Acute myeloid leukemia (AML) harboring KMT2A rearrangements (KMT2A-r) accounts for approximately 5–10% of newly diagnosed cases and represents a high-risk AML subtype associated with poor clinical outcomes despite intensive treatment strategies, including allogeneic hematopoietic stem cell transplantation (HSCT). KMT2A-r AML is also characterized by a higher incidence of extramedullary disease compared with other AML subtypes. Therapeutic options for patients with relapsed/refractory (R/R) disease, particularly after post-HSCT relapse, remain extremely limited. In recent years, menin inhibitors have emerged as a promising targeted therapeutic class for KMT2A-r and NPM1-mutated AML by disrupting the aberrant HOX/MEIS1 transcriptional program. Revumenib, a first-in-class menin inhibitor, has shown encouraging efficacy in early-phase clinical trials. Other menin inhibitors, including ziftomenib, bleximenib, and enzomenib, have also demonstrated clinical activity, with distinct pharmacokinetic, pharmacodynamic, and safety profiles. We report the case of a 36-year-old patient with KMT2A-r AML who relapsed after HSCT with both bone marrow and hepatic involvement. Compassionate-use treatment with revumenib (160 mg twice daily on days 1–28 of each 28-day cycle) induced, after two treatment cycles, complete hematologic remission with no detectable abnormal myeloid blast population by multiparameter flow cytometry (MFC) and complete radiological resolution of hepatic lesions. However, despite prior intrathecal CNS-directed therapy and sustained systemic disease control, the patient subsequently developed an isolated central nervous system (CNS) relapse. This case highlights a potential discordance between systemic and CNS disease control during menin inhibitor therapy and emphasizes the need for further investigation into CNS surveillance and disease management in patients achieving deep systemic responses.

Pure red cell aplasia (PRCA) following major ABO-mismatched allogeneic hematopoietic stem cell transplantation (HSCT) is a challenging complication, affecting 7–10% of patients and significantly impacts quality of life. Despite half of patients showing a resolution within three–six months after HSCT, PRCA might require treatment. Various therapeutic approaches have been investigated, including erythropoietin, plasmapheresis or immunomodulatory therapies (rituximab, bortezomib, corticosteroids, donor lymphocyte infusion (DLI), or the early tapering of immunosuppressive drugs), and TPO-mimetic agents, though responses have generally remained suboptimal. Recently, daratumumab has emerged as a promising, safe, and effective treatment for PRCA, documented by numerous case reports and series. We present a case of PRCA arising in a patient with mixed chimerism following a sibling HSCT for aplastic anemia (AA). In line with the literature, our findings highlight the effectiveness of daratumumab in PRCA from the first dose, although daratumumab administrations were delayed by the onset of infectious complications. Our case supports the earlier introduction of daratumumab in the treatment strategy of PRCA to avoid patient exposure to ineffective therapies that carry risks of increased immunosuppression and infections. Indeed, in our specific case, the early introduction of daratumumab may interrupt the immune hematologic mechanism underlying PRCA, which, in the context of mixed chimerism, could increase the risk of graft failure.

For patients with relapsed/refractory (R/R) follicular lymphoma (FL) after ≥2 prior lines of therapy, T-cell-redirecting therapies—including the bispecific CD3xCD20 antibody (BsAbs) mosunetuzumab (mosu) and chimeric antigen receptor T-cell (CAR-T) therapies such as axicabtagene ciloleucel (axi-cel), lisocabtagen maraleucel (liso-cel), and tisagenlecleucel (tisa-cel)—are approved by the FDA and EMA. Treatment selection should consider patient-related factors, prior therapeutic exposure, and toxicity profiles. We describe the 20-year history of a patient with R/R FL. At the fourth relapse, both BsAbs and CAR-T cells were available; however, due to the cumulative toxic burden and the high risk of cytopenias, mosu was selected as the preferred option. During mosu, the patient developed pure red cell aplasia unrelated to infections. Despite achieving a partial response after eight cycles of mosu, this complication led to the decision to proceed with allogeneic stem cell transplantation (allo-HSCT). The course was ultimately complicated by severe early toxicity with massive hemoptysis, acute respiratory failure, and hemorrhagic alveolitis, resulting in a fatal outcome. This case illustrates the delicate balance required in selecting between BsAbs and CAR-T therapy in R/R FL. Contributing factors to the patient’s fragility included profound immune status, transfusion-dependent red cell aplasia, prior cumulative chemotherapy, and pulmonary toxicity associated with conditioning regimens. The case underscores the importance of individualized treatment strategies and suggests that earlier integration of novel T-cell-redirecting therapies may mitigate cumulative toxicity and infection risk. Individualized therapeutic planning is critical in heavily pretreated R/R FL. In select cases, bridging strategies using BsAbs can provide disease control and facilitate transplantation. Still, careful assessment of patient fitness, marrow reserve, and cumulative toxicity is essential to minimize the risk of fatal complications.

Chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment landscape of relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL), non-Hodgkin lymphoma (NHL), and multiple myeloma (MM); however, a substantial proportion of patients eventually experience disease relapse despite an initial response. This review provides a brief overview of CAR-T cell therapy, including its manufacturing process and associated toxicities, before examining the biological mechanisms underlying post-CAR-T relapse in B-ALL, NHL—particularly large B-cell lymphoma (LBCL)—and MM. We critically review current and emerging strategies to prevent and manage relapse. Strategies for relapse prevention primarily include consolidation approaches, such as allogeneic hematopoietic stem cell transplantation (allo-HSCT), maintenance with targeted agents (e.g., tyrosine kinase inhibitors in Philadelphia chromosome-positive B-ALL), and CAR-T cell reinfusion, whereas relapse management is disease-specific and increasingly incorporates novel therapeutic agents, including bispecific antibodies (BsAbs) and other targeted therapies. However, current evidence remains largely preliminary and is limited by the paucity of randomized prospective trials.