Phase II study of tailored S-1 monotherapy with a 1-week interval after a 2-week dosing period in elderly patients with advanced non-small cell lung cancer

S-1 is an oral fluoropyrimidine that is active in the treatment of non-small cell lung cancer (NSCLC); however, an optimal treatment schedule and appropriate dose adjustments of S-1 in elderly patients have not yet been established.

We conducted a phase II trial to evaluate the efficacy and safety of a 2-week S-1 monotherapy treatment followed by a 1-week interval as a first-line treatment of elderly NSCLC patients, by adjusting the dose based on the individual creatinine clearance (Ccr) and body surface area (BSA). The primary endpoint was the disease control rate.

Forty patients were enrolled. The disease control and response rates were 89.5% (95% confidence interval [CI] = 79.8-99.2) and 7.9% (95% CI = 0.0-16.4), respectively. The median progression-free survival and overall survival times were 4.4 months (95% CI = 4.2-8.5) and 17.0 months (95% CI = 11.2-18.7), respectively. Neutropenia, anorexia, hyponatremia, hypokalemia, and pneumonia of grade ≥ 3 occurred in 5.0%, 7.5%, 5.0%, 2.5%, and 2.5% of patients, respectively. Among the patient-reported outcomes, most of the individual factors in the patients' quality of life, including upper intestine-related symptoms improved with the treatment, except for dyspnea, which slightly albeit continuously worsened throughout the study.

In elderly patients with previously untreated advanced NSCLC, a 2-week S-1 monotherapy treatment, tailored to both the Ccr and BSA, with a 1-week interval was well tolerated and demonstrated promising efficacy. This study was registered at the University Hospital Medical Information Network (UMIN) Center (ID: UMIN000002035), Japan.