A Study of IMGN632, a Novel CD123-Targeting Antibody-Drug Conjugate, for Patients with Frontline and Relapsed/Refractory Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN)
Authors: Pemmaraju Naveen , Marconi Giovanni , Todisco Elisabetta , Montesinos Pau , Lane Andrew A. , Sweet Kendra , Wang Eunice S. , Deconinck Eric , Rizzieri David A , Walter Roland B. , Aribi Ahmed , Lebon Delphine , Levy Moshe Y. , Mazzarella Luca , Martinelli Giovanni , Gigli Federica , Erba Harry P. , Acuña-Cruz Evelyn , Konopleva Marina , Kantarjian Hagop , Sloss Callum M , Wang Jiuzhou , Malcolm Kara E , Zweidler-McKay Patrick A , DeAngelo Daniel J. , Daver Naval 
Published: November 2021

Abstract
Background: Overexpression of CD123 (IL-3Rα receptor) is a hallmark of blastic plasmacytoid dendritic cell neoplasm (BPDCN), thus making this antigen an attractive target for the development of new therapeutics. IMGN632 is a CD123-targeting antibody-drug conjugate (ADC) comprising a novel anti-CD123 antibody coupled, via a highly-stable peptide linker, to a unique DNA-alkylating cytotoxic payload of the recently developed IGN (indolinobenzodiazepine pseudodimer) class. Preclinically, IMGN632 has demonstrated potent activity against BPDCN cells with remarkable sensitivity of patient derived xenografts to IMGN632 (Blood 2018 132:3956). IMGN632 has demonstrated a wide therapeutic index in vitro and in vivo (PMIDs: 29661755, 30361418). Importantly IMGN632 has demonstrated favorable safety profile and has demonstrated evidence of promising efficacy in patients with BPDCN (ASH 2020: Blood 2020, vol 136, suppl 1, 11-13) and AML (ASH 2019: Blood 2019, vol 134, suppl 1, 734). Based on this data, IMGN632 was granted FDA Breakthrough Therapy Designation for BPDCN (Oct 2020). Initial experience with 3 frontline BPDCN patients showed clinical complete remissions (CRc) in all three patients. Subsequently an FDA-aligned pivotal cohort enrolling frontline BPDCN patients has been added to this study.
Methods: This study is currently enrolling two expansion cohorts for adults with CD123 positive BPDCN. The pivotal cohort is enrolling patients with frontline/untreated (no prior systemic therapy) BPDCN who do not have CNS involvement and meet other basic eligibility. This cohort is designed to support an application for FDA approval for IMGN632 in patients with BPDCN. An additional cohort is enrolling patients with relapsed/refractory BPDCN, which may have had up to 3 prior lines of therapy, including CD123-targeted therapies and prior hematopoietic stem cell transplant (after 120 days) and may have CNS involvement (if cleared with intrathecals), but who must not have prior history of veno-occlusive disease of the liver, or history of grade 4 capillary leak syndrome or non-cardiac grade 4 edema, and other eligibility. Both cohorts are enrolling patients at the RP2D (0.045 mg/kg IV Q 3 weeks) in the US and EU (NCT03386513, https://BPDCNtrial.com).

Disclosures
Pemmaraju: Clearview Healthcare Partners: Consultancy; Cellectis S.A. ADR: Other, Research Funding; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; Protagonist Therapeutics, Inc.: Consultancy; Celgene Corporation: Consultancy; MustangBio: Consultancy, Other; Plexxicon: Other, Research Funding; Blueprint Medicines: Consultancy; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Affymetrix: Consultancy, Research Funding; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy; Daiichi Sankyo, Inc.: Other, Research Funding; Roche Diagnostics: Consultancy; DAVA Oncology: Consultancy; Aptitude Health: Consultancy; CareDx, Inc.: Consultancy; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Springer Science + Business Media: Other; Sager Strong Foundation: Other; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; LFB Biotechnologies: Consultancy; Bristol-Myers Squibb Co.: Consultancy; Samus: Other, Research Funding; ImmunoGen, Inc: Consultancy; Pacylex Pharmaceuticals: Consultancy. Montesinos: Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Tolero Pharmaceutical: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Forma Therapeutics: Consultancy; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Stemline/Menarini: Consultancy; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Glycomimetics: Consultancy; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Agios: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas Pharma, Inc.: Consultancy, Honoraria, Other: Advisory board, Research Funding, Speakers Bureau. Lane: Qiagen: Consultancy, Honoraria; N-of-One: Consultancy, Honoraria; Stemline Therapeutics: Research Funding; AbbVie: Research Funding. Sweet: AROG: Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Meyers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees. Wang: Kite Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; Mana Therapeutics: Consultancy, Honoraria; Kura Oncology: Consultancy, Honoraria, Other: Advisory board, steering committee, Speakers Bureau; Stemline Therapeutics: Consultancy, Honoraria, Other: Advisory board, Speakers Bureau; Pfizer: Consultancy, Honoraria, Other: Advisory Board, Speakers Bureau; DAVA Oncology: Consultancy, Speakers Bureau; GlaxoSmithKline: Consultancy, Honoraria, Other: Advisory Board; Genentech: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS/Celgene: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board; Novartis: Consultancy, Honoraria, Other: Advisory Board; Takeda: Consultancy, Honoraria, Other: Advisory board; Rafael Pharmaceuticals: Other: Data safety monitoring committee; Gilead: Consultancy, Honoraria, Other: Advisory board; Daiichi Sankyo: Consultancy, Honoraria, Other: Advisory board; PTC Therapeutics: Consultancy, Honoraria, Other: Advisory board; Genentech: Consultancy; MacroGenics: Consultancy. Deconinck: Imunogen: Membership on an entity's Board of Directors or advisory committees; Stemline Therapetutics: Membership on an entity's Board of Directors or advisory committees; Chugai: Research Funding; Novartis: Research Funding; Pfizer: Other: Travel Grants, Research Funding; Abbevie: Research Funding. Rizzieri: AbbVie: Membership on an entity's Board of Directors or advisory committees; AROG: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Teva: Membership on an entity's Board of Directors or advisory committees; Acrotech: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Stemline: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kite: Honoraria, Speakers Bureau; Karyopharm: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees; Celltrion: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Mustang: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Honoraria; Pharmacyclics: Honoraria. Walter: Agios Pharmaceuticals, Inc.: Consultancy, Research Funding; Amgen, Inc.: Consultancy, Research Funding; Amphivena Therapeutics, Inc.: Current equity holder in publicly-traded company; Aptevo Therapeutics, Inc.: Consultancy, Research Funding; Arog Pharmaceuticals, Inc.: Research Funding; Astellas Pharma US, Inc.: Consultancy; BioLineRx, Ltd.: Consultancy, Research Funding; Boston Biomedical, Inc.: Consultancy; Bristol Myers Squibb, Inc.: Consultancy; Celgene, Inc.: Consultancy, Research Funding; Genentech, Inc.: Consultancy; GlaxoSmithKline, Inc.: Consultancy; ImmunoGen, Inc.: Research Funding; Janssen Global Services, LLC: Consultancy; Janssen Research & Development, Inc.: Research Funding; Jazz Pharmaceuticals, Inc.: Consultancy, Research Funding; Kite Pharma, Inc.: Consultancy; Kronos Bio, Inc.: Consultancy; Kura Oncology, Inc.: Research Funding; Macrogenics, Inc.: Research Funding; New Link Genetics: Consultancy; Pfizer, Inc.: Consultancy, Research Funding; Race Oncology Ltd.: Consultancy; Selvita: Research Funding; Stemline Therapeutics, Inc.: Research Funding. Aribi: Seagen: Consultancy. Levy: Bristol Myers Squibb: Consultancy, Honoraria, Other: Promotional speaker, Speakers Bureau; Amgen Inc.: Consultancy, Honoraria, Other: Promotional speaker, Speakers Bureau; Janssen Pharmaceuticals: Consultancy, Honoraria, Other: Promotional speaker, Speakers Bureau; Takeda: Consultancy, Honoraria, Other: Promotional speaker, Speakers Bureau; Beigene: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Other: Promotional speaker; AstraZeneca: Consultancy, Honoraria, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Honoraria, Speakers Bureau; Morphosys: Consultancy, Honoraria, Other: Promotional speaker, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Other: Promotional speaker, Speakers Bureau; Karyopharm: Consultancy, Honoraria, Other: Promotional speaker, Speakers Bureau; GSK: Consultancy, Other: Promotional speaker; TG Therapeutics: Consultancy, Honoraria, Speakers Bureau; Gilead Sciences, Inc.: Consultancy, Honoraria, Speakers Bureau; Epizyme: Consultancy, Other: Promotional speaker; AbbVie: Consultancy, Honoraria, Other: Promotional speaker, Speakers Bureau; Dova: Consultancy, Other: Promotional speaker. Martinelli: Pfizer: Consultancy, Speakers Bureau; Stemline Therapeutics: Consultancy; Abbvie: Consultancy; Jazz Pharmaceuticals: Consultancy; Celgene /BMS: Consultancy, Speakers Bureau; Incyte: Consultancy; Roche: Consultancy; Astellas: Consultancy, Speakers Bureau; Daichii Sankyo: Consultancy. Erba: AbbVie Inc; Agios Pharmaceuticals Inc; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Incyte Corporation; Jazz Pharmaceuticals Inc; Novartis: Speakers Bureau; AbbVie Inc: Other: Independent review committee; AbbVie Inc; Agios Pharmaceuticals Inc; ALX Oncology; Amgen Inc; Daiichi Sankyo Inc; FORMA Therapeutics; Forty Seven Inc; Gilead Sciences Inc; GlycoMimetics Inc; ImmunoGen Inc; Jazz Pharmaceuticals Inc; MacroGenics Inc; Novartis; PTC Therapeutics: Research Funding; AbbVie Inc; Agios Pharmaceuticals Inc; Astellas; Bristol Myers Squibb; Celgene, a Bristol Myers Squibb company; Daiichi Sankyo Inc; Genentech, a member of the Roche Group; GlycoMimetics Inc; Incyte Corporation; Jazz Pharmaceuticals Inc; Kura Oncology; Nov: Other: Advisory Committee. Konopleva: KisoJi: Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Rafael Pharmaceuticals: Other: grant support, Research Funding; Sanofi: Other: grant support, Research Funding; Ablynx: Other: grant support, Research Funding; Agios: Other: grant support, Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; Stemline Therapeutics: Research Funding; AstraZeneca: Other: grant support, Research Funding; Ascentage: Other: grant support, Research Funding; Calithera: Other: grant support, Research Funding; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Cellectis: Other: grant support; Forty Seven: Other: grant support, Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding. Kantarjian: Aptitude Health: Honoraria; Novartis: Honoraria, Research Funding; Jazz: Research Funding; Immunogen: Research Funding; Pfizer: Honoraria, Research Funding; KAHR Medical Ltd: Honoraria; NOVA Research: Honoraria; Ipsen Pharmaceuticals: Honoraria; Taiho Pharmaceutical Canada: Honoraria; Astellas Health: Honoraria; Precision Biosciences: Honoraria; Daiichi-Sankyo: Research Funding; BMS: Research Funding; Astra Zeneca: Honoraria; Ascentage: Research Funding; Amgen: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding. Wang: Immunogen: Current Employment. Malcolm: Immunogen: Current Employment. Zweidler-McKay: ImmunoGen: Current Employment. DeAngelo: Abbvie: Research Funding; GlycoMimetics: Research Funding; Pfizer: Consultancy; Shire: Consultancy; Incyte Corporation: Consultancy; Blueprint Medicines Corporation: Consultancy; Amgen: Consultancy; Agios: Consultancy; Autolus: Consultancy; Takeda: Consultancy; Jazz: Consultancy; Forty-Seven: Consultancy; Novartis: Consultancy, Research Funding. Daver: Pfizer: Consultancy, Research Funding; Novartis: Consultancy; FATE Therapeutics: Research Funding; Gilead Sciences, Inc.: Consultancy, Research Funding; Sevier: Consultancy, Research Funding; Hanmi: Research Funding; Abbvie: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Trovagene: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Glycomimetics: Research Funding; Novimmune: Research Funding; ImmunoGen: Consultancy, Research Funding; Trillium: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding.