Smith, Angela R.

Background: The potent and selective oral menin-histone-lysine N-methyltransferase 2A (KMT2A) inhibitor revumenib (SNDX-5613) induced complete remissions with clearance of residual disease in acute leukemias refractory to multiple previous lines of therapy ( Nature. 2023;615:920-924). Here we report outcomes following the resumption of revumenib after hematopoietic stem cell transplant (HSCT). Methods: Patients aged ≥30 days with relapsed or refractory (R/R) acute leukemias with genetic alterations associated with HOXA overexpression, including KMT2A-rearranged ( KMT2Ar) or nucleophosmin 1 ( NPM1)-mutated leukemias, were enrolled in the AUGMENT-101 phase 1/2, multicenter, open-label, dose-escalation study (NCT04065399). Patients received revumenib every 12 hours (q12h) in 28-day continuous cycles. Patients who achieved a complete response (composite definition [CRc]), morphological leukemia-free state, or partial response could undergo HSCT without leaving the study. Revumenib was stopped before the HSCT conditioning regimen but, per a protocol amendment, could be resumed after HSCT if the patient was in CRc. Measurable residual disease (MRD) was assessed using multiparameter flow cytometry and/or polymerase chain reaction. Results: Between November 5, 2019, and June 28, 2023, a total of 131 phase 1 patients were enrolled and treated in the AUGMENT-101 study. Nine patients with acute myeloid leukemia (AML) from the AUGMENT-101 study resumed revumenib (8 after transplant and 1 after a stem cell boost [Table 1]). Seven patients had KMT2Ar and 1 patient each had nucleoporin 98 rearranged (NUP98r) and mutated NPM1. Revumenib was resumed 59 to 180 days after HSCT (Table 2). Dose was reduced for 4 of 9 patients to mitigate adverse events of thrombocytopenia (n=3) and leg pain (n=1), and revumenib was discontinued in 4 of 9 patients because of progressive disease (n=2), cytopenias (n=1), and not reported (n=1). Revumenib duration of treatment (DOT) in the maintenance setting at the time of this analysis ranged from 23 to 588 days, with treatment ongoing for 5 of the 9 patients. CRc was maintained in 6 of 9 patients after HSCT and maintenance revumenib. One patient with reported MRD after HSCT converted to MRD-negative status following initiation of revumenib maintenance therapy. Overall, MRD-negative remissions were maintained in 5 patients as of the data cut off. Conclusions: With 3 patients on revumenib maintenance therapy for more than a year, long-term responses, including conversion to MRD-negative status, were seen in these heavily pretreated patients with AML. Resuming revumenib post HSCT had a tolerable safety profile consistent with that previously reported for the AUGMENT-101 study.

Abstract Wiskott-Aldrich syndrome (WAS) is an X-linked disease caused by mutations in the WAS gene, leading to thrombocytopenia, eczema, recurrent infections, autoimmune disease, and malignancy. Hematopoietic cell transplantation (HCT) is the primary curative approach, with the goal of correcting the underlying immunodeficiency and thrombocytopenia. HCT outcomes have improved over time, particularly for patients with HLA-matched sibling and unrelated donors. We report the outcomes of 129 patients with WAS who underwent HCT at 29 Primary Immune Deficiency Treatment Consortium centers from 2005 through 2015. Median age at HCT was 1.2 years. Most patients (65%) received myeloablative busulfan-based conditioning. With a median follow-up of 4.5 years, the 5-year overall survival (OS) was 91%. Superior 5-year OS was observed in patients <5 vs ≥5 years of age at the time of HCT (94% vs 66%; overall P = .0008). OS was excellent regardless of donor type, even in cord blood recipients (90%). Conditioning intensity did not affect OS, but was associated with donor T-cell and myeloid engraftment after HCT. Specifically, patients who received fludarabine/melphalan-based reduced-intensity regimens were more likely to have donor myeloid chimerism <50% early after HCT. In addition, higher platelet counts were observed among recipients who achieved full (>95%) vs low-level (5%-49%) donor myeloid engraftment. In summary, HCT outcomes for WAS have improved since 2005, compared with prior reports. HCT at a younger age continues to be associated with superior outcomes supporting the recommendation for early HCT. High-level donor myeloid engraftment is important for platelet reconstitution after either myeloablative or busulfan-containing reduced intensity conditioning. (This trial was registered at www.clinicaltrials.gov as #NCT02064933.)

Abstract Introduction Expanding treatment options for MDS have changed therapeutic decision-making for clinicians. To better characterize therapeutic choices in newly diagnosed MDS, we report the practice patterns captured during the first year of MDS diagnosis for patients enrolled in our statewide population-based study. We highlight a comparison of treatment in community and academic centers. Methods Adults in Minnesota with MDS (AIMMS) is a statewide prospective population-based study conducted by the University of Minnesota (UMN), Mayo Clinic, and Minnesota Department of Health. Starting in April 2010, all newly diagnosed adult cases (ages 20+) of MDS were invited to participate. After patient enrollment, central review was performed consisting of independent hematopathology and cytogenetic review coupled with oncologist chart review assigning prognostic risk scores [International Prognostic Scoring System (IPSS) and IPSS-R (Revised)] and abstracting treatment exposures. All enrolled patients with one year follow-up were included in this analysis. Treatment was divided into supportive, active, transplant, or other. Supportive care included observation, growth factors, and transfusions. Active care included azacitidine, decitabine, lenalidomide, or 7+3 chemotherapy. Academic centers were defined as the UMN and Mayo Clinic; all other centers were designated as community based practices. Results The median patient age was 73 years, with 68% males. IPSS and IPSS-R risk scores were calculated for 100% and 97% of patients, respectively. Treatment choices stratified by IPSS risk group showed 89% low risk, 53% INT-1, 31% INT-2, and 13% high risk with supportive care; active and transplant strategies were utilized for 9% low risk, 44% INT-1, 64% INT-2, and 88% high risk. INT-1 in the community received 70% supportive treatment, in academic 35%. Active treatment for INT-1 was 30% in community and 45% in academic. Community INT-2 received supportive care in 45% of cases, in academic 23%. Transplants were limited to academic centers, with the highest rate in INT-2 at 34%. Among community diagnoses, 100% of high risk, 52% INT-2, 26% INT-1, and 13% low risk were referred to an academic center. Comparison of age <65 and 65+ years showed 83% of transplants occurred in those <65. INT-2/high risk group patients <65 received 95% active therapy or transplant, compared to 51% of those 65+. Discussion This prospective, population based study provides a well-defined patient cohort based on central review of pathologic and clinical data. Evaluation of practice patterns during the first year after diagnosis showed higher utilization of active and transplant treatment strategies as IPSS risk score increased. Further, compared to community, higher utilization occurred for patients at academic centers, suggesting more aggressive treatment in these settings. Age was also a predictor of treatment choice. In addition, referral patterns followed IPSS score. Whether these treatment differences are driven by patient preference and/or translate into improved disease control and decreased mortality requires continued prospective analysis and will be detailed in future reports. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 906 Background: Single-arm Phase 2 trials of DF in the treatment of severe VOD/MOF post-SCT demonstrated a complete response (CR) in 36–46% of patients (pts). A subsequent Phase 3 trial enrolling pts with more severe VOD (28%/24% with ventilator/dialysis dependence at study entry vs 5%/7%) demonstrated a CR of 24% compared to 9% in a matched Historical Control (HC); p=0.0148; Richardson ASH 2009). Given the life-threatening nature of VOD/MOF, DF was made available in the United States through a Treatment IND protocol (T-IND) in December 2007 to gather additional safety and response data. Methods: Pts were required to have a diagnosis of VOD based upon Baltimore criteria (total bilirubin ≥ 2.0 mg/dL with ≥ 2 of the following: hepatomegaly, ascites or 5% weight gain) with MOF (either renal and/or pulmonary failure). Pts without a Baltimore diagnosis could enroll with biopsy-proven evidence of VOD. Eligibility criteria were expanded to permit patients with late onset VOD (VOD diagnosed after 21 days (d) or VOD/MOF after 28d post-SCT). Key exclusion criteria included clinically significant bleeding or need for >1 pressor to maintain BP. CR was defined as bilirubin < 2 mg/dL + resolution of MOF. Mortality was assessed at D+100. DF was given at 6.25 mg/kg IV q6h (25 mg/kg/d); treatment duration was recommended for at least 21d. Results: This interim analysis is based on 104 pts enrolled between14Dec2007-29Sep2009 and treated at 36 institutions. Most sites (n=23) enrolled only 1–2 pts. Nearly all pts (n=98) had undergone prior SCT; 6 had prior chemotherapy only; and 29 pts had late onset VOD post-SCT. Of the SCT pts, 69 pts enrolled in the T-IND met eligibility criteria for the original Phase 3 trial. Baseline demographics included median age 17 years (range 0.1 – 66); 59% male; and 16% with prior SCT. The most common diagnosis was leukemia (30% AML; 22% ALL; 7% other leukemia). The majority of pts had undergone allogeneic SCT (88%) with conditioning consisting of cyclophosphamide (76%), busulfan (42%) and/or TBI (41%). Mean onset of VOD post-SCT was 17 days. At entry, 20% of pts were dialysis dependent; 28% were ventilator dependent. Mean number of days of DF administration was 20 (range 2–88). Of the 104 pts, 36 (35%) achieved a CR by D+100. For the various sub-populations, the CR by D+100 rate was 24% for pts with late-onset VOD (n=29); 35% for those pts undergoing SCT (n=98); and 39% for the 69 pts who matched the entry criteria for the Phase 3 trial. Comparison of this group of 69 pts to the Phase 3 HC showed a statistically improved outcome (p=0.0007). Similar to the Phase 3 results, the CR rate was higher in pts who were not on dialysis/ventilator at study entry (41% vs 23%). Although children had previously been noted to have a higher CR rate in prior studies, the CR rate in the T-IND was similar in children compared to adults (35% and 34%, respectively). Overall D+100 mortality rate equaled 61% (n=104). Comparing the 69 pts who met Phase 3 entry criteria, D+100 mortality was 58% (p=0.0465 compared to the HC using Kaplan Meier estimates by log-rank analysis). Toxicity proved manageable: 11 pts experienced a total of 13 drug-related AEs including pulmonary hemorrhage (n=5), GI hemorrhage (n=3), hypotension (n=2), rectal hemorrhage, cerebral hemorrhage and pulmonary alveolar hemorrhage (1 pt each). Overall, 10% of pts experienced a drug-related toxicity that led to discontinuation. Similar to the observation of decreased GvHD in pediatric pts undergoing SCT who received prophylactic DF compared to best supportive care, the incidence of all grade GvHD was relatively low (8%). Conclusions: In 104 pts with severe VOD/MOF enrolled at 36 US institutions, use of DF demonstrated a 35% CR by D+100. Comparing those pts who met criteria for the Phase 3 trial to the HC used in that study, D+100 CR and survival were significantly improved in this study population. DF-associated toxicities are consistent with prior studies. Following an amendment in 30Sep2009, entry criteria for the T-IND study were expanded to permit enrollment of pts without SCT (VOD post chemotherapy) as well as pts without MOF to evaluate earlier intervention. Analysis of this group will be performed separately. Enrollment into the T-IND study continues. Disclosures: Richardson: Gentium: Membership on an entity's Board of Directors or advisory committees. Massaro:Gentium: Consultancy. Hannah:Gentium: Consultancy. Iacobelli:Gentium: Employment.

Abstract Background MDS is a clonal hematopoietic stem cell disorder characterized by dysplastic changes in the bone marrow, ineffective hematopoiesis and an increased risk for developing acute myeloid leukemia (AML). The majority of MDS cases are sporadic, but rare familial cases have been described and are often ascertained through clinic-based referrals. To our knowledge, no population based study of MDS has examined the frequency of family history of hematologic malignancies and disorders in patients, nor associations with disease characteristics and outcomes. Methods Newly diagnosed MDS cases are being identified by rapid case ascertainment by the Minnesota Cancer Surveillance System (MCSS), a population-based cancer registry in Minnesota. Eligibility criteria include all newly diagnosed cases of MDS during the period April 1, 2010-October 31, 2014, between 20-85 years, Minnesota resident, and ability to understand English or Spanish. Proxy interviews are not being conducted. Medical records and biologic samples are obtained and questionnaires are filled out by participants. Centralized pathology and cytogenetics review confirm diagnosis and classify by subtype and risk score including the Revised International Prognostic Scoring System (IPSS-R). Since 2010, information on family history has been obtained through questionnaire responses and/or medical record review on 353 MDS patients. Cases were considered to have a positive family history if they reported a first degree relative with MDS, leukemia, lymphoma or other hematologic condition (multiple myeloma [n=4], Waldenstrom’s macroglobulinemia [n=1] and idiopathic thrombocytopenic purpura [n=1]). Treatment related MDS cases were excluded leaving 330 MDS patients for analysis. Unconditional logistic regression was used to calculate crude odds ratios (ORs) and 95% confidence intervals (CI) overall and by sex. Results A total of 61/330 (18.5%) cases reported a family history of a hematologic condition. The mean age at diagnosis was 71.3 years in those with a family history compared to 72.2 years in those without a family history (p=0.53). There was no difference in the sex distribution between the two groups. Though not statistically significant, the odds of having abnormal cytogenetics or an IPSS-R of High/Very High was lower for those having a positive family history (OR 0.57 [CI 0.25-1.33, p=0.19 and 0.67 [CI 0.24-1.84, p=0.29], respectively). The odds of survival at one year after diagnosis was significantly higher in those with a family history (OR 2.79 [CI 1.04-7.51, p=0.04]) compared to those without (Table). Further stratification by sex revealed that this association was strongest for males (OR=4.23, [CI 0.94-19.0, p=0.06] compared to females (OR=1.84 [CI=0.47-7.19, p=0.38]). Discussion In this population based study of adults with MDS, the prevalence of MDS cases having a positive family history was higher than previous reports. Additionally, cases reporting a family history of hematologic malignancies and disorders appear to experience lower risk disease and have significantly improved overall survival, especially males. It is possible that patients with a family history of hematologic conditions are diagnosed earlier in the course of their disease secondary to increased awareness about blood disorders and/or more active screening within the family. Our analysis is limited by relatively small numbers, but enrollment is ongoing so subsequent analyses with larger numbers of subjects may be more revealing. Additionally, a prospective study to examine these families further, including detailed medical histories and collection of biospecimens (saliva, blood, skin) for genetic analyses is underway in order to identify potential mechanisms and mutations involved in the development of MDS and progression to AML. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 487FN2 Background: Given the life-threatening nature of severe VOD (sVOD) and multi-organ failure (MOF), DF was made available in the US through a prospective treatment IND protocol (T-IND) to gather additional safety and response data from SCT patients (pts) with sVOD who were not eligible for a pivotal Phase 3 trial. Following completion of this Phase 3 trial, the T-IND protocol has continued and been amended to include pts who would have met eligibility criteria for the completed phase 3 trial, as well as pts with non-severe VOD and non-SCT pts who develop VOD after chemotherapy (chemo). This is the largest prospective evaluation of DF for the treatment of sVOD/MOF post SCT and non-SCT pts to date. Methods: Pts were initially required to have a diagnosis of VOD by Baltimore criteria (total bilirubin > 2.0 mg/dL with > 2 of the following: hepatomegaly, ascites or 5% weight gain) with MOF (either renal and/or pulmonary failure) that followed SCT. Following treatment of 104 pts, an amendment expanded eligibility criteria to include pts with VOD after chemo and pts with non-severe VOD (defined as no MOF). Key exclusion criteria included clinically significant bleeding or >1 pressor to maintain BP. CR was defined as bilirubin < 2 mg/dL + resolution of MOF (if applicable). Mortality was assessed at Day +100 (D+100) in all pts. DF was given at 6.25 mg/kg IV q6h (25 mg/kg/d) with treatment duration recommended for at least 21d. Results: This interim analysis is based on 269 pts enrolled between December 2007 and March 2011 at 67 centers. Nearly all pts (n=251) had undergone SCT (with allogeneic SCT in 225, 90%); 18 developed VOD after chemo alone. Of the 269 cases of VOD, 200 were severe at study entry, with 25% (66/269) of all pts dialysis dependent and 31% (83/269) ventilator dependent. Median age was 16 years (range 0.1 – 70); 55% were male. In the SCT pts, the most common diagnosis was leukemia (29% AML; 22% ALL; CML 3%; 4% other), with conditioning of CY (71%), BU (46%) and TBI (38%) respectively; 18% had undergone multiple SCTs (>1 SCT). Median onset of VOD was 15 d post-SCT. When presenting after chemo alone (n=18), median onset of VOD was 16 d after the first dose, most frequently after CY (61%), cytarabine (44%) and vincristine (39%), and for treatment of leukemia (AML 33%, ALL 33%, other 6%). Overall mean number of days of DF administration in all pts was 22 (range 1–88).Of 269 pts, 32% (85/269) achieved a CR and 50% [ by Kaplan-Meier estimate] survived to D+100. In the subgroup of SCT pts, 31% (78/251) achieved CR and 50% survived to D+100; 134 pts met entry criteria for the original Phase 3 trial and comparison to the Phase 3 historical control showed a statistically improved outcome in CR (30% vs 9%, p=0.0006) and D+100 survival (46% vs 25%; p=0.006). Of 200 pts with sVOD, CR was 28% and D+100 survival was 44%. In the 18 chemo only pts, CR was 39% and D+100 survival was 50%. CR rate and D+100 survival for the 69 pts with non-severe VOD were 42% and 62%, respectively. Delay of >2 d (vs < 2 d) in the start of DF after VOD diagnosis resulted in reduced CR (23% vs 35%, p=0.0339) and survival (37% vs 56%, p=0.01). Children as compared to adults had higher rates in CR (35% vs 29%) and survival (55% vs 43%). Toxicity proved generally manageable: 22% of pts experienced a total of 81 related AEs, primarily consisting of hemorrhage (19%) and hypotension (4%). Hemorrhage included pulmonary bleeding (6%), GI hemorrhage (3%), epistaxis (3%) and hematuria (3%). Similar to the observation of decreased GvHD in other studies, the incidence of all grade GvHD in the allogeneic SCT pts was 8%. Conclusions: In 269 pts with mainly sVOD/MOF, DF therapy achieved significantly improved outcome compared to an untreated historical control. Importantly, CR and survival were improved in pts who were treated within 2d of VOD diagnosis (vs. later) and in pts who had not yet progressed to sVOD. As with prior studies, there was a low incidence of DF-associated toxicities. Interestingly, the incidence of GvHD in allo-SCT pts was low, consistent with the reduction of GvHD seen in the large randomized EBMT pediatric prevention study. These results confirm the findings of previous trials and strongly support early intervention with DF once the diagnosis of VOD is made after SCT, as well as its use in pts who have not progressed to advanced MOF. The use of DF for VOD following intensive chemotherapy without SCT also appears promising, but more research in this patient population is needed. Enrollment to the T-IND study continues. Disclosures: Richardson: Gentium: Membership on an entity's Board of Directors or advisory committees. Arai:Gentium: Research Funding. Symons:Otsuka Pharmaceuticals: Research Funding. Martin:Gentium: Research Funding. Massaro:Gentium: Consultancy. D'Agostino:Gentium: Membership on an entity's Board of Directors or advisory committees. Hannah:Gentium: Consultancy. Tudone:Gentium: Employment. Hume:Gentium: Employment. Iacobelli:Gentium SpA: Employment. Soiffer:Gentium: Honoraria.