A phase Ib/II study of ivosidenib with venetoclax +/- azacitidine in IDH1-mutated hematologic malignancies

7018

Background: Isocitrate dehydrogenase-1 mutations ( IDH1+) result in production of the oncometabolite 2-hydroxyglutarate, arrested differentiation, and increased dependence on the anti-apoptotic protein BCL-2, enhancing susceptibility to the BCL-2 inhibitor venetoclax (VEN). Herein, we report the completed P1b portion of the P1b/II study combining the IDH1 inhibitor ivosidenib (IVO; 500 mg PO daily D15-continous) with VEN (D1-14), with or without azacitidine (AZA; 75mg/m2 D1-7 every 28 days). Methods: Eligible patients age 18 with IDH1+ MDS, newly diagnosed (ND: de novo and secondary/treated secondary AML) or relapsed/refractory (R/R) AML were enrolled into 4 dose levels (DL): DL1 (IVO+VEN 400 mg), DL2 (IVO+VEN 800 mg), DL3 (IVO+VEN 400 mg+AZA), DL4 (IVO+VEN 800 mg+AZA). Primary objectives included safety and tolerability, and IWG defined overall response (ORR: CR+CRi+CRh+PR+ MLFS). Results: 31 patients (DL1: 6, DL2: 6, DL3: 13, DL4: 6) enrolled with a median follow-up of 26 months. Median age was 67 years (range: 44-84). 71% had AML (ND: N = 14, R/R: N = 8), 29% (N = 9) had MDS. ELN risk was intermediate and adverse in 19% (N = 6) and 55% (N = 17). Median baseline IDH1+ VAF was 23% (5%-48%). Median time on study was 6.4 (range: 4 -not reached [NR]) months. The ORR was 94% (DL1: 67%, DL2-DL4: 100%); Composite CR (CRc: CR+CRi+CRh) was 87% (DL1: 67%, DL2: 100%, DL3: 85%, DL4: 100%). 63% of AML patients attained measurable residual disease negative CRc by multiparameter flow cytometry (ND-AML: 64%, R/R-AML: 60%). Addition of AZA increased MRD clearance in ND-AML compared to the doublet regimen (86% vs. 25%, p: 0.09). IDH1+ mutation clearance by digital droplet PCR (sensitivity: 0.1-0.25%) was attained in 67% of patients (ND-AML: 83%, R/R-AML: 50%, MDS: 50%) following cycle 5. 35% of patients required dose reductions for cytopenias (DL2: 2 [33%], DL3: 6 [46%], DL4: 3 [50%]). Grade 3-5 adverse events (AEs) occurring in 10% of patients included febrile neutropenia (29%; one episode resulted in death in a R/R-AML patient relapsing on study) and pneumonia (23%). AEs of special interest (AESI) included grade 3 tumor lysis syndrome in two patients (dose-limiting toxicity in one), and differentiation syndrome in 4 (G2: N = 2, G3: N = 2) patients. All AESIs were transient and reversible. Median EFS and OS were 36 and 42 months. 24-month OS was 71% (95% CI: 55-91; [ND-AML: 67%, R/R-AML: 50%, MDS: 100%]). MRD-negative CRc improved OS (median NR vs. 8 months, p: 0.002) in ND and R/R-AML. 100% of patients (N = 4) relapsing after IDH1+ clearance demonstrated no IDH1+ at relapse. Based on efficacy and toxicity, DL3 (IVO+VEN400+AZA) was the recommended phase 2 dose. Conclusions: IVO+VEN +/- AZA is an effective treatment for IDH1+ myeloid malignancies with an expected toxicity profile and notable efficacy across disease groups. Single-cell sequencing and CyTOF correlatives will also be presented. Phase 2 enrollment is ongoing. Clinical trial information: NCT03471260.

A phase Ib/II study of ivosidenib with venetoclax +/- azacitidine in IDH1-mutated myeloid malignancies

7012

Background: Isocitrate dehydrogenase-1 ( IDH1+) mutations are present in 5-15% of myeloid malignancies, promoting leukemogenesis through production of the oncometabolite 2-hydroxyglutarate resulting in arrested myeloid differentiation. IDH1+ malignancies demonstrate increased reliance on the anti-apoptotic protein BCL-2, enhancing susceptibility to the BCL-2 inhibitor venetoclax (VEN). We report an interim safety and efficacy analysis of the IDH1 inhibitor ivosidenib (IVO; 500 mg PO daily D15-continuous) combined with VEN (D1-14) +/- azacitidine (AZA; 75mg/m2 D1-7 every 28 days). Methods: Eligible patients age ≥18 with IDH1+ MDS, newly diagnosed AML (ND: treatment naïve [TN] or secondary/treated secondary AML [sAML]), or relapsed/refractory (R/R) AML enrolled into three dose levels (DL): DL1 (IVO+VEN 400 mg), DL2 (IVO+VEN 800 mg), DL3 (IVO+VEN 400 mg+AZA). Primary objectives included safety and tolerability, and IWG defined overall response (ORR: CR+CRi+CRh+PR+MLFS). Prior receipt of IVO or VEN was exclusionary. Results: 25 evaluable patients (DL1: 6, DL2: 6, DL3: 13) enrolled with a median follow-up of 16.1 months. Median age was 67 (range: 44-84). 84% (N=21) of patients had AML (ND: N=13 [TN: 8, sAML: 5], R/R: N=8), while 16% (N=4) had MDS. ELN risk was intermediate and adverse in 16% (N=4) and 56% (N=14). Median IDH1 VAF at enrollment was 22.7% (range: 5.1%-47.8%). Two patients had received a prior IDH1 inhibitor. The ORR was 92% (DL1: 67%, DL2: 100%, DL3: 100%). Composite CR (CRc: CR+CRi+CRh) was 84% (DL1: 67%, DL2: 100%, DL3: 85%) including 92% (TN: 100%, sAML: 80%), 63%, and 100% of patients with ND-AML, R/R-AML, or MDS. Median number of cycles received was 4 (DL1: 8.5, DL2: 6, DL3: 4) with ongoing responses in 62% (DL1: 33%, DL2: 50%, DL3: 82%) at 1-year. 8 patients transitioned to SCT (DL1: 0, DL2: 2, DL3: 6), and 8 patients remain on study (DL1: 2, DL2: 1, DL3: 5). 1-year OS was 68% for the entire study population (DL1: 50%, DL2: 67%, DL3: 78%), 71% in ND-AML (TN: 86%, sAML: 60%), 50% in R/R-AML, and 100% in MDS. Measurable residual disease negative CRc by multiparameter flow cytometry was attained in 60% (ND-AML: 67%, R/R-AML: 60%, MDS: 33%) correlating with improved OS (median OS: NR vs. 8.5 months, p-value: 0.038). Common grade 3/4 adverse events included febrile neutropenia (28%) and pneumonia (24%). Tumor lysis and differentiation syndrome occurred in two and four patients; all cases resolved with medical management. Conclusions: IVO+VEN +/- AZA is an effective treatment regimen in patients with IDH1+myeloid malignancies. The combination therapy is associated with an acceptable and expected toxicity profile with notable efficacy and high rates of MRD-negative CRc in AML. Enrollment into the study continues. Clinical trial information: NCT03471260. [Table: see text]

Phase Ib/II study of the IDH1-mutant inhibitor ivosidenib with the BCL2 inhibitor venetoclax +/- azacitidine in IDH1-mutated hematologic malignancies

7500

Background: Mutations in the isocitrate dehydrogenase-1 gene ( IDH1) result in myeloid differentiation arrest and accumulation of the oncometabolite 2-hydroxyglutarate (2-HG), promoting leukemogenesis. We report a primary safety and efficacy analysis of the IDH1 inhibitor ivosidenib (IVO; 500 mg PO daily D15-continous) combined with venetoclax (VEN; D1-14 per 28-day cycle), with and without azacitidine (AZA; 75mg/m2 D1-7). Methods: Eligible patients age ≥18 with IDH1 mutated myeloid malignancies (high-risk MDS and AML) enrolled into one of three successive cohorts (Cohort 1: IVO+VEN 400 mg, Cohort 2: IVO+VEN 800 mg, Cohort 3: IVO+VEN 400 mg+AZA). Primary endpoints include safety and tolerability and overall response rate (ORR) by revised IWG criteria. Key secondary endpoints include survival endpoints and PK correlates. Results: 19 patients (median age 68) enrolled, 17 with AML: 9 relapsed/refractory AML (R/R; median 1 prior line of therapy), 5 treatment naïve AML, and 3 HMA-failure MDS with secondary AML. Two patients had high-risk MDS. ELN risk was favorable, intermediate, and adverse risk in 37%, 15%, and 47%. Co-mutations included NPM1 (37%), chromatin-spliceosome (32%), methylation (16%), and RAS pathway (21%). Adverse events of special interest included IDH differentiation syndrome (n=4, grade > 3 in 1) and tumor lysis syndrome (TLS; n=2), including one grade 3 TLS event in a NPM1+ patient (successfully managed without hemodialysis). In evaluable patients (n=18), composite complete remission (CRc: CR+CRi+CRh) rates were 78% overall (treatment naive: 100%, R/R: 75%), and 67%, 100%, and 67% by cohort (median time to best response: 2 months). 7 (50%) patients achieving CRc were also MRD negative by flow cytometry. 1 patient had HI without CR/CRi and 1 had a MLFS. 9 (50%) patients remain on study, 3 (17%) proceeded to SCT in CR, 2 were non-responders, and 5 (22%) experienced progressive disease following CRc occurring after a median of 3 months. After a median follow up of 3.5 months, median OS was not reached in treatment naïve patients, and 9.7 months in R/R patients. Conclusions: IVO+VEN +AZA therapy is well tolerated and highly effective for patients with IDH1 mutated AML. Follow up and accrual is ongoing to better define duration and biomarkers of response. Clinical trial information: NCT03471260 . [Table: see text]

Allogeneic transplant leads to markedly improved survival in older patients with AML

7048

Background: AML is a disease of the elderly, and outcomes with standard treatment are dismal. Allogeneic transplant is the only curative therapy for most patients with AML. Recent work has shown age is not a factor in transplant outcomes, and should not be a limiting factor for transplant. The treatment pathway for older patients with AML should take into account their disease risk, comorbidities, and treatments with a proven survival advantage. We investigated our institutional experience to help guide the establishment of optimal pathways for patients. Methods: We conducted a retrospective analysis of 118 patients over age 65 with AML treated at our institution between 2010-2015. Patients receiving therapy (n = 90) were categorized into two groups: intensive induction therapy (7+3 based) or induction therapy with a hypomethylating agent. The groups were well matched in regard to comorbidities. Results: In poor risk patients, complete remission (CR) was achieved in 42% (n = 30/71). Select patients up to age 75 proceeded to allogeneic transplant if they achieved CR. Survival in CR1 was higher in the transplant (n = 22, median 719 days, 95% CI: 366-1071 days), than in the non-transplant group (n = 8, median 257 days, 95% CI: 92-421 days, p-value < .001). In analyzing all risk groups, overall survival was superior in transplant (median 1188 days) versus non-transplant recipients (median 185 days) (see 1, 2, and 3 year survival in table). No difference in median survival occurred based on age at induction (older than 70: n = 9, younger than 70: n = 16, p-value = 0.316). There was no difference in median survival based on chemotherapy regimen without transplant: intensive induction (n = 24, survival 250 days, p-value 0.179) compared to hypomethylating agents (n = 22, survival 139 days). Conclusions: We confirm that transplant can be safely performed in patients over 70 years of age, and highlight the survival advantage of transplant to chemotherapy alone. Additionally, our data found no survival benefit of hypomethylating agents in elderly patients with poor risk AML.[Table: see text]

Implementation of a screening program for identification of unrecognized inherited marrow failure syndromes

7055

Background: Inherited marrow failure syndromes (IMFS) are considered diseases of childhood, but testing adults with atypical presentations of diseases associated with IMFS is critical for establishing an optimal treatment protocol. The most common IMFS, Fanconi Anemia and Telomere Biology Diseases, are associated with MDS and aplastic anemia (AA), head and neck cancers, skin, and cervical cancer. Such patients can have profound toxicity with standard chemotherapy regimens. Methods: We implemented a screening protocol in patients at highest risk of an undiagnosed IMFS (MDS under age 60, AA patients under age 65, and head and neck cancers under age 60) with chromosome breakage analysis and telomere length testing. Results: Our protocol diagnosed nine patients (estimated ~10% of patients < age 60 with these diseases) with IMFS. The features of these patients are described in the table. Only three (33%) patients had the classic physical characteristics of IMFS. Three patients were over age 50 when diagnosed with an inherited disorder. Most importantly, in all patients the treatment approach was modified significantly, including minimizing conditioning for BMT, utilizing danazol as first line treatment for AA, as well as aggressive cancer and endocrinopathy screening. Outcomes with modified treatment have been favorable, and occult malignancies were detected through screening in two patients. Conclusions: Inherited marrow failure syndromes are uncommon yet under recognized disorders that significantly impact treatment decisions in addition to implementation of surveillance programs for both the affected individual and their relatives alike. Through this approach of thoughtful screening of patients presenting to our institution with marrow failure we identified an unrecognized IMFS in an estimated 10% of patients. [Table: see text]