Loss of GABARAP mediates resistance to immunogenic chemotherapy in multiple myeloma.

Immunogenic cell death (ICD) is a form of cell death by which cancer treatments can induce a clinically relevant anti-tumor immune response in a broad range of cancers. In multiple myeloma (MM), the proteasome inhibitor bortezomib is an ICD inducer and creates durable therapeutic responses in patients. However, eventual relapse and resistance to bortezomib appear inevitable. Here, by integrating patient transcriptomic data with an analysis of calreticulin (CRT) protein interactors, we found that GABARAP is a key player whose loss prevented tumor cell death from being perceived as immunogenic after bortezomib treatment. GABARAP is located on chromosome 17p, which is commonly deleted in high-risk MM patients. GABARAP deletion impaired the exposure of the eat-me signal CRT on the surface of dying MM cells in vitro and in vivo, thus reducing tumor cell phagocytosis by dendritic cells and the subsequent anti-tumor T cell response. Low GABARAP was independently associated with shorter MM patient survival and reduced tumor immune infiltration. Mechanistically, we found that GABARAP deletion blocked ICD signaling by decreasing autophagy and altering Golgi apparatus morphology, with consequent defects in the downstream vesicular transport of CRT. Conversely, upregulating autophagy using rapamycin restored Golgi morphology, CRT exposure and ICD signaling in GABARAPKO cells undergoing bortezomib treatment. Therefore, coupling an ICD inducer, like bortezomib, with an autophagy inducer, like rapamycin, may improve patient outcomes in MM, where low GABARAP in the form of del(17p) is common and leads to worse outcomes.

Round Table Discussion on Optimal Clinical Trial Design in Precursor Multiple Myeloma.

SUMMARY: While the current approach to precursor hematologic conditions is to "watch and wait," this may change with the development of therapies that are safe and extend survival or delay the onset of symptomatic disease. The goal of future therapies in precursor hematologic conditions is to improve survival and prevent or delay the development of symptomatic disease while maximizing safety. Clinical trial considerations in this field include identifying an appropriate at-risk population, safety assessments, dose selection, primary and secondary trial endpoints including surrogate endpoints, control arms, and quality-of-life metrics, all of which may enable more precise benefit-risk assessment.

DAMPening Tumor Immune Escape: The Role of Endoplasmic Reticulum Chaperones in Immunogenic Chemotherapy.

Significance: Preclinical and clinical research in the past two decades has redefined the mechanism of action of some chemotherapeutics that are able to activate the immune system against cancer when cell death is perceived by the immune cells. This immunogenic cell death (ICD) activates antigen-presenting cells (APCs) and T cells to induce immune-mediated tumor clearance. One of the key requirements to achieve this effect is the externalization of the damage-associated molecular patterns (DAMPs), molecules released or exposed by cancer cells during ICD that increase the visibility of the cancer cells by the immune system. Recent Advances: In this review, we focus on the role of calreticulin (CRT) and other endoplasmic reticulum (ER) chaperones, such as the heat-shock proteins (HSPs) and the protein disulfide isomerases (PDIs), as surface-exposed DAMPs. Once exposed on the cell membrane, these proteins shift their role from that of ER chaperone and regulator of Ca2+ and protein homeostasis to act as an immunogenic signal for APCs, driving dendritic cell (DC)-mediated phagocytosis and T-mediated antitumor response. Critical Issues: However, cancer cells exploit several mechanisms of resistance to immune attack, including subverting the exposure of ER chaperones on their surface to avoid immune recognition. Future Directions: Overcoming these mechanisms of resistance represents a potential therapeutic opportunity to improve cancer treatment effectiveness and patient outcomes.

Epigenetic regulation of CD38/CD48 by KDM6A mediates NK cell response in multiple myeloma.

Anti-CD38 monoclonal antibodies like Daratumumab (Dara) are effective in multiple myeloma (MM); however, drug resistance ultimately occurs and the mechanisms behind this are poorly understood. Here, we identify, via two in vitro genome-wide CRISPR screens probing Daratumumab resistance, KDM6A as an important regulator of sensitivity to Daratumumab-mediated antibody-dependent cellular cytotoxicity (ADCC). Loss of KDM6A leads to increased levels of H3K27me3 on the promoter of CD38, resulting in a marked downregulation in CD38 expression, which may cause resistance to Daratumumab-mediated ADCC. Re-introducing CD38 does not reverse Daratumumab-mediated ADCC fully, which suggests that additional KDM6A targets, including CD48 which is also downregulated upon KDM6A loss, contribute to Daratumumab-mediated ADCC. Inhibition of H3K27me3 with an EZH2 inhibitor resulted in CD38 and CD48 upregulation and restored sensitivity to Daratumumab. These findings suggest KDM6A loss as a mechanism of Daratumumab resistance and lay down the proof of principle for the therapeutic application of EZH2 inhibitors, one of which is already FDA-approved, in improving MM responsiveness to Daratumumab.

Isatuximab-pomalidomide-dexamethasone versus pomalidomide-dexamethasone in patients with relapsed and refractory multiple myeloma: final overall survival analysis.

The primary and pre-specified updated analyses of ICARIA-MM (NCT02990338) demonstrated improved progression-free survival and a benefit in overall survival (OS) was reported with the addition of isatuximab, an anti-CD38 monoclonal antibody, to pomalidomide-dexamethasone (Pd) in patients with relapsed/refractory multiple myeloma. Here, we report the final OS analysis. This multicenter, randomized, open-label, phase 3 study included patients who had received and failed ≥2 previous therapies, including lenalidomide and a proteasome inhibitor. Between January 10, 2017, and February 2, 2018, 307 patients were randomized (1:1) to isatuximab-pomalidomide- dexamethasone (Isa-Pd; n = 154) or Pd (n = 153), stratified based on age (3). At data cutoff for the final OS analysis after 220 OS events (January 27, 2022), median follow-up duration was 52.4 months. Median OS (95% confidence interval) was 24.6 months (20.3-31.3 months) with Isa-Pd and 17.7 months (14.4-26.2 months) with Pd (hazard ratio = 0.78; 95% CI, 0.59-1.02; 1-sided P = 0.0319). Despite subsequent daratumumab use in the Pd group and its potential benefit on PFS in the first subsequent therapy line, median PFS2 was significantly longer with Isa-Pd vs. Pd (17.5 vs. 12.9 months; log-rank 1-sided P = 0.0091). In this analysis, Isa-Pd continued to be efficacious and well tolerated after follow-up of approximately 52 months, contributing to a clinically meaningful, 6.9-month improvement in median overall survival in patients with relapsed/refractory multiple myeloma.

Development and validation of an individualized and weighted Myeloma Prognostic Score System (MPSS) in patients with newly diagnosed multiple myeloma.

Current standard predictive models of disease risk do not adequately account for the heterogeneity of survival outcomes in patients with new-diagnosed multiple myeloma (NDMM). In this retrospective, multicohort study, we collected clinical and genetic data from 1792 NDMM patients and identified the prognostic impact of all features. Using the top-ranked predictive features, a weighted Myeloma Prognostic Score System (MPSS) risk model was formulated and validated to predict overall survival (OS). In the training cohort, elevated lactate dehydrogenase level (LDH), International Staging System (ISS) Stage III, thrombocytopenia, and cumulative high-risk cytogenetic aberration (HRA) numbers were found to have independent prognostic significance. Each risk factor was defined as its weighted value respectively according to their hazard ratio for OS (thrombocytopenia 2, elevated LDH 1, ISS III 2, one HRA 1, and ≥2 HRA 2, points). Patients were further stratified into four risk groups: MPSS I (22.5%, 0 points), II (17.6%, 1 points), III (38.6%, 2-3 points), and IV (21.3%, 4-7 points). MPSS risk stratification showed optimal discrimination, as well as calibration, of four risk groups with median OS of 91.0, 69.8, 45.0, and 28.0 months, for patients in MPSS I to IV groups (p < .001), respectively. Importantly, the MPSS model retained its prognostic value in the internal validation cohort and an independent external validation cohort, and exhibited significant risk distribution compared with conventional prognostic models (R-ISS, R2-ISS, and MASS). Utilization of the MPSS model in clinical practice could improve risk estimation in NDMM patients, thus prompting individualized treatment strategies.

Longitudinal genetically detectable minimal residual disease by fluorescence in situ hybridization confers a poor prognosis in myeloma.

Background: Deeper depth of response (DpR) after induction therapy, especially gain of negative minimal residual disease (MRD), has been linked to prolonged survival in multiple myeloma (MM). However, flow-MRD examination focuses on the numbers but not on the biological characteristics of residual plasma cells (PCs). Objectives: To explore whether the genetic features of residual tumor cells affect the survival time of patients with MM. Design: A retrospective cohort study. Methods: We investigated the clonality of cytogenetic abnormalities (CAs) of the residual PCs using interphase fluorescence in situ hybridization (iFISH) in the National Longitudinal Cohort of Hematological Diseases in China (NCT04645199). Here, a longitudinal cohort of 269 patients with patient-paired diagnostic and post-induction iFISH results was analyzed. Results: Persistent CAs after induction therapy were detected in about half of the patients (118/269, 43%), and patients with undetectable CAs showed significantly improved survival compared with those with genetically detectable MRD [median progression-free survival (mPFS): 59.7 versus 35.7 months, p < 0.001; median overall survival (mOS): 97.1 versus 68.8 months, p = 0.011]. In addition, different patterns of therapy-induced clonal evolution were observed by comparing the clonal structure of residual PCs with paired baseline samples. Patients who maintained at a high risk during follow-up had the worst survival (mPFS: 30.5 months; mOS: 54.4 months), while those who returned to lower risk or had iFISH- at both time points had the best survival (mPFS: 62.0 months, mOS: not reached). Conclusion: These findings highlighted the prognostic value of genetic testing in residual tumor cells, which may provide a deep understanding of clonal evolution and guide clinical therapeutic strategies.

Study using fluorescence in situ hybridization (iFISH) to investigate the clonality of cytogenetic abnormalities of the residual plasma cells in multiple myeloma Gain of negative minimal residual disease (MRD) has been linked to prolonged survival in cancer treatment. However, in multiple myeloma (MM), detection of MRD-negativity (MRD-) using multiparameter flow cytometry (MFC) only reflects the quantitative characteristics of residual plasma cells (PCs), while the biological and genetic features of MRD are neglected. To address this gap, our study has employed interphase fluorescence in situ hybridization (iFISH) to evaluate the clonality of cytogenetic abnormalities (CAs) of the bone marrow residual PCs after induction therapy, in combined with MRD detection by MFC to predict the prognosis of MM patients. A total of 396 patients from the database of National Longitudinal Cohort of Hematological Diseases in China (ClinicalTrials.gov identifiers: NCT04645199) were enrolled. Persistent CAs after induction therapy were detected in about half of the patients (118/269, 43%), and patients with undetectable CAs showed significantly improved survival compared with those without genetically detectable MRD. In addition, different patterns of therapy-induced clonal evolution were observed by comparing the clonal structure of residual PCs with paired baseline samples. And therapy-induced clonal evolution exerted a significant impact on patient outcomes. These findings highlighted the importance of genetic testing of residual tumor cells after induction therapy, which may represent a reliable complementary technique for flow-MRD detection and provide a further understanding of clonal evolution.