Benzinga | Dec 12, 2021 09:51AM EST

ImmunoGen Presented Initial Findings From the Phase 1b/2 Study of IMGN632 in Combination With Vidaza and Venclexta in Relapsed/Refractory Acute Myeloid Leukemia at ASH 2021; Said Triplet Data Demonstrating Manageable Safety Profile and Promising Anti-Leukemia Activity Highlighted in Oral Presentation

ImmunoGen, Inc. (NASDAQ:IMGN), a leader in the expanding field of antibody-drug conjugates (ADCs) for the treatment of cancer, today announced that updated initial safety and efficacy findings from the Phase 1b/2 study of IMGN632 in combination with Vidaza(r) (azacitidine) and Venclexta(r) (venetoclax) in patients with relapsed/refractory (R/R) acute myeloid leukemia (AML) were presented in an oral session at the 63rd American Society of Hematology (ASH) Annual Meeting. Data for IMGN632 in frontline patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN) were also presented in a poster session at the conference.

"The unmet need in AML remains large, as patients typically have low survival rates despite initial response," said Naval Daver, MD, Associate Professor in the Department of Leukemia at The University of Texas MD Anderson Cancer Center. "Together, the observed anti-leukemia activity and tolerability of IMGN632 in the relapsed/refractory setting are compelling and support the continued evaluation of this triplet in AML patients. I look forward to the next steps for IMGN632 in combination with azacitidine and venetoclax, with preparations for Phase 2 expansion cohorts already underway in both the relapsed and frontline AML settings."

IMGN632 TRIPLET DATA IN AML

Title (Abstract #372): "Safety and Efficacy from a Phase 1b/2 Study of IMGN632 in Combination with Azacitidine and Venetoclax for Patients with CD123-Positive Acute Myeloid Leukemia"

Oral Session: 616

Session Date: Sunday, December 12, 2021

Session Time: 9:30 am - 11:00 am

Updated key findings from the Phase 1b/2 study of IMGN632 in combination with azacitidine and venetoclax include:

Safety

IMGN632 was administered to 51 patients at 15 mcg/kg or 45 mcg/kg, azacitidine at 50-75 mg/m2 for 7 days, and venetoclax at 400 mg daily for 8-21 days per 28-day cycle.IMGN632 continued to display a manageable safety profile in R/R AML patients.The most common treatment emergent adverse events all grades [grade 3+ events] seen in >20% of patients were infusion-related reactions (33% [2%]), febrile neutropenia (31% [26%]), dyspnea (28% [8%]), fatigue (28% [0%]), hypophosphatemia (26% [2%]), diarrhea (22% [0%]), hypokalemia (22% [2%]), nausea (22% [0%]), vomiting (22% [0%]), and pneumonia (20% [16%]).No tumor lysis syndrome, veno-occlusive disease, capillary leak, or cytokine release were reported.Efficacy

Responses were seen across all cohorts/doses and schedules (efficacy evaluable population, n=46). The objective response rate (ORR) was 48%, with a composite complete remission (CCR) rate of 30% (4 CR, 8 CRh, 1 CRp, 1 CRi).Higher intensity cohorts (n=29) were associated with higher response rates including an ORR of 59% and a CCR rate of 38% (4 CR, 6 CRh, 1 CRp).Significant activity was also observed in the FLT3 mutant subset (n=9), with ORR and CCR rates of 89% and 78%, respectively.Enrollment continues at the putative recommended Phase 2 dose (IMGN632 45 mcg/kg IV on day 7, azacitidine 50 or 75 mg/m2 on days 1-7, and venetoclax 400 mg on days 1-14)."These data reinforce the potential of IMGN632 as a new therapy for patients with relapsed/refractory AML. We are very encouraged by the manageable safety profile and 38% composite complete remission rate seen in the higher intensity cohorts," said Anna Berkenblit, MD, Senior Vice President and Chief Medical Officer of ImmunoGen. "We look forward to further exploring the safety and efficacy of this triplet in Phase 2 expansion cohorts planned for next year. We believe IMGN632 also has the potential to become a best-in-class monotherapy treatment option for patients with BPDCN. Based on the results seen in three frontline patients, we continue to enroll patients in our pivotal study, CADENZA, and look forward to sharing top-line data in the second half of 2022."

IMGN632 MONOTHERAPY IN FRONTLINE BPDCN

Poster Presentation, Abstract #1284

IMGN632, administered as a brief outpatient infusion, was evaluated as monotherapy in frontline BPDCN patients. Three patients received IMGN632 prior to commencement of the enrolling pivotal cohort and achieved a clinical complete remission (CRc). IMGN632 in these three frontline BPDCN patients was associated with a favorable safety profile and limited grade 3+ TEAEs. Enrollment continues in the pivotal frontline and R/R cohorts.

Additional information can be found at www.hematology.org, including abstracts.