Abstract 1084P
Background
Cosibelimab is a high affinity, fully-human IgG1 monoclonal antibody that directly binds to programmed death ligand-1 (PD-L1) and blocks its interaction with the programmed death receptor-1 (PD-1) and B7.1 receptors to restore an anti-tumor immune response. Cosibelimab has the additional benefit of a functional Fc domain capable of inducing antibody-dependent cellular cytotoxicity against tumor cells. Study CK-301-101 is a global, multicenter, multicohort trial that is enrolling patients (pts) with select advanced cancers, including a pivotal cohort of mCSCC (nodal and/or distant). Here we present preliminary safety data from the trial and efficacy data from the mCSCC cohort.
Methods
Eligible mCSCC pts (aged ≥18 years with histologically confirmed mCSCC and Eastern Cooperative Oncology Group performance status of 0-1) received a fixed dose of 800 mg cosibelimab administered intravenously every two weeks. The primary efficacy endpoint of objective response rate (ORR; complete response + partial response) by independent central review as per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 is intended to provide the primary evidence of efficacy for product registration. The safety analysis includes all pts treated with at least one dose of cosibelimab.
Results
As of 17 April 2020, 103 pts have been treated, of which 92% experienced ≥1 treatment-emergent adverse event (AE), 36% experienced a grade ≥3 AE, and 6% experienced a grade ≥3 drug-related AE. The most common treatment-emergent AEs were fatigue (24%), anemia (22%), nausea and rash (17% each) and the most common drug-related AEs were rash (15%) and fatigue (13%). In 32 mCSCC pts evaluable for response, ORR based on investigator assessment of tumor response was 47%, including 3 complete responses and 12 partial responses. At the time of analysis, median duration of response was not reached, with 14/15 (93%) responses ongoing and 9 responses ≥6 months (longest, 14+).
Conclusions
Cosibelimab has a predictable and manageable safety profile and demonstrated robust clinical activity in mCSCC pts, including durable complete and partial responses. Enrollment is ongoing and updated results will be presented.
Clinical trial identification
NCT03212404.
Editorial acknowledgement
Legal entity responsible for the study
Checkpoint Therapeutics, Inc.
Funding
Checkpoint Therapeutics, Inc.
Disclosure
P. Clingan: Research grant/Funding (institution): Checkpoint Therapeutics, Inc.; Research grant/Funding (institution): Merck; Research grant/Funding (institution): AbbVie; Research grant/Funding (institution): Eli Lilly; Research grant/Funding (institution): Bristol-Myers Squibb. D. Brungs, A.M. Mant, A. Tazbirkova, P. Koralewski: Research grant/Funding (institution): Checkpoint Therapeutics, Inc. R. Ladwa: Research grant/Funding (institution): Checkpoint Therapeutics, Inc.; Honoraria (self), Advisory/Consultancy: Roche; Honoraria (self), Advisory/Consultancy: Merck; Honoraria (self), Advisory/Consultancy, Travel/Accommodation/Expenses: Ipsen; Advisory/Consultancy: Sanofi. M. McGrath: Research grant/Funding (institution): Checkpoint Therapeutics, Inc.; Advisory/Consultancy: Bristol Myers. I. Lugowska: Research grant/Funding (institution): Checkpoint Therapeutics, Inc.; Honoraria (self), Research grant/Funding (institution): Bristol-Myers Squibb; Honoraria (self): Merck; Honoraria (self), Research grant/Funding (institution): Roche; Honoraria (self): Amgen; Honoraria (self): Janssen; Honoraria (self), Research grant/Funding (institution): Novartis. C. Charoentum: Research grant/Funding (institution): Checkpoint Therapeutics, Inc.; Research grant/Funding (institution): Roche; Research grant/Funding (institution): AstraZeneca. A. Dechaphunkul: Research grant/Funding (institution): Checkpoint Therapeutics, Inc.; Travel/Accommodation/Expenses: Eisai. V. Sriuranpong: Research grant/Funding (institution): Checkpoint Therapeutics, Inc.; Honoraria (self), Research grant/Funding (institution): AstraZeneca; Honoraria (self), Research grant/Funding (institution): Novartis; Honoraria (self), Research grant/Funding (institution): Roche; Honoraria (self), Research grant/Funding (institution): Pfizer; Honoraria (self): Sanofi; Honoraria (self), Research grant/Funding (institution): Eisai; Honoraria (self), Research grant/Funding (institution): Boehringer; Honoraria (self), Research grant/Funding (institution): Taiho; Honoraria (self), Research grant/Funding (institution): Merck; Honoraria (self): Bristol Myers; Advisory/Consultancy: Amgen. J. Oliviero: Shareholder/Stockholder/Stock options, Full/Part-time employment, Officer/Board of Directors: Checkpoint Therapeutics, Inc. D.L. Harris: Research grant/Funding (institution): Checkpoint Therapeutics, Inc.; Research grant/Funding (institution): Merck; Research grant/Funding (institution): Roche; Research grant/Funding (institution): Targovax.