Abstract 38MO
Background
CFI-402257 (CFI) is a selective oral inhibitor of TTK protein kinase, a critical regulator of the mitotic spindle assembly checkpoint, is overexpressed in BC and enhances activity of Px in BC xenografts.
Methods
Define recommended phase II dose (RP2D) of CFI in combination with weekly Px using 3+3 escalation. Patients with HER2- advanced BC with adequate organ function, PS=0-1, previously treated with 1 or more non-taxane chemotherapy, were eligible. CFI was given on a 2-day on, 5-day off schedule with Px 80mg/m2 on day 1, 8, 15 every 28 days. Starting dose, based on the CFI phase I study, was 84mg PO. Five dose levels (DL) were planned: 84, 112, 168, 210 and 252mg.
Results
29 patients received a total of 169 cycles. Median age was 58 years; 90% ER+/HER2-; 45% PS=1; 21% 3 or more prior chemotherapy regimens (76% received CDK4/6 inhibitors). Grade (G) 3 or more ANC was reported in 66%, G4 in 39%, and 2 patients had infection (febrile neutropenia and skin). Five patients met criteria for dose limiting toxicity (DL3=2; DL4=2; DL5=1): all were G4 ANC. ANC appeared dose dependent and G4 ANC was only reported in DL3, 4 and 5. Increased age was also associated with higher likelihood of G4 ANC (median age of patients with G4 ANC 68 years vs. 51 years; p=0.0025). Adverse events related to CFI and or Px G2 or more included: alopecia (3%), fatigue (10%) and nausea (3%). Partial response was reported for 3 patients.
Conclusions
CFI plus Px has a manageable toxicity profile, with anticancer activity in this heavily pretreated population. Expansion at DL3 (168mg) is ongoing; updated safety/efficacy data will be presented at the meeting.
Clinical trial identification
CCTG IND.236; NCT03568422.
Editorial acknowledgement
Legal entity responsible for the study
Queen's University.
Funding
CCTG is supported by the Canadian Cancer Society (704970). This study was supported by a SU2C Canada - Canadian Cancer Society Breast Cancer Dream Team Research Funding (SU2C-AACR-DT-18-15) and OICR, funding provided by the Government of Ontario.
Disclosure
M. Mates: Honoraria (self), Advisory/Consultancy: Seagen; Honoraria (self), Advisory/Consultancy: Novartis; Honoraria (self), Advisory/Consultancy: Pfizer; Honoraria (self), Advisory/Consultancy: GenomicHealth; Honoraria (self), Advisory/Consultancy: BMS. P. Bedard: Advisory/Consultancy, Research grant/Funding (institution): Seattle Genetics; Advisory/Consultancy, Research grant/Funding (institution): Lilly; Advisory/Consultancy: Amgen; Advisory/Consultancy, Research grant/Funding (institution): Merck; Advisory/Consultancy, Research grant/Funding (institution): BMS; Advisory/Consultancy, Research grant/Funding (institution): Sanofi; Advisory/Consultancy: Pfizer; Research grant/Funding (institution): AstraZeneca; Research grant/Funding (institution): Genentech/Roche; Research grant/Funding (institution): Servier; Research grant/Funding (institution): GlaxoSmithKline; Research grant/Funding (institution): Novartis; Research grant/Funding (institution): SignalChem; Research grant/Funding (institution): PTC Therapeutics; Research grant/Funding (institution): Nektar; Research grant/Funding (institution): Mersana; Research grant/Funding (institution): Immunomedics. J. Hilton: Advisory/Consultancy, DSBM: BMS; Advisory/Consultancy: AstraZeneca; Advisory/Consultancy: Novartis; Advisory/Consultancy: Pfizer; Advisory/Consultancy: Eli Lilly; Advisory/Consultancy: Merck; Research grant/Funding (institution): GSK. K.A. Gelmon: Advisory/Consultancy, Research grant/Funding (self): AstraZeneca; Advisory/Consultancy, Research grant/Funding (self): Roche; Advisory/Consultancy, Research grant/Funding (self): Novartis; Advisory/Consultancy, Research grant/Funding (self): Pfizer; Advisory/Consultancy: Oncotheryon; Advisory/Consultancy: NanoString; Advisory/Consultancy: Merck; Advisory/Consultancy: Mylan; Advisory/Consultancy: Eli Lilly; Advisory/Consultancy: Genomic Health; Advisory/Consultancy, Research grant/Funding (self): BMS; Research grant/Funding (self): Expert Testimony; Research grant/Funding (self): Genentech. A. Awan: Advisory/Consultancy: Eli Lily; Advisory/Consultancy: Exact Sciences; Advisory/Consultancy: Exactis; Advisory/Consultancy: Novartis; Advisory/Consultancy: Pfizer; Honoraria (self): Apotex; Honoraria (self), Travel/Accommodation/Expenses: Roche. X. Song: Advisory/Consultancy, attended advisory board meetings: Novartis; Advisory/Consultancy, attended advisory board meetings: Merck; Advisory/Consultancy, attended advisory board meetings: Pfizer. C. Lohrisch: Advisory/Consultancy: AstraZeneca. M. Bray: Full/Part-time employment, CSO: Treadwell Therapeutics. All other authors have declared no conflicts of interest.