Rees, Matthew J.

Abstract BCMA-directed CAR T-cell and T-cell engager (TCE) therapies produce high response rates in relapsed multiple myeloma, yet most patients progress. Prior work identified TNFRSF17 alterations mediating antigen escape in up to 43% of TCE progressions. To evaluate the generalizability of these findings and examine antigen-loss-independent resistance, we performed whole-exome sequencing on 32 paired pre- and post-treatment progression bone marrow samples from 15 patients (5 CAR T, 10 TCE); two patients received both agents. TNFRSF17 alterations were infrequent and restricted to TCE recipients (one concurrent frameshift and missense mutation; two heterozygous copy-number losses); no biallelic loss or CAR T-associated events were observed. In contrast, deleterious/loss-of-function variants in NF-κB, PI3K-AKT-mTOR, and MAPK/ERK pathways were universal in pre-treatment samples and acquired or clonally enriched in 80% of patients at progression. Acquired events included loss-of-function alterations in CYLD , activating mutations in KRAS , NRAS and BRAF , and acquired TP53 mutations. In this series, antigen escape via TNFRSF17 /BCMA alteration was uncommon. Instead, pre-existing, acquired and clonally enriched pathogenic variants in NF-κB, PI3K-AKT-mTOR and MAPK cascades, together with TP53 mutation, emerged as a frequent finding. These alterations suggest that deregulation of BCMA-downstream survival signaling, enhanced proliferative fitness, and elevation of apoptotic threshold constitute antigen-loss-independent mechanisms of resistance.

Summary Renal response (RenR) in light‐chain (AL) amyloidosis is associated with a lower risk of end‐stage kidney disease and improved survival. However, substantial variation exists in the time to and depth of RenR. We investigated variables associated with RenR in a retrospective study of newly diagnosed AL amyloidosis patients ( n = 350) assessable for RenR between 2010 and 2022. RenRs were recorded at 6, 12 and 24 months and best response. Deep RenR was defined as a ≥renal very good partial response (RenVGPR, >60% reduction in 24‐h proteinuria or ≤200 mg). Logistic regression and competing risk methods were used to examine variables associated with RenR. The median age was 64 years, and median follow‐up was 5.5 years. On multivariable logistic regression, obtaining ≥HemVGPR within 6 months, kappa isotype, high baseline difference between involved and uninvolved free light chains (dFLC ≥40 mg/dL), renal stage and autologous haematopoietic stem cell transplant (AHSCT) were significantly associated with deep RenR. Cumulative incidence rates for deep RenR, treating death or renal progression as a competing event, demonstrated that early HemR, first‐line AHSCT, lower renal stage and dFLC ≥40 mg/dL significantly increased the likelihood of deep RenR. Specific clonal plasma cell features, namely light‐chain isotype and baseline dFLC levels, independently influence the timing and depth of RenRs in AL amyloidosis following treatment, in addition to renal stage and HemR.

Abstract Solitary bone plasmacytoma (SBP) and SBP with minimal marrow involvement (SBPmm) are treated similarly with definitive radiation therapy (RT) followed by observation. However, differences in the natural disease course after RT between the two, are not well described. We performed a multicenter study assessing outcomes after RT in 141 patients with SBP and 102 with SBPmm diagnosed between January 2010 and December 2024. About 92% of patients with SBPmm progressed to multiple myeloma (MM) vs 76% of those with SBP (P = .01). Among patients with SBP, 21% progressed with a second solitary bone lesion vs 4% with SBPmm (P< .01). Patients with longer time to progression (TTP) after initial RT could achieve durable responses with RT to a second solitary plasmacytoma in the absence of other myeloma-defining events (MDE). Multifocal lytic bone lesions were the most common MDE, occurring in 89% and 81% of patients with SBPmm and SBP, respectively. Patients with SBPmm had a median TTP of 15 months (95% confidence interval [CI], 14-21) compared to 43 months (95% CI, 34-55) for those with SBP (P< .0001); 67% with SBPmm progressed within 2 years of diagnosis. Del(17p) and 1q+ (gain or amplification) were associated with shorter TTP to MM in SBPmm, with 2-year progression rates of 100% and 82%, respectively. We report significant differences in risk and modes of progression between SBP and SBPmm. Patients with SBPmm are at particularly high risk for early progression to MM, with most developing bone disease as the MDE. These findings support prospective studies incorporating frontline systemic therapy for SBPmm.

Abstract Introduction: The CAR-T therapies ide-cel and cilta-cel are approved for patients (pts) with relapsed/refractory multiple myeloma (RRMM). The aim of this study was to determine the incidence, subtypes, and associated risk factors for subsequent primary malignancies (SPMs) in MM pts treated with CAR-T therapy in the real-world setting. Methods: A retrospective, multicenter observational cohort study was conducted of pts who received CAR-T therapy between May 2021 and Dec 2024 at 15 centers within the US Multiple Myeloma Immunotherapy Consortium. Logistic models were used for univariable analyses of invasive SPMs (excluding non-melanoma skin cancers). Variables significant at p < 0.10 were included as candidate variables in the multivariable analysis. Time to event endpoints were analyzed using Kaplan-Meier curves. Results: Of n=1460 CAR-T recipients, median follow-up from the time of CAR-T infusion for the entire cohort, ide-cel, and cilta-cel pts was 13.1, 16.9, and 10 months, respectively. A total of 55 invasive SPMs were noted in 53 pts (SPM incidence 3.6%). The incidence rate of SPMs was 4.55 per 1,000 person-years, based on 53 SPMs occurring over 11,646.14 person-years (calculated from CAR-T to the SPM diagnosis, death, or last follow-up). Baseline characteristics were similar for pts with no SPM versus SPM including: age at CAR-T (median 67 vs 65), female (36% vs 43%), Black (13% vs 16%), prior autologous transplant (87% vs 80%), lenalidomide for ≥2 years (31% vs 27%), high risk cytogenetics (23% vs 29%), and known clonal hematopoiesis (7.5% vs 9.9%). Differences were observed in baseline characteristics among pts with SPM versus no SPM for ≥2 prior alkylator lines of therapy (LOT) (82% vs 60%, p=0.002) and median prior LOT (6 vs 5, p=0.008). There was a trend for more patients with SPMs being age ≥70 (35% vs 37%, p=0.074). Of the 53 SPMs, 26 (49%) were myeloid (MDS or AML), 19 (35.8%) were solid, 7 (13.2%) were of T-cell origin, and 1 was a B-cell lymphoma. Of the T-cell SPMs, three were of T-LGL, though one of the T-LGL pts later developed an invasive CNS T-cell lymphoma (CAR-negative). There were four cases of confirmed CAR-positive T-cell SPMs (all pts treated with cilta-cel), of which two were indolent T-cell lymphoma of the GI tract and two were cutaneous PTCL. There was no difference in total incidence of SPMs among pts who received ide-cel (total=4.4%; myeloid=2.2%, T-cell=0.04%) versus cilta-cel (total=3%; myeloid=1.4%; T-cell=0.5%) (p=0.21). Median OS from the time of CAR-T therapy was 40.8 months for pts without SPM compared to 27.6 months for pts with SPM (p=0.4). Median OS did not differ by myeloid, solid, and T-cell subgroup: 26.4, 37.2, and 24 months, respectively (p=0.21). Median time from CAR-T cell to SPM was 12 months overall, and by subtypes of myeloid, solid, and T-cell was 13.2, 9.6, and 9.6 months, respectively (p=0.74). There was no difference in time to any SPM among pts receiving ide-cel versus cilta-cel (p=0.61). An earlier time to diagnosis of myeloid SPM was observed for cilta-cel versus ide-cel (4.8 vs 20.4 months; p=0.003). Median OS from the time of diagnosis of any SPM, myeloid, solid, or T-cell SPM was 9.6, 7.2, 15.6, and not reached in months, respectively (p=0.006), demonstrating that pts diagnosed with myeloid subtype SPM had inferior OS from the time of their SPM diagnosis compared to other subtypes. The cause of death of 4/11 myeloid SPM pts was the myeloid SPM itself. In univariable analysis for the entire cohort, age ≥70 (p=0.079), ≥5 prior LOT (p=0.012), and ≥2 prior alkylator LOT (p<0.001) were associated with higher risk for SPM. In multivariable analysis, ≥2 LOT containing alkylators was associated with higher risk of SPM (p=0.005). For the univariable analysis of the myeloid subgroup, ≥2 prior alkylator LOT (p=0.016) and ≥2 years of lenalidomide maintenance (p=0.063) were associated with higher risk of SPM. In multivariable analysis, ≥2 years of lenalidomide (p=0.065) was associated with a trend toward increased risk of myeloid SPM. Conclusions: With a median follow up of 13.1 months, the incidence of developing a SPM following CAR-T in pts with RRMM was 3.6%, of which approximately half were myeloid malignancies. There was no difference in SPM incidence when comparing the two CAR-T products. Pts treated with ≥2 alkylator LOT had a higher risk of SPM in multivariable analysis and may warrant additional monitoring for SPM development.

ABSTRACT Anaplastic lymphoma kinase‐positive large B‐cell lymphoma (ALK+ LBCL) is a rare, aggressive subtype of diffuse large B‐cell lymphoma with poor outcomes using standard chemotherapy. In this multi‐institutional retrospective study, we analyzed 39 cases of ALK+ LBCL identified at six US academic centers from 2002 to 2024, with treatment including conventional cytotoxic regimens in frontline and biologically informed and nonchemotherapy‐based strategies in the relapsed setting. Ninety‐two percent of patients received frontline anthracycline‐based chemotherapy; 43% received intensified regimens, and 15% underwent upfront autologous stem cell transplantation (ASCT). Despite these approaches, outcomes remained poor. At a median follow‐up of 5.4 years, median event‐free survival (EFS) was 0.6 years (95% CI, 0.4–0.9), and median overall survival (OS) was 1.5 years (95% CI, 1.3–NR). One‐ and five‐year EFS rates were 28% and 17%, while corresponding OS rates were 72% and 42%, respectively. Advanced stage and high IPI scores were associated with inferior outcomes. Twelve patients received ALK inhibitors, with alectinib showing more durable responses than crizotinib. Lenalidomide and immune checkpoint inhibitors also demonstrated activity, including durable complete responses. Five patients underwent allogeneic stem cell transplantation, with three achieving sustained remission. In conclusion, our findings highlight the limited benefit of chemotherapy, even when intensified or followed by ASCT, and support the integration of biologically targeted therapies, which may have contributed to improved OS in our cohort compared to historical outcomes. Prospective, collaborative studies are needed to better understand disease biology and define optimal use of modern therapies in this rare lymphoma.

Multiple myeloma (MM) is predominantly a disease of the elderly. In recent years, a surge of highly effective plasma cell therapies has revolutionized the care of elderly multiple myeloma (MM) patients, for whom frailty and age-related competing causes of mortality determine management. Traditionally, the treatment of newly diagnosed elderly patients has centered on doublet or triplet combinations composed of immunomodulators (IMIDs), proteasome inhibitors (PIs), anti-CD38 monoclonal antibodies (mAbs), and corticosteroids producing median progression-free survival (PFS) rates between 34 and 62 months. However, recently, a series of large phase III clinical trials examining quadruplet regimens of PIs, IMIDs, corticosteroids, and anti-CD38 mAbs have shown exceptional outcomes, with median PFS exceeding 60 months, albeit with higher rates of peripheral neuropathy (≥Grade 2: 27% vs. 10%) when PIs and IMIDs are combined, and infections (≥Grade 3: 40% vs. 29–41%) with the addition of anti-CD38mAbs. The development of T-cell redirecting therapies including T-cell engagers (TCEs) and CAR-T cells has further expanded the therapeutic arsenal. TCEs have shown exceptional activity in relapsed disease and are being explored in the newly diagnosed setting with promising early results. However, concerns remain regarding the logistical challenges of step-up dosing, which often necessitates inpatient admission, the infectious risks, and the financial burden associated with TCEs in elderly patients. CAR-T, the most potent commercially available therapy for MM, offers the potential of a ‘one and done’ approach. However, its application to elderly patients has been tempered by significant concerns of cytokine release syndrome, early and delayed neurological toxicity, and its overall tolerability in frail patients. Robust data in frail patients are still needed. How CAR-T and TCEs will be sequenced among the growing therapeutic armamentarium for elderly MM patients remains to be determined. This review explores the safety, efficacy, cost, and logistical barriers associated with the above treatments in elderly MM patients.

Abstract Ciltacabtagene autoleucel (cilta-cel) and idecabtagene vicleucel (ide-cel), 2 B-cell maturation antigen (BCMA)–directed chimeric antigen receptor T-cell (CAR-T) therapies, have transformed outcomes for relapsed/refractory multiple myeloma; however, the 6 to 8 weeks manufacturing time risks disease progression or death in up to 10% of patients. Talquetamab, a G-protein–coupled receptor, family C, group 5, member D (GPRC5D)–targeting bispecific antibody, represents a promising option. We performed a multi-institutional retrospective analysis across 20 centers (18 United States, 2 Germany) evaluating talquetamab as a bridging therapy prior to cilta-cel or ide-cel. Among 134 patients receiving talquetamab, 119 proceeded to CAR-T (n = 98 cilta-cel, n = 21 ide-cel). Reasons for not proceeding (n = 15) included progression (n = 7), manufacturing failure (n = 6), or patient decision (n = 2). Median age was 65 years and had median 5 prior lines of therapy. Notably, 85% would not have met CARTITUDE-1/KarMMa eligibility criteria. Talquetamab was administered for a median 23 days. Toxicity was manageable: no grade ≥3 cytokine release syndrome (CRS), 2% grade 3 immune effector cell–associated neurotoxicity syndrome (ICANS) and grade 1 to 2 talquetamab unique toxicities (70% oral, 38% skin, and 17% nail; 60% resolved). Talquetamab achieved 71% response rate. After CAR-T, 88% responded (54% complete response), with low-grade toxicities (2 grade ≥3 CRS, 1 grade 3 ICANS, and 5% grade ≥3 infections). Two cases of facial palsy and 1 acute myeloid leukemia occurred. Talquetamab correlated with sustained soluble BCMA decline and peak CAR-T expansion around day 14. Talquetamab bridging appears safe, enabling the majority of difficult-to-treat patients to successfully proceed to BCMA CAR-T therapy.