ABSTRACT
BACKGROUND: BPDCN is a rare, aggressive hematologic malignancy characterized by historically poor overall survival and limited therapeutic options. Despite the recent approval of tagraxofusp-erzs for BPDCN, outcomes remain suboptimal for many patients. Additionally, patients with BPDCN are older and often have co-morbidities at baseline, preventing them from receiving tagraxofusp-erzs. Therefore, novel therapies are needed in the frontline setting for patients with BPDCN. Overexpression of CD123 (IL-3Rα) is present in all BPDCN cases, thereby establishing this surface marker as a target for therapeutic intervention. IMGN632 is a CD123-targeting ADC, comprised of a high-affinity anti-CD123 antibody coupled to a DNA-alkylating payload of the novel IGN (indolinobenzodiazepine pseudodimer) class. IMGN632 has demonstrated favorable safety and promising clinical activity in relapsed/refractory (R/R) BPDCN [Blood (2020) 136 (Supplement 1): 11-13], leading to the FDA granting IMGN632 Breakthrough Therapy Designation (BTD) for R/R BPDCN (Oct 2020). Following BTD and alignment with FDA, a pivotal cohort in frontline (no prior systemic treatment) BPDCN patients was initiated in addition to a continuing cohort of patients with R/R disease, where we have enrolled 33 patients to date. Here we report the initial experience of three frontline patients who are not part of the pivotal cohort. METHODS: IMGN632 was administered IV at a dose of 0.045 mg/kg on day 1 of a 21-day cycle to all patients. Efficacy was assessed using modified Severity Weighted Assessment Tool (for skin lesions), PET/CT, and blast percentage in bone marrow aspirates. The response criteria were adapted from established BPDCN criteria (Pemmaraju NEJM 2019). RESULTS: Three patients with frontline BPDCN (no prior systemic therapy) received IMGN632. All three of these frontline patients achieved a clinical complete remission (CRc). Patient 1 was a 79yo woman who presented with skin, nodal, and extensive bone marrow disease (80% involvement). After one dose of IMGN632, she cleared her bone marrow (0%), and after 3 cycles, her nodal lesions and skin lesions resolved to achieve a CRc. Upon complete response, treatment was held due to patient co-morbidities. With just 3 cycles of IMGN632, this patient achieved duration of response (DOR) of 10.7 months without further therapy. Patient 2 was a 67yo man who had extensive skin disease covering >20% of the body;over several cycles, he achieved a PR then a CRc and bridged to an allogeneic stem cell transplant (SCT). The patient achieved a DOR of 13.5 months, with no evidence of disease relapse when he died from graft versus host disease. Patient 3 was a 66yo woman who presented with extensive skin and nodal lesions. After improvement over 4 cycles, she achieved a CRc with clearing of most of her skin lesions and all nodal lesions. Unfortunately, while still in CRc, the patient died of COVID-19 pneumonia, with a DOR of 3.7 months. CONCLUSION: Administration of IMGN632 to frontline BPDCN patients resulted in clinical complete remission in the initial three patients with durable responses in the two non-COVID impacted patients. None of these patients progressed while on therapy, and one patient successfully bridged to SCT. Enrollment continues in the pivotal frontline and R/R cohorts. (BPDCNtrial.com;NCT03386513).
ABSTRACT
Background: Acute myeloid leukemia (AML) is driven by aberrant leukemic stem cells (LSCs) that initiate and sustain malignancy. To circumvent resistance to therapy, combination therapies with additive mechanisms of action are needed. CD70, a tumor necrosis factor receptor ligand, and its receptor CD27 are expressed on LSCs and AML blasts, but not on hematopoietic stem cells. Cusatuzumab, a high-affinity humanized monoclonal anti-CD70 antibody, kills CD70-expressing cells by Fc domain-mediated effector functions and is a potent inhibitor of CD70-CD27 signaling. Here we report initial results of a study of cusatuzumab in combination with the current standard of care therapy, venetoclax plus azacitidine (CVA), in patients with untreated AML (de novo or secondary) ineligible for intensive chemotherapy due to age ≥75 years or medical comorbidities. Methods: The primary objective of this open label, multicenter, phase 1b study was to assess safety and tolerability of CVA. Key secondary objectives included response rate per ELN 2017 criteria and time to response. Patients received cusatuzumab 10 or 20 mg/kg IV on Day 3 and Day 17, a 3-day ramp-up of venetoclax (100, 200, and 400 mg PO) followed by 400 mg daily dosing, and azacitidine 75 mg/m 2 SC or IV on Days 1-7 of each 28-day cycle. Results: Based on data through Jul 9, 2021, 44 patients enrolled with median age 75 years (range 32-89), 36.4% had secondary AML, 40.9% had an ECOG performance status of 2, and ELN risk was favorable, intermediate and adverse in 18.2%, 20.5% and 61.4%, respectively. All patients received 20 mg/kg cusatuzumab except for 3 patients who received a starting dose of 10 mg/kg with the option to escalate to 20 mg/kg. Of these 3 patients, 1 escalated to 20 mg/kg. At a median follow-up of 29.1 weeks, the median number of treatment cycles was 4.0 (range 1.0-11.0). Grade 3 or above TEAEs were reported in 97.7% of patients;the most common (reported in ≥10%) were neutropenia (68.2%), thrombocytopenia (65.9%), febrile neutropenia (36.4%), anemia (34.1%), leukopenia (29.5%), sepsis (27.3%), and lymphopenia (15.9%). Treatment-emergent serious adverse events (SAEs) were reported in 75% of patients;the most common (reported in at least ≥5%) were febrile neutropenia (27.3%), sepsis (22.7%), COVID-19 (6.8%), and thrombocytopenia (6.8%). Treatment-emergent SAEs of grade ≥3 were reported in 72.7% of the patients. Infusion-related reactions (IRRs) were reported for 11.4% of patients with 2.3% at grade ≥3. Six (13.6%) patients discontinued treatment due to AEs, and 5 (11.4%) TEAEs resulted in death. The mortality rate within 30 days from start of treatment was 4.5%. Table 1 summarizes best response to study treatment. In the intent-to-treat analysis set (n=44) complete remission (CR) rate was 45.5%, while CR + CR with partial hematologic recovery (CRh) + CR with incomplete hematologic recovery (CRi) was 77.3%;MLFS was observed in 11.4% of patients. Of 34 responders (defined as CR, CRi or CRh), 47% were MRD negative by flow cytometry at or after achievement of response. Median time to first response for patients who achieved CR, CRh or CRi was 4.21 (3.0-25.0) weeks. Best response rates in the post-hoc response evaluable analysis set (n=42) that excluded two patients who died before the first disease evaluation were: CR in 47.6%, CR + CRh + CRi in 81.0% and MLFS in 11.9% of patients (Table 1). The majority (97.1%) of responders experienced at least one cycle delay in administration of CVA post response. Conclusions: Cusatuzumab administered in combination with venetoclax and azacitidine to elderly patients with untreated AML was generally well tolerated and demonstrated a safety profile consistent with that previously reported with venetoclax-azacitidine, with the addition of generally manageable IRRs. Response rates support an additive effect of cusatuzumab to the standard of care with potential for improved clinical outcomes. However, further clinical trials are needed for validation of these initial results. HK and GB contributed equally to this publ cation. [Formula presented] Disclosures: Roboz: AstraZeneca: Consultancy;Janssen: Research Funding;Bristol Myers Squibb: Consultancy;Jasper Therapeutics: Consultancy;Agios: Consultancy;Novartis: Consultancy;Amgen: Consultancy;Blueprint Medicines: Consultancy;Janssen: Consultancy;Helsinn: Consultancy;Daiichi Sankyo: Consultancy;Glaxo SmithKline: Consultancy;Celgene: Consultancy;Jazz: Consultancy;MEI Pharma - IDMC Chair: Consultancy;Mesoblast: Consultancy;Actinium: Consultancy;AbbVie: Consultancy;Astex: Consultancy;Bayer: Consultancy;Astellas: Consultancy;Roche/Genentech: Consultancy;Pfizer: Consultancy;Otsuka: Consultancy. Aribi: Seagen: Consultancy. Brandwein: Astellas: Honoraria;Jazz: Honoraria;Amgen: Honoraria;Taiho: Honoraria;BMS/Celgene: Honoraria;Pfizer: Honoraria;Abbvie: Honoraria;University of Alberta: Current Employment. Döhner: Astellas: Consultancy, Honoraria, Research Funding;AstraZeneca: Consultancy, Honoraria;Berlin-Chemie: Consultancy, Honoraria;Amgen: Consultancy, Honoraria, Research Funding;Abbvie: Consultancy, Honoraria, Research Funding;Agios: Consultancy, Honoraria, Research Funding;Celgene: Consultancy, Honoraria, Research Funding;GEMoaB: Consultancy, Honoraria;Helsinn: Consultancy, Honoraria;Janssen: Consultancy, Honoraria;Jazz: Consultancy, Honoraria, Research Funding;Novartis: Consultancy, Honoraria, Research Funding;Oxford Biomedicals: Consultancy, Honoraria;Pfizer: Research Funding;Roche: Consultancy, Honoraria;Gilead: Consultancy, Honoraria;Bristol Myers Squibb: Consultancy, Honoraria, Research Funding;Astex: Consultancy, Honoraria;Ulm University Hospital: Current Employment. Fiedler: Jazz Pharmaceuticals: Consultancy, Other: support for meeting attendance;Abbvie: Consultancy, Honoraria;Morphosys: Consultancy;Celgene: Consultancy;Pfizer: Consultancy, Research Funding;Novartis: Consultancy;ARIAD/Incyte: Consultancy;Amgen: Consultancy, Other: support for meeting attendance, Patents & Royalties, Research Funding;Servier: Consultancy, Other: support for meeting attendance;Daiichi Sankyo: Consultancy, Other: support for meeting attendance;Stemline: Consultancy. Gandini: argenx: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Geddes: University of Calgary: Current Employment;Taiho: Consultancy, Membership on an entity's Board of Directors or advisory committees;Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees;Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees;Novartis: Consultancy;BMS: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau;Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees;Amgen: Consultancy;Paladin: Consultancy;Janssen: Research Funding;Geron: Research Funding;Abbvie: Membership on an entity's Board of Directors or advisory committees, Research Funding. Hou: University of Pittsburgh Medical Center Hillman Cancer Centers: Current Employment;AbbVie: Honoraria;AstraZeneca: Honoraria;Karyopharm: Honoraria;Chinese American Hematology Oncology Network: Membership on an entity's Board of Directors or advisory committees. Howes: Janssen R&D, part of Johnson & Johnson: Current Employment;Johnson & Johnson: Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Hultberg: argenx: Current Employment, Patents & Royalties. Huselton: University of Rochester: Current Employment. Jacobs: Argenx BV: Current Employment, Current equity holder in publicly-traded company;University of Antwerp: Ended employment in the past 24 months. Kane: Janssen R&D, part of Johnson & Johnson: Current Employment, Current equity holder in publicly-traded company. Lech-Marańda: Takeda: Membership on an entity's Board of Directors or advisory committees;AbbVie: Membership on an entity's Board of Directors r advisory committees;Novartis: Membership on an entity's Board of Directors or advisory committees;Roche: Membership on an entity's Board of Directors or advisory committees;Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees;Amgen: Membership on an entity's Board of Directors or advisory committees;Sanofi: Membership on an entity's Board of Directors or advisory committees;Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding. Louwers: argenx: Current Employment, Patents & Royalties: Patents (no royalties). Nottage: Janssen R&D, part of Johnson & Johnson: Current Employment;Johnson & Johnson: Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Platzbecker: Novartis: Honoraria;AbbVie: Honoraria;Janssen: Honoraria;Celgene/BMS: Honoraria;Geron: Honoraria;Takeda: Honoraria. Rampal: Pharmaessentia: Consultancy;BMS/Celgene: Consultancy;Abbvie: Consultancy;Sierra Oncology: Consultancy;Incyte: Consultancy, Research Funding;Blueprint: Consultancy;Disc Medicine: Consultancy;Jazz Pharmaceuticals: Consultancy;Constellation: Research Funding;Kartos: Consultancy;Stemline: Consultancy, Research Funding;CTI: Consultancy;Novartis: Consultancy;Memorial Sloan Kettering: Current Employment. Salman: Janssen: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Shah: Janssen R&D, part of Johnson & Johnson: Current Employment. Stuart: Clinical Drug Development Consultants LLC: Current Employment;Argenx: Consultancy;Cleave Therapeutics: Consultancy;Triphase Accelerator Corp: Consultancy;IgM Biosciences: Consultancy;Revolution Medicines: Consultancy;Jiya Corp:Consultancy;Geron Corp: Current holder of individual stocks in a privately-held company. Subklewe: Janssen: Consultancy;Pfizer: Consultancy, Speakers Bureau;Takeda: Speakers Bureau;Klinikum der Universität München: Current Employment;MorphoSys: Research Funding;Novartis: Consultancy, Research Funding, Speakers Bureau;Roche: Research Funding;Seattle Genetics: Consultancy, Research Funding;Miltenyi: Research Funding;Gilead: Consultancy, Research Funding, Speakers Bureau;Amgen: Consultancy, Research Funding, Speakers Bureau;BMS/Celgene: Consultancy, Research Funding, Speakers Bureau. Sumbul: argenx: Current Employment. Wang: Takeda: Consultancy, Honoraria, Other: Advisory board;Jazz Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board;Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees;Stemline Therapeutics: Consultancy, Honoraria, Other: Advisory board, Speakers Bureau;AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees;Kite Pharmaceuticals: Consultancy, Honoraria, Other: Advisory Board;GlaxoSmithKline: Consultancy, Honoraria, Other: Advisory Board;Genentech: Membership on an entity's Board of Directors or advisory committees;BMS/Celgene: Membership on an entity's Board of Directors or advisory committees;DAVA Oncology: Consultancy, Speakers Bureau;Kura Oncology: Consultancy, Honoraria, Other: Advisory board, steering committee, Speakers Bureau;Novartis: Consultancy, Honoraria, Other: Advisory Board;Mana Therapeutics: Consultancy, Honoraria;Pfizer: Consultancy, Honoraria, Other: Advisory Board, Speakers Bureau;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. Wierzbowska: Jazz: Research Funding;Pfizer: Honoraria;Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees;Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees;Astellas: Honoraria, Membership on an entity's Board of Directors or advisory comm ttees;Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees;BMS: Honoraria. Yao: Statagize LLC: Current Employment;Puma Biotechnology, Inc.: Ended employment in the past 24 months;Argenx: Consultancy. Yee: Astex: Membership on an entity's Board of Directors or advisory committees, Research Funding;Janssen: Research Funding;TaiHo: Membership on an entity's Board of Directors or advisory committees;Otsuka: Membership on an entity's Board of Directors or advisory committees;Onconova: Research Funding;Pfizer: Membership on an entity's Board of Directors or advisory committees;Tolero: Research Funding;Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding;Paladin: Membership on an entity's Board of Directors or advisory committees;MedImmune: Research Funding;AbbVie: Honoraria;Bristol-Myers Squibb/Celgene: Membership on an entity's Board of Directors or advisory committees;Shattuck Labs: Membership on an entity's Board of Directors or advisory committees;Forma Therapeutics: Research Funding;Takeda: Membership on an entity's Board of Directors or advisory committees;Geron: Research Funding;Genentech: Research Funding;F. Hoffmann La Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding;Jazz: Research Funding. Kantarjian: Immunogen: Research Funding;Astra Zeneca: Honoraria;KAHR Medical Ltd: Honoraria;Astellas Health: Honoraria;Pfizer: Honoraria, Research Funding;NOVA Research: Honoraria;Ascentage: Research Funding;Precision Biosciences: Honoraria;Novartis: Honoraria, Research Funding;Aptitude Health: Honoraria;Ipsen Pharmaceuticals: Honoraria;Jazz: Research Funding;Daiichi-Sankyo: Research Funding;BMS: Research Funding;Amgen: Honoraria, Research Funding;AbbVie: Honoraria, Research Funding;Taiho Pharmaceutical Canada: Honoraria. Borthakur: Protagonist: Consultancy;Ryvu: Research Funding;Astex: Research Funding;GSK: Consultancy;Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees;Takeda: Membership on an entity's Board of Directors or advisory committees;University of Texas MD Anderson Cancer Center: Current Employment;ArgenX: Membership on an entity's Board of Directors or advisory committees.