Hwa, Yi L.

ABSTRACT The prognostic relevance of multiple myeloma (MM)‐defined high‐risk (HR) cytogenetic abnormalities in AL amyloidosis is incompletely defined. We retrospectively evaluated 517 newly diagnosed AL amyloidosis patients seen at Mayo Clinic between 2012 and 2021 who had baseline plasma cell FISH. HR cytogenetics were defined as t (4;14), t (14;16), t (14;20), del(17p), or 1q gain/amplification (+1q). HR abnormalities were identified in 151 patients (29%); +1q accounted for most HR cases (122/151, 81%). Compared with standard‐risk (SR), patients harboring +1q demonstrated a greater clonal disease burden, including higher dFLC and bone marrow plasma cells, greater intact immunoglobulin secretion, higher plasma cell proliferative index, and enrichment for modified SLiM‐CRAB features. Hematologic and organ response patterns of +1q patients were generally comparable to SR patients, whereas non‐1q HR patients had a higher proportion of early hematologic responses. Patients harboring +1q demonstrated significantly inferior overall survival (OS) compared with both non‐1q HR patients and SR patients (median OS 57 months vs. not reached vs. 120 months, p = 0.02). In multivariable piecewise Cox analysis, the adverse prognostic impact of +1q was most evident beyond 24 months from diagnosis (HR 2.89, 95% CI 1.64–5.09, p < 0.001), whereas non‐1q HR lesions were not independently prognostic. These findings suggest that +1q identifies a biologically distinct AL amyloidosis subset characterized by plasma cell–dominant features and inferior long‐term disease control. In contrast, other MM‐defined HR cytogenetic abnormalities appear to have limited prognostic relevance in AL amyloidosis.

Summary Iron deficiency (ID) is often overlooked in patients with haematological malignancies due to other potential aetiologies. Daratumumab, an anti‐cluster of differentiation 38 (anti‐CD38) monoclonal antibody, is commonly used for treating multiple myeloma (MM) in the upfront and relapsed/refractory settings. Although anaemia is a common haematological toxicity associated with daratumumab, the contribution of ID in MM patients has not been systematically investigated. We conducted a retrospective case–control study to evaluate the prevalence of ID in newly diagnosed MM (NDMM) patients. Cases were patients receiving daratumumab, ixazomib, lenalidomide and dexamethasone (Dara‐IRD, n = 55). We compared this group with an age‐ and sex‐matched cohort of patients with NDMM who received bortezomib, lenalidomide and dexamethasone (VRD, n = 20) as induction therapy. At 1‐year, nearly 50% of Dara‐IRD‐treated patients met the criteria for ID (ferritin <30 mcg/L) compared with none of the VRD‐treated controls. All Dara‐IRD‐treated patients had a decrease in ferritin at 1‐year from baseline compared with only 45% of VRD‐treated patients. These findings identify a marked clinical signal of ID among NDMM patients receiving daratumumab‐based treatment. Although the study design does not establish causality or exclude regimen‐related confounding, it highlights the need for increased awareness of the importance of monitoring iron status in MM patients treated with daratumumab‐containing regimens.

ABSTRACT Ciltacabtagene autoleucel (cilta‐cel) has demonstrated excellent efficacy and long‐term disease control in patients with relapsed/refractory multiple myeloma (RRMM). However, a proportion of patients experience early treatment failures. We investigated clinical factors associated with early progression or death (within 12 months) in patients with RRMM receiving standard‐of‐care cilta‐cel across the three Mayo clinic centers. Patients with a follow‐up of at least 12 months or progression or death within 12 months from infusion were included. Of the patients with early treatment failure ( n = 52), 69% had progressive disease and 31% had a non‐relapse mortality (NRM) event. In patients without early treatment failure ( n = 164), 13% of events were NRM. Among pretreatment factors, prior BCMA‐directed therapy, presence of extramedullary disease and a CAR‐HEMATOTOX score of ≥ 2 were independent predictors of early progression or death. The utilization of cilta‐cel in earlier lines of treatment (1–3 vs. 4 or more) demonstrated comparable PFS (12‐month PFS 73% vs. 77%, p = 0.94). Measurable residual disease positivity in the bone marrow at 3 months (11/197 patients) identified a small but high‐risk group with an increased risk of early treatment failure (OR 5.68; p = 0.012). Patients with less than a complete response on a FDG PET/CT at 3 months also had an increased risk of early treatment failure (OR 11.8; p < 0.0001). Our findings may help identify patients at high‐risk for early adverse outcomes despite receiving highly effective therapy, and support consideration of novel therapeutic strategies within a clinical trial setting.

Abstract Background The prognostic relevance of fluorescence in-situ hybridization (FISH) abnormalities is well-established in multiple myeloma (MM), where high-risk (HR) abnormalities are associated with poor survival. In AL amyloidosis, however, the cytogenetic landscape and its implications might be different. For example, t(11;14), common in AL amyloidosis, has historically been linked to inferior outcomes in the pre-daratumumab era. HR FISH abnormalities are less common and less well-defined in this setting, underscoring the need to evaluate their significance in this disease. Methods We retrospectively analyzed 698 newly diagnosed AL amyloidosis patients seen at Mayo Clinic, Rochester, between 2012–2021 who had baseline FISH testing. HR FISH was defined as del(17p)/monosomy 17, t(4;14), t(14;16) or t(14;20). Baseline characteristics and treatment patterns were compared between the HR and the standard-risk (SR) groups. Staging used the Mayo 2004 system with European modification. Hematologic responses were assessed at 2 and 6 months, and cardiac/renal responses at 3, 6, 12, and 24 months per consensus criteria. Overall response rate (ORR) for hematologic and organ responses included patients who achieved partial response (PR), very good partial response (VGPR), and complete response (CR). Overall survival (OS) was estimated via Kaplan-Meier; comparisons used log-rank testing. Cox regression was used for univariate and multivariable analyses. Results Among 698 patients, 73 (10.4%) had HR FISH. The most common HR abnormality was t(14;16) (n=34, 4.9%), followed by del(17p)/monosomy 17 (n=21, 3%), and t(4;14)/t(14;20) (n=12 each, 1.7%). Across the cohort, t(11;14) was most frequent (51.3%), followed by del(13q) (36.2%), hyperdiploidy/tetraploidy (26.3%), and 1q gain/amp (23.6%). Compared to SR group, HR FISH group had fewer males (43% vs. 69%, p&lt;0.0001), with no difference in age (62.5 vs. 65, p=0.44), cardiac (73% each, p=1) or renal involvement (52% vs. 54%, p=0.71). More HR patients had early cardiac stage (69% vs. 55.9%, p=0.04). Both groups were predominantly lambda isotype (82% vs. 74%, p=0.15), with similar baseline dFLC (21.6 vs. 28.4 mg/dL; p=0.81). Intact immunoglobulin secretion was more common in the HR group (68% vs. 45%, p=0.004). The HR group more often underwent advanced bone imaging (44% vs. 29%, p = 0.015) and had a higher incidence of lytic lesions or fractures (27% vs. 15%, p = 0.046). Use of bortezomib-based therapy, primarily CyBorD, was similar between the groups (67% each). Daratumumab-based therapy (16% vs. 11%, p=0.25) and autologous stem cell transplantation (ASCT) (33% vs. 25%, p=0.16) were numerically higher in the HR group, though not statistically significant. Post-ASCT maintenance was more frequent in the HR group (17% vs. 7%, p=0.006). At 2 months, hematologic ORR was higher in the HR group (90% vs. 72%, p=0.007), with higher ≥VGPR (67% vs. 32%, p&lt;0.0001) and CR rates (24% vs. 8%, p=0.0004). At 6 months, the HR group maintained higher ≥VGPR (89% vs. 71%, p=0.008) and CR rates (41% vs. 26%, p=0.04), with no difference in ORR (98% vs. 92%, p=0.18). Cardiac responses at 6 months favored the HR group (VGPR or better: 29% vs. 12%, p=0.013; CR: 13% vs. 3%, p=0.007). At 12 months, cardiac ≥VGPR remained higher (50% vs. 29%, p=0.01), though CR was not significantly different (18% vs. 9%, p=0.1). Renal ≥VGPR at 6 months was more common in the HR group (47% vs. 22%, p=0.004), but not renal CR (9% vs. 7%, p=0.95). At 12 months, renal ≥VGPR remained higher in HR (61% vs. 40%, p=0.004). With a median follow-up of 87 months, median OS was not reached in HR (95% CI: 72.6–NR) vs. 88.9 months (95% CI: 72.8–110.5) in SR (p=0.03). In multivariable analysis, age ≥65 (HR 1.56, p=0.0001) and &gt;2 organ involvement (HR 1.46, p=0.002) were associated with worse OS, while ASCT (HR 0.35, p&lt;0.0001) and cardiac stage I/II (HR 0.48, p&lt;0.0001) predicted better OS. HR FISH was not independently associated with OS (HR 0.74, p=0.14). Conclusions HR FISH abnormalities in AL amyloidosis are not independently associated with OS, unlike in MM. Patients with HR FISH abnormalities more often presented with earlier cardiac stage and demonstrated deeper hematologic and organ responses than patients with SR FISH abnormalities. This study underscores how clonal characteristics can potentially aid in more personalized treatment approaches for patients.

Abstract Background Multiple myeloma, the second most common hematologic malignancy, has witnessed incremental progress in its management over the past decade underscored by substantial improvement in patient outcomes, although it remains largely incurable. Due to its relapsing-remitting course with current therapies, patients experience considerable burden, particularly with the use of parenteral regimens that are administered on a continuous basis. As such, exploration of newer oral, finite-duration therapeutic options may be of benefit. Selinexor, an oral selective exportin (XPO)-1 inhibitor has an established synergistic activity with other antimyeloma therapies, including immunomodulatory drugs and proteasome inhibitors. In combination with dexamethasone, selinexor is currently approved at 80 mg twice a week dose, and in combination with bortezomib plus dexamethasone, it is approved at 100 mg once weekly dose for patients with relapsed and/or refractory multiple myeloma (RRMM). Herein, we present the results of Arm B of the 2-arm SCOPE trial that examined an all-oral regimen of selinexor, pomalidomide and low-dose dexamethasone (SPd) regimen for RRMM. Methods The SCOPE trial is an investigator-initiated, single arm, phase 2 study that assessed the efficacy and safety of selinexor (S), 60 mg orally (PO) weekly, pomalidomide (P), 4 mg PO, days 1-21 and dexamethasone (d), 40 mg PO, weekly in 28-day cycles given for a fixed duration (total 18 cycles ) in patients who were exposed to up to 2 prior lines of antimyeloma therapy, at least one of which included both a proteasome inhibitor and the immunomodulatory agent, lenalidomide. Olanzapine, along with a 5-HT3 antagonist comprised the mandatory anti-emetic prophylactic regimen. The trial's primary endpoint was overall response rate (ORR), based on confirmed response, and the key secondary endpoints were progression-free survival (PFS), duration of response (DOR), overall survival (OS), and safety of SPd. The International Myeloma Working Group (IMWG) 2016 criteria were used for response assessment in addition to reporting of the minor response. The distribution of PFS and OS was estimated using the Kaplan Meier method. Toxicity was graded using the Common Terminology Criteria for Adverse Events (CTCAE), version 5. Results At the data cutoff date (May 28, 2025), 28 of 29 enrolled patients with RRMM were evaluable. The median age at study entry was 67.5 years (range: 65-72 years). SPd was used as the first salvage regimen in 21% of patients, and the remaining 79% of patients had previously received 2 lines of therapy at study entry. All patients had previously been exposed to a proteasome inhibitor and an immunomodulatory agent, and 32% were dual refractory. Notably, 64% of patients had previously been exposed to the anti-CD38 monoclonal antibody, daratumumab, and 11% of patients were daratumumab-refractory. The median follow-up was 23.9 months (range: 2.9-38.8 months). The patients had received a median of 9 cycles of SPd (range:1-18 cycles), and at data cutoff, 36% of patients had completed all the planned 18 cycles of SPd. The ORR was 61% (95% CI:41-78) and the rate of measurable residual disease (MRD)-negative complete response (CR) was 21%, CR 11%, very good partial response (VGPR) 18%, partial response (PR) 11% as the best response achieved. Additionally, 7% and 25% of patients had attained a minor response (MR) and stable disease (SD), respectively. The median PFS was 24 months [95% CI: 7.1– not-estimable (NE)] months, and the median DOR was not reached (NR). 2-year OS rate was 93%. The toxicity associated discontinuation rate was 7%, and no grade (Gd) 5 events or unexpected toxicities were encountered during treatment. Gd 3 or higher hematologic toxicities occurred in 43% [Gd 3/4 anemia (11%/0%), thrombocytopenia (14%/0%), neutropenia (25%/7%), lymphopenia (4%/4%)]. Gd 3+ non-hematologic toxicities occurred in 46% [Gd 3 /4 (%) infections (21%/0%), fatigue (4%/0%), nausea (7%/0%) and anorexia (0%/7%). No patients experienced Gd 3 or 4 diarrhea, vomiting or weight loss. Additional data will be presented at the meeting. Conclusion Weekly selinexor in combination with pomalidomide and dexamethasone is an effective and safe, all-oral regimen for patients with RRMM who are previously exposed to a proteasome inhibitor and lenalidomide. SPd regimen is currently being examined in an ongoing phase 3 randomized controlled trial.

Abstract Introduction Cila-cel is associated with a 10-15% risk of delayed neurotoxicity (DNT) with rates of cranial nerve palsies (IEC-NP) and parkinsonism (IEC-PKS) seen at a rate of 10% and 1-4% respectively and can occur as early as 3-4 weeks after infusion. We and others have shown that high post-infusion peak absolute lymphocyte count (ALCpeak) of &gt;3x10^9/L is associated with an increased risk of delayed neurotoxicity (Lim et al., ASCO 2025) whilst the risk was negligible (~1%) when ALCpeak fell below that threshold. Since December 2024, we implemented prophylactic administration of dexamethasone (PPX DEX) when ALC was &gt;3x10^9/L (defined as high ALCpeak). Outcome of these patients are described here. Methods Analysis of clinical outcome included 230 pts treated between Feb 2022 and Nov 2024 as a historical cohort and 102 patients treated between Dec 2024 and May 2025 after the introduction of dexamethasone prophylaxis using an oral dose of 10mg twice a day for at least three days in the high ALCpeak cohort. Results No significant differences were seen between the new and historical cohort in pre-lymphodepletion disease burden (bone marrow plasma cell %, involved light chain or M-spike level), and rates of all/high-grade CRS or ICANS, IEC-HS and rates of tocilizumub use. Median follow-up in the new cohort of 102 pts was 3.6 months (95% CI 3.3-4.2). Eleven (10.8%) developed DNT [3 (2.9%) with IEC-PKS, 8 (7.8%) with IEC-NP]. High ALCpeak of &gt;3x10^9/L was observed in 51 (50%) pts. Among pts with high ALCpeak, DNT was observed in 10 (20%) pts [3 (5.9%) with IEC-PKS, 7 (13.7%) with IEC-NP] whereas among 51 pts with ALCpeak &lt;3x10^9/L, DNT was observed in 1 (2%) pt [1 (2%) with IEC-NP]. In the high ALCpeak cohort, 38 (75%) received DEX [6 (12%) for toxicity management, 32 (63%) PPX DEX]. Of the 38 pts treated with DEX, DNT was observed in 6 (16%) pts (2 (5.3%) IEC-PKS, 4 (10.5%) IEC-CNP). We next compared DNT rates between this new cohort of high ALCpeak pts receiving DEX (n=38) against the historical cohort with high ALCpeak (n=98). Estimated 90-day DNT by Kaplan-Meier method was (19.2% vs 20.5%; p=0.53): IEC-PKS (5.8% vs 7.2%; p=0.60) and IEC-NP (11.7% vs 13.3%; p=0.58). In patients with high ALCpeak, the use of DEX did not appear to significantly reduce the risk of DNT compared to historical controls (HR 0.76, 0.33-1.78), IEC-PKS (HR 0.67, 0.14-3.10) or IEC-NP (0.73, 0.24-2.23). We next compared ALC expansion over the first month post CAR-T infusion (area under the curve, AUC). Among the new cohort of 102 patients, no difference was seen in the AUC of pts who received DEX but did not develop DNT vs those who developed DNT (31.0 vs 57.9, p=0.28); No difference in AUC was seen in the new high ALCpeak cohort receiving DEX vs the historical cohort with high ALCpeak (36.0 vs 43.8, p=0.15) Of the eight cases of IEC-NP, 4 received PPX DEX. No noticeable differences were observed in the severity of presentation, laterality of cranial nerve involvement and rates of multiple cranial nerve involvement between these 4 cases who received PPX DEX and the 16 cases from the historical cohort. At the time of database freeze, 3 of the 4 cases had resolved and 1 was improving. Median time to complete symptom resolution was 38 days vs 69 days in the historical cohort. Of the three cases of IEC-PKS, 2 received PPX DEX. Median time to symptom onset for IEC-PKS was 46 days (vs. 24 days in historical cohort). Both cases had severe symptoms non-responsive to first line high-dose methylprednisolone, second line intrathecal chemotherapy and third line high-dose cyclophosphamide. Both pts subsequently died from sepsis 28 and 67 days post-cyclophosphamide. Conclusion While ALCpeak &gt;3x10^9/L predicts risk of DNT in pts treated with cilta-cel, the use of PPX DEX does not appear to significantly reduce ALC expansion and does not appear to significantly reduce the risk of DNT, IEC-PKS or IEC-NP. Other strategies to reduce ALC or alter T cell functions may need to be considered.

Abstract Background Central nervous system involvement in multiple myeloma (CNS-MM) is a rare but highly aggressive manifestation. Limited data exists regarding its incidence, biology, treatment patterns, and outcomes. A deeper understanding of the features unique to CNS-MM will help inform risk stratification and management strategies. Methods We conducted a retrospective study of CNS-MM patients at our institution between January 2000 and December 2023. We identified 305 MM patients with pathology-proven extramedullary disease (EMD). CNS involvement was defined as the presence of parenchymal (brain or spine) or leptomeningeal involvement by MM. Univariate analysis was performed to compare the clinical characteristics between EMD patients with and without CNS-MM. Results Out of 305 patients with EMD, we identified 22 patients with CNS-MM. Common symptoms prompting evaluation of CNS-MM were headaches (32%), numbness or tingling (32%), weakness (27%), confusion (23%), falls (23%), and visual disturbances (14%). Among these patients, 17 (77%) had detectable disease in cerebrospinal fluid (CSF), 12 (55%) in the brain parenchyma, 4 (18%) in the spinal cord parenchyma and 6 (27%) in the leptomeninges. Of the CNS-MM patients, the median age at diagnosis of MM was 58.3 years and the median time to CNS-MM involvement was 16.2 months, with 3 (14%) patients having CNS involvement at diagnosis. The predictors of CNS-MM development were high-risk cytogenetics (OR 2.9, p=0.04) and presence of additional visceral organ involvement outside of the CNS (OR 3.4, p=0.03). EMD was multifocal in 20 CNS-MM patients (83%) and visceral organ involvement [most commonly lymphadenopathy (27%), solid organ (18%) and pleural fluid (14%)] was present in 14 (64%) of these patients, compared to 54% in EMD patients without CNS-MM. High-risk cytogenetics [del(17p), 1q gain/amplification, t(4;14), t(14;16), t(14;20)] were seen in 16 (73%) patients, most commonly 1q gain or amplification (40%), t(4;14) (23%), and del(17p) (18%). Five (23%) exhibited a double-hit profile. In comparison, 113 (40%) EMD patients without CNS-MM had high risk cytogenetics. The median overall survival (OS) from diagnosis of CNS-MM was 6 months (95%CI:1.26-36) compared to 15.6 months (95%CI: 12-18) from diagnosis of EMD in EMD patients without CNS-MM (p=0.05). Median OS from diagnosis of MM in the CNS-MM cohort was 36 months (95%CI: 22.8-NA) compared to 55.2 months (95%CI: 45.6-68.4) in EMD patients without CNS-MM (P=0.11). When excluding CAR-T or bispecific therapy recipients, median OS from diagnosis of MM for CNS-MM was 22 months versus 48 months in EMD patients without CNS-MM (P=0.02). Overall response rate in our CNS-MM cohort with first treatment for EMD was 32% compared to 48% in EMD patients without CNS-MM (p=0.04). In patients with CNS-MM, median progression-free survival (PFS) from CNS-MM diagnosis was 3.3 months (95%CI: 0.8-12) versus 3.9 months (95%CI: 3-5.1) in EMD patients without CNS involvement (p=0.2). Six (27%) CNS-MM patients received CAR-T; 3 received cilta-cel, 2 received ide-cel and one received a BCMA CAR-T on trial. Bispecific therapy was used in 4 (18%) patients, with 2 receiving Teclistamab and 2 Talquetamab. Three (14%) CNS-MM patients received both CAR-T and bispecific therapy. The median PFS on CAR-T therapy was 10.5 (95%CI: 5.6-NA) months and 12.7 (95%CI: 10.2-NA) months on bispecific therapy. The median OS from diagnosis of CNS-MM for patients who received CAR-T or bispecific therapy was 36 months (95%CI: 14.0-NA), compared to 1.2 months (95%CI: 0-14.4) for those who did not (p=0.002). Six (27%) patients with CNS-MM, all of whom had CSF involvement of disease, received intrathecal therapy; methotrexate in 3, cytarabine in 2, and one receiving both. Two of these patients demonstrated improvement in cerebrospinal fluid findings following intrathecal chemotherapy, in conjunction with other therapies. Patients who received intrathecal chemotherapy had a median OS measured from development of EMD of 10.8 (95%CI: 3.6-NA) months, compared to 15 months (95%CI: 4.8-NA) in those without IT chemotherapy (p=0.59). Conclusion Central nervous system involvement in MM is relatively uncommon and associated with dismal outcomes. High-risk cytogenetics and involvement of other visceral sites are associated with a higher risk of CNS involvement. Intrathecal therapy offers limited value and immune effector therapies represent efficacious options for treatment.

Abstract Background Measurable residual disease (MRD) negativity post- autologous stem cell transplantation (ASCT) in newly diagnosed multiple myeloma (MM) is associated with favorable outcomes and may overcome the adverse impact of high-risk cytogenetic abnormalities (HRCAs). However, as the definition of high risk evolves and MRD emerges as a key endpoint, understanding its prognostic value within individual HRCAs is critical for treatment guidance. Methods We retrospectively included patients with NDMM that underwent an ASCT between September 19, 2016, and October 19, 2023, and achieved MRD negativity on Day 100 post ASCT. The MRD testing was conducted using multiparameter flow cytometry with a sensitivity of 2x10. HRCAs were defined as del(17p), 1q21+ gain or amplification (1q21+), t(4;14), t(14;16), t(14;20) and del(1p) and rest were considered standard risk (SRCA). Patients were grouped by the number of HRCAs (0, 1, ≥2). An adaptation of the recently proposed International Myeloma Society (IMS)/International Myeloma Working Group (IMWG) classification for high-risk disease (TP53 mutation unavailable) was also used. Progression-free survival (PFS), measured from stem-cell infusion to progression or death, was estimated using Kaplan–Meier methodology and compared using log-rank test. Results We identified 386 patients with MRD negativity post ASCT, of which 381 had cytogenetic data available for analysis. The median follow-up for the study cohort was 47.3 months (95% CI: 43.2-50). The median age at the time of ASCT was 65.7 (25.4-79.2) years and 58.3% patients were males. A total of 49% (n=189) patients had standard-risk cytogenetics, 31.4 % (n=121) harbored 1 HRCA, 15.3% (n=59) patients had two HRCAs and 3.1% (n=12) had 3 HRCAs. The individual HRCA by their prevalence were: 1q21+ in 35.5%(n=137), del(17p) in 14.3% (n=55), t(4;14) in 10.9% (n=42), t(14;16) in 5.4% (n=21), del(1p) in 4.2% (n=16), and t(14;20) in 1.04% (n=4) of patients. The most common double-hit lesions were1q21+ gain and/or amplification co-occurring with t(4;14) (33.9%, n=20) and del(17p) with 1q21+ (18.6%, n=11). Despite universal MRD negativity at Day 100, several HRCAs remained prognostically significant for PFS. Patients with del(17p) had worse 3-year PFS (71%) than those without (81%) [hazard ratio (HR)=1.85, 95% CI 1.11–3.07, p = 0.0172], though 3-year OS did not significantly differ at data cutoff (80% vs. 92%, p=0.1176). Presence of 1q21+ was associated with an inferior 3-year PFS (73%) compared to those without [84%, HR: 1.96 (95% CI: 1.25–3.06), p=0.0026], while 3-year OS was similar (88% vs. 91%, HR:1.33 p=0.36). Isolated 1q21+ had inferior PFS with comparable OS when compared to SRCA [3-year PFS of 82% vs. 88% respectively (HR:1.97, p=0.0177)]; 3-year OS was 91% vs. 94% (HR:1.38, p=0.44)]. Among 1q21+ patients, those with co-occurring HRCAs had a 3-year PFS of 66% vs. 81% for isolated 1q21+ (HR: 1.47, p=0.21). Patients with t(4;14) had worse 3-year PFS (64%) vs. 82% in non t(4;14) [HR 2.11(95% CI: 1.21-3.67) p=0.0064], and 3-year OS of 82% compared to 91% [HR 2.14 (95% CI: 1.02–4.49), p=0.038]. Isolated t(4;14) showed a 3-year PFS of 59% vs. 87% in standard-risk (p=0.06), and 3-year OS of 90% vs. 93% [HR 3.29, 95% CI 0.95–11.33, p = 0.06]. The presence of t(14;16), t(14;20), and del(1p) did not significantly affect 3-year PFS (all p&gt;0.1), likely due to small subsets. When patients were grouped by the number of HRCAs, PFS declined with increasing cytogenetic complexity. Compared to standard risk, the 3-year PFS was 77% for 1 HRCA vs [HR = 2.11 (95% CI: 1.29–3.46), p = 0.0027], 67% for ≥2 HRCA [HR = 2.64 (95% CI: 1.53–4.57), p = 0.0005]. Maintenance therapy was used in 98% of patients. Patients with HRCAs received a doublet maintenance compared to SRCA (p&lt;0.0001), even in MRD negative disease post ASCT. Conclusion In patients with certain HRCA, achievement of MRD negativity post-ASCT does not overcome the adverse impact of HRCA on PFS. In our cohort, patients with del(17p), t(4;14), or 1q21+ continued to exhibit significantly shorter PFS despite achieving MRD-negative status. These findings underscore the need for ongoing risk-adapted strategies even in patients with MM who attain MRD-negative state. The OS estimates are immature at this time.

Abstract Background Primary plasma cell leukemia (pPCL) is a rare and aggressive variant of multiple myeloma (MM), characterized by the presence of more than 5% circulating plasma cells on a peripheral blood smear. Despite advancements in therapy, including novel agents and autologous stem cell transplantation (ASCT), pPCL remains associated with markedly poorer survival outcomes compared to newly diagnosed MM. Although disease progression is common in pPCL, individual courses vary widely upon relapse and thereafter. We aim to describe the natural history of pPCL, focusing on clinical features and survival outcomes at the time of relapse or disease progression. Methods Patients with pPCL who were followed at our institution's cancer center between 2006-2024 were included for retrospective analysis. The electronic health record was reviewed to provide detailed information on patient demographics, disease characteristics, treatment regimens, and clinical outcomes. Time to next treatment (TTNT) and overall survival (OS) analysis were performed using the Kaplan-Meier method. Statistical analyses were performed using the SAS biostatistical software JMP 17.0.1 (SAS Institute Inc). Results We analyzed a cohort of 106 patients with relapsed pPCL after first-line therapy, all of whom received induction with novel agents. To date, 64 patients (60%) have died. Across the entire cohort, median OS is 39 months (mos) (95% CI: 25-68). 59 patients (56%) were diagnosed after 2015. Baseline FISH cytogenetics were available for 100 patients; 57 (57%) had one or more high-risk cytogenetic abnormality. Nearly all patients (96%) had ≥50% clonal plasma cells on initial bone marrow biopsy. While most patients (n = 61; 58%) were planned to undergo upfront ASCT, 20 (33%) experienced disease progression during induction therapy and required a more intensive salvage regimen (often infusional chemotherapy) prior to ASCT. The median TTNT after first-line therapy (TTNT#1) for the entire cohort was 10.4 mos (95% CI: 8–14). The median TTNT after second-line therapy (TTNT#2) for the entire cohort was 5.7 mos (95% CI: 4.3–7.1). Clinical details at first relapse, prompting initiation of second-line therapy, were available for 91 patients. Of these, 26 patients (29%) had symptomatic relapses—due to CRAB features or extramedullary disease—while 65 patients (71%) experienced asymptomatic biochemical progression. Symptomatic relapses were followed by significantly shorter TTNT#2 (3.9 vs. 7.0 mos; p = 0.039) and inferior OS from the start of second-line therapy (7.5 vs. 31.2 mos; p &lt;0.0001) compared to asymptomatic relapses. The median TTNT#2 for patients who relapsed during induction and received salvage ASCT was 6.9 mos (n=20). In contrast, those treated after relapse with non-ASCT regimens (n = 86) fared worse; those receiving novel agent-based combinations, including doublets, triplets, or quadruplets (n=64) had respective median TTNT#2 of 3.3, 6.0, and 3.3 mos. Patients treated with infusional chemotherapy (n = 9) had the poorest outcomes, with a median TTNT#2 of just 1.4 mos. The median TTNT diminished with each subsequent line of therapy: TTNT#3 (n = 73) was 5.8 mos, TTNT#4 (n = 53) was 4.0 mos, and TTNT#5 (n = 35) was 2.6 mos. Patients with pPCL harboring the t(11;14) cytogenetic abnormality who were treated with venetoclax-based regimens (n = 8) during any line of therapy had a longer corresponding median TTNT of 15.0 mos. Additionally, 23 patients received anti-BCMA CAR-T cell therapy as a post-relapse line of therapy. At last follow-up, 15 of these patients (65%) had not relapsed, and after a median 20.7 mos of follow-up, the median TTNT following CAR-T cell therapy had not yet been reached. Patients who received CAR-T after 1-3 prior lines (n=15) had a median TTNT that was not reached; those who had received 4 or more prior lines (n=8) had a median TTNT of 20 mos. ConclusionsDespite the use of novel agent-based combination regimens and ASCT as first-line therapy, most patients with pPCL eventually experience disease progression. Consistent with MM, symptomatic relapse in pPCL is associated with poorer outcomes compared to asymptomatic biochemical progression. Additionally, the duration of response shortens with each successive line of therapy. Notable exceptions include venetoclax-based regimens in patients with t(11;14), and anti-BCMA CAR-T cell therapies: each appear to confer more durable responses than historical treatments in patients with relapsed pPCL.

ABSTRACT Light chain multiple myeloma (LCMM) is a subtype of multiple myeloma (MM) characterized by the exclusive production of immunoglobulin light chains and accounts for 15%–20% of newly diagnosed MM. A comprehensive comparison of LCMM with MM producing intact immunoglobulin (non‐LCMM) remains limited. In this retrospective study, we described distinct clinical and cytogenetic features and assessed long‐term outcomes in 852 LCMM patients diagnosed between 01/01/2004 and 12/31/2022, compared with non‐LCMM controls matched for age, sex, and year of diagnosis. On univariable analysis, LCMM patients were more likely to present with elevated creatinine (> 2 mg/dL), beta‐2‐microglobulin ≥ 5.5 mg/L, elevated LDH, hypercalcemia, t(11;14), del(13q), and t(6;14). Conversely, IMS‐IMWG high‐risk disease, hyperdiploidy, t(4;14), and serum albumin < 3.5 g/dL were less common. On multivariable analysis, elevated creatinine (OR: 5.1, 95% CI: 1.2–27, p = 0.04), t(11;14) (OR: 2.6, 95% CI: 1.3–5.2, p = 0.006), and del(13q) (OR: 4.1, 95% CI: 2.1–8.2, p < 0.001) were independently associated with LCMM, while IMS‐IMWG high‐risk disease (OR: 0.3, 95% CI: 0.1–0.8, p = 0.02) and hyperdiploidy (OR: 0.3, 95% CI: 0.1–0.7, p = 0.002) were less frequent. Despite these differences, progression‐free survival with frontline treatment (HR: 0.97, 95% CI: 0.84–1.11, p = 0.63) and overall survival (HR: 0.99, 95% CI: 0.87–1.13, p = 0.94) were similar between LCMM and non‐LCMM patients. This study highlights the distinct clinical and cytogenetic features of LCMM, marked by higher rates of renal failure, t(11;14), and del(13q), lower prevalence of IMS‐IMWG high‐risk disease, and comparable survival outcomes.