Platelets play crucial roles in hemostasis, thrombosis, and immunity, but our understanding of their complex biogenesis (thrombopoiesis) is currently incomplete. Deeper insight into the mechanisms of platelet biogenesis inside and outside the body is fundamental for managing hematological disorders and for the development of novel cell-based therapies. In this article, we address the current understanding of in vivo thrombopoiesis, including mechanisms of platelet generation from megakaryocytes (proplatelet formation, cytoplasmic fragmentation, and membrane budding) and their physiological location. Progress has been made in replicating these processes in vitro for potential therapeutic application, notably in platelet transfusion and bioengineering of platelets for novel targeted therapies. The current platelet-generating systems and their limitations, particularly yield, scalability, and functionality, are discussed. Finally, we highlight the current controversies and challenges in the field that need to be addressed to achieve a full understanding of these processes, in vivo and in vitro.

Complement-mediated thrombotic microangiopathy (CM-TMA) or hemolytic uremic syndrome, previously identified as atypical hemolytic uremic syndrome, is a TMA characterized by germ line variants or acquired antibodies to complement proteins and regulators. Building upon our prior experience with the modified Ham (mHam) assay for ex vivo diagnosis of complementopathies, we have developed an array of cell-based complement "biosensors" by selective removal of complement regulatory proteins (CD55 and CD59, CD46, or a combination thereof) in an autonomously bioluminescent HEK293 cell line. These biosensors can be used as a sensitive method for diagnosing CM-TMA and monitoring therapeutic complement blockade. Using specific complement pathway inhibitors, this model identifies immunoglobulin M (IgM)-driven classical pathway stimulus during both acute disease and in many patients during clinical remission. This provides a potential explanation for ∼50% of patients with CM-TMA who lack an alternative pathway "driving" variant and suggests at least a subset of CM-TMA is characterized by a breakdown of IgM immunologic tolerance.

Diffuse large B-cell lymphoma (DLBCL) is an aggressive, yet curable, malignancy, but older patients are at higher risk of relapsed disease because they may not be eligible for full-intensity frontline chemoimmunotherapy or have comorbidities that limit standard treatments. Recent years have brought more treatment options than ever for this patient population, but it remains challenging to determine which can be safely and effectively offered to older patients. Formal determinations of fitness including geriatric assessments remain critical, but there is less guidance on how to best use this tool in the relapsed setting. Chimeric antigen receptor T-cell therapy is accessible to older patients, provided they can be supported through the intensive road to this treatment. If relapse occurs despite this or alternative therapies are preferred, many novel therapeutic options and combinations exist with some potential modifications for older adults, such as bispecific antibodies, tafasitamab and lenalidomide, polatuzumab-containing regimens, or loncastuximab tesirine. This article provides a summary of our approach to the management of this diverse population of older patients with relapsed or refractory DLBCL.

In 2023, 2 different gene therapies were approved for individuals with severe sickle cell disease (SCD). The small number of patients treated on the pivotal clinical trials that led to these approvals have experienced dramatic short-term reductions in the occurrence of painful vaso-occlusive crises, but the long-term safety and efficacy of these genetic therapies are yet to be ascertained. Several challenges and treatment-related concerns have emerged in regard to administering these therapies in clinical practice. This article discusses the selection and preparation of individuals with SCD who wish to receive autologous gene therapy, as well as the salient features of the care needed to support them through a long and arduous treatment process. I specifically focus on postinfusion care, as it relates to immune monitoring and infection prevention. Compared with allogeneic hematopoietic cell transplantation, delivering autologous gene therapy to an individual with SCD has distinct nuances that require awareness and special interventions. Using clinical vignettes derived from real-life patients, I provide perspectives on the complex decision-making process for gene therapy for SCD based on currently available data and make recommendations for evaluating and supporting these patients.

Secondary acute myeloid leukemia (sAML) has traditionally been used to designate any AML disease arising from an antecedent hematologic disorder or after prior cytotoxic or radiation therapy. We now know sAML comprises multiple disease entities with distinct clinical and biological features: AML, myelodysplastic related; myeloproliferative neoplasm-blast phase; and AML post-cytotoxic therapy. These entities largely represent adverse-risk phenotypes with the majority of patients experiencing suboptimal outcomes with standard therapeutic options. Given the aging general population and the increased life span of individuals receiving DNA-damaging agents for other medical conditions, the incidence of these diseases is steadily rising and now comprise ∼25% to 30% of all new AML diagnoses. Despite the plethora of novel agents approved for AML since 2017, many either are not applicable to sAML (ie, lacking a targetable mutation), have limited efficacy, or have not been studied in these specific entities. Furthermore, these patients are underrepresented in clinical trials, and novel therapeutic options are critically needed. Here, we present multiple patient cases exemplifying the new nomenclature and classification of the diseases comprising sAML and highlighting their diverse presentations. We provide our therapeutic approach for each clinical scenario and discuss the challenges of treatment with the currently available armamentarium.

No randomized trial has directly compared daratumumab and lenalidomide (D-R) maintenance with standard-of-care lenalidomide (R) alone after transplant. Herein, we report the primary results of the phase 3 AURIGA study evaluating D-R vs R maintenance in patients with newly diagnosed multiple myeloma (NDMM) who had very good or better partial response, were minimal residual disease (MRD)-positive (10-5) and anti-CD38-naïve after transplant. Two hundred patients were randomly assigned (1:1) to D-R (n = 99) or R (n = 101) maintenance for up to 36 cycles. The MRD-negative (10-5) conversion rate by 12 months from start of maintenance (primary end point) was significantly higher for D-R than R (50.5% vs 18.8%; odds ratio [OR], 4.51; 95% confidence interval [CI], 2.37-8.57; P < .0001). MRD-negative (10-6) conversion rate was similarly higher with D-R (23.2% vs 5.0%; OR, 5.97; 95% CI, 2.15-16.58; P = .0002). At median follow-up (32.3 months), D-R achieved a higher overall MRD-negative (10-5) conversion rate (D-R, 60.6% vs R, 27.7%; OR, 4.12; 95% CI, 2.26-7.52; P < .0001) and complete response rate or better (75.8% vs 61.4%; OR, 2.00; 95% CI, 1.08-3.69; P = .0255) vs R. Progression-free survival (PFS) favored D-R vs R (hazard ratio, 0.53; 95% CI, 0.29-0.97); estimated 30-month PFS rates were 82.7% for D-R and 66.4% for R. Incidences of grade 3/4 cytopenias (54.2% vs 46.9%) and infections (18.8% vs 13.3%) were slightly higher with D-R than R. In conclusion, D-R maintenance achieved a higher MRD-negative conversion rate and improved PFS after transplant vs R, with no new safety concerns. This trial was registered at www.clinicaltrials.gov as #NCT03901963.

Dexamethasone is a key component of induction for newly diagnosed multiple myeloma (NDMM), despite common toxicities, including hyperglycemia and insomnia. In the randomized ECOG E4A03 trial, dexamethasone 40 mg once weekly was associated with lower mortality than higher doses. However, the performance of dexamethasone dose reductions below this threshold with regard to progression-free survival (PFS) and overall survival (OS) in NDMM has not been fully characterized. We conducted a secondary pooled analysis of the SWOG 0777 and SWOG 1211 studies of NDMM, which used lenalidomide and dexamethasone (Rd) alone, with or without bortezomib, and with or without elotuzumab. The planned dexamethasone intensity was 40 to 60 mg weekly in all arms. Patients were categorized into FD-DEX (full-dose dexamethasone maintained throughout induction) or LD-DEX (lowered-dose dexamethasone or discontinuation; only permitted for grade 3+ toxicities per both study protocols). Of the 541 evaluated patients, the LD-DEX group comprised 373 patients (69%). There were no differences in PFS or OS between the FD-DEX and LD-DEX groups, which were balanced in terms of age, stage, and performance status. Predictors of PFS and OS in the multivariate models were treatment arm, age ≥70 years, and thrombocytopenia. FD-DEX did not significantly improve either outcome. Our study suggests that dexamethasone dose reductions are common in multiple myeloma, even within clinical trials. Given the many toxicities and unclear benefits of dexamethasone in the era of modern treatment regimens, dexamethasone dose reduction during NDMM induction warrants further prospective studies. These trials were registered at www.clinicaltrials.gov as #NCT00644228 and NCT01668719.

Adoptive T-cell therapy is a promising therapy for multiple myeloma (MM), but its efficacy hinges on understanding the relevant biologic and predictive markers of response. B-cell maturation antigen (BCMA) is a key target antigen in MM with active development of multiple anti-BCMA T-cell engagers (TCEs) and chimeric antigen receptor T-cell therapies. The regulation of surface BCMA expression by MM cells, which leads to shedding of soluble BCMA (sBCMA), has triggered debate about the significance of sBCMA as a predictive marker and its potential impact on treatment outcomes. To address this, we leveraged whole-genome sequencing and in vitro assays to demonstrate that sBCMA may independently predict primary refractoriness to anti-BCMA therapies. In addition to sBCMA, tumor burden and surface BCMA antigen density collectively influenced the anti-BCMA TCE cytotoxic efficacy. Correlative analyses of 163 patients treated with the anti-BCMA TCE teclistamab validated and further underscored the association between elevated baseline sBCMA (>400 ng/mL) and refractoriness. Importantly, increasing the TCE dose, using TCE against alternative targets (eg, GPRC5D), and gamma secretase inhibitors were able to overcome the high sBCMA levels. These findings highlight the importance of taking into account the baseline sBCMA levels, disease burden, and TCE dose intensity when administering anti-BCMA TCEs, thereby offering critical insights for optimizing therapeutic strategies to overcome specific high-risk features and primary anti-BCMA TCE refractoriness.

A metronomic, low-dose schedule of decitabine and venetoclax was safe and effective in myeloid malignancies with few dose reductions or interruptions in an older diverse population. Median overall survival for patients with acute myeloid leukemia and a TP53-mutation was 16.1 and 11.3 months, respectively. This trial was registered at www.clinicaltrials.gov as #NCT05184842.

Telomere biology disorders (TBDs), caused by pathogenic germ line variants in telomere-related genes, present with multiorgan disease and a predisposition to cancer. Clonal hematopoiesis (CH) as a marker of cancer development and survival in TBDs is poorly understood. Here, we characterized the clonal landscape of a large cohort of 207 patients with TBD with a broad range of age and phenotype. CH occurred predominantly in symptomatic patients and in signature genes typically associated with cancers: PPM1D, POT1, TERT promoter (TERTp), U2AF1S34, and/or TP53. Chromosome 1q gain (Chr1q+) was the commonest karyotypic abnormality. Clinically, multiorgan involvement and CH in TERTp, TP53, and splicing factor genes were associated with poorer overall survival. Chr1q+ and splicing factor or TP53 mutations significantly increased the risk of hematologic malignancies, regardless of clonal burden. Chr1q+ and U2AF1S34 mutated clones were premalignant events associated with the secondary acquisition of mutations in genes related to hematologic malignancies. Similar to the known effects of Chr1q+ and TP53-CH, functional studies demonstrated that U2AF1S34 mutations primarily compensated for aberrant upregulation of TP53 and interferon pathways in telomere-dysfunctional hematopoietic stem cells, highlighting the TP53 pathway as a canonical route of malignancy in TBD. In contrast, somatic POT1/PPM1D/TERTp mutations had distinct trajectories unrelated to cancer development. With implications beyond TBD, our data show that telomere dysfunction is a strong selective pressure for CH. In TBD, CH is a poor prognostic marker associated with worse overall survival. The identification of key regulatory pathways that drive clonal transformation in TBD allows for the identification of patients at a higher risk of cancer development.

Venetoclax (VEN) received full approval in October 2020 for use in older patients who are unfit with acute myeloid leukemia (AML) combined with either hypomethylating agents or low-dose cytarabine. This ended a semicentennial of stalled clinical progress and initiated a new treatment option with proven capacity to enhance response and prolong survival in older patients with AML. Despite widespread use of azacitidine-VEN (AZA-VEN), there is increasing appreciation that this regimen is myelosuppressive and associated with a higher risk of infectious complications than AZA alone. Key principles of initial management include prevention of tumor lysis syndrome in patients at high risk and minimizing infectious complications during induction. In the postremission phase, limiting cumulative marrow suppression by allowing sufficient time between cycles for optimal marrow recovery and truncating the duration of VEN exposure for those with delayed blood count recovery have emerged as important axioms of effective care. This article casts a clinical spotlight on important challenges and dilemmas encountered in practice. We also outline a structured framework to assist in the safe management of AZA-VEN in the clinic.

Oncogenes can be activated in cis through multiple mechanisms including enhancer hijacking events and noncoding mutations that create enhancers or promoters de novo. These paradigms have helped parse somatic variation of noncoding cancer genomes, thereby providing a rationale to identify noncanonical mechanisms of gene activation. Here we describe a novel mechanism of oncogene activation whereby focal copy number loss of an intronic element within the FTO gene leads to aberrant expression of IRX3, an oncogene in T-cell acute lymphoblastic leukemia (T-ALL). Loss of this CTCF-bound element downstream to IRX3 (+224 kb) leads to enhancer hijack of an upstream developmentally active super-enhancer of the CRNDE long noncoding RNA (-644 kb). Unexpectedly, the CRNDE super-enhancer interacts with the IRX3 promoter with no transcriptional output until it is untethered from the FTO intronic site. We propose that "promoter tethering" of oncogenes to inert regions of the genome is a previously unappreciated biological mechanism preventing tumorigenesis.

At least 25% to 35% of patients with large B-cell lymphoma (LBCL) are not cured with frontline treatment, with generally poor subsequent outcomes. This motivates ongoing and intense interest in improving the frontline treatment of this disease. R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) has remained the standard of care for 20 years despite dozens of trials aiming to improve upon this regimen, and only recently has a novel regimen (pola-R-CHP [polatuzumab vedotin, rituximab, cyclophosphamide, doxorubicin, and prednisone]) challenged its supremacy. Fortunately, at least 15 promising randomized trials evaluating new treatments in frontline LBCL treatment are underway. They differ not only in the therapy evaluated in the experimental arm, but in the choice of control arm, primary end point, and patient selection strategy, with some targeting specific biologic subtypes, some focusing on specific high-risk patient populations, and others enrolling older or frail patients. Novel response-adapted strategies leveraging circulating tumor DNA are also underway. Although this variety of approaches provides a welcome increase in the overall likelihood of success, it will also present challenges if several of these trials are successful and we must choose among multiple potential treatment options that were not all tested in the same fashion. In this review, we summarize the main ongoing frontline randomized trials and discuss some of the questions that we will face in interpreting and applying their results in clinical practice in the next few years.