Background: 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.
Methods: 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).
Results: 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).
Conclusion: 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.
Keywords: Chemotherapy; Metastatic colorectal cancer; Neutropenia; Predictive factor; TAS-102.
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