Neutropenia as a Predictive Factor in Metastatic Colorectal Cancer Treated With TAS-102

TAS-102 significantly improves overall survival in patients with metastatic colorectal cancer. The most common treatment-related adverse event of TAS-102 is bone marrow suppression, which leads to neutropenia. The potential predictive value of neutropenia caused by cytotoxic drugs has been reported in various types of cancer.

We retrospectively analyzed 95 consecutive patients with metastatic colorectal cancer who received TAS-102 at 2 Japanese institutions between May 2014 and May 2015. To evaluate the association between efficacy and neutropenia, patients were divided into 4 categories according to the grade of neutropenia during the first cycle of TAS-102: Category A (grade 0-1), B (grade 2-4), C (grade 0-2), and D (grade 3-4).

Patient characteristics were as follows: median age, 64 years; male, 58%; Eastern Cooperative Oncology Group performance status 0 to 1, 91%; primary site colon, 49%; KRAS exon 2 wild, 57%; and number of metastatic site ≥ 3, 55%. The disease control rate was significantly different between Category A and B (29.2% vs. 52.6%; P = .045) and between Category C and D (30.9% vs. 72.2%; P = .002). In multivariate analysis, Category D remained a significant predictive factor for progression-free survival compared with Category C (4.3 vs. 2.0 months; hazard ratio, 0.45; P = .01).

Neutropenia caused by TAS-102 during the first cycle was associated with better efficacy. Neutropenia may be a surrogate marker for adequate antitumor doses of TAS-102.