A phase 1b trial of the combination of an all-oral regimen of capecitabine and erlotinib in advanced non-small cell lung cancer in Caucasian patients

Erlotinib is active in advanced non-small cell lung cancer (aNSCLC) particularly in patients with EGFR-sensitizing mutations. The thymidylate synthase inhibitors are active in NSCLC, but capecitabine is not well studied. This study explored the safety and activity of this oral combination. This phase Ib trial used a 3 + 3 escalation design with a combination of erlotinib (100 mg daily) with increasing doses of capecitabine (500, 750 and 1000 mg/m(2) BD, 14/21 days), in first- and second-line aNSCLC of adenocarcinoma histology. The DLT was any drug-induced toxicity a parts per thousand yengrade (G)2 causing dose interruption or dose delay during the first 2 cycles. Forty patients were recruited, and 1 patient had an EGFR mutation. Dose escalation stopped at capecitabine 1000 mg/m(2) with expansion to 6 patients due to unpredicted DLTs in 2/6 patients: G2 creatinine rise, G2 anaemia, G3 atrial fibrillation and G3 pneumonia. MTD was capecitabine 750 mg/m(2). First-line dose escalation at the MTD led to unpredicted DLTs in 3/4 patients (G3 troponin rise, G2 rash and G2 hyperbilirubinaemia). MTD expansion in the second-line setting was well tolerated. The most common drug toxicities were gastrointestinal (35 %), followed by skin disorders (28 %). The response rate was 3 % with a disease control rate of 34 %. Median progressive-free survival was 1.6 months (95 % CI 1.4-3.5), and median overall survival was 6.1 months (95 % CI 5.1-10.1). The MTD for the combination of capecitabine and erlotinib is 750 mg/m(2) BD, 14/21 days, and 100 mg daily, respectively, which is lower than predicted. Capecitabine did not improve the efficacy of erlotinib in aNSCLC unselected for EGFR mutation.