Broijl, Annemiek

Abstract Outcomes are poor in triple-class–exposed (TCE) relapsed and refractory multiple myeloma (R/RMM). In the phase 3 KarMMa-3 trial, patients with TCE R/RMM and 2 to 4 prior regimens were randomized 2:1 to idecabtagene vicleucel (ide-cel) or standard regimens (SRs). An interim analysis (IA) demonstrated significantly longer median progression-free survival (PFS; primary end point; 13.3 vs 4.4 months; P < .0001) and higher overall response rate (ORR) with ide-cel vs SRs. At final PFS analysis (median follow-up, 30.9 months), ide-cel further improved median PFS vs SRs (13.8 vs 4.4 months; hazard ratio [HR], 0.49; 95% confidence interval [CI], 0.38-0.63). PFS benefit with ide-cel vs SRs was observed regardless of number of prior lines of therapy, with greatest benefit after 2 prior lines (16.2 vs 4.8 months, respectively). ORR benefit was maintained with ide-cel vs SRs (71% vs 42%; complete response, 44% vs 5%). Patient-centric design allowed crossover from SRs (56%) to ide-cel upon progressive disease, confounding overall survival (OS) interpretation. At IA of OS, median was 41.4 (95% CI, 30.9 to not reached [NR]) vs 37.9 (95% CI, 23.4 to NR) months with ide-cel and SRs, respectively (HR, 1.01; 95% CI, 0.73-1.40); median OS in both arms was longer than historical data (9-22 months). Two prespecified analyses adjusting for crossover showed OS favoring ide-cel. This trial highlighted the importance of individualized bridging therapy to ensure adequate disease control during ide-cel manufacturing. Ide-cel improved patient-reported outcomes vs SRs. No new safety signals were reported. These results demonstrate the continued favorable benefit-risk profile of ide-cel in early-line and TCE R/RMM. This trial was registered at www.ClinicalTrials.gov as #NCT03651128.

Introduction A single ide-cel infusion showed significantly longer median progression-free survival (PFS) vs std regimens (13.3 vs 4.4 months [mo], HR 0.49, 95% CI 0.38-0.65, P < 0.001) with deep, durable responses in heavily pretreated TCE RRMM at an interim analysis (IA) of KarMMa-3 (NCT03651128); safety data were consistent with prior studies (Rodríguez-Otero et al. NEJM 2023). Ide-cel benefits were consistent across pts in high-risk subgroups and across 2-4 prior lines of therapy (Tx). Results of the preplanned final PFS analysis of KarMMa-3 with 12.3 mo additional follow-up are reported. Methods In the phase 3 KarMMa-3 trial, pts with RRMM who received 2-4 prior regimens, including an immunomodulatory agent, proteasome inhibitor, and daratumumab, and were refractory to last regimen were randomized 2:1 to ide-cel or a std regimen (DPd, DVd, IRd, Kd, or EPd). In the ide-cel arm, pts could receive ≤ 1 cycle of optional bridging Tx for disease control. Pts in the std regimens arm could receive ide-cel after confirmed disease progression (PD). The primary endpoint was IRC-assessed PFS in the ITT population; final PFS was planned to be analyzed with ~289 events. Key secondary endpoints were IRC-assessed overall response rate (ORR) and overall survival (OS); other secondary endpoints included complete response rate (CRR), duration of response (DOR), minimal residual disease (MRD) status, time to next anti-myeloma Tx (TTNT; time from randomization to next anti-myeloma Tx [MTx]), event-free survival (EFS; time from randomization to first PD, next MTx or any-cause death, whichever is first), PFS2 (time from randomization to second objective PD or any-cause death, whichever is first), safety, and health-related quality of life (QOL). Results Of 386 randomized pts (ide-cel, n = 254; std regimens, n = 132), 225 received ide-cel and 126 received a std regimen. Baseline characteristics were generally balanced. Median follow-up from randomization to data cutoff (April 28, 2023) was 30.9 mo (range 12.7-47.8). Ide-cel significantly improved median PFS (95% CI) vs std regimens (13.8 [11.8-16.1] vs 4.4 [3.4-5.8] mo), representing a 51% reduced risk of PD or death (HR 0.49, 95% CI 0.38-0.63; Figure); 18 mo PFS rates were 41% vs 19%, respectively. Ide-cel significantly improved ORR vs std regimens (71% vs 42%) with deeper (CRR 44% vs 5%; ≥CR and MRD negative status [sensitivity level 10 -5], 22% vs 1%), more durable responses (median DOR 16.6 vs 9.7 mo; Table). PFS and ORR benefits of ide-cel vs std regimens were consistent with the IA. Interim OS will be included in the presentation. In pts who received ide-cel (n = 225) or a std regimen (n = 126), median PFS (95% CI) was 15.7 (12.5-18.9) vs 4.4 (3.4-5.8) mo, respectively. In the ITT population, median TTNT, EFS, and PFS2 were numerically longer with ide-cel vs std regimens. Median (range) TTNT was 20.9 (16.6-24.2) vs 7.0 (5.3-8.5) mo. Median (95% CI) EFS was 13.3 (11.3-15.7) vs 3.9 (3.0-5.3) mo. Median PFS2 (95% CI) was 23.5 (18.4-27.9) vs 16.7 (12.2-20.3) mo; ide-cel was next MTx in 70 (53%) pts in the std regimens arm. In the treated population, grade (gr) 3/4 infections occurred in 66/249 (27%) pts in the ide-cel arm vs 25/126 (20%) in the std regimens arm. In the ide-cel safety population, any gr cytokine release syndrome occurred in 197/225 (88%) pts, gr ≥ 3 in 11 (5%); median time to first onset was 1 d (1-14), median duration was 4 d (1-51). Any gr investigator-identified neurotoxicity occurred in 34/225 (15%) pts, gr ≥ 3 in 7 (3%); median time to onset was 3 d (range 1-317); median duration was 2.5 d (range 1-252). Ide-cel continued to demonstrate durable, clinically meaningful improvements in pt-reported outcomes, including symptoms, functioning, and QOL vs std regimens. Conclusions In this final PFS analysis of KarMMa-3, significantly longer PFS was maintained with ide-cel; PD or death risk reduced by 51%; responses were deeper and more durable vs std regimens. CRR with ide-cel increased since the IA, indicating a deepening response, but were unchanged with std regimens. A single ide-cel infusion vs continuous treatment with std regimens resulted in longer median TTNT and PFS2, indicating improved long-term disease control. The ide-cel safety profile was consistent with previous reports, with no parkinsonism or Guillain-Barré syndrome reported. These data continue to support use of ide-cel in pts with TCE RRMM. Study support 2seventy bio and Celgene, a Bristol-Myers Squibb Company.

Abstract Introduction Multiple myeloma (MM) is characterized by a highly variable disease course, which can be traced to initiating and acquired genomic events. Whole exome analysis of matched tumor and germline DNA from 287 MM patients identified recurrently somatically mutated genes (RSMGs) (Lohr et al. - Cancer Cell 2014, Bolli et al. - Nat Commun 2014). Despite the fact that these RSMGs affect pathways that are biologically important in MM, the clinical relevance of many of these genes in the context of conventional prognostic markers remains to be elucidated. Aims The aims of this pilot study were: (1) To validate the prevalence of RSMGs in our newly diagnosed MM patient cohort; (2) To assess the correlation between RSMGs, clinical parameters and outcome; (3) To thereby identify the potential clinical usefulness of introducing RSMG mutational profiling in larger MM trial cohorts. Material and Methods CD138+ enriched MM cells and peripheral blood were obtained with informed consent from chemotherapy-naive patients, participating in 3 clinical trials: HOVON-65/GMMG-HD4, HOVON-87/NMSG-18 and Carthadex (EudraCT number 2004-000944-26, 2007-004007-34 and 2009-014922-40, respectively). Matched tumor and germline DNA were sequenced on an Ion Torrent sequencing platform (PGM, Life Technologies), using the M3 P Mutational Panel v3.0, comprising 1327 customized oligos (Life Technologies), targeted at the coding sequences of 88 MM-relevant genes, including the RSMGs. Somatic mutations were considered positive when present in >=10% of tumor reads and <=10% germline reads, with a minimal coverage of 10x and being non-synonymous, or splice donor variants. All statistical analyses were performed in SPSS version 23, using the log-rank and Mann-Whitney U-test, with the Bonferroni test to correct for multiple comparisons. Results A total of 206 DNA samples were sequenced from 103 patients (HOVON-65/GMMG-HD4 (n=16), HOVON-87/NMSG-18 (n=67), Carthadex (n=20)) with an average coverage of 574x in tumor DNA, 451x in germline DNA and an overall coverage of 98%. We collected follow-up data from 102/103 patients, with a median follow-up time of 30 months. 168 somatic mutations were detected in 44/88 genes. 82% of patients had at least 1 somatic mutation. Genes most frequently mutated were: (1) NRAS (26%), (2) KRAS (22%), (3) DIS3 (14%), (4) FAM46C (9%), (5) TP53 (7%) and (6) BRAF (6%) (Figure 1). Of note, NRAS and KRAS mutations were mutually exclusive in our cohort. Moreover, all TP53 mutations were located in its DNA binding domain. Three out of 6 BRAF mutations were predicted to cause a V600E amino acid change. We focused on these 6 RSMGs in all further analyses. Correlating mutational status with Progression Free Survival (PFS) and Overall Survival (OS) showed that TP53 mutated patients had a significantly shorter PFS compared to those with wildtype TP53 (adj. p-value=0,018; n=7 versus n=95). Comparing the mutational status of the 6 RSMGs, transplant versus non-transplant protocol, number of mutated genes in the M3 P panel, del17p and t(4;14) status, EMC92 score and ISS stage between patients with a PFS <=1 year and >1 year (n=23 versus n=79), only showed a significant correlation with TP53 mutational status (adj. p-value=0,012). TP53 mutational status remained the only significant prognostic factor when comparing patients with an OS <=1 year and >1 year (adj. p-value=0,003; n=13 versus n=89). When comparing the number of mutated genes, del17p and t(4;14) status, EMC92 score, transplant versus non-transplant protocol and ISS stage between TP53 mutated and wildtype MM, TP53 mutated patients had a significantly higher number of mutated genes in the M3 P panel (adj. p-value=0,001). Conclusions (1) With the M3 P Mutational Panel, we confirm the published prevalence of RSMGs in MM in our cohort of chemotherapy-naive patients. NRAS, KRAS, DIS3, FAM46C, TP53 and BRAF are the most frequently mutated genes. (2) TP53 mutational status is the strongest unfavorable prognostic factor in our cohort and it seems to be associated with greater mutational burden. Validation in a more extensive population is planned. (3) This warrants further investigation of the mutational status of these genes in larger clinical trial cohorts, enabling a more robust comparison with conventional prognostic markers in a multivariate analysis. Disclosures Broijl: Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Zweegman:Takeda: Research Funding; Janssen: Research Funding; Celgene: Research Funding. Sonneveld:Janssen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Karyopharm: Research Funding; SkylineDx: Membership on an entity's Board of Directors or advisory committees.