Kumar, Shaji

Abstract Introduction Detecting genetic abnormalities is mandatory during diagnostic workup and for potential individualization of therapy selection in multiple myeloma (MM) and its precursor conditions. At present, this requires invasive bone marrow (BM) biopsies, severely limiting early detection, patient monitoring, and the precise selection of therapy. The current standard for detecting genetic alterations in MM is fluorescence in situ hybridization (FISH), which cannot detect point mutations and other clinically relevant alterations. Consequently, the IMS-IMWG guidelines were recently updated to require next-generation sequencing for the classification of high-risk MM. Moreover, the importance of identifying alterations in therapeutic targets (e.g., BCMA, GPRC5D) for guiding immunotherapies is becoming increasingly recognized. To address this need, we recently launched GenoPredicta, a CLIA-approved Laboratory Developed Test that enables routine monitoring, informing diagnosis, and treatment selection by comprehensively and robustly characterizing MM genomes with whole genome sequencing (WGS) from a minimum of ~50 circulating tumor cells (CTCs) isolated from peripheral blood (PB) or tumor cells from BM. Here, we describe the characterization of clinical and research samples with GenoPredicta, highlighting resistance-conferring genetic alterations that can only be detected by sequencing and that are consistent with patients' clinical histories, while further demonstrating the complete concordance of GenoPredicta with prior FISH results. Methods Tumor cells were isolated from BM and/or PB samples using fluorescence-activated cell sorting (FACS) (after CD138+ enrichment for PB) and subjected to whole genome sequencing (WGS), from which we identified copy number alterations, structural variants, and single nucleotide variants and indels. For a subset of samples, the BM was also characterized by FISH, using a standard clinical panel for characterizing MM; for other samples prior FISH results were available from patients' clinical records. Results The analytical validation of GenoPredicta, conducted on a retrospective cohort of >60 viably frozen samples from >30 patients, showed complete concordance between BM and PB for detected genomic abnormalities, with all clinically relevant events (11 translocations and 125 CNVs) observed in BM recapitulated in PB (100% recall). All events identified by FISH in 14 samples (8 translocations and 30 CNVs) were also identified in the BM (100% recall), with 50 translocations and 30 CNVs not detected by FISH also absent in the WGS data (100% precision). The abnormalities detected in these samples also included multiple high-risk events not assayed by FISH, including biallelic TP53 loss (Del 17p coupled with a deleterious TP53 mutation, observed in 4 patients) and MYC::IGL translocations (2 patients). Moreover, for all fresh peripheral blood clinical samples with FISH results available from patients' histories, GenoPredicta recalled 100% of reported events. Among these clinical samples, we notably observed a case with both a biallelic GPRC5D deletion and a TNFRSF17 (BCMA) deletion combined with a truncating mutation on the remaining allele. This was consistent with the patient's clinical history showing progression after therapy with talquetamab (anti-GPRC5D bispecific), and previous nonresponse to teclistamab (anti-BCMA bispecific) after prior therapy with Cilta-cel (BCMA-directed CAR T). GenoPredicta also detected other mutations likely to confer resistance to immunotherapies, including loss-of-function mutations in IKZF3 and deletions of FCRL5 in frozen peripheral blood research samples. Conclusion We demonstrate that WGS-based characterization of MM from BM or CTCs is a viable replacement for FISH for clinical diagnosis and monitoring, with blood-based measurements enabling comprehensive profiling of the myeloma cancer genome. Importantly, this includes genetic alterations that confer resistance to therapy, allowing for both early detection of such alterations and more precise selection of therapy.

Abstract Multiple myeloma (MM) is the second-most common hematological malignancy in the United States. Myeloma tumors have significant genetic heterogeneity that impacts disease progression and promotes resistance to treatment. RAS is a key oncogenic driver that activates the mitogen-activated protein kinase (MAPK) and the phosphatidylinositol 3-kinase (PI3K)/AKT pathways..Mutations in genes that code for RAS isozymes, KRAS, HRAS, or NRAS, lead to increased levels of activated GTP-RAS and are associated with the most aggressive forms of cancer. Mutations in the RAS family of genes are most common (40-50%) in myeloma. We and others have reported that RAS mutations may not be disease-initiating but rather arise during disease progression and relapse or as subclonal events that impart selective growth advantage and emerging drug resistance. In addition, non-mutant RAS can also be hyperactivated from upstream signaling (like receptor tyrosine kinases) or loss-of-function mutations in GTPase-activating proteins (GAPs). Given the importance of RAS mutations, allele-specific RAS inhibitors have long been considered an attractive strategy for myeloma treatment. However, multiple studies have reported various mechanisms of resistance to allele-specific RAS inhibitors as well as isoform-specific pan-RAS inhibitors, including newly acquired activating RAS mutations, RAS amplification, unchecked activation of co-expressed wild-type RAS (WT-RAS) isozymes, or acquired bypass mechanisms like new oncogenic fusions. Since MM remains incurable, we sought to improve upon currently available treatments by developing small-molecule inhibitors that preferentially inhibit myeloma cells with activated RAS isozymes. We have created NRasQ61X and KRasG12X mutations by CRISPR-Cas directed edits in a single endogenous RAS allele in human myeloma cell lines (HMCLs) that initially had two wild-type alleles. We found that these mutant-NRAS and mutant-KRAS edited cells have increased proliferation compared to cells with WT-RAS, as well as acquired resistance to several commonly used therapeutics. In this study, we used a triangulation method that combines our drug combination candidate prediction algorithm called ‘secDrug’ and the ‘Direct to Drug’ screening platform that evaluated 84 FDA-approved oncology drugs and emerging therapeutics in these RAS mutant myeloma lines. We identified BIRC5 as a potential target for RAS-mutant myeloma. BIRC5 expression is a key mechanism for the evasion of apoptosis. Notably, oncogenic RAS has been shown to promote MYC stabilization via upregulation of BIRC5. Earlier studies suggested that BIRC5 inhibitors are potent in targeting drug-resistant subclones in hematological malignancies. We performed in vitro cytotoxicity studies and cell-based assays using an in-house panel of HMCLs (n>50) representing WT- and mutant-RAS, as well as innate and acquired response/resistance to the standard of care drugs, proteasome inhibitors (PIs) and immunomodulatory drugs (IMiDs), to confirm the potency of novel selective BIRC5 inhibitors, as single agent (IC50 range 0.22-15.30 nM; Mean 4.431±1.041 nM) and in combination with PIs and IMiDs (Chou-Talalay's Combination Index or CI <0.3, indicating strong synergism). Further, we used bulk and single-cell whole-transcriptomics, siRNA-mediated gene knockdown studies, and functional validation to characterize the treatment-induced genes and molecular pathways underpinning the mechanism of action and drug synergy at the subclone level. Finally, we compared the efficacy of these BIRC5 inhibitors against several RAS inhibitors, including cyclorasin B4-27, a bicyclic peptidyl pan-RAS inhibitor, RMC-6236, a multi-selective noncovalent RAS(on) inhibitor, and ADT-007, a novel, highly potent, and selective pan-RAS inhibitor that we have synthesized, and observed comparable effects on cell death and apoptosis. Ex vivo analysis in bone marrow-derived CD138+ cells from myeloma patients using high-throughput Mass Cytometry (CyTOF or Cytometry by Time-Of-Flight) confirmed the dose-dependent reduction of MCL1, Ki-67, CCND1, c-KIT, and MYC. We will present these results that demonstrate the clinical potential of BIRC5 inhibitors as novel candidates in curbing progression and drug resistance in RAS-mutant myeloma.

7541 Background: Multiple myeloma (MM) is characterized by recurrent cytogenetic abnormalities, including translocations involving the immunoglobulin heavy chain locus on chromosome 14 and trisomies, which are considered primary and clonal. Throughout disease progression, MM cells may acquire additional abnormalities, which include chromosome 1 abnormalities (gain or amplification of 1q or deletion of 1p) and chromosome 17 abnormalities (del 17p or monosomy 17p). All these factors are considered high-risk markers that predict below-average outcomes. While outcomes related to 1q have been documented, their relationship with other abnormalities and clinical characteristics is less clearly defined. Methods: We created a cohort of newly diagnosed MM (NDMM) patients from April 1996 to December 2023 for whom FISH testing was performed using a panel that included 1q findings. Data on clinical and laboratory characteristics, other FISH abnormalities, and survival outcomes were collected from existing databases and the electronic medical record (EMR). Results: The cohort included 875 patients, with a median age of 65. Of these patients, 60% were male and 91% identified as white. A 1q abnormality was observed in 443 patients (51%); 87% exhibited a gain of 1q, while 13% showed amplification of 1q. Among those tested, other abnormalities included del13 (58%), t(11;14) (25%), t(4;14) (17%), t(14;16) (6%), del 17p (13%), and trisomies (51%). The distribution of abnormalities concerning the presence of 1q is presented in the table. Patients with 1q abnormalities were more likely to present with additional high-risk cytogenetic abnormalities. The median overall survival (OS) for those with a 1q abnormality was 73 months, compared to 105 months for those without it. Among these, patients with 1q amplification tended to have worse outcomes than those with a 1q gain, though this observation did not reach statistical significance. Conclusions: Abnormalities of chromosome 1, including 1q gain and amplification, can be seen in nearly 50% of patients with NDMM who are tested. 1q abnormalities are associated with other high-risk cytogenetic abnormalities. Measures of disease burden are higher among those with a 1q abnormality. Interestingly, we observed a higher proportion of patients with lambda light chain and those with IgA among those with a 1q abnormality. The presence of a 1q abnormality was associated with inferior survival, with a trend towards worse outcomes among those with 1q amplification compared to 1q gain. Clinical characteristics and cytogenetic associations of multiple myeloma patients with and without 1q abnormalities. 1q abnormality present 1q abnormality absent P del13 78% 39% <0.01 t(4;14) 25% 8% <0.01 t(11;14) 22% 27% NS t(14;16) 15% 3% <0.01 Trisomies 48% 53% NS 17p del 24% 12% <0.01 Lambda light chain 45% 26% <0.01 IgA 32% 16% <0.01 Hemoglobin 10.3 g/dL 11.2 g/dL <0.01

7522 Background: Movement and neurocognitive treatment emergent adverse events (MNTs), cranial nerve palsies (CNPs) and immune-effector cell enterocolitis (IEC-EC) are late onset toxicities associated with cilta-cel and are associated with significant morbidity and mortality. We aimed to identify predisposing risk factors to allow for formulating risk-reduction strategies. Methods: Retrospective study of MM pts who received FDA approved cilta-cel at Mayo Clinic between Feb 2022-Dec 2024. Interrogated factors included demographics, disease and treatment characteristics, and selected lab values at different time points. In odds ratio (OR) analyses, pts were divided by toxicity type (1) No delayed toxicity (2) MNT (3) IEC-EC without MNT (4) isolated CNP. Differences between pts in the MNT, IEC-EC and CNP groups were compared separately in a pairwise manner vs. those with no delayed toxicity. Results: Of 235 pts, 26 (11%) had delayed toxicity [MNT = 8 (3%), IEC-EC = 9 (4%), CNP = 14 (6%)]; 3 pts had both MNT/IEC-EC and 2 had both CNP/IEC-EC. Median onset from CAR-T infusion for MNT, IEC-EC and CNP was 19 (range 8-96), 106 (35-169) and 21 (7-43) days respectively. Of 164 evaluable pts, those who had ICANS had increased odds for any delayed toxicity (OR 4.7; 95% CI 1.6-13.8). Pts who had ICANS (OR 7.7; 1.6-36.9), HLH/MAS (OR 6.2; 1.1-6.7) and Ferritin >400mcg/L at time of lymphodepletion (OR 6.3; 1.5-32) had increased odds for MNTs. Pts who received alkylator-based bridging therapy had increased odds (OR 6.1; 1.1-35) for IEC-EC. Analysis of serial post-CAR infusion lab values showed that peak ALC was the most significant variable with differences between groups shown in table. Median time to peak ALC was 12 days (IQR 11-13). ROC analysis determined peak ALC >3 x 10 9 /L as a meaningful cut point. Pts with peak ALC >3.0 x 10 9 /L had increased odds of developing any delayed toxicity (OR 9.3; 3.5-29.3), MNT and CNP (table). Absolute risk of any delayed toxicity was 33% in pts with peak ALC >3 x 10 9 /L vs 5% without. At this threshold, number needed to treat was 3.6. Conclusions: Real-world data shows that cilta-cel associated delayed toxicity is seen in ~10% of patients, with specific toxicity rates between 4-8%. Factors associated with these toxicities predominantly occur in the post CAR-T infusion period. Given that ALC expansion in the first 2 weeks correlate with CAR-T expansion, peak ALC is potentially predictive of toxicity and 3 x 10 9 /L may be an interventional threshold for primary prophylaxis. Peak ALC by toxicity groups. No ToxN=138 MNTN=8 CNPN=12 IEC-ECN=6 p value Peak ALC (10 9 /L), median (IQR) 1.8 (1.0-4.1) 6.2 (4.8-14.4) 4.3 (3.2-6.7) 3.6 (1.9-5.2) <0.001 1 ALC >3 x 10 9 /L, n (%) 43 (31%) 7 (88%) 10 (83%) 4 (67%) <0.001 2 Odd Ratios vs no Tox 3 , 95% CI 15.5 (2.6-293.7) 11.0 (2.8-73.9) 4.4 (0.8-25.0) 1 Wilcoxon/Kruskal-Wallis Tests, 2 Chi square test, 3 Logistic regression analysis.

e18356 Background: Carfilzomib plus dexamethasone (Kd) dosed once weekly at 70 mg/m2 (QW Kd70) was recently approved in the US for treating patients with relapsed and refractory multiple myeloma (RRMM). To assess the cost-effectiveness (CE) of QW Kd70 vs twice weekly Kd dosed at 27 mg/m2 (BIW Kd27), data from the phase 3 ARROW trial, which directly compared these regimens in patients with 2-3 prior lines of therapy were used. Methods: A partitioned survival model was developed for the CE analysis. Time to treatment discontinuation, progression-free survival, and overall survival (OS) were estimated from the ARROW trial. Long-term OS was extrapolated using Surveillance Epidemiology and End Results registry data after matching characteristics of patients in the registry and ARROW trial. Direct costs were estimated from a US health care payer perspective. Utilities collected in the ARROW trial using the five-level version of the EuroQol questionnaire (EQ-5D-5L) were applied to estimate the quality-adjusted life years (QALYs). Uncertainty was explored using sensitivity analyses. Two subgroups of patients refractory to lenalidomide or bortezomib were assessed. Main outcomes were mean life-years (LYs), QALYs, lifetime costs, and incremental cost-effectiveness ratios (ICERs). Results: For QW Kd70 and BIW Kd27, the model predicted mean LYs of 4.17 and 3.07 years, QALYs of 2.98 and 2.03 years, and mean total lifetime costs of $444,563 and $373,364, respectively. The incremental LYs gain, QALY gain, and incremental costs of QW Kd70 vs BIW Kd27 were estimated to be 1.10 years, 0.95 year, and $71,199, respectively, resulting in an ICER of $64,595 per LY gained and $75,204 per QALY gained. For patients refractory to lenalidomide and bortezomib, similar results were found with ICERs of $79,988 and $76,793, respectively. Conclusions: In line with ARROW trial results, this CE analysis showed that QW Kd70 is expected to provide considerable additional benefit in terms of LYs and QALYs gained compared with BIW Kd27. In the RRMM setting, QW Kd70 is cost-effective with ICERs below accepted willingness to pay thresholds in US and represents an efficient utilization of the health care budget.