Abstract No : 1076
Abstract Type : Poster Session (Board #161)
Indication : TNBC
Intervention : dinaciclib + pembrolizumab
Company : Merck, U.S. National Institutes of Health
Technology : CDK1/5 inhibitor
32 pts were enrolled (median age 53, median 2 prior lines of therapy, 13 pts (41%) had disease which was previously ER+). 18 pts were enrolled in the dose escalation phase with no observed DLTs; 33 mg/m2 was determined to be the recommended phase 2 dose (RP2D). 14 additional patients were enrolled in dose expansion at 33 mg/m2, completing trial accrual. Grade $3 adverse events (AEs) in all pts included neutropenia (ntp) (37.5%), febrile ntp (12.5%), fatigue (12.5%), transaminitis (3.2%), and neuromuscular weakness (3.2%). Most common all grade AEs included fatigue (63%), diarrhea (63%), nausea (63%), and ntp (53%). Possible immune-related AEs included sinusitis (4 pts), hemolytic anemia (1 pt), pneumonitis (1 pt), rash (2 pts), neuromuscular weakness (1 pt), and transaminitis (1 pt). Of the 29 patients evaluable for response, 1 pt (3.4%) had a CR, 4 pts (13.8%) had a PR, and 6 pts (20.6%) had SD. MYC IHC staining on baseline metastatic tumor biopsies in 19 pts correlated significantly with clinical response. Additional biomarker testing will be reported.
The RP2D of dina given in combination with standard dose P is 33 mg/m2 on D1, 8 of a 21-day cycle. Toxicities were generally manageable and non-overlapping. In exploratory analysis, greater MYC IHC staining correlated significantly with response to study therapy.
A new sub-type of CDK may bring a new hope and competition to existing CDK4/6 class in HER2- breast cancer.