Factors associated with efficacy of TAS-102 in patients with refractory metastatic colorectal cancer (mCRC).

Abstract

858 Background: TAS-102 significantly improved progression free survival (PFS) and overall survival (OS) versus placebo in patients with treatment refractory mCRC. We analyzed potential predictive and prognostic factors in patients treated with TAS-102 in real-world practice. Methods: We retrospectively evaluated the clinical data of 129 patients who received TAS-102. Different factors associated with PFS and OS were analyzed. Results: Baseline characteristics were: median age 67 (range 37-83), male 63.6%, ECOG PS 0 in 40.3% and 1 in 59.7%. Primary tumor location: right 20.2%, left 79.2%, wt RAS 45%. Median number of TAS-102 treatment line 3 (range 2-8). Prior treatment: anti-EGFR 45%, anti-VEGF 83%, and regorafenib 20.9%. Median follow-up was 9.4 months. The median number of cycles of TAS-102 was 3 (range 1-14). Best achieved response was SD in 23%. Median PFS was 3.3 months and OS was 11.1 months. Any ≥ grade 3 AE was in 45%, the most common ≥ grade 3 AEs were neutropenia (40.2%), anemia (6.2%), thrombocytopenia (4.7%), febrile neutropenia (2.3%), diarrhea (1.6%), nausea (1.6%), and asthenia (1.6%). Dose reduction was needed in 29.5% and cycle delay in 53.5%. Factors significantly associated with longer PFS were: initiation of TAS-102 treatment more than 3 months from last fluoropyrimidine therapy (p = 0.022, HR 0.633), normal baseline CRP level (p = 0.004, HR 0.479), baseline WBC < 8 × 109/L (p = 0.025, HR 0.641), monocytes < 0.5 × 109/L (p = 0.016, HR 0.522), neutropenia ≥ grade 2 during treatment (p < 0.0001, HR 0.349), TAS-102 dose reduction during treatment (p < 0.0001, HR 0.397), and TAS-102 cycle delay (p < 0.0001, HR 0.402). Factors associated with longer OS were normal CRP (p = 0.001, HR 0.295), normal LDH (p = 0.006, HR 0.422), WBC < 8 × 109/L (p = 0.0001, HR 0.357), monocytes < 0.5 × 109/L (p = 0.016, HR 0.373), neutropenia ≥ G2 during treatment (p = 0.0002, HR 0.343), TAS-102 cycle delay (p = 0.002, HR 0.421), wt RAS (p = 0.05, HR 0.578). Conclusions: This analysis confirms that TAS-102 is effective in patients with refractory mCRC treated in a real-world setting. Factors associated with better outcomes were baseline CRP, WBC, monocytes, and neutropenia, dose reduction and cycle delays during the treatment.