ImmunoGen Presents Updated Findings from Phase 1 Study of IMGN632 at ASH Annual Meeting
Data Demonstrating Potential in AML and BPDCN Presented During Oral Presentation; Dose and Schedule Selected for
Preclinical Combination Data Also Presented; Support Further Evaluation of IMGN632 Doublets and Triplet in AML
“The data presented at ASH demonstrate the potential of IMGN632 to offer a new treatment option for patients with AML and BPDCN,” said
“We are particularly encouraged by the activity and tolerability of IMGN632 in heavily pre-treated patients, including a 40% ORR in relapsed and refractory de novo AML patients treated at the recommended phase 2 dose, and the responses in relapsed or refractory BPDCN patients previously treated with Elzonris® (tagraxofusp-erzs) and intensive chemotherapy,” said Naval Daver, MD, Associate Professor in the
PHASE 1 DATA ON IMGN632 AS A MONOTHERAPY IN AML AND BPDCN
Oral Presentation, Abstract #734
Updated key findings from the Phase 1 study of IMGN632 include the following:
- IMGN632 was administered to 95 patients over dose levels ranging from 0.015 to 0.45 mg/kg intravenously on the every 3 week schedule and 0.015 to 0.06 mg/kg on the fractionated day 1, 4, and 8 schedule every 3 weeks.
- IMGN632 displays a well tolerated safety profile and activity at doses up to and including 0.09 mg/kg per cycle.
- The most common treatment-related adverse event was infusion-related reactions (24% all grades, 8% grade 3); none required IMGN632 discontinuation.
- Single dose-limiting toxicities were seen at the highest dose levels tested (0.18-0.45 mg/kg): three reversible cases of veno-occlusive disease and one prolonged neutropenia; no patterns of hepatotoxicity or cytopenias occurred with doses below 0.18 mg/kg.
- Although no maximum tolerated dose was determined on either schedule, based on the efficacy, safety, and pharmacokinetic data generated, the dose and schedule of 0.045 mg/kg given on day 1 every 3 weeks has been selected as the monotherapy recommended Phase 2 dose.
- Across all dose levels and both schedules, of the patients assessable for efficacy (n=71), 38 (54%) had a reduction in bone marrow blasts and 13 (18%) achieved an objective response, including 2 complete remissions (CR) and 10 with incomplete recovery (CRi) and one morphologic leukemia free state (MLFS) in heavily pretreated patients. The vast majority of these responders (92%) had failed prior intensive therapies, including 3 with prior transplant, 69% had failed 2-3 prior lines of therapy, and 54% had an adverse risk classification.
- At the dose and schedule selected as the recommended Phase 2 dose (0.045 mg/kg Q3W), a 40% response rate was seen in relapsed and refractory patients with de novo AML, including 1 CR, 4 CRi, and 1 MLFS (with subsequent conversion to CRi).
- 3 of 9 (33%) evaluable relapsed/refractory BPDCN patients achieved a response after a 1-2 doses of 0.045 mg/kg IMGN632 (1 CR, 1 CRi, and 1 partial remission); all three patients had received prior SL-401 (tagraxofusp-erzs), two had received intense multi-agent chemotherapy, and one had prior stem cell transplant.
PRECLINICAL DATA ON IMGN632 IN COMBINATION WITH AZACITIDINE AND VENETOCLAX
Poster Presentation, Abstract 1375
IMGN632 was evaluated in combination with azacitidine, and as a triplet with azacitidine and venetoclax in AML models, including patient derived xenografts (PDX). The addition of IMGN632 to azacitidine alone or to azacitidine plus venetoclax consistently led to reductions in tumor burden and to improved survival in these murine models. These data support clinical testing of the addition of IMGN632 to standard of care therapy including azacitidine, and azacitidine plus venetoclax in AML patients.
Additional information, including abstracts, can be found at www.hematology.org.
IMGN632 is a CD123-targeting ADC in Phase I testing for hematological malignancies, including acute myeloid leukemia (AML), blastic plasmacytoid dendritic cell neoplasm (BPDCN), and acute lymphocytic leukemia (ALL). IMGN632 uses one of ImmunoGen's novel indolino-benzodiazepine (IGN) payloads, which alkylate DNA without crosslinking. IGNs have been designed to have high potency against AML blasts, while demonstrating less toxicity to normal marrow progenitors than other DNA-targeting payloads.
ABOUT ACUTE MYELOID LEUKEMIA (AML)
AML is a cancer of the bone marrow cells that produce white blood cells. It causes the marrow to increasingly generate abnormal, immature white blood cells (blasts) that do not mature into effective infection-fighting cells. The blasts quickly fill the bone marrow, impacting the production of normal platelets and red blood cells. The resulting deficiencies in normal blood cells leave the patient vulnerable to infections, bleeding problems, and anemia. It is estimated that, in the U.S. alone, 21,380 patients will be diagnosed with AML this year and 10,590 patients will die from the disease.
ABOUT BLASTIC PLASMACYTOID DENDRITIC CELL NEOPLASM (BPDCN)
BPDCN is a rare form of blood cancer that has features of both leukemia and lymphoma, with characteristic skin lesions, lymph node involvement, and frequent spread to the bone marrow. This aggressive cancer requires intense treatment often followed by stem cell transplant. Despite the recent approval of a CD123-targeting therapy, the unmet need remains high in the relapsed/refractory setting.
CD123, the interleukin-3 alpha chain, is expressed on multiple myeloid and lymphoid cancers including AML, BPDCN, ALL, chronic myeloid leukemia, and myeloproliferative neoplasms. With limited expression on normal hematopoietic cells, rapid internalization, and expression on AML leukemia stem cells, CD123 is a validated therapeutic target, with the recent approval of a CD123-targeting therapy for BPDCN.
ImmunoGen is developing the next generation of antibody-drug conjugates (ADCs) to improve outcomes for cancer patients. By generating targeted therapies with enhanced anti-tumor activity and favorable tolerability profiles, we aim to disrupt the progression of cancer and offer our patients more good days. We call this our commitment to “target a better now.”
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