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Abstract Background: Higher-risk myelodysplastic syndromes/neoplasms (HR-MDS) and secondary acute myeloid leukemia (sAML) share overlapping molecular features but both remain clinically diverse with poor prognosis. Machine learning (ML)-based genomic clustering offers an opportunity to redefine disease subgroups beyond traditional clinical prognostic schemes or pathologic classifications. Prognostic scoring systems emphasize outcomes while pathologic classifications morphology resulting in inclusion of patients (pts) with different genetic background into same outcome or morphologic subgroup. We compared our ML-unsupervised clustering (UC) model named molecular nosology1 with the taxonomy model2 to evaluate differences in cluster architecture and clinical relevance in HR-MDS and sAML. Methods We analyzed HR-MDS (≥10% blasts) and sAML pts with available molecular data at diagnosis from a well-annotated cohort. Our molecular nosology model used UC via a binary latent-factor model to generate molecular clusters (MCs). The taxonomy model assigned pts to predefined genomic classes. We compared MC size, genomic enrichment, and overall survival (OS) across diagnostic categories. Concordance was assessed using Adjusted Rand Index (ARI) and Normalized Mutual Information (NMI). Purity and entropy were calculated to assess how concentrated (purity) or dispersed (entropy) each taxonomy group was across MCs. Results Among 898 pts, 367 (41%) had HR-MDS and 531 (59%) had sAML. Median age was 71 (IQR 65–77) years. Compared to sAML, HR-MDS pts had similar age (71 vs. 72, p=0.556) but higher hemoglobin (9.9 vs. 9.3, p<0.001) and platelet counts (91 vs. 50, p<0.001). Normal karyotype was more common in HR-MDS (55% vs. 42%, p<0.001). TET2 (24%), ASXL1 (24%), RUNX1 (23%), and SRSF2 (22%) were the most frequently mutated genes. Using our nosology model, we identified 14 MCs.1 The most frequent were MC2 (normal karyotype) at 22% and MC13 (TP53-complex) at 17%, followed by MC1 (+8/ASXL1/TET2/RUNX1, 12%), MC6 (SRSF2/RAS-pathway, 9%), and MC9 and MC14 (each 8%). Less common clusters included MC12 (5%) and MC3–MC5 (2–3%). For comparison, the taxonomy model included 18 genomic groups: TP53-complex (20%), mNOS (13%), bi-TET2, IDH-STAG2, and no event (each 10%), CCUS-like, SETBP1/-7, and AML-like (each 6%), SRSF2 (4%), del(5q), BCOR/L1, EZH2-ASXL1, and SF3B1 (each 3%), and five rare subgroups (DDX41, der(1;7), U2AF1157, U2AF134, ZRSR2; all <1%). Our MCs aligned closely with several taxonomy groups: 82% of TP53-complex cases were assigned to MC13, 99% of no event cases mapped to MC2, and 97% of del(5q) cases mapped to MC8. Bi-TET2 cases were distributed across MC6 and MC12 (both TET2-enriched); SETBP1/-7 to MC11; and EZH2-ASXL1 cases to MC1 and MC12. In contrast, mNOS, AML-like, and CCUS-like groups were genomically heterogeneous and spanned multiple MCs. ARI and NMI values were 0.391 and 0.458, indicating moderate concordance. Purity was highest in no event (0.989), del(5q) (0.967), and TP53-complex (0.823), and lowest in IDH-STAG2 (0.247), CCUS-like (0.241), and AML-like (0.347), all with high entropy (>2.5), reflecting genomic diversity not captured by taxonomy groups alone. Median OS for the entire cohort was 17 mo (95%CI: 14–20). HR-MDS pts had longer OS vs. sAML (26 vs. 12 mo, p<0.001). OS did not differ significantly between HR-MDS and sAML within most taxonomy groups or MCs, except for MC3 (NA vs. 11 mo, p=0.014), MC6 (111 vs. 15 mo, p<0.001), and MC9 (18 vs. 9 mo, p=0.027) for the nosology model and SF3B1 (129 vs. 23 mo, p=0.033), del(5q) (33 vs. 6 mo, p=0.022), bi-TET2 (25 vs. 8 mo, p=0.019), mNOS (34 vs. 9 mo, p<0.001) for taxonomy. Conclusions Some molecular taxonomy groups showed strong concordance with our nosology-defined clusters, which served as the gold standard for genomically distinct subsets (e.g., TP53-complex, del(5q), and no event), irrespective of diagnosis or blast percentage which may present the stage of the disease. In contrast, taxonomy-defined categories such as CCUS-like, AML-like, and mNOS were more genetically diverse and less aligned with specific clusters in the nosology model. Median OS within most clusters was not significantly influenced by blast count, underscoring the potential of molecular-driven clustering to reveal underlying disease biology not captured by morphology and to refine classification in MDS/AML and sAML with few exceptions (SF3B1 or biTET2). Ref 1.Kewan, Durmaz et al.Nat Commun 2023 2.Bernard, et al.Blood 2024

Abstract Background & aim: Myelodysplastic syndromes with isolated deletion of chromosome 5q (MDS-del(5q)) are associated with low-risk features and favorable prognosis. In contrast, TP53 multihit alterations, typically reflecting biallelic inactivation, are associated with high-risk features and adverse outcomes across MDS subtypes. Although current classification systems exclude MDS-del(5q) cases with TP53 multihit from low-risk categories, the prognostic significance of these alterations in this specific context remains unclear. Methods: We conducted an international, multicenter, retrospective study comparing MDS-del(5q) per 2017 WHO criteria with TP53 multihit alterations (MDS-del(5q) TP53 multihit) from 21 international institutions, to MDS with low blast counts with TP53 multihit alterations without isolated del(5q) (MDS-LB TP53 multihit) from the public data from the study of Bernard et al., Nat Med 2020. Clinical and biological data were collected at diagnosis. Genetic profiling included G-banding and NGS of myeloid genes. TP53 multihit was defined as >1 TP53 mutation or a single mutation with 17p deletion, copy-neutral loss of heterozygosity (LOH), or variant allele frequency (VAF) ≥50%. Patients were stratified as lower- or higher-risk based on IPSS-R and IPSS-M scores. Lower-risk included those with IPSS-R ≤3.5 points or very-low, low, or moderate-low IPSS-M, while higher-risk included those with IPSS-R >3.5 points or moderate-high, high, or very-high IPSS-M. Clinical, molecular features, overall survival (OS), and AML progression were compared between MDS-del(5q) TP53 multihit and MDS-LB TP53 multihit groups. Finally, outcomes between patients with likely biallelic TP53 multihit status, defined as harboring a single TP53 mutation accompanied by a co-occurring deletion/LOH of 17p or a TP53 VAF ≥50%, versus those considered less likely to be biallelic, thus still classified as multihit, defined as having >1 TP53 mutation but a combined VAF <50%, were compared in both MDS-del(5q) and MDS-LB groups. Statistical analysis was performed using R (version 4.2.2). Results: We included 113 patients with a median follow-up of 81.1 months (95% CI 74.9–NR). A total of 45 (39.8%) were MDS-del(5q) TP53 multihit, and 68 (60.2%) MDS-LB TP53 multihit. Compared to MDS-LB TP53 multihit, patients with MDS-del(5q) TP53 multihit had significantly higher platelet counts (209 ×10⁹/L vs. 77 ×10⁹/L) and were more frequently classified as lower-risk by both IPSS-R (75.4% vs. 9.8%) and IPSS-M (90.2% vs. 24.6%). The median number of mutations per patient, excluding TP53, was 1 in both groups, and only SF3B1 mutations were significantly more frequent in the MDS-del(5q) TP53 multihit group compared to MDS-LB TP53 multihit (20.5% vs. 2.9%; p<0.01). Regarding survival, MDS-del(5q) TP53 multihit patients showed an improved OS compared to MDS-LB TP53 multihit (median OS of 57.0 months (95%CI, 43.0–112.0) vs 14.0 months (95%CI, 8.6–19.0); p<0.01). Moreover, while the risk of progression to AML at 48 months were comparable between groups (34.9% for MDS-del(5q) TP53 multihit and 33.0% for MDS-LB TP53 multihit; p=0.8), a significant difference was observed in the timing of AML progression: median time to AML evolution of 31.7 months (IQR 23.4–55.3) in the MDS-del(5q) TP53 multihit group and 7.2 months (IQR 4.1–12.9) in the MDS-LB TP53 multihit group (p<0.01). Notably, no significant differences in outcomes were found between TP53 multihit and most likely biallelic cases in both MDS-del(5q) and MDS-LB cohorts. The impact of complex karyotype (CK) in MDS-LB TP53 multihit was also explored. MDS-LB TP53 multihitwith CK showed a significantly worse OS compared to MDS-LB TP53 multihitwithout CK (median OS of 10.0 months (95% CI 7.5–17.0) vs 40.0 months (95% CI 14.0–NA); respectively; p<0.001. However, the incidence of AML and median time to AML evolution were comparable between both groups. Finally, OS between MDS-LB TP53 multihit patients without CK and the MDS-del(5q) TP53 multihit cohort was compared. Median OS was significantly shorter in the former group (median of 40 months) compared to the latter (median of 61 months) (p <0.01) Conclusions: These findings underscore that, in contrast to other TP53-multihit MDS subtypes, MDS-del(5q) with TP53 multihit alterations constitute a clinically distinct entity with better outcomes, thereby warranting reconsideration of its place in current classification systems.

Abstract Background Blast transformation (BT) occurs in approximately 15-30% of patients with chronic myelomonocytic leukemia (CMML) and remains a leading cause of death. Allogeneic stem cell transplantation (ASCT) is currently the only treatment modality with the potential to cure the disease or prolong survival. Optimal timing of ASCT is critical for maximizing benefit while minimizing risks. To that end, contemporary risk models have focused on the prognostic relevance of individual, as opposed to concurrent mutations. In the current study, we looked into the possibility of prognostic prominence from concurrent mutations in predicting BT in CMML. Methods CMML diagnostic criteria were according to the International Consensus Classification (Arber et al. Blood 2022; 140:1200). A machine-learning hierarchical clustering algorithm was developed and tailored for patient stratification using survival outcomes and co-expression of genomic alterations. To reduce complexity and improve interpretability, we generalized each cluster using existing rule induction algorithms, including the in Trees framework and JRip. The final output was a set of mutation-based cluster definitions, each representing a distinct patient subgroup with similar survival trajectories. Competing risk analysis and cumulative incidence functions were used in downstream evaluation to validate the clinical distinctiveness of the clusters. For all survival analysis, patients were censored at the time of ASCT. Time-to-BT was calculated from the date of diagnosis to the date of BT or ASCT or last contact. BT-free-survival was calculated from the date of diagnosis to the date of BT, ASCT, death, or last contact. Results The core study cohort included 605 patients from the Mayo Clinic, USA, and the external validation cohort 501 patients from Humanitas Cancer Center, Milan, Italy. Using the patient cohort from the Mayo Clinic, machine-learning algorithms identified five molecular clusters with 3-year blast transformation (BT) rates ranging from 0% to 100% (AUC at 3 years 0.78): the order of molecular signature assignment (probability of BT/death from another cause) was i) PHF6MUT/ASXL1WT (0%/17% at 3 years; N=32), ii) NPM1MUT OR BCORMUT/ASXL1MUT OR SETBP1MUT/NRASMUT (48%/30% at 1 year; N=24), iii) RUNX1MUT/ASXL1MUT OR SRSF2MUT/NRASMUT OR EZH2MUT/ASXL1MUT OR SETBP1MUT OR BCORMUT (31%/55% at 3 years; N=132), iv) ASXL1MUT/TET2MUT OR DNMT3AMUT OR JAK2MUT (24%/28% at 3 years; N=123), and v) all other permutations (10%/40% at 3 years; N=294) [Figure 1]. Additional analysis confirmed significant differences in survival between RUNX1MUT/ASXL1MUT vs. RUNX1MUT/ASXL1WT (p<0.01) OR RUNX1WT/ASXL1WT (p<0.01) OR RUNX1WT/ASXL1MUT (p=0.038) [Figure 2]. Similar patterns of differences in survival were also documented for NRAS/SETBP1, ASXL1/EZH2, and NRAS/SRSF2 mutation combinations (Figure 2). A subsequent Cox regression analysis confirmed independent prognostic contributions from “PHF6MUT/ASXL1WT” (HR 5.43e-10; p<0.01), NPM1MUT (HR 26.7; p<0.01), “SETBP1MUT/NRASMUT” (HR 12.7; p<0.01), BCORMUT(HR 5.8; p<0.01), “RUNX1MUT/ASXL1MUT” (HR 2.3, p<0.01), JAK2MUT (HR 2.1; p<0.01), and “ASXL1MUT/TET2MUT” (HR 1.7; p=0.02). The prognostic relevance of “SETBP1MUT/NRASMUT”, “RUNX1MUT/ASXL1MUT”, NPM1MUT, and BCORMUT was validated in the external cohort from Italy (N=501). In the Mayo Clinic cohort, presence of any of the latter mutations was associated with 1-, 3-, and 5-year BT (death from other cause) rates of 27% (21%), 44% (49%), and 44% (51%), respectively (Figure 3). The corresponding values in the absence of high risk mutations were 7% (15%), 15% (37%), and 18% (52%) [Gray's p value <0.01 for both BT and death from another cause; Figure 3]. Similarly, the 1-, 3-, and 5-year BT (death from another cause) rates in the Italian cohort were 21% (19%), 37% (47%), and 42% (54%) in the presence and 8% (14%), 20% (35%), and 24% (45%) in the absence of high-risk mutations (Gray's p value <0.01 for BT and 0.18 for death from another cause; Figure 4). Conclusions In the current study, machine-learning algorithms enabled the discovery of concurrent mutations in CMML that were shown to be prognostically more significant than their individual constituents. Such prognostic interaction might have contributed to some of the discrepancies noted in current literature regarding the prognostic relevance of certain mutations in CMML and should be accounted for in the development of future risk models.

Abstract Introduction: Standardized reporting of clinical trials results for MDS is essential to improve clinical interpretation and cross-study comparison. However, reporting of patient characteristics, response criteria, and endpoints in publications is often inconsistent; there is no systemic analysis of MDS trial reporting available. We conducted a systematic review of published MDS trial manuscripts on behalf of the international consortium for MDS (icMDS) to assess variability in reporting practices. Methods We searched ClinicalTrials.gov to identify all clinical trials registered for adults (≥18 years) with MDS that reported results between 2015-2024. Clinical trials that included acute myeloid leukemia (AML) or MDS/myeloproliferative neoplasms (MPN) were included if they enrolled ≥5 MDS patients. We excluded trials without an MDS cohort; non-therapeutic trials; trials focused on transplant interventions; or those which enrolled solid malignancies or other hematologic malignancies (chronic myeloid leukemia or lymphoid diseases). Finally, trials were required to have a manuscript available on Larvol, PubMed, or Google Scholar. Trials were categorized by disease risk (lower-risk [LR] vs. higher-risk [HR]) and trial phase (early phase [EP] vs. late phase [LP]). Results We identified 502 MDS trials on ClinicalTrials.gov, of which 351 did not meet inclusion criteria and 79 lacked a manuscript. A total of 72 trials (32 EP, 40 LP) with 80 publications (34 EP, 46 LP) were analyzed. Frequently reported baseline characteristics included age (100% EP, 100% LP), disease risk (74% EP, 74% LP), Eastern Cooperative Oncology Group performance status (85% EP, 72% LP), prior treatments (71% EP, 67% LP), and RBC transfusion dependency (32% EP, 70% LP). Less frequently reported characteristics included blood counts (hemoglobin [Hb; 38% EP, 54% LP], platelet count [38% EP, 54% LP], neutrophil count [24% EP and LP]) and bone marrow blasts (29% EP, 43% LP). Although disease risk was widely reported, definitions varied: IPSS and IPSS-R were each reported in 54% of manuscripts, while IPSS-M appeared in only 3%. Cytogenetic risk was separately reported in 39% of manuscripts (38% EP, 39% LP), and mutational data in 45% (47% EP, 43% LP). Responses per IWG 2006 criteria were reported in 84% of manuscripts. The primary endpoint involved safety/tolerability in 85% of EP manuscripts, though definitions were variable; recommended phase 2 dose was the most common (26% of EP manuscripts). In LP trials, primary endpoints were risk-specific: transfusion independence (TI) in 77% of LR, overall response rate (ORR) in 28% of HR, and complete remission (CR) or overall survival (OS) in 22% of HR. In HR manuscripts, CR was reported in 100%, ORR in 73%, hematologic improvement (HI) in 48%, RBC-TI in 23%, and OS in 80%. However, seven different definitions were used for ORR: CR + marrow CR + partial remission + HI per IWG 2006 was most common (35%). Event-free survival was reported in 25%; progression-free survival and relapse-free survival in 13%; and leukemia-free survival in 5%. Early mortality rate was reported in 35% (18% EP, 56% LP) and transplant rate in 58% (50% EP, 67% LP). Only 47% of HR and 90% of LR manuscripts identified HI-eligible patients. In LR-MDS, RBC-TI was reported in 72% of manuscripts but used six definitions. The most common were RBC-TI ≥8 weeks at any time during treatment (24%), ≥8 weeks within 28 weeks of treatment (13%), ≥8 weeks with Hb increase ≥1.0 (4%), ≥12 weeks with Hb increase ≥1.5 (4%), and ≥16 weeks within 24 weeks of treatment (12%). The remainder did not report RBC-TI, did not define it, or used a custom definition not used in another trial. HI was reported in 80% of LR papers with most of those reporting HI using IWG 2006 criteria (90%). Conclusion Reporting of baseline characteristics, response criteria, and outcomes is inconsistent in MDS clinical trials, with wide variability in response definitions, including ORR and TI. This heterogeneity limits interpretability, hampers historical comparisons and may obscure efficacy signals. Our findings highlight the need for standardized reporting guidelines to ensure clarity and consistency in MDS trial publications. As a next phase of this effort, we will conduct a formal Delphi process among icMDS experts to establish consensus recommendations for minimal and optimal MDS clinical trial reporting in manuscripts by disease risk (LR/HR) and trial phase (EP/LP).

Abstract Introduction TP53MT are associated with poor outcomes in MDS, especially in the context of biallelic MT. We have previously reported on outcomes of pts with HR-MDS with TP53MT who received HMA in the VALIDATE dataset (Kewan T et al, ASH 2023). Here we provide expanded analyses focusing on outcomes post allo-HCT, and we explore the prognostic significance of different classification methods for biallelic TP53MT. Methods The VALIDATE database includes 4,732 pts with MDS who received HMA-based frontline therapy from 32 international centers in 9 countries. For this study, only pts with HR-MDS with molecular data at time of diagnosis were included. Biallelic TP53MT status was assessed using three classification schemes: WHO 2022, ICC 2022, and a VAF-based Cleveland Clinic Foundation (CCF) method.1TP53 copy neutral loss of heterozygosity (CN-LOH) was evaluable in 386 pts (118 had TP53MT). Treatment responses were evaluated using IWG 2023 criteria (Zeidan A et al, Blood 2023). Composite complete remission (cCR) was defined as CR+CRbi+CRuni+CRh+CRequivalent. We calculated OS from time of HMA initiation to date of death or last follow up. Unsupervised clustering (MOSAIC framework) was applied to identify molecular subgroups within the TP53MT cohort. The study was funded by an independent grant from Abbvie. Results A total of 1,485 pts were included. Median age was 69 years (IQR: 62–76), with 66% male pts. Median bone marrow blast was 7%, and 28% had a complex karyotype. Treatment regimens included azacitidine (68%), decitabine (15%), HMA/Venetoclax (8%), and other HMA combinations (9%); 34% underwent allo-HCT. Overall, 392 (26%) had TP53MT with 430 TP53 mutations (missense: 316; truncating: 89). Biallelic TP53MT % varied by classification: 72% (WHO), 84% (ICC), and 85% (CCF). Compared to TP53 wild-type (TP53WT) pts, pts with TP53MT had worse OS (median: 11.5 vs. 23.9 months [mo], p< 0.001), were younger (68 vs. 70 years, p=0.039), and had lower counts at diagnosis. Complex karyotype (81% vs. 14%) and chromosomal abnormalities were more frequent in TP53MT pts. Pts with TP53MT also had fewer co-mutations in other genes. Response to HMA was evaluable in 1,094 pts: cCR and CR were 32% and 13%, respectively. TP53MT pts had higher cCR (39% vs. 29%, p=0.001) than TP53WT, but similar CR rates (16% vs. 12%, p=0.093). According to WHO 2022, biallelic TP53MT had higher CR rates than monoallelic TP53MT (18% vs. 8%, p=0.03), but similar cCR. ICC and CCF classifications did not differentiate response rates. Median OS did not differ by TP53MT allelic status using WHO or ICC definitions. However, using the CCF method, pts with biallelic TP53MT had shorter OS than monoallelic TP53MT (10.4 vs. 17.2 mo, p=0.038). In multivariable models adjusted for age, gender, and allo-HCT, only the CCF-defined biallelic TP53MT group had significantly worse OS (HR: 1.6; 95% CI: 1.1–2.4). TP53MT pts undergoing allo-HCT had improved OS regardless of allelic status. Median OS for TP53MT pts with allo-HCT was 18.9 vs. 9.2 mo without all-HCT. This benefit was observed across WHO, ICC, and CCF classifications. However, a TP53MT VAF ≥19% predicted worse OS even post allo-HCT (14.6 vs. 47.1 mo, p<0.001). At 1 year, the survival rate was 78% (95%CI: 69-89%) in TP53MT pts who underwent allo-HCT and had cCR vs. 68% (95%CI: 55-84%) in pts who did not have cCR. However, 1 year survival rate was significantly higher for pts with TP53MT who did not have allo-HCT and achieved cCR (60%, 95%CI: 48-76%) vs. no cCR (26%, 95%CI: 20-35%). Unsupervised clustering of 335 TP53MT pts identified 9 molecular clusters (MCs). MC2, characterized by low TP53MT VAF (median 17%), fewer co-mutations, and frequent del17p, was associated with significantly improved OS (17.9 mo) and predicted favorable outcome (HR for death: 0.6; 95% CI: 0.4–0.8). Other clusters were enriched for adverse features (e.g., high VAF, multi-hit TP53MT).Conclusions The CCF method appears to best classify biallelic TP53MT pts with worse survival in the absence of accurate assessment of LOH status. Treatment response per IWG 2023 for TP53MT pts was associated with OS only in non-transplanted pts. Allo-HCT improved survival across TP53MT subsets, but TP53 VAF ≥19% at diagnosis remained a strong negative prognostic factor. Integrative clustering revealed a less aggresive molecular subset among TP53MT pts, suggesting refined risk stratification may guide therapy in this high-risk population. Ref: 1.Bahaj et al. J Hematol Oncol 2023.

Abstract Introduction: Marrow complete remission (mCR) in 2006 IWG criteria for MDS (Cheson B et al, Blood 2006) reflects achieving bone marrow (BM) blast percentage below 5% but is frequently not associated with meaningful count recovery. While mCR + hematologic improvement (HI) does reflect wide ranges of count improvement or transfusion reductions, HI is difficult to measure accurately in routine clinical practice. The 2023 International Working Group (IWG) response criteria (Zeidan A et al, Blood 2023) eliminated the mCR category without meaningful count recovery and reclassified mCR associated with meaningful count recovery into specific “less-than-CR” categories. Still, many clinical trials continue to use mCR as a secondary efficacy endpoint or as a part of overall response rate (ORR). Within the icMDS VALIDATE database, we assessed the association of mCR with OS in hypomethylating agent (HMA)-treated higher risk (HR)-MDS patients among both (1) transplanted and (2) non-transplanted patients. Methods We included patients with HR-MDS (defined as IPSS ≥1.5 and/or IPSS-R >3.5) who received HMA-based therapies from the international icMDS VALIDATE dataset. We evaluated the best response by IWG 2006 criteria into CR, mCR, or no CR/mCR. We then reclassified patients with mCR per IWG 2023 criteria into either (A) having achieved a composite CR (cCR) defined as CR + CR equivalent (CRequ) + CR with bilineage count recovery (CRbi) + CR with unilineage count recovery (CRuni) + CR with partial hematologic recovery (CRh) or (B) not having achieved cCR (no cCR). OS was calculated from time of HMA initiation to date of death or last follow-up by using 6-month landmark analyses. We used Kaplan-Meier methods to estimate OS, and the Log-rank test to compare OS. VALIDATE is supported by an independent grant from AbbVie. Results A total of1049 patients met eligibility.Median age of patients was 69 (range 21-95), 64% were men. While 61% received azacitidine, 17% received decitabine, and 22% received HMA-based combination therapy. In total, 37% underwent subsequent allogenic stem cell transplantation (allo-HCT). Based on IWG 2006 criteria, 17%, 33%, and 50% achieved CR, mCR, and no CR/mCR as their best response, respectively. Patients achieving CR had superior median OS (25 months, 95% CI: 21-34 months) compared to those with mCR (16 months, 95% CI: 13-18 months; p=0.038) and no CR/mCR (15 months, 95% CI: 12-17 months; p=0.001). In patients who received a subsequent allo-HCT, the median OS for patients with mCR (30 months, 95% CI: 21-54 months; 1 year OS: 71%, 2 year OS: 55%) did not significantly differ compared to patients with CR (59 months, 95% CI: 25 months-not reached, p=0.80; 1 year OS: 73%, 2 year OS 62%) and patients with no CR/mCR (32 months, 95% CI: 21-45 months, p=0.46; 1 year OS: 69%, 2 year OS 54%). In contrast, in patients treated with HMA therapy alone without subsequent allo-HCT, median OS for patients with mCR (11 months, 95% CI: 9-15 months; 1 year OS: 46%, 2 year OS: 23%) did not significantly differ compared to patients with no CR/mCR (11 months, 95% CI: 9-14 months, p=0.85; 1 year OS: 47%, 2 year OS: 22%) but was significantly shorter compared to patients with CR (20 months, 95% CI: 17-28 months, p<0.001; 1 year OS: 69%, 2 year OS: 46%). Patients with mCR by IWG 2006 (N=347) were reclassified per IWG 2023 into having either achieved a cCR (N=219, 63%) or no cCR (N=128, 37%). Specifically, patients with mCR were reclassified per IWG 2023 into CR (4.9%), CRequ (0.6%), CRbi (26.8%), CRuni (29.4%), CRh (1.4%), PR (0%), HI (10%), no response (21.9%) and PD (4.9%). Patients with mCR who were reclassified into cCR had an improved median OS (16 months, 95% CI: 15-26 months; 1 year OS: 62%; 2 year OS: 43%) compared to patients reclassified into no cCR per IWG 2023 (13 months, 95% CI: 11-17 months, p=0.023; 1 year OS: 52%; 2 year OS: 31%). Conclusions Using the large icMDS VALIDATE dataset, we found that achievement of mCR by 2006 IWG criteria was not associated with improved OS compared to patients who did not achieve CR/mCR. Reclassification of mCR using IWG 2023 highlights the heterogeneity within the mCR group and suggests that IWG 2023 criteria stratifies outcomes in patients previously labeled as mCR by IWG 2006. IWG 2023 should be the standard used for ORR assessment in all future clinical trials involving patients with HR-MDS.

Abstract Introduction: Iptacopan, the first oral complement inhibitor, offers an attractive alternative to parenteral complement blockers in paroxysmal nocturnal hemoglobinuria (PNH). While clinical trials have confirmed its efficacy vs terminal C5 inhibition, real-world data on breakthrough hemolysis (BTH), complement-activating conditions (CACs), and switching patients with satisfactory response to prior therapy (hemoglobin [Hgb] ≥10 g/dL) are limited. We studied a large multi-institutional PNH cohort treated with iptacopan. Methods: We performed a retrospective analysis of 62 patients with PNH who received iptacopan for ≥3 months between FDA approval in December 2023 and April 2025 (mean exposure, 1.01 years; 62 patient-years). Patients from the Cleveland Clinic network and Mayo Clinic were analyzed. Demographics, prior therapies, reasons for transition, Hgb, lactate dehydrogenase (LDH), platelet counts, thrombotic events, CACs, BTH, and adverse events were extracted. Efficacy was assessed separately for treatment-naive patients and treatment-experienced patients (sub-optimal responders [Hgb <10 g/dL] and optimal responders to prior therapy). Results: Overall, 12 of 62 patients were treatment naive and 50 switched from prior therapy (of whom 21 had sub-optimal responses and 29 had optimal responses). In the 50 patients who switched, 60% transitioned from ravulizumab, 30% from pegcetacoplan, 8% from eculizumab, and 2% from ravulizumab and danicopan. The primary reasons for switching were the convenience of oral medications (n=17), extravascular hemolysis or BTH (n=10), prior medication side effects (n=5), desire to further improve Hgb (n=6), and not documented (n=12). A total of 4 patients discontinued iptacopan (2 pregnancies, 1 insurance reversal, 1 intolerable gastrointestinal toxicity). Three patients reported headaches, and 1 reported abdominal pain; all resolved within 1 week from treatment start. Across the 62 patient-years, no thrombotic events occurred, 18 CAC episodes were managed with iptacopan 200 mg BID (10 infections, 1 heart-failure exacerbation, 2 minor surgeries, 1 traumatic brain injury, 2 pancreatitis, 2 pregnancies), and none triggered BTH. Overall, 3 clinically significant BTH events (in 3 patients; 4.8% annualized) were recorded: 2 infection-related (managed outpatient) and 1 alcoholic pancreatitis; all resolved with a 1- to 2-day increase to iptacopan 400 mg BID ± single-dose eculizumab. Two hemolytic events secondary to non-adherence were reported (4 days after stopping iptacopan). These resolved after resuming iptacopan 200 mg BID without need for hospitalization. In treatment-naive patients, mean Hgb increased significantly by 1.87 g/dL from iptacopan initiation (baseline) to 3 months (9.9±1.9 to 11.8±1.3 g/dL; P=.005), sustained until last follow-up at 12 months. LDH decreased by 369 U/L at 3 months (P=.058), sustained through 12 months. No significant change was seen in platelets, absolute neutrophil count (ANC), or white blood cell (WBC) count. In treatment-experienced sub-optimal responders, mean Hgb increased significantly by 2.16 g/dL from baseline to 3 months (8.6±.89 to 10.8±2.1; P<0.001). At 12 months, 85% of patients had increased Hgb compared with baseline (median increase: 3.31±1.62 g/dL). LDH decreased significantly from baseline to 3 months by 229 U/L (P=.03), with no significant changes noted in LDH from 3 to 12 months or in platelets, ANC, or WBC counts. In previously treated complement inhibitor responders, mean Hgb increased significantly by 0.75 g/dL from baseline to 3 months (12.0±1.3 to 12.8±1.7 g/dL; P=.004), with 79% showing improvements from baseline at 12-month follow-up (median increase: 1.16±0.82 g/dL). LDH decreased significantly by 45 U/L from baseline to 3 months (P=.03), with no further significant changes from 3 to 12 months. Conclusions: In this real-world cohort, iptacopan provided substantial and durable hemoglobin improvement across naive and previously treated patients with PNH, with meaningful reduction in hemolytic parameters, absence of thrombosis, and low BTH rate predominantly linked to infection. Patients with previous satisfactory responses also showed improved Hgb levels. The favorable safety profile and high treatment persistence underscore iptacopan's role as an effective first-line or switch therapy and support its incorporation into evidence-based sequencing algorithms in the evolving PNH treatment landscape.

Abstract Introduction: The therapeutic landscape for paroxysmal nocturnal hemoglobinuria (PNH) has rapidly evolved with multiple proximal complement inhibitors now available, including pegcetacoplan (C3 inhibitor) and iptacopan (oral factor B inhibitor). While clinical trials have established individual drug efficacy compared with terminal complement inhibitors, real-world evidence regarding therapeutic transitions between proximal complement inhibitors remains extremely limited. As patients and clinicians increasingly seek to optimize treatment through sequential therapy approaches, understanding the outcomes of transitioning from pegcetacoplan to iptacopan becomes critical for evidence-based treatment sequencing in this rare hematologic disorder. Methods: We conducted a retrospective multicenter analysis across 3 academic medical centers (Cleveland Clinic, Mayo Clinic, Levine Cancer Institute) that evaluated 15 consecutive patients with PNH who were considered for transition from pegcetacoplan to iptacopan. Patients had confirmed PNH by flow cytometry and ≥3 months pegcetacoplan exposure. After switching to iptacopan, we assessed treatment acceptance rates, demographic characteristics, clinical outcomes including hemoglobin and lactate dehydrogenase (LDH) levels, and safety parameters. Responses to iptacopan were classified as optimal (hemoglobin >10.5 g/dL with clinical improvement) or suboptimal. Statistical analysis used paired t tests for continuous variables. Results: Of the 15 patients evaluated (median age [range]: 53 [22-81] years; 73% female), 14 patients (93.3%) elected to transition to iptacopan, demonstrating high treatment acceptance. Disease subtypes included classic PNH (36%) and PNH (64%) in the setting of another bone marrow disorder (n=7), multiple myeloma (n=1), and myelofibrosis (n=1). Median (range) duration of pegcetacoplan treatment pre-switch was 3 months (2-7 months), and median (range) duration of iptacopan treatment was 24 months (6-36 months). Among patients who transitioned, 79% (11/14) achieved hemoglobin improvement, with a mean increase from 9.2±1.8 to 10.8±2.1 g/dL (P=.028). Overall, optimal response was achieved in 64% (9/14) of patients. Response rates varied significantly by disease subtype: 80% in patients with classic PNH vs 56% in patients with PNH and aplastic anemia, with particularly poor outcomes in patients with concurrent hematologic malignancies (0%). LDH levels improved in 86% of patients, decreasing from 400±152 to 310±95 U/L (P=.015). PNH clone sizes remained stable throughout transition (erythrocyte: 75.1%±9.2% vs 75.4%±9.4%, P=.62; granulocyte: 95.0%±3.9% versus 95.2%±4.0%, P=.45). Treatment was well tolerated with no serious adverse events, breakthrough hemolysis, thrombosis, or discontinuations required. Two patients experienced mild self-limited gastrointestinal symptoms. Conclusions: This first multicenter real-world analysis demonstrates that the pegcetacoplan-to-iptacopan transition provides clinical benefit in the majority of this initial set of patients with PNH, with significant improvements in hemoglobin and an excellent safety profile while maintaining clone stability. The high acceptance rate suggests that patients prefer oral therapy over subcutaneous administration. These findings address a critical knowledge gap in proximal complement inhibitor sequencing, suggesting that iptacopan is an effective therapeutic option for patients with inadequate pegcetacoplan response and supporting the development of evidence-based treatment algorithms for optimal PNH care in the era of multiple complement inhibitor options.

Abstract Background: Systemic mastocytosis (SM) comprises a spectrum of subtypes characterized by neoplastic mast cell (MC) infiltration of tissues and release of MC mediators. Non-advanced SM (NonAdvSM), including indolent SM (ISM), smoldering SM (SSM), and bone marrow mastocytosis (BMM) subtypes, is the most prevalent form of SM. NonAdvSM can be associated with debilitating symptomology which can significantly impair quality of life. The gain-of-function somatic KIT c.2447 C>T (p.D816V) mutation is found in up to 95% of patients with SM. Bezuclastinib (CGT9486) is an oral, potent, and selective type 1 tyrosine kinase inhibitor with activity against KIT D816V. Results from Summit (NCT05186753) Part 1 informed the recommended phase 2 dose (100 mg QD bezuclastinib) for Part 2. We report topline results from the 24-week assessment of Summit Part 2. Methods: Summit is a multi-center, randomized, double-blind, placebo (PBO)-controlled Phase 2 trial of bezuclastinib in patients with NonAdvSM who had inadequate symptom control despite best supportive care (BSC) medications. The primary endpoint was 24-week mean change from baseline in Mastocytosis Symptom Severity Daily Diary (MS2D2) total symptom score (TSS) (range 0–110), which is a fit-for-purpose patient-reported outcome measure of NonAdvSM symptom severity. Key secondary endpoints included the proportion of patients with ≥50% reduction in serum tryptase, KIT p.D816V variant allele frequency (VAF), bone marrow (BM) MC burden, and MS2D2 TSS, ≥30% TSS reduction. Patients were randomized 2:1 to receive 100mg QD bezuclastinib + BSC or PBO + BSC. Results: As of May 22, 2025, 179 patients were enrolled in Part 2: 119 were randomized to receive bezuclastinib and 60 to placebo. Patients enrolled were representative of the NonAdvSM population with moderate to severe symptoms. Median age (range) was 51 (23-78) years; 65.9% female; mean (SD) baseline MS2D2 TSS 55.6 (19.8); 82% of patients had ISM, 11% had BMM, and 7% had smoldering SSM. At baseline, median (range) KIT p.D816V VAF in whole blood, BM MC burden, and serum tryptase was 0.25% (0-34%), 10% (1-75%), and 40 (6-692) ng/mL, respectively. Bezuclastinib demonstrated statistically significant superiority to placebo on all primary and key secondary endpoints. At Week 24, bezuclastinib led to significantly greater symptom improvement vs placebo (LS mean [95% CI] MS2D2 TSS change: –24.3 [–27.6 to –21.1] vs –15.4 [–19.6 to –11.2]; placebo-adjusted difference: –8.9 points; P=0.0002). A ≥50% reduction in serum tryptase was achieved in 87.4% of bezuclastinib-treated patients vs 0% on placebo (P<0.0001). Significantly more patients receiving bezuclastinib achieved ≥50% reductions in KIT D816V VAF, serum tryptase, BM MCs (P<0.0001), MS2D2 TSS (P=0.01), and ≥30% reduction in MS2D2 TSS (P=0.0004). Most treatment-emergent adverse events (TEAEs) were low grade (gr; 70% Gr 1) and reversible. The most common TEAEs (≥10%) in any treatment group and occurring in greater frequency in the bezuclastinib arm were hair color changes (69.5% vs 5.0%), altered taste (23.7% vs 0%), nausea (22.0% vs 13.3%), increased ALT/AST (22.0% vs 6.6%), headache (17.8% vs 11.7%), alopecia (11.9% vs 3.3%), and increased ALP (10.2% vs 3.3%). TEAEs (≥10%) that occurred more often in the placebo group were diarrhea (13% vs 18%), dizziness (10% vs 12%), fatigue (7% vs 12%), and arthralgia (6% vs 15%). ALT/AST elevations ≥Gr 3 were experienced by 5.9% of patients. The only hepatic adverse events (AEs) reported were transient lab abnormalities; none required hospitalization. Treatment-related AEs requiring dose reductions occurred in 11% of patients receiving bezuclastinib. All discontinuations (5.9%) due to treatment-related AEs were due to transaminase elevations; all fully resolved. Conclusions: At 24-weeks, bezuclastinib 100 mg QD demonstrated statistically and clinically significant improvements in symptom burden and biomarkers of disease vs placebo in patients with NonAdvSM. The treatment was generally well-tolerated and effective across a population that is representative of the real-world NonAdvSM population, including SSM. These results support the use of bezuclastinib to reduce SM burden and symptoms in pts with NonAdvSM, and a potentially disease-modifying impact.

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.