The review, which synthesized gastric cancer-specific clinical and translational evidence from a structured PubMed search through late August 2026, arrives at a deliberately sobering conclusion. While the tumor microenvironment and gut microbiome together form a biologically plausible framework for understanding why checkpoint inhibitors fail, the authors caution that current evidence does not justify empiric microbiome-directed anticancer therapy in gastric cancer. In an era when probiotic supplements and fecal transplants are frequently touted as immune-boosting hacks, the paper is a reminder that rigorous clinical evidence lags far behind biological enthusiasm.

At the heart of the resistance problem is the tumor microenvironment itself, the cellular and molecular ecosystem surrounding cancer cells. The review details how cancer-associated fibroblasts, a heterogeneous population of stromal cells, can physically and immunologically wall off tumors from attacking T cells. Single-cell analyses have identified fibroblast clusters specifically linked to immunotherapy resistance across cancer types, and in gastric cancer, recent work has shown that fibroblast-macrophage crosstalk governs the response to immune checkpoint blockade in peritoneal metastases, one of the most aggressive manifestations of the disease. FAP-positive fibroblasts have also been implicated in skewing CD4-positive T cell polarization in ways that blunt anti-PD-1 therapy.

Myeloid cells add another layer of immunosuppression. Tumor-associated macrophages and other myeloid populations can secrete suppressive cytokines, present antigen poorly and recruit regulatory T cells that actively dampen antitumor immunity. The extracellular matrix they help remodel, together with tumor hypoxia and abnormal angiogenesis, creates physical barriers that prevent cytotoxic T cells from reaching cancer cells. Compounding all of this is T cell exhaustion, a state of progressive dysfunction in which chronically stimulated T cells lose their effector function and become unresponsive even to checkpoint blockade. The review emphasizes that these mechanisms are not independent; they converge to produce immune exclusion, where T cells remain stranded outside the tumor, or immune dysfunction, where T cells inside the tumor are simply paralyzed.

Gastric cancer presents a particularly complex version of this problem because of its molecular heterogeneity and its inflammatory origins. The Cancer Genome Atlas has defined distinct molecular subtypes of gastric adenocarcinoma, and decades of research into the precancerous cascade, from chronic gastritis through atrophy and intestinal metaplasia, show how inflammation shapes the immune landscape long before immunotherapy begins. Distinct immunosuppressive microenvironments have been documented in gastric cancers with peritoneal metastasis, helping explain why patients with this pattern of spread respond particularly poorly to checkpoint inhibitors.

Into this already hostile environment enters the gut microbiome, the collection of microbes whose influence on cancer immunotherapy burst into mainstream oncology in 2018. That year, three landmark papers in Science showed that the composition of gut bacteria predicted responses to anti-PD-1 therapy in melanoma and epithelial tumors, and that fecal microbiota transplantation could reverse resistance in mice. Subsequent studies identified specific organisms, such as Akkermansia muciniphila, associated with better outcomes in lung cancer patients treated with PD-1 blockade. The proposed mechanisms are diverse: microbial metabolites like short-chain fatty acids can modulate T cell activity, microbial antigens can cross-react with tumor antigens, and the overall diversity of the gut ecosystem appears to shape systemic immune tone.

But translating these findings to gastric cancer is fraught with difficulty, and the review is explicit about the evidentiary gaps. Most human data linking the microbiome to immunotherapy outcomes are retrospective, cross-sectional, or derived from non-gastric cancers such as melanoma, renal cell carcinoma and lung cancer. The stomach itself is a microbial habitat altered by acid suppression, Helicobacter pylori infection and prior gastric surgery, making the gut-stomach axis in these patients uniquely complicated. Cross-cohort studies in melanoma have already shown that microbiome signatures associated with immunotherapy response often fail to replicate across patient populations, a cautionary tale for any attempt to define a universal resistance-associated microbiome in gastric cancer.

Two classes of commonly used medications have emerged as potential modulators of the microbiome-immunotherapy axis: antibiotics and proton pump inhibitors. Multiple studies and meta-analyses have reported negative associations between antibiotic exposure and checkpoint inhibitor efficacy in renal cell carcinoma, lung cancer and gastrointestinal tumors, plausibly reflecting antibiotic-induced depletion of beneficial commensal bacteria. Proton pump inhibitors, which raise gastric pH and alter the gut microbial composition, have likewise been linked in several analyses to reduced immunotherapy benefit, including a 2025 study specifically showing reduced nivolumab efficacy in unresectable advanced gastric cancer. The review concludes that antibiotic stewardship and reassessment of unnecessary acid suppression are reasonable supportive measures for patients on checkpoint inhibitors, while stopping short of claiming causation, since confounding by indication and disease severity remains a persistent problem in observational data.

What about actively manipulating the microbiome to sensitize tumors to immunotherapy? The review examines the evidence and finds it promising but immature for gastric cancer. Defined live biotherapeutics have shown early signals, including a randomized phase 1 trial in metastatic renal cell carcinoma that tested nivolumab and ipilimumab with or without bacterial supplementation, and retrospective data suggesting a prognostic benefit of Clostridium butyricum MIYAIRI 588 combined with pembrolizumab in urothelial carcinoma. Preclinical work has even shown antitumor effects of this strain through enhanced release of TRAIL from neutrophils. Fecal microbiota transplantation, meanwhile, has produced striking case series in immunotherapy-refractory melanoma, with two 2021 Science papers documenting responses after transplant from responding donors, and a 2025 meta-analysis has begun to synthesize this literature. Yet none of these interventions has been validated in gastric cancer, and the review classifies routine probiotic supplementation, Clostridium butyricum MIYAIRI 588 for ICI sensitization and fecal microbiota transplantation as investigational in this disease. Diet adds yet another variable: a study in melanoma patients found that dietary fiber and probiotic use influenced the gut microbiome and immunotherapy response, suggesting that nutritional optimization may matter, though again the evidence in gastric cancer is indirect.

The authors close with a roadmap for future research that is as much about methodology as biology. They call for studies that integrate longitudinal exposures, serial profiling of the tumor microenvironment, stool metagenomics, medication use, nutritional status and clinical outcomes, rather than the single-timepoint snapshots that dominate the current literature. Only such integrated designs, they argue, can disentangle whether the microbiome genuinely drives resistance or merely correlates with it. For now, the practical takeaways for clinicians are modest but concrete: use antibiotics judiciously, question unnecessary proton pump inhibitor prescriptions, and optimize nutrition, while resisting the temptation to prescribe probiotics or fecal transplants outside of clinical trials. The tumor microenvironment-gut microbiome axis may well hold the key to overcoming immunotherapy resistance in gastric cancer, but as this review makes clear, the field must first prove that the key actually turns the lock.

Subject of Research: Tumor microenvironment and gut microbiome mechanisms of immune checkpoint inhibitor resistance in gastric cancer

Article Title: Tumor microenvironment and gut microbiome in immunotherapy resistance in gastric cancer: clinical questions, biological mechanisms, and evidence-based therapeutic perspectives

Article References: Sagawa, T., Hirakawa, M., Nagashima, H., & Fujikawa, K. (2026). Tumor microenvironment and gut microbiome in immunotherapy resistance in gastric cancer: clinical questions, biological mechanisms, and evidence-based therapeutic perspectives. Medical Oncology, 43(11), Article 308. https://doi.org/10.1007/s12032-026-03434-z

Image Credits: AI Generated

DOI: 10.1007/s12032-026-03434-z

Keywords: gastric cancer, immune checkpoint inhibitors, immunotherapy resistance, tumor microenvironment, gut microbiome, cancer-associated fibroblasts, T cell exhaustion, antibiotics, proton pump inhibitors, fecal microbiota transplantation, probiotics, microbiome modulation

The case is striking not only because of the dramatic recovery but also because of the therapeutic history that preceded it. The patient had been treated with a proton pump inhibitor, a class of acid-suppressing drugs used by millions of people worldwide for reflux and ulcer disease, as well as with metformin, the first-line medication for type 2 diabetes. Both drugs are increasingly recognized as causes of magnesium depletion. Proton pump inhibitors interfere with intestinal magnesium absorption, while metformin has been linked to urinary magnesium losses in patients with diabetes. The Belgian authors note that their patient had also experienced unexplained transient neurological deficits in the past, episodes that now appear, in retrospect, to have been heralds of the same underlying electrolyte disturbance.

Magnesium is the fourth most abundant cation in the body and the second most abundant inside cells, and its physiological reach is enormous. It serves as a cofactor for hundreds of enzymatic reactions, stabilizes the electrical gradients of excitable membranes, regulates calcium channels, and modulates the release of neurotransmitters at both central and peripheral synapses. Because roughly two thirds of body magnesium is stored in bone and only a tiny fraction circulates in the plasma, the serum level is an imperfect window into total body stores. This biochemical reality helps explain why hypomagnesemia is frequently overlooked: clinicians may assume that a normal-looking electrolyte panel excludes deficiency, or simply never order the measurement at all during the chaotic early minutes of a suspected stroke.

The neurological consequences of magnesium depletion are well documented in other contexts. Low magnesium lowers the seizure threshold, produces tremor, muscle cramps, and tetany, and can cause characteristic eye-movement abnormalities and ataxia. Severe cases have even produced reversible cerebellar syndrome with brain imaging showing swelling of the cerebellum, a phenomenon described in several case reports over the past decade. What has been far rarer in the literature is the attribution of focal deficits, weakness or speech disturbance confined to one side of the body in a pattern that strongly suggests a localized brain lesion, to magnesium deficiency alone. The Belgian team argues that this rarity is at least partly an artifact of under-testing rather than a true biological rarity.

The mechanisms by which magnesium depletion could produce focal symptoms are biologically plausible. Experimental work on cerebral penetrating arterioles has shown that magnesium promotes vasodilation in these small vessels, so its absence may impair the fine regulation of blood flow in deep brain regions. Magnesium also acts as a natural antagonist of the NMDA receptor, damping excitotoxic cascades that amplify injury during ischemia, and clinical studies in patients with aneurysmal subarachnoid hemorrhage have explored magnesium infusions as a protective agent during episodes of critical perfusion. In a deficient state, the loss of these protective functions could render vulnerable brain circuits transiently dysfunctional, producing deficits that mimic vascular occlusion but reverse when the electrolyte balance is restored.

Stroke mimics are far from a marginal concern in emergency neurology. Large registries of patients referred to stroke services have found that a substantial proportion of code-stroke activations ultimately receive a non-ischemic diagnosis, ranging from seizures and migraines to metabolic derangements and functional disorders. Distinguishing true stroke from mimic is one of the hardest tasks in acute medicine, because the cost of missing a real infarct is measured in dead brain tissue, while the cost of treating a mimic with thrombolytics includes potentially catastrophic bleeding. Imaging tools such as CT perfusion have improved this discrimination, but they depend on recognizing which metabolic conditions can distort the pictures they produce. A severe electrolyte abnormality that resolves with repletion belongs firmly on that list.

The literature review accompanying the Belgian case assembles the scattered evidence that severe hypomagnesemia can indeed present as an acute stroke. Earlier reports have described patients in emergency settings and in rehabilitation units whose hemiparesis and aphasia cleared after magnesium replacement, and a 2025 review in Neurological Sciences explicitly asked whether hypomagnesemia is a rare but overlooked stroke mimic. The pattern across these reports is consistent: the patients often carry risk factors for magnesium wasting, such as proton pump inhibitor use, diuretics, alcohol use, diabetes, or diarrhea, and their deficits improve as the serum level normalizes, a trajectory that would be unusual for a completed infarct. The authors of the new report emphasize that despite this documentation, magnesium levels are rarely measured during the acute phase of a suspected stroke.

Why does this gap persist? Part of the answer lies in the historical organization of emergency testing. A classic study from 1990 found that when serum magnesium was measured routinely rather than only when specifically requested, previously unrecognized hypomagnesemia was detected at a meaningful rate, suggesting that clinicians systematically underestimate its prevalence. Magnesium also interacts closely with potassium homeostasis, so refractory hypokalemia is a well-known clue to coexisting magnesium depletion, yet this teaching point competes with dozens of others in crowded emergency protocols. In the hyperacute stroke pathway, where every additional test is weighed against the clock, magnesium has simply never earned a place on the mandatory panel. The Belgian authors argue that the case they present, together with the accumulating literature, makes a compelling case for changing that practice.

The clinical implications are considerable. For patients on proton pump inhibitors and metformin, the combination seen in this case, the possibility of drug-induced magnesium wasting deserves explicit attention whenever neurological symptoms appear, particularly if the deficits fluctuate or if vascular imaging fails to show an occlusion. For stroke teams, the report suggests that a serum magnesium level, a cheap and rapid assay available in virtually every hospital laboratory, could be added to the initial workup of suspected stroke without meaningfully delaying treatment. Identifying a reversible metabolic mimic before administering thrombolytic drugs would spare patients an unnecessary bleeding risk, and correcting the deficiency could resolve deficits that would otherwise trigger days of admission, monitoring, and secondary stroke workup aimed at a vascular cause that does not exist.

The Belgian case report, approved by the ethics committee of the Hopital Civil Marie Curie in Charleroi and published with the patient’s informed consent, is unlikely to overturn stroke care on its own. But it adds a vivid data point to a quiet shift in neurological thinking: that the electrolyte milieu of the brain is not a background variable but an active determinant of focal function. As the authors and their predecessors in the literature suggest, some of the deficits long assumed to be vascular may instead be the nervous system’s distress signal when a critical mineral runs out. For a condition whose treatment is as simple as magnesium repletion, overlooking it is a luxury that emergency medicine can no longer afford.

Subject of Research: Severe hypomagnesemia as a reversible stroke mimic causing focal neurological deficits

Article Title: Stroke mimic caused by severe hypomagnesemia: a case report and literature review

Article References: Vidal Bankier, D., Renard, F., & Manto, M. (2026). Stroke mimic caused by severe hypomagnesemia: a case report and literature review. Journal of Neurology, 273(10), Article 632. https://doi.org/10.1007/s00415-026-14155-8

Image Credits: AI Generated

DOI: 10.1007/s00415-026-14155-8

Keywords: hypomagnesemia, stroke mimic, magnesium, neurology, proton pump inhibitors, metformin, aphasia, hemiparesis, emergency medicine, electrolytes, case report, Journal of Neurology

Peptic ulcer bleeding, often abbreviated PUB, is one of the most feared complications in gastroenterology. It occurs when an open sore in the lining of the stomach or the first part of the small intestine erodes into a blood vessel, producing external digestive hemorrhage or a drop in hemoglobin greater than two grams per deciliter. Despite major advances in endoscopic therapy and acid suppression over the past two decades, patients who experience one such bleed remain at elevated risk of another. For those also taking antithrombotic medications—drugs such as antiplatelet agents and anticoagulants that are essential for preventing heart attacks and strokes—the calculus becomes even more delicate, because both the ulcer and the cardiovascular system compete for clinical attention.

The conventional wisdom, embedded in multiple international guidelines, holds that eradicating H. pylori, a spiral-shaped bacterium that colonizes the gastric mucosa and is a principal cause of peptic ulcer disease, is a cornerstone of preventing recurrent bleeding. Yet much of the evidence underpinning that recommendation predates the era of widespread, long-term proton pump inhibitor use, the powerful acid-suppressing drugs that have become near-universal prescriptions after a bleeding event. The Spanish team set out to test whether the bacterium still drives recurrence in a contemporary, real-world population in which acid suppression is the norm rather than the exception.

To answer the question, the investigators conducted a retrospective, multicenter cohort study of consecutive patients who suffered a first episode of peptic ulcer bleeding between 2008 and 2023 in real clinical settings across Spain. To be included, patients required endoscopically confirmed gastric or duodenal ulcers or erosions together with evidence of bleeding. Those with non-peptic causes of upper gastrointestinal hemorrhage, peptic ulcers without bleeding, bleeding from the small bowel or colon, missing clinical data, or death during the index hospitalization were excluded. Follow-up continued until the first recurrence of ulcer bleeding, death, loss to follow-up, or the end of the review period, yielding a mean observation time of 6.4 years with a standard deviation of 4.7 years—a remarkably long window for a study of this kind.

The cohort ultimately comprised 1,675 patients. At discharge after their first bleeding episode, 525 of them, or 31 percent, were prescribed antithrombotic therapy, while 1,021 patients, or 61 percent of the entire cohort, received long-term proton pump inhibitor prescriptions. Notably, among the antithrombotic users themselves, 429 patients, representing 82 percent, were given indefinite PPI therapy, underscoring just how thoroughly acid suppression has penetrated routine care for this group. After the initial bleed and any eradication treatment, 94 patients, or 5.6 percent, remained H. pylori-positive, 936 patients, or 56 percent, tested negative, and 645 patients, or 38 percent, were never tested for the bacterium—a sizable untested fraction that itself reflects themessiness of real-world medicine.

The headline finding for the whole cohort was striking. Overall, 7.2 percent of patients experienced a first recurrence of peptic ulcer bleeding during follow-up. But when the researchers stratified by H. pylori status, recurrence climbed to 22 percent among those who remained positive, fell to 7.7 percent among those who were negative, and dropped to just 4.2 percent among the untested. Using Cox regression analysis adjusted for age, sex, use of non-steroidal anti-inflammatory drugs, and long-term PPI prescription, the team calculated that patients who stayed H. pylori-positive had a 3.7-fold higher risk of recurrence compared with H. pylori-negative patients, with a 95 percent confidence interval of 2.3 to 6.1. When the comparison was restricted to patients who remained positive versus those who had been successfully eradicated, the risk was 4.7 times higher, with a confidence interval of 2.6 to 8.7. In other words, in the general population of bleeders, the bacterium remains a potent and measurable driver of recurrent hemorrhage.

The picture changed dramatically, however, when the researchers turned to the 525 patients on antithrombotic drugs. In this subgroup, the overall incidence of first recurrence was only 5.1 percent. Among H. pylori-positive antithrombotic users, recurrence reached 7.1 percent; among H. pylori-negative users, 8 percent; and among the untested, just 2 percent. Counterintuitively, the positive patients did not fare worse than the negative ones, and after statistical adjustment the team found no significant risk differences across H. pylori status groups. The wide confidence intervals that accompany such subgroup analyses temper any strong claims, but the signal is clear: within this heavily PPI-protected population, H. pylori status no longer predicted who would bleed again.

What might explain this apparent paradox? One plausible mechanism centers on gastric acidity itself. H. pylori promotes ulcer formation and recurrence partly through inflammation and disruption of the mucosal barrier, but acid secretion remains a critical cofactor in the cascade that turns a colonized stomach into a bleeding ulcer. Proton pump inhibitors suppress acid output profoundly and durably, and with 82 percent of antithrombotic users in this cohort taking them indefinitely, the pharmacological floor beneath the mucosa may be high enough that eradicating the bacterium adds little additional protection. In patients without such acid suppression, or in whom PPI therapy is intermittent, the bacterium retains its full pathogenic force—precisely the pattern the whole-cohort analysis revealed. The finding also echoes a broader shift in ulcer epidemiology: as H. pylori prevalence falls and non-steroidal anti-inflammatory drug and antithrombotic use rises, drug-induced mucosal injury has overtaken infection as the dominant cause of bleeding ulcers in many settings.

The authors are careful to frame their work as preliminary, and several limitations deserve attention. The retrospective design means the researchers depended on records and testing practices that varied across centers and years, and the 38 percent of patients never tested for H. pylori introduce the possibility of selection effects—clinicians may have been less likely to test patients they judged to be at low risk. The antithrombotic subgroup, though sizable at 525 patients, yielded relatively few recurrence events, which limits statistical power and widens uncertainty around the null finding. Confounding by indication is also possible, since patients receiving antithrombotics differ systematically from those who do not. The study’s ethics approval came from the ethics committee of Aragón under code EPA22/065, with the informed consent requirement waived owing to the observational design, and the statistical analysis was supported by the Group of Translational Research in Digestive Diseases of the Aragón Health Research Institute, the CIBERehd network, and the FORTALECE program of the Spanish Ministry of Science and Innovation.

Even with those caveats, the implications are hard to ignore. Millions of people worldwide take antithrombotic drugs for cardiovascular protection, and a meaningful share of them carry H. pylori or have uncertain infection status. If prolonged acid suppression largely neutralizes the bacterium’s contribution to recurrent bleeding in these patients, clinicians may be able to prioritize adherence to PPI therapy, careful antithrombotic dosing, and avoidance of non-steroidal anti-inflammatory drugs over exhaustive pursuit of eradication in every case. At the same time, the stark 3.7-fold elevation in recurrence risk among H. pylori-positive patients in the broader cohort is a vivid reminder that eradication remains essential for most survivors of ulcer bleeding. The study does not overturn the eradication paradigm; it carves out a well-defined exception and, in doing so, maps the boundary conditions of one of gastroenterology’s most durable beliefs. Larger prospective studies, ideally with systematic testing of all patients, will be needed to confirm where that boundary truly lies—but for now, the message from Spain is that in the modern, acid-suppressed, real-world clinic, the bacterium’s grip on bleeding risk may be loosening, at least for those whose hearts and vessels demand blood thinners.

Subject of Research: Helicobacter pylori status and recurrence of peptic ulcer bleeding in antithrombotic users

Article Title: No significant association between H. pylori status and peptic ulcer bleeding recurrence among antithrombotic users: a preliminary study in a real-world population with high PPI use

Article References: Martínez-Domínguez, S. J., Ceamanos-Ibarra, E., Gallego-Llera, B., Jiménez-Benedí, M., Bujanda, L., Jardón-Piérola, O., Izaguirre-Arostegi, A., Cuarán, C., Pascual, A., Almenara, L., & Lanas, Á. (2026). No significant association between H. pylori status and peptic ulcer bleeding recurrence among antithrombotic users: a preliminary study in a real-world population with high PPI use. BMC Medicine. https://doi.org/10.1186/s12916-026-05275-z

Image Credits: AI Generated

DOI: 10.1186/s12916-026-05275-z

Keywords: Helicobacter pylori, peptic ulcer bleeding, antithrombotics, proton pump inhibitors, gastrointestinal bleeding, ulcer recurrence, Cox regression, retrospective cohort study, NSAIDs, eradication, BMC Medicine, gastroenterology

The review, led by Lotte M.G. Hulskotte and colleagues in the Netherlands, systematically searched PubMed and Embase for evidence on drug–drug and food–drug interactions and pharmacodynamic adverse effects of all thirty SMIs approved by the US Food and Drug Administration and the European Medicines Agency for non-small cell lung cancer, from long-standing agents such as erlotinib and crizotinib to newcomers including zongertinib, sevabertinib and sunvozertinib. The searches, initiated in October 2025 and finalised in July 2026, were supplemented with regulatory documents from both agencies, and the authors applied a pragmatic hierarchy of evidence ranking pharmacokinetic studies and meta-analyses above phase 1/2 trials, observational data, label information and expert opinion.

At the heart of the pharmacokinetic problem lies chemistry. Most SMIs are weakly basic, lipophilic molecules whose absorption depends delicately on the acidity of the stomach. When acid-reducing agents such as proton pump inhibitors raise gastric pH, the drugs shift toward a less soluble, non-ionised form that dissolves poorly, cutting systemic exposure. The magnitude is striking: selpercatinib exposure fell by roughly 70 percent when omeprazole was given in the fasted state, and sotorasib lost 57 percent of its exposure with omeprazole even when taken with food. Erlotinib, co-administered with esomeprazole, lost nearly half its area under the curve. Bioequivalence standards allow exposure to vary only within 80 to 125 percent of the reference value, so deviations of this size translate directly into subtherapeutic concentrations, lost efficacy and, ultimately, disease progression.

Liver enzymes provide the second major axis of interaction. Most SMIs are metabolised primarily by cytochrome P450 iso-enzymes, above all CYP3A, so potent inducers such as rifampicin can collapse drug levels while inhibitors such as itraconazole can push them to toxic heights. Rifampicin cut adagrasib exposure by 95 percent, while itraconazole raised repotrectinib exposure nearly sevenfold. Compounding the problem, several agents are themselves auto-inducers or auto-inhibitors of CYP enzymes — dabrafenib, encorafenib, lorlatinib and osimertinib induce their own clearance, while adagrasib, ceritinib and taletrectinib inhibit it — meaning that single-dose interaction studies may not predict steady-state behaviour. Transporters such as P-glycoprotein and breast cancer resistance protein add further complexity, although their intestinal contribution is generally considered minor.

Food, by contrast, can be an ally. High-fat meals delay gastric emptying, increase bile flow and create a lipophilic environment that enhances solubilisation of many of these drugs. Alectinib is the poster child: a high-fat meal raised its systemic exposure by roughly 230 to 250 percent, and a clinical crossover study showed that 35 percent of patients failed to reach the alectinib exposure threshold when taking the drug with low-fat yoghurt, compared with only 5 percent eating a continental breakfast or lunch. This very property has been exploited therapeutically — ceritinib’s approved dose fell from 750 mg fasted to 450 mg with food after feeding studies showed comparable exposure with less gastrointestinal toxicity, and the FDA has required a post-marketing evaluation of taletrectinib dosing with food for the same reason. Food also reduced inter-individual variability for several agents, improving predictability of therapeutic exposure.

The interplay between food and acid suppression, however, is drug-specific and sometimes counterintuitive. Selpercatinib’s PPI-induced exposure loss is largely rescued by co-administration with a meal. Sotorasib behaves in the opposite way, losing even more exposure when food and a PPI are combined. For erlotinib, an acidic glass of cola partially reversed the damage done by esomeprazole, restoring roughly 40 percent of lost exposure. The authors conclude that when PPI use is unavoidable, clinicians should weigh the individual pharmacokinetics of each SMI, considering food co-administration, acidic beverages or staggered dosing as mitigation strategies.

Turning to the drugs’ intrinsic toxicities, the review paints a landscape where class effects mask considerable agent-to-agent variation. Corrected QT interval prolongation, which can degenerate into dangerous arrhythmias, affects the entire class but is most pronounced with adagrasib, ceritinib, crizotinib, encorafenib, osimertinib and taletrectinib, with median increases exceeding ten milliseconds and the highest rates of clinically significant prolongation seen with adagrasib, encorafenib, taletrectinib, entrectinib and selpercatinib. Because the effect is largely exposure-dependent, any interaction that raises drug levels also raises arrhythmia risk. Others, including alectinib, gefitinib, capmatinib and the newer HER2 inhibitors, showed no clinically meaningful QTc changes. Management centres on electrocardiographic monitoring, correction of concomitant QT-prolonging factors, and dose interruption or discontinuation when the QTc exceeds 500 milliseconds.

Pneumonitis, the non-infectious inflammation of lung tissue that can prove fatal, occurs with most SMIs but clusters around particular agents. Brigatinib carried the highest trial incidence at 9 percent of all-grade events, with an unusual early onset within the first week — the rationale for its mandatory one-week 90 mg lead-in dose before escalation. Pralsetinib affected about 12 percent of patients including one fatal case, while adagrasib, capmatinib, ensartinib and sunvozertinib each produced events in 5 to 6 percent. Strikingly, ethnicity emerged as an independent risk factor: all-grade interstitial lung disease was reported in up to 15 percent of Japanese patients on gefitinib and 17 percent on osimertinib. Rechallenge after pneumonitis remains fraught — one real-world study found a 50 percent twelve-month recurrence rate when patients were rechallenged with osimertinib itself, versus 15 percent with alternative EGFR inhibitors.

Among the quieter but increasingly recognised toxicities is weight gain. NTRK inhibitors cause weight gain in 53 percent of patients, likely through on-target inhibition of TRKB, a hypothalamic receptor governing appetite, with entrectinib reaching roughly 66 percent incidence. Among ALK inhibitors, lorlatinib produced all-grade weight gain in up to 81 percent of patients, with grade 3 events in up to 23 percent and a median gain of 4.5 kilograms in a prospective study; alectinib added an average 9 centimetres of waist circumference over a year. The irony is acute for alectinib, whose absorption depends on high-fat meals. Management spans lifestyle counselling, systematic weight monitoring and, where needed, GLP-1 receptor agonists — though even here caution is warranted, as semaglutide was recently shown to reduce alectinib exposure by 32 percent.

Further distinguishing the class, EGFR inhibitors uniquely damage the ocular surface — keratitis in 1 to 3 percent of patients and conjunctivitis up to 24 percent with dacomitinib — because EGFR sustains corneal epithelium and tear production, while BRAF/MEK combinations bring uveitis and retinal pigment epithelial detachment, the latter affecting roughly 30 percent of patients on encorafenib plus binimetinib. Central neurotoxicity, including cognitive disorders in up to a third of patients on capmatinib, entrectinib, lorlatinib and repotrectinib, peripheral neuropathy in up to 44 percent on lorlatinib, dabrafenib-driven pyrexia in 39 percent of combination-treated patients, severe stomatitis with second-generation EGFR inhibitors, and hepatotoxicity necessitating intra-class switches — erlotinib after gefitinib injury, adagrasib after sotorasib injury — complete the picture. The authors’ overarching message is that safe prescribing of these transformative drugs demands equal attention to what patients eat, what else they swallow, and which specific molecule sits in the capsule: pharmacokinetic–pharmacodynamic associations remain under-studied, and filling that gap could enable personalised dosing that maximises efficacy while sparing patients avoidable harm.

Subject of Research: Pharmacokinetic and pharmacodynamic considerations for prescribing small molecule kinase inhibitors in non-small cell lung cancer

Article Title: Pharmacological considerations for prescribing of small molecule inhibitors in patients with non-small cell lung cancer

Article References: Hulskotte, L. M., Veerman, G. M., Lanser, D. A., Reyners, A. K., van Schaik, R. H., Dingemans, A.-M. C., Taxis, K., Mathijssen, R. H., & Jansman, F. G. (2026). Pharmacological considerations for prescribing of small molecule inhibitors in patients with non-small cell lung cancer. eClinicalMedicine, 100, Article 104199. https://doi.org/10.1016/j.eclinm.2026.104199

Image Credits: AI Generated

DOI: 10.1016/j.eclinm.2026.104199

Keywords: non-small cell lung cancer, small molecule inhibitors, drug-drug interactions, pharmacokinetics, CYP3A, proton pump inhibitors, food-drug interactions, QTc prolongation, pneumonitis, weight gain, ocular toxicity, targeted therapy

The study, conducted by a team led by Dong Keon Yon of Kyung Hee University College of Medicine and published in the World Journal of Pediatrics, capitalized on a uniquely powerful data resource: the National Health Insurance Service of Korea, which covers virtually the entire population. The researchers identified 3,012,992 mother-child pairs between January 1, 2009, and December 31, 2023, and after applying inclusion criteria, followed 2,777,119 children for a mean of 9.6 years. Of these, 507,845 had been exposed in utero to acid-suppressive medications, making this by far the largest dataset ever assembled to address the question of whether these common drugs leave a lasting imprint on the developing immune system.

Acid-suppressive medications are among the most frequently prescribed drugs in pregnancy. Proton pump inhibitors, or PPIs, block the hydrogen-potassium ATPase enzyme in gastric parietal cells, dramatically reducing stomach acid secretion, while histamine-2 receptor antagonists, or H2RAs, achieve a similar effect by blocking histamine signaling at the H2 receptor. Pregnant women take them for gastroesophageal reflux disease, dyspepsia, and related conditions, and their use has been considered relatively safe based on decades of pharmacovigilance. Yet the biological rationale for concern is real. Gastric acid serves as a chemical barrier shaping the gut microbiome, and animal and human studies have shown that acid suppression can alter microbial composition, promote oral-to-gut bacterial transmission, and influence immune programming. Because the fetal immune system undergoes critical developmental windows in utero—including thymic selection of the T cell repertoire—researchers have long wondered whether perturbing the maternal and fetal microbial environment could tilt immune development toward autoreactivity.

To answer that question rigorously, the team classified outcomes using International Classification of Diseases, 10th Revision codes, capturing systemic autoimmune diseases, autoimmune endocrine diseases, autoimmune thyroid diseases, autoimmune hepatitis, and other autoimmune conditions such as lupus erythematosus, psoriasis, and rheumatoid arthritis. To reduce the bias that plagues observational studies of medication use, the researchers employed propensity score-based overlap weighting, a technique that reweights exposed and unexposed children so that their measured baseline characteristics—maternal age, comorbidities, co-medications, and other confounders—become statistically balanced. After weighting, the analytic cohort comprised 404,550 exposed and 404,551 unexposed pairs, and Cox proportional hazards models were used to estimate adjusted hazard ratios with 95 percent confidence intervals.

The headline findings were statistically significant but numerically small. Prenatal exposure to acid-suppressive medications was associated with an 11 percent increase in the risk of systemic autoimmune diseases (adjusted hazard ratio 1.11, 95 percent confidence interval 1.01 to 1.21) and a 9 percent increase in other autoimmune diseases (adjusted hazard ratio 1.09, 95 percent confidence interval 1.05 to 1.12). Translated into absolute terms, however, the excess risk was vanishingly small: the numbers needed to harm were 37,716 per year for systemic autoimmune diseases and 6,102 per year for other autoimmune conditions. In other words, for every several thousand exposed pregnancies followed for a year, at most one additional case of autoimmune disease would be expected beyond what would occur anyway—a magnitude of risk that is difficult to detect at the individual patient level and of questionable clinical consequence.

The most informative analysis came from the sibling comparison. By treating each mother as a separate stratum and comparing exposed children with their unexposed siblings, the researchers effectively controlled not only for measured confounders but also for the stable, unmeasured factors that siblings share: genetics, household environment, socioeconomic background, and maternal health tendencies. In this within-family analysis, the associations vanished entirely. The adjusted hazard ratio for systemic autoimmune diseases fell to 0.89 (95 percent confidence interval 0.77 to 1.03) and for other autoimmune diseases to 0.97 (95 percent confidence interval 0.92 to 1.02)—both statistically indistinguishable from no effect. Because familial confounding is the dominant alternative explanation in pharmacoepidemiology, the null sibling findings weigh heavily against a causal interpretation of the modest between-family associations.

Timing mattered in one respect. When the researchers examined exposure by trimester, first-trimester exposure was associated with a slightly elevated risk of any autoimmune disease (adjusted hazard ratio 1.09, 95 percent confidence interval 1.06 to 1.13). The first trimester coincides with the earliest phases of immune system organogenesis, including the initial establishment of hematopoietic and lymphoid lineages, and it is also the window in which maternal physiological changes make reflux symptoms particularly common—raising the possibility that the underlying indication for treatment, rather than the medication, contributes to the observed signal. The authors note that exposure during this period may warrant careful clinical consideration, even as they emphasize that the overall evidence points to limited clinical concern.

The study’s sensitivity analyses strengthened its robustness. The team examined risks separately by medication type, distinguishing PPIs from H2RAs, and by trimester of exposure, and they modeled risk as a function of time since exposure. They also conducted stratified analyses across numerous subgroups. This methodological architecture matters because prior research on acid suppression in pregnancy and early life has produced a patchwork of associations with allergic diseases, asthma, celiac disease autoimmunity, and even neuropsychiatric disorders, and much of that literature has struggled to separate drug effects from confounding by indication. The present study’s scale—nearly 2.8 million children followed for close to a decade—gives it statistical power that smaller cohorts cannot match, while the sibling design addresses the confounding problem that has undermined earlier work.

The biological plausibility of a link between acid suppression and autoimmunity rests on several converging lines of evidence. Randomized trials have shown that PPIs induce stronger oral-to-gut microbial transmission and greater gut microbiome alterations than H2RAs, and the gut microbiome is increasingly recognized as a modulator of systemic immune tolerance. H2 receptor blockade has been shown to selectively affect B and T cell function in healthy subjects, and cimetidine in particular possesses immunomodulatory properties. Meanwhile, large-scale single-cell atlases of the human thymus have illuminated how precisely T cell self-tolerance is calibrated during development, and epidemiological studies have linked gut microbiota composition to genetic risk for rheumatoid arthritis. Against this backdrop, a true drug effect on fetal immune programming was biologically conceivable—which is precisely why a study of this scale was needed to test it.

For clinicians and expectant mothers, the practical takeaway is one of measured reassurance. Untreated severe gastroesophageal reflux in pregnancy carries its own burdens, from pain and sleep disruption to impaired nutrition, and the new findings provide no compelling basis to withhold acid-suppressive therapy when it is indicated. The authors conclude that the low absolute excess risks and the null sibling-comparison findings indicate limited clinical concern, while flagging first-trimester exposure as the one scenario deserving of thoughtful prescribing decisions. As with all observational research, residual confounding cannot be excluded entirely, and the study population was confined to South Korea, which may limit generalizability to other genetic and dietary environments. But in the hierarchy of evidence on prenatal medication safety, a nationwide cohort of 2.7 million children with sibling-based negative controls represents about as close to a definitive answer as the field can currently achieve—and that answer is, on balance, a comforting one.

Subject of Research: Prenatal exposure to acid-suppressive medications and the risk of autoimmune diseases in offspring

Article Title: Association between prenatal exposure to acid-suppressive medications and subsequent risk of autoimmune diseases in offspring: a nationwide birth cohort study in South Korea

Article References: Lee, Y., Lee, K., Jo, Y., Hong, S., Lee, S., Jo, H., Woo, S., Hwang, Y., Kim, S., Hwang, H. S., Lee, J., Park, J., Lee, H., & Yon, D. K. (2026). Association between prenatal exposure to acid-suppressive medications and subsequent risk of autoimmune diseases in offspring: a nationwide birth cohort study in South Korea. World Journal of Pediatrics. https://doi.org/10.1007/s12519-026-01077-8

Image Credits: AI Generated

DOI: 10.1007/s12519-026-01077-8

Keywords: acid-suppressive medications, proton pump inhibitors, histamine-2 receptor antagonists, autoimmune diseases, prenatal exposure, birth cohort, pediatrics, South Korea, National Health Insurance Service, gut microbiome, pregnancy, first trimester