Acute myeloid leukemia (AML) is an aggressive myeloid malignancy with a poor prognosis. Venetoclax (Ven), a BCL2 inhibitor, has shown promising results but often leads to relapse due to mitochondrial dysregulation, particularly due to upregulation of the anti-apoptotic protein MCL1. Overexpression of the transcription factor STAT3 has been linked to poor survival in AML patients. Overexpression of STAT3 in a transgenic murine model induces a myeloid malignancy with a short latency period and inflammatory upregulation. The current study identifies STAT3 upregulation as a key mechanism of Ven resistance. A clinically relevant STAT3 degrader effectively reduces both total and phosphorylated STAT3, corrects mitochondrial structural and functional dysregulation, and induces apoptosis in Ven-resistant AML cell lines. KT-333 significantly decreases STAT3 and MCL1 protein levels and improves survival in Ven-resistant (Ven-Res) AML murine models. In summary, STAT3 hyperactivation is leukemogenic, is further potentiated in Ven-resistance and can be clinically targeted with a novel and specific STAT3 degrader. Pictorial representation depicting upregulation of STAT3 and MCL1 in venetoclax resistant myeloid malignancies such as MDS and AML causing mitochondrial structural abnormalities and dysfunction. By using specific STAT3 degrader, STAT3 inhibition, and thereby indirect downregulation of MCL1 can be a promising therapeutic intervention to target drug resistant clones in MDS and AML.

Multiple myeloma (MM) resistant to CD38 antibodies, two immunomodulatory drugs (IMiDs), two proteasome inhibitors (PIs), and both BCMA- and GPRC5D-directed immunotherapies defines hepta-refractory MM, a novel end-stage entity. In a multi-center cohort of 37 patients, median overall survival was 12.8 months, with progression-free survival across salvage therapy lines of only 2.7-3.7 months. Whole genome sequencing (WGS) revealed frequent biallelic tumor suppressor gene events, particularly TP53, consistent with proliferative, apoptosis-resistant disease. Genomic alterations linked to IMiD, BCMA, GPRC5D, and CD38 resistance occurred in 71%, 41%, 35%, and 12% of patients, respectively. Almost one-third of patients showed concurrent loss of BCMA (TNFRSF17) and GPRC5D. Sequential WGS demonstrated branching evolutionary trajectories with multiple distinct TNFRSF17 and GPRC5D variants arising within individual patients, pointing to a hidden reservoir of persistent clones with ongoing mutational processes even after deep remissions. Immunohistochemistry (IHC) confirmed loss of BCMA expression caused by biallelic TNFRSF17 genomic events but also revealed loss of expression attributable to other mechanisms. Importantly, BCMA status predicted benefit from BCMA re-treatment. Hepta-refractory MM is marked by profound genomic complexity, antigen loss, and poor outcomes, highlighting the need for novel therapies and broader diagnostics such as integrated genomic and IHC testing for this ultra-refractory population.

Deleterious germline DDX41 variants are the leading cause of heritable predisposition to myelodysplastic neoplasia and acute myeloid leukemia (MDS/AML). Accurate classification of pathogenicity is crucial for managing patients and their families. The absence of specific guidelines, along with late-onset disease, incomplete penetrance, and founder variants, poses challenges in clinical and laboratory practice. We aggregated a synthetic cohort (ASC) of DDX41 germline and somatic variants from 35 studies, including 1796 cases among 53686 patients, plus an additional 832 cases from non-cohort publications. We aimed to leverage the DDX41-ASC to develop and refine ACMG/AMP criteria on case enrichment (PS4), somatic associations (PP4), and computational prediction (PP3/BP4). Analysis confirmed that deleterious germline DDX41 variants are most common in MDS/AML. A quasi-case-control study with ancestry matching revealed overestimated odds ratios for variants in underrepresented groups. Exploiting germline-somatic associations, we developed a Bayesian multinomial model that updates the odds of pathogenicity based on the presence and number of somatic patterns. Comparison of prediction tools showed that AlphaMissense outperformed REVEL in sensitivity. These results were integrated into an online tool to facilitate the consistent application of criteria. Overall, this comprehensive analysis of DDX41-ASC provides an evidence framework to inform the development of DDX41-specific curation guidelines.

Aggressive B-cell lymphomas, driven by MYC overexpression, exhibit rapid progression, resistance to therapies, and poor survival. While chimeric antigen receptor (CAR)-engineered T cells have demonstrated remarkable clinical efficacy in B-cell lymphomas, nearly half of patients who initially respond to CAR-T therapy eventually develop resistance and disease progression. In this study, we report the presence of residual drug-tolerant persister (DTP) and resistant lymphoma cells remaining within a highly immunogenic tumor microenvironment (TME) induced by the MCL-1 inhibitor (MCL-1i) S63845. MCL-1 inhibition downregulates MYC and activates the STAT1-interferon inflammatory pathway, promoting cytotoxic T-cell infiltration with reduced tumor-associated myeloid cells both in vitro and in vivo. Sublethal dose of the MCL-1i enhances TME immunogenicity and reawakens anti-tumor immune responses in murine models. We show that MCL-1i and CD19-targeted CAR-T cells reciprocally overcome resistance to each single-agent therapy, and combining MCL-1i with CD19 CAR-T cells significantly improves treatment efficacy, resulting in near-complete eradication of MYC-driven lymphoma in vivo. Together, these findings highlight a synergistic, dual-pronged therapeutic strategy targeting both tumor-intrinsic survival pathways and the immunosuppressive TME. This combinatorial one-two-punch approach offers a promising path to eliminate DTP and residual disease, prevent relapse and pave the way for deep clinical remissions in aggressive B-cell lymphomas.