three instances of low-grade adverse effects were noted, indicating that RB-1355 is not only efficacious but also well tolerated in a fragile patient population with limited alternatives.

From an immunological standpoint, the macrophage-centric approach of RB-1355 leverages the plasticity of these myeloid cells to break the immune tolerance often established in the tumor microenvironment. By instigating an inflammatory cascade, it promotes antigen presentation and stimulates both innate and adaptive immune components. This dual activation is critical for achieving sustained anti-lymphoma activity, given the complex immune evasion strategies employed by malignant lymphocytes. Furthermore, this method does not depend on the presence of specific actionable mutations in the lymphoma cells, enabling a broad-spectrum therapeutic effect that could redefine treatment algorithms for refractory lymphomas.

The potential implications for patients are profound. Historically, relapsed and refractory non-Hodgkin lymphoma cases have represented a therapeutic dead-end with limited durable options. RB-1355’s promising early results suggest it could fill this unmet need by offering a new avenue for disease control, especially for those who have exhausted conventional chemotherapy, targeted agents, and even advanced therapies like CAR T cells. The rapid preparation and administration of RB-1355 could also minimize delays in treatment initiation, a critical factor in managing aggressive lymphomas.

Current ongoing investigations aim to optimize RB-1355 through dose escalation and repeated treatment cycles to enhance the durability of responses and potentially increase remission rates. Researchers are also exploring synergistic combinations with other immunomodulatory agents to further amplify anti-lymphoma immunity. As the body of evidence grows, RB-1355 may represent the next frontier in cell therapy by expanding the types of immune cells engineered and by circumventing the limitations associated with existing therapies that primarily target T cells.

Moreover, the development of RB-1355 reflects a growing appreciation in oncology of the tumor microenvironment’s role in cancer progression and response to therapy. Unlike approaches that solely target malignant cells, therapies like RB-1355 aim to re-educate the immune ecosystem surrounding the tumor, creating an inhospitable environment for cancer cell survival. Such strategies could herald a new class of treatments for hematologic malignancies and potentially solid tumors, enabling a more holistic immune-based eradication of cancer.

The involvement of BobcatBio in supporting this research illustrates the critical importance of collaboration between academic institutions and biotechnology enterprises in translating cutting-edge science into clinical realities. The rapid translation from bench to bedside exemplifies how innovations in cellular manufacturing and immune engineering can swiftly impact patient care in fields where therapeutic needs remain urgent.

In conclusion, RB-1355 represents an innovative and promising cell therapy that reshapes the landscape of non-Hodgkin lymphoma treatment by utilizing hyperactivated macrophages to generate a multi-dimensional immune response without the need for conventional preconditioning regimens. Early clinical data show encouraging safety and efficacy profiles in patients with relapsed or refractory disease, including those unresponsive to CAR T therapies. Continued clinical development will delineate its role within the expanding arsenal against aggressive lymphomas, potentially offering hope to a patient population with critical unmet needs.

Subject of Research: Novel cell therapy RB-1355 for relapsed and refractory non-Hodgkin lymphoma

Article Title: RB-1355: A Macrophage-Based Cell Therapy Revolutionizing Treatment of Refractory Non-Hodgkin Lymphomas

News Publication Date: 2026 (Date of presentation at ASTCT/CIBMTR 2026 Tandem Meetings)

Web References:

• MD Anderson Non-Hodgkin Lymphoma Overview: https://www.mdanderson.org/cancer-types/non-hodgkin-lymphoma.html
• CAR T Cell Therapy at MD Anderson: https://www.mdanderson.org/treatment-options/car-t-cell-therapy.html
• Paolo Strati, M.D. Profile: https://faculty.mdanderson.org/profiles/paolo_strati.html
• ASTCT/CIBMTR Tandem Meetings 2026 Program: https://www.tandemmeetings.com/
• Full Abstract: https://tandem.virtual-meeting.org/programme/presentation/677607

Keywords:
Cell therapies, macrophage immunotherapy, non-Hodgkin lymphoma, relapsed lymphoma, refractory lymphoma, diffuse large B-cell lymphoma, peripheral T-cell lymphoma, mycosis fungoides, tumor microenvironment, immunotherapy, RB-1355, novel cancer treatments

Aging is invariably accompanied by a decline in the efficacy of the immune response, often referred to as immunosenescence. However, the adaptive immune system’s deterioration transcends mere decline in functionality; it adopts a dualistic role with profound implications. On the one hand, the system’s waning capacity impairs immunosurveillance, the critical process by which the body identifies and clears damaged or senescent cells. On the other hand, aging adaptive immune cells themselves become culprits by often assuming pro-inflammatory and autoaggressive phenotypes that exacerbate tissue damage and chronic inflammation—a hallmark of aging known as inflammaging.

One of the most intriguing revelations from Delgado-Pulido and colleagues is the concept that the adaptive immune system’s age-related changes contribute to the aging process through two fundamentally distinct mechanisms. The first mechanism is the failure of immune surveillance. As adaptive immune cells, particularly lymphocytes, lose their potency over time, they become less effective at detecting and eliminating dysfunctional cells. These damaged or senescent cells accumulate within tissues, secreting pro-inflammatory factors that disrupt local homeostasis and impair regenerative processes. The consequence is a vicious cycle where tissue integrity deteriorates, function declines, and ultimately, age-related pathologies emerge.

Of particular importance is the role of the gut, a critical organ system where immune-tissue homeostasis is tightly regulated by a complex interplay between the adaptive immune system and the microbiota. The gut mucosa represents a frontline of interaction between the host immune system and trillions of microorganisms. In youth, adaptive lymphocytes maintain a careful balance, promoting tolerance to beneficial microbes while mounting defenses against pathogens. However, with aging, this immune-microbiota harmony is lost. Impaired immune surveillance in the gut leads to dysbiosis, disruption of barrier integrity, and excessive inflammation, which not only compromises gut health but has systemic repercussions on aging and metabolic regulation.

The second mechanism highlighted by the researchers involves the transformation of adaptive immune cells themselves into sources of chronic inflammation and tissue damage. Aging lymphocytes often acquire what can be described as a “rogue” phenotype—characterized by increased secretion of pro-inflammatory cytokines and autoantibodies, as well as altered interactions with other immune and non-immune cells. These phenotypic changes do not simply reflect a loss of function but represent an active pathogenic process whereby the adaptive immune system drives tissue senescence, fibrosis, and degeneration. This shift from a healing to harmful role fuels inflammaging, which is increasingly recognized as a critical factor in common age-related diseases including neurodegeneration, cardiovascular disease, and metabolic disorders.

The interplay between the immune system and cellular senescence is particularly noteworthy. Cellular senescence—where cells lose the ability to divide and secrete inflammatory and tissue-damaging factors—has dual roles, acting as a tumor suppressive mechanism in youth but becoming maladaptive in aging. Adaptive immune cells are essential in clearing senescent cells under normal conditions, but when their surveillance capacity diminishes, senescent cell accumulation spikes. Worse yet, the pro-inflammatory lymphocyte phenotypes seen in aged individuals may further induce senescence in neighboring cells, amplifying tissue dysfunction in a feed-forward loop.

At the molecular level, several factors underpin these age-related immune changes. Chronic antigenic stimulation, metabolic alterations, telomere attrition, and altered signaling pathways all contribute to the declining quality and changing function of adaptive lymphocytes. For example, T cells show reduced proliferative capacity and changes in surface marker expression, such as PD-1 and CTLA-4, which modulate their activity and exhaustion status. B cells also undergo phenotype shifts, producing more autoantibodies and less protective antibody diversity. These cellular and molecular alterations provide mechanistic insights into how the adaptive immune system’s recalibration with age both compromises defense and accelerates pathology.

Importantly, this model of immune dysregulation in aging opens exciting opportunities for therapeutic intervention. By better understanding the specific changes that drive immune dysfunction and pathogenicity, researchers envision strategies to rejuvenate immune surveillance capacities or to specifically suppress the harmful, pro-inflammatory phenotypes of aged lymphocytes. Such approaches could profoundly improve tissue regeneration, restore homeostasis, and reduce inflammaging, ultimately promoting healthier aging and potentially extending health span.

One avenue under active investigation is the modulation of immune checkpoint pathways and metabolic reprogramming of adaptive immune cells in aged individuals. Pharmacological agents or biologics that can reverse T cell exhaustion or reinvigorate their senescent cell clearance capabilities are promising. Similarly, targeting aberrant B cell responses may mitigate autoimmunity-related tissue damage. Another complementary approach might involve manipulating the gut microbiota or the gut-associated lymphoid tissue to restore the delicate immune-microbiota equilibrium for systemic benefits.

These insights also elevate the importance of personalized medicine in aging research. Since immune aging is influenced by genetics, environment, infection history, and lifestyle factors, interventions may need to be tailored to an individual’s unique immune landscape. Biomarkers reflecting adaptive immune cell status and inflammation profiles may guide the timing and type of immunomodulatory treatment, optimizing therapeutic outcomes while minimizing risks.

Moreover, this research challenges us to expand our perspective on the immune system beyond its canonical roles. Adaptive immunity is not a static, isolated network but a dynamic interface that shapes and is shaped by tissue physiology, microbial milieu, and systemic metabolic states. As this holistic view gains traction, it reshapes conventional paradigms of aging biology, inspiring novel hypotheses about how immune dysregulation intersects with other hallmarks of aging such as genomic instability, epigenetic alterations, and mitochondrial dysfunction.

Delgado-Pulido and collaborators also emphasize the bidirectional relationship between immune aging and inflammaging. Not only do aged lymphocytes promote a pro-inflammatory environment, but chronic, low-grade inflammation in tissues further drives immune cell dysfunction and senescence. This reciprocal interaction highlights the potential of combined anti-inflammatory and immune-enhancing therapies as a promising dual-pronged strategy in combating age-associated disorders.

Lastly, the translational implications of these findings are vast. Understanding the adaptive immune system’s reshaping could inform vaccine strategies for the elderly, improve outcomes in cancer immunotherapies, and provide insights into managing autoimmune diseases that disproportionately affect older adults. By shifting therapeutic goals from simply boosting immunity to refining immune quality and composition, medicine edges closer to interventions that support resilience and repair in the aging organism.

In summary, the work presented by Delgado-Pulido, Yousefzadeh, and Mittelbrunn transforms our understanding of the adaptive immune system’s complex journey through aging. Rather than serving solely as a defender, aged adaptive immunity emerges as a double-edged sword whose failings and malfunctions can accelerate tissue decline and systemic aging. This new framework propels immunology and aging biology into exciting frontiers, heralding a future where modulating immune system dynamics becomes a cornerstone of healthy longevity.

Subject of Research: Aging-related changes in the adaptive immune system and their impact on inflammaging, tissue homeostasis, and age-associated pathologies.

Article Title: Aging reshapes the adaptive immune system from healer to saboteur.

Article References:
Delgado-Pulido, S., Yousefzadeh, M.J. & Mittelbrunn, M. Aging reshapes the adaptive immune system from healer to saboteur. Nat Aging 5, 1393–1403 (2025). https://doi.org/10.1038/s43587-025-00906-1

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s43587-025-00906-1