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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 Introduction: Light chain (AL) amyloidosis is a rare multi-systemic disease where abnormal proteins in plasma cells misfold and create amyloid fibrils that can deposit in organs and tissues, where they cause damage and increased risk of mortality. Cardiac involvement is the most important factor in determining AL amyloidosis prognosis as well as the difference in free light chains (dFLC), with a dFLC less than 50 mg/L indicating better prognosis. In most countries, daratumumab in combination with cyclophosphamide, bortezomib, and dexamethasone (CyBorD) is the preferred first-line therapy (FLT) for AL amyloidosis. There is no expert consensus for definitions of relapsed/refractory AL amyloidosis and preferred second-line therapy (SLT). This prospective study examined healthcare professional (HCP) perspectives on treatment and management of newly diagnosed and relapsed/refractory AL amyloidosis patients building on research by Milani, et al (2017). Methods: The Amyloidosis Research Consortium (ARC) conducted an international cross-sectional online survey from April to July 2025. HCPs who treat AL amyloidosis patients were identified from ARC's database and sent an email with individual links to complete the survey. Members of the International Society of Amyloidosis also received email notifications for study participation. Measures included HCP demographics, practice characteristics, FLT and SLT preferences, clinical trial perspectives, and use of clinical criteria including dFLC values, relapsed/refractory definitions, and hematologic and organ progression. Target enrollment was 50 HCPs. Final enrollment was 55 HCPs with evaluable data from 49 respondents included in analysis. This preliminary analysis examined respondent characteristics, treatment preferences, and clinical trial perspectives; results of the full analysis will be presented in a forthcoming manuscript. Responses were analyzed descriptively using STATA. Results: Respondents were based in the United States (60%), Europe (30%), Australia (4%), South America (4%), and South Korea (2%). The majority were hematologists or oncologists (85% and 10%, respectively), male (67%), between the ages of 36 and 65 years old (90%), and practice at academic institutions (94%). Most had more than 10 years of experience treating AL amyloidosis patients (80%), with almost half having 20 years or more experience (46%) On average, HCPs treat 100 AL amyloidosis patients per year (mean 63.9, SD 111.1), with 30% newly diagnosed (mean 25.1%, SD 17.8%), 30% observed off therapy (mean 27.0%, SD 13.8%), 18% on maintenance therapy (mean 16.7%, SD 9.7%), and 23% relapsed/refractory (mean 19.8%, SD 10.7%). Half of respondents (50%) use the EU modification of the 2004 Mayo Clinic staging system and 42% use the 2012 Mayo Clinic staging system for AL amyloidosis. Most HCPs treat all newly diagnosed AL patients with the same regimen (88%). HCPs primarily use D-CyBorD as their preferred FLT (88%). Less than 10% of HCPs use autologous stem cell transplants (ASCT) for FLT. One-quarter of clinicians routinely conduct bone marrow biopsies to confirm CR after FLT (25%). Nearly all HCPs participated in at least one interventional clinical trial (91%) for AL amyloidosis in the past 5 years, with average participation in 5 interventional trials (mean 4.81, SD 2.75). Most HCPs have participated in at least one observational clinical trial (66.7%) for AL amyloidosis with an average participation of 3 observational trials (mean 2.3, SD 1.8). Most HCPs were uncomfortable waiting for a patient's dFLC to rise to greater than 50 mg/L to meet eligibility for trials of relapsed/refractory AL amyloidosis patients. (60%). Conclusions: These preliminary findings provide insight into HCPs real-world FLT preferences for AL amyloidosis patients. More than 90% of HCPs in our study prefer to use D-CyBorD as FLT, with less than 10% preferring ASCT as FLT. This is a significant shift from the 2017 study, which found that more than 70% of HCPs preferred ASCT as FLT, however this was conducted prior to FDA approval of daratumumab (2021). Like the 2017 study, most HCPs remain uncomfortable waiting for dFLC to rise to 50 mg/L to meet clinical trial eligibility for relapsed/refractory patients. The findings from our subsequent full analysis will provide additional insights into the real-world management of more advanced AL patients and may help inform future research.

Abstract Introduction Systemic light chain (AL) amyloidosis is a clonal plasma cell disorder characterized by the deposition of misfolded immunoglobulin light chains in vital organs, often resulting in irreversible organ damage. While plasma cell-directed therapies have improved clinical outcomes, the molecular mechanisms driving disease pathogenesis remain poorly understood. Our previous studies identified overactivation of the PI3K/AKT signaling pathway in AL amyloidosis (Zvida et al., Blood, 2024; Fishov et al., Cancer Med., 2023), a central regulator of cellular and lipid metabolism. Dysregulated lipid metabolism has been implicated in several hematologic malignancies, yet its role in AL amyloidosis remains largely unexplored. Objectives To characterize the lipidomic landscape in AL amyloidosis compared to multiple myeloma (MM) and healthy controls (HC) in the context of inflammatory signaling. The ultimate goal of this work is to uncover novel metabolic-immunologic targets for therapeutic intervention. Methods Lipidomic profiling was performed by liquid chromatography-mass spectrometry (LC-MS) on plasma samples from AL patients (n=30), MM (n=30), and HCs (n=15). Fatty acid synthase (FASN) expression was validated by qRT-PCR in CD138+ bone marrow (BM) samples. A lipogenesis index was calculated using the ratio of palmitoleic acid to linoleic acid as a surrogate marker of FASN activity. Additionally, RNA-seq was conducted on CD138⁺ BM cells from AL and HC samples (n=8). Cytokine profiling was performed on serum from AL, MM, and HC subjects (n=10 each). Functional assays and lipidomic analysis were conducted in ALMC1 cells using the FASN inhibitor TVB-2640 and the MEK inhibitor cobimetinib. Results Lipidomic analysis of pre-treatment plasma samples revealed a significant increase in the lipogenesis index in AL patients, indicating elevated FASN activity. This was consistent with increased FASN mRNA expression in bone marrow CD138⁺ cells, suggesting both transcriptional upregulation and enzymatic activation. In ALMC1 cells, dose- and time-dependent FASN inhibition with TVB-2640 (0-2 μM, 24-72h) significantly reduced cell viability (IC50=1.3 μM), suggesting that FASN activity supports AL plasma cell survival. In addition, AL patients demonstrated a significant decrease in polyunsaturated fatty acids (PUFAs) levels, including docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and linoleic acid (LA), compared to MM and HC. As PUFAs are known suppressors of FASN expression and activity, their depletion may contribute to sustained FASN upregulation and a metabolic shift toward de novo lipogenesis. Pathway enrichment analysis of patient lipidomic data revealed significant enrichment of omega-3/6 fatty acid metabolism, ATP generation, and inflammation-related pathways. Notably, imbalances in omega-3 and omega-6 fatty acids ratio have been associated with heightened inflammatory responses. In parallel, RNA-seq analysis identified several upregulated pathways in AL amyloidosis patients compared to controls, including immune regulation, MAPK signaling, mitochondrial dysfunction, oxidative phosphorylation, and IL-13 signaling. Both IL-13 and MAPK are known to transcriptionally induce FASN and regulate immune responses, providing a possible mechanistic link between inflammation and lipid remodeling. Cytokine profiling revealed elevated levels of IL-1β, IL-13, IL-8, IFN-γ, MIP-1α (CCL3), G-CSF, MCP-1 (CCL2), and IP-10 (CXCL10) in AL serum samples, consistent with a systemic inflammatory phenotype. Pharmacologic inhibition of MAPK signaling (by cobimetinib) in ALMC1 cells led to restoration of PUFA levels and a concurrent reduction in cytokine secretion, suggesting that MAPK activity sustains both the inflammatory and lipogenic phenotype in AL. ConclusionsOur findings identify metabolic-inflammatory axis in AL amyloidosis, in which IL-13 and MAPK signaling may promote fatty acid reprogramming through FASN activation and PUFA suppression. This axis sustains a pro-inflammatory environment that may contribute to disease pathogenesis. Thus, FASN and MAPK may represent promising metabolic-immunologic targets for therapeutic intervention in AL amyloidosis.

Abstract Background Extramedullary disease (EMD) in multiple myeloma (MM) represents an aggressive phenotype with poor outcomes. We performed single-cell RNA sequencing (scRNA-seq) on clonal plasma cells (CPCs) from EMD tissue, solitary plasmacytomas (SPM), and bone marrow aspirates (BMAs) from patients with MM to identify transcriptional states unique to EMD. Methods We processed FFPE tumor samples from EMD and SPMs and cryopreserved CD138+ BMAs from MM, using the 10x Genomics FLEX platform. Cells/nuclei were fixed, hybridized with Human WTA probes, pooled, and sequenced (10,000–40,000 cells/library) on NovaSeq X. After removing low quality cells, data was normalized and integrated using RPCA in Seurat. Plasma cell identity was assigned via Cellarium and canonical markers. Clonality was inferred by light chain restrictions and refined via random forest modeling. Cell cycle effects were regressed out to reduce proliferation bias. Results We analyzed 128, 908 CPCs from 16 samples [8 EMD (62, 669 CPCs), 4 SPM (20, 607 CPCs), 4 BMA (45, 632 CPCs)] and identified eight transcriptionally distinct cell clusters. Differential expression and pathway comparisons were performed between EMD/SPM/BMA within each of these clusters. Integration of gene expression and pathway analyses revealed consistent upregulation of cell cycle and E2F pathways in EMD. We identified two highly proliferative cell cycle clusters (Cluster 2 with S-phase genes and Cluster 4 with a G2/M transcriptional program) that were expanded in EMD compared to BMA and SPM. Cluster 0 comprised a quiescent CPC population enriched for RNA processing pathways alongside downregulation of ER stress and autophagy. EMD cells demonstrated suppressed interleukin signaling [fold change (FC) –33.8), and class I MHC antigen processing (FC –23.5) relative to BMA, suggestive of an immune suppressive transcriptional program. Angiogenesis-related genes [VEGFA (log2FC 2.4), ADM2 (log2FC 2.2)] and EZH2 [log2FC 2.1; q<0.0001)] were upregulated in EMD. Compared to SPM, EMD plasma cells in this cluster demonstrated marked downregulation of CD74 (log2FC –2.6; q<0.0001), a key modulator of MHC class II antigen presentation. Cluster 1 comprised of metabolically stressed secretory CPCs and displayed downregulation of early growth response pathways in EMD compared to BMA, concurrent with upregulation of E2F signaling. Suppression of IL-2/STAT5, IL-6/JAK/STAT3, and TGF-β pathways in EMD suggests reduced reliance on bone marrow–derived cytokines and impaired immunoregulatory signaling. CD44 was upregulated in EMD versus BMA (log2FC 3.2), consistent with its role in EMD spread and marrow independence. Cluster 3 was enriched for extracellular matrix–interacting plasma cells (COL1A1, MMP2) with upregulated epithelial–mesenchymal transition (EMT) pathways in EMD compared to both BMA (FC 7.5) and SPM (FC 7.07). Cluster 6 was defined by a migratory, motility-primed plasma cell population (CD44, AHNAK, LMNA and S100A10). Notably, IL32 was overexpressed in EMD compared to BMA (log2FC 5.1; adj. p = 2.02×10⁻¹⁴), a finding linked to hypoxia-driven proliferation. Compared to SPM, EMD cells also had elevated MYC/E2F activity and DNA repair, hallmarks of a proliferative phenotype. Cluster 5 displayed a strong interferon-stimulated gene signature (ISG15, IFIT1, TNFSF10), with enrichment of type I IFN, JAK–STAT, and TNF pathways. Within this inflammatory cluster, EMD exhibited marked suppression of immune signaling, metabolism (TCA, OXPHOS), and TP53 programs, consistent with an immune-evasive, metabolically suppressed, and deregulated state. Finally, within Cluster 7, a smaller subset defined by NFκB–driven anti-apoptotic transcriptional activity, EMD exhibited significant downregulation of KLF2 (log2FC –3.7; adj. p = 1.77×10⁻²⁷), likely reflecting disruption of the KDM3A–KLF2–IRF4 axis, a transcriptional network critical for bone marrow homing and plasma cell survival. We consistently observed downregulation of the MAPK pathway in EMD compared to BMA, aligning with prior bulk RNA-seq data and contrasting with the near-universal presence of MAPK mutations, highlighting a disconnect between mutational status and pathway activation. Conclusion In the largest yet reported single-cell transcriptional atlas of EMD and SPM, we demonstrate EMD to be highly proliferative with metabolic reprogramming, EMT, and downregulation of key immunologic signaling pathways, indicating immune escape and microenvironmental independence.

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>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<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 <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 Cardiac involvement in AL amyloidosis significantly impacts both short and long-term survival. Achieving cardiac complete response (CarCR) is linked to excellent survival, comparable to that of the general population. We undertook this study to characterize patients with AL amyloidosis who achieved CarCR. Methods: A single-center retrospective study of patients diagnosed with cardiac AL amyloidosis between 2004 and 2023 and achieved a documented CarCR for at least 12 months. Patients were included if they had evidence of cardiac involvement confirmed by cardiac imaging (transthoracic echocardiogram or cardiac magnetic resonance) and Congo red–positive tissue (non-cardiac or heart biopsy), and were evaluable for cardiac response based on baseline NT-proBNP > 650 pg/mL or BNP > 150 pg/mL. CarCR was defined as a reduction in NT-proBNP to less than 350 pg/mL (or BNP less than 80 pg/mL). Heart transplant patients were excluded. Results: Sixty-three patients were included, representing 4.6% of the cardiac evaluable population in the study period. This proportion increased in the second period compared to the first period (7.5% vs 3.2%, P<0.001). The median age at diagnosis of 57 years (ranging from 29 to 79); 63% were male. Lambda light chain disease was evident in 63% of patients. The median difference between the involved and uninvolved light chain (dFLC) at baseline was 429 mg/L (interquartile range [IQR] 143-708). While all patients had cardiac involvement, 63% also presented with extra-cardiac involvement [kidneys (52%), liver (16%), autonomic nerves (14%), luminal gastrointestinal tract (11%), and peripheral nerves (10%)]. The median baseline NT-proBNP for the entire cohort was 1977 pg/mL (IQR 1393-3026). The median troponin T (n=43) was 0.02 ng/mL (IQR <0.01-0.05) and the median high-sensitivity troponin T (n=19) was 49 ng/L (IQR 38-79 ng/L). Cardiac stage distribution, according to the European modification of the Mayo 2004 staging model, was as follows: 59% stage II, 39% stage IIIa, and 2% stage IIIb. At baseline, echocardiogram features included a median left ventricular (LV) ejection fraction of 63%, a median intraventricular septum thickness of 14 mm, and a median average LV longitudinal strain of -12%. The most common first-line therapies were autologous stem cell transplantation (ASCT; with or without induction, 54%), bortezomib-containing therapy (22%), and daratumumab-containing therapy (13%). Hematological complete response rates at 3-month, 6-month, and best response prior to CarCR were 32%, 49% and 76%, respectively. At CarCR, the median NT-proBNP was 265 pg/mL (IQR 220-307) with a median time from treatment onset to CarCR achievement of 20.6 months. At CarCR, 33% of patients were on loop diuretics. The CarCR rate at 6, 12, 24, 36, 48 and 60 months from treatment onset was 10%, 39%, 81%, 90%, 95% and 96%, respectively. Temporary increase of NT-proBNP above 350 pg/mL with return to CarCR was documented in 46% of patients. Echocardiogram parameters also improved significantly at the time of CarCR, with average left ventricular longitudinal strain showing the greatest median improvement in relation to baseline (from -12% to -17%, p<0.001). However, echocardiographic parameters did not fully normalize in all patients. Cardiac progression was seen in 14% of patients, at a median of 7.6 years from the initial time of CarCR. In addition, subsequent clone-directed therapy was given in 44% of patients at a median of 4.6 years from the initial treatment. With a median follow-up of 9.5 years, eight patients (13%) died, 4 due to causes unrelated to AL. We compared the survival of patients who achieved CarCR to the general U.S. population, matching for age, sex, and the year treatment. The observed survival of CarCR patients was similar to that of the general population (p=0.35). Conclusion: Patients with persistent CarCR >12 months in AL amyloidosis are uncommon and demonstrate excellent outcomes. The achievement of hematological CR was required in 3 out of 4 patients reaching a CarCR. Echocardiographic changes of amyloid infiltration may still persist in this highly favorable cohort, indicating that “complete” response refers primarily to functional and prognostic improvement, not necessarily a full restoration to pre-disease cardiac morphology and function. Achieving CarCR is associated with a low risk of cardiac progression, but the need for subsequent clone-directed therapy remains elevated.

Abstract Background: Gastrointestinal (GI) symptoms are frequent in patients (pts) with systemic light chain amyloidosis (AL), yet their clinical significance remains poorly defined. We investigated the role of symptomatic GI involvement in disease burden, survival, and organ-specific outcomes in a large single-center cohort. Methods From 2010–2025, 4,396 AL pts were evaluated at our center; 560 pts (13%) had provider-attributed symptomatic GI AL. Pts with localized AL or positive biopsy without GI symptoms were excluded (n=38). We analyzed relationships between GI symptoms, anatomic/histologic involvement, laboratory parameters, survival, and need for nutritional support using Wilcoxon rank-sum, Chi-square, Kaplan-Meier, and logistic regression tests. Results GI symptoms included early satiety (n=320/57%), diarrhea (n=189/34%), nausea (n=184/33%), abdominal pain (n=148/26%), dysphagia (n=119/21%), vomiting (n=75/13%), GI bleeding (n=74/13%), and heartburn (n=71/13%). Only nausea and GI bleeding were not associated with cardiac (n=366/65%) renal (n=274/49%) or hepatic (n=84/15%) AL, whereas dysphagia, early satiety and heartburn were more frequent with cardiac (all OR=1.7), abdominal pain and diarrhea with hepatic (OR=2 and 1.6, respectively), and vomiting with renal involvement (OR=2; all p<0.04). Autonomic involvement impacted GI symptoms, often without proof of parenchymal GI amyloid. Of the 124 pts with formal autonomic testing, only 44 (35%) had positive GI biopsies as compared to AL GI pts without proven autonomic involvement (240/436, 55%). Pts with autonomic involvement were more symptomatic than pts with positive GI biopsies, suffering more often from dysphagia (29% vs 19%), diarrhea (41% vs 32%), and gastroparesis (34% vs 9%, all p<0.001). We screened changes in body weight, calcium, VitB12, Hb, PO4, and albumin at diagnosis. Of the 175 pts with documented weight loss in this cohort, pts with GI AL lost more weight compared to those with other organ involvement (21% vs 14% of weight, p=0.002), and had lower phosphate (3.7 vs 4.0 mg/dL, p=0.06). In our cohort of pts with GI symptoms, 298 (53%) had a positive GI biopsy. Biopsy-proven anatomic involvement dictated symptoms (all p<0.05): Of the 20 pts with positive esophageal biopsy, dysphagia was present in 45%; only 33% of the pts without an esophageal biopsy had dysphagia. Similar patterns were seen for the 170 pts with a positive gastric biopsy (n=170) in terms of heartburn (21% vs 11%), for the 165 pts with positive small bowel biopsies in terms of abdominal pain (68% vs 32%), and for the 130 pts with positive colon biopsies and diarrhea (46% vs 33%). Specific histopathological patterns were prognostic. Mucosal involvement (n=161) was an independent risk factor for survival compared to submucosal (n=64) and vascular (n=102) involvement throughout the GI tract (HR 1.83; p=0.03). Three-layer GI infiltration was associated with inferior mOS (2.4 vs 5.1 vs 7.8 y for 3 vs 2 vs 1-layer involvement, HR 3.19/1.56/1; p<0.05). Counterintuitively, vascular involvement had the lowest risk of bleeding in all GI anatomic sites (p=0.02). In the colon, only mucosal involvement was associated with a higher risk of bleeding (OR=5; p=0.04). GI involvement in AL pts did not worsen prognosis (mOS 10.0/6.3y, p=0.02), and pts with isolated GI AL (n=74/13%) had an even better survival (55% surviving at 10 y). Cachexia (n=120; mOS 3.5 vs 7.8 y, p<0.001), need for nutritional support (n=36; mOS 0.9 vs 7.0 y, p<0.001), and diarrhea (mOS 5.8 vs 6.9 y, p=0.06) were risk factors for death. In pts with hematologic response (≥PR), bleeding did not recur within 3 y (n=27), but even with response, diarrhea (n=160) persisted in 39%. Resolution was less frequent without hematologic response (persistence in 69%, OR=3.5). Improvement was most often due to treatment of bacterial overgrowth (11/35 pts; 68%) and loperamide (54/59 pts; 91%). Conclusion In AL, meaningful GI involvement is defined by nausea, diarrhea, occurrence of bleeding, and malnutrition. These are primarily associated with mucosal infiltration. GI symptoms can occur in the face of autonomic involvement. While long-term persistence of GI bleeding is rare after serologic response, cachexia and persistent diarrhea drive morbidity, need for nutritional support, and poor survival.