Hans Christian Reinhardt

Background: Upfront allogeneic stem cell transplantation (allo-SCT) without pretransplant cytoreduction is an established concept in patients with myelodysplastic syndromes with increased blasts (MDS-IB), but the optimal conditioning strategy remains to be defined. While fludarabine and treosulfan (Flu/Treo) has become an established regimen for older patients based on its favorable ratio between toxicity and efficacy, its impact when used in the context of upfront transplant is less well described. Methods: Here, we retrospectively investigated Flu/Treo as the backbone for conditioning in 35 patients with MDS-IB (median blast count 13%) receiving upfront transplantation. Results: Outcomes in this high-risk cohort (75% IPSS-M high or very high) were promising, with an estimated 2-year overall (OS), relapse-free survival (RFS) and non-relapse mortality (NRM) of 76%, 56% and 13%, respectively. Relapse was the major cause of treatment failure, reflected by a relapse incidence (CIR) of 31%. We identified the TP53 mutation status as the main driver of relapse (2-year RFS TP53 mutated 17% vs. 67%, p = 0.01; 2-year CIR 54% vs. 24%, p = 0.08) and an adverse prognostic factor, while the pretransplant blast count did not affect the post-transplant outcome. Intensification with the addition of melphalan (Mel, n = 18) to a sequential conditioning approach did not improve the outcome (Mel vs. Flu/Treo 2-year OS 62% vs. 87%, RFS 50% vs. 63%, CIR 37% vs. 24%, NRM 14% vs. 12%, all not significant). Conclusions: This pilot series shows that upfront transplantation using Flu/Treo conditioning in high-risk MDS patients facilitates promising post-transplant outcomes and may serve as a backbone to further improve these results through innovative peri-transplant interventions.

Generated by stochastic V(D)J recombination, unique B-cell receptors (BCRs) consist of IgH and IgL chains, recognize antigens, and serve as distinct barcodes to identify each individual B cell. Once a B-cell acquires its BCR, does it maintain its identity, or does a peripheral B-cell ever rearrange its BCR again? Under what circumstances a peripheral B-cell would undergo secondary V(D)J recombination at its Igh locus, termed V_H gene replacement (VHR), remains poorly understood. Using hen egg lysozyme (HEL) BCR knock-in mice, we observed that when the BCR cannot bind to any foreign or self-antigen, peripheral B cells upregulate the expression of the VDJ recombinase RAG-1 and undergo VHR to acquire new BCRs and become non-HEL-binding. TRAF3 deficiency increased the frequency of VHR-experienced B cells and predisposed them to abnormal oligoclonal expansion by preventing B cells from dying from RAG-initiated DNA double-stranded breaks in an NF-κB2-dependent manner. Engaging the HEL BCR or inhibiting proximal BCR signaling modulated RAG-1 expression. The frequency of VHR was substantially inhibited by enhanced BCR signaling caused by a gain-of-function mutant allele of Cd79b, a signaling component of the BCR complex. We conclude that BCR signaling strength influences the probability of a given B-cell undergoing VHR. Furthermore, signaling molecules such as TRAF3 can serve as nonclassical checkpoints to maintain B-cell genome stability during VHR. Our studies provide fundamental insights into the mechanisms underlying the dynamic regulation of antigen receptor identity in peripheral B cells, with implications for immune tolerance and B-cell homeostasis. Our studies reveal novel mechanisms of genomic instability in VHR-experienced peripheral B cells and provide fundamental insights into the conditions under which B cells alter their identity via VHR, as well as the regulatory mechanisms governing the VHR process.

Objectives: Primary plasma cell leukemia (pPCL) is a rare disease with poor outcomes. As data on randomized phase‐III trials are lacking, treatment recommendations are predominately based on retrospective analyses incorporating time periods with outdated therapies. Thus, the optimal consolidation strategy remains to be defined. Methods: We conducted a retrospective, multi‐center analysis with 49 transplant‐eligible patients diagnosed with pPCL between 2011 and 2025 focusing on different stem cell transplantation (SCT) strategies as consolidation treatment in first remission: single autologous (auto) or single allogeneic (allo) SCT versus patients with tandem cell therapy strategies (auto‐auto, allo‐auto, auto‐chimeric antigen receptor therapy). Results: The median follow‐up after first SCT was 31 months. The cumulative incidence of initiating next treatment was lower after tandem cell therapy compared to single SCT (at 12 months: 42% vs. 57%, p = 0.006). Moreover, in a multivariable analysis incorporating cytogenetic risk and response to induction therapy, tandem transplantation strategies tended to be the only independent predictor for prolonged time to next treatment (TTNT, p = 0.077). Noteworthy, differences in TTNT between patients with a single SCT and patients with tandem cell therapy did not translate into an improved overall survival, possibly due to potent salvage therapies. Conclusions: Our data support recent recommendations advising treating patients with tandem transplantation regimes.

Body composition analysis (BCA) provides an objective assessment of metabolic states, but its prognostic value in diffuse large B-cell lymphoma (DLBCL) remains unclear. We applied machine learning–supported BCA to computed tomography imaging from patients with newly diagnosed DLBCL enrolled in the prospective phase 3 PETAL trial to quantify radiologic sarcopenia. We assessed BCA results in relation to survival after first-line immunochemotherapy, treatment-related hematologic toxicities, and molecular disease features. Patients in the lowest tertile of normalized skeletal muscle mass exhibited inferior survival after adjustment for established risk factors. Cause-specific time-to-event analyses revealed that sarcopenia was not associated with lymphoma-specific death but strongly predicted nonrelapse mortality, indicating a potential role as a biomarker of host vulnerability. Consistent with these findings, sarcopenic patients had a higher probability of experiencing hematologic toxicity during immunochemotherapy, and sarcopenia was the only independent risk factor for higher-grade hematotoxicity in multivariable analyses. Longitudinal BCA revealed inferior survival in patients with early muscle loss during therapy. Baseline sarcopenia and treatment-emergent muscle loss were not correlated, suggesting that these represent distinct biological phenomena, and only a small fraction of the interindividual variability in muscle mass could be attributed to age and lymphoma burden. Both phenotypes were independent of DLBCL molecular clusters, and no recurrently mutated gene was associated with lower skeletal muscle mass. Taken together, our results establish baseline sarcopenia and treatment-emergent muscle loss as orthogonal risk factors for adverse outcomes in DLBCL, supporting the evaluation of BCA for risk stratification in personalized lymphoma therapy.

This retrospective, single‐center study aimed to characterize clonal dynamics of GPI‐deficient cells in patients with paroxysmal nocturnal hemoglobinuria (PNH) or PNH/aplastic anemia (AA) syndrome using multiparameter flow cytometry including FLAER. Among 108 patients diagnosed and treated at our center, 83 had longitudinal monitoring of GPI‐deficient neutrophils; 53 of these also had data on monocytes and lymphocytes. Median observation time was 29.4 months (range 1.1–162.7 months). Clone size in neutrophils showed a strong correlation with monocytes, but not with lymphocytes. Clonal persistence represented the most frequent individual pattern of clone evolution observed during follow‐up; clonal persistence was observed in 32/83 patients, while 24 patients exhibited clonal expansion (≥ 10%) and 13 showed regression. Expansion frequently involved all three lineages, suggesting ongoing biological mechanisms contributing to clonal selection. Regression was more likely in patients with small initial clones. In six patients undergoing allogeneic stem cell transplantation, complete eradication of PNH clones was achieved. Clonal dynamics were independent of eculizumab treatment; however, regression was observed in some patients treated with ATG and cyclosporine A. These findings support the need for longitudinal clone size monitoring, particularly in neutrophils and monocytes. Further studies are warranted to elucidate factors influencing clone expansion and remission. Trial Registration: 25‐12 634‐BO

Combined SpenLOF and Notch2GOF mutations induce formation of a non-canonical AiBC with MZB features.

Combined SpenLOF and Notch2GOF mutations lead to increased fitness of female AiBC.

Differentially Expressed Genes per cluster from multiome analysis

Combined SpenLOF and Notch2GOF mutations drive an increase in AiBCs