Sex differences in outcome with bevacizumab therapy: analysis of patients with advanced-stage non-small cell lung cancer treated with or without bevacizumab in combination with paclitaxel and carboplatin in the Eastern Cooperative Oncology Group Trial 4599.

Introduction: E4599 compared carboplatin and paclitaxel with (PCB) or without (PC) bevacizumab in patients with advanced-stage non-small cell lung cancer. Bevacizumab improved overall survival. However, an unplanned subset analysis did not show a survival benefit for females treated with bevacizumab.

Methods: Known prognostic factors and toxicities were compared by sex. Proportional hazards models of survival with multiple factor combinations were used to adjust for treatment effect.

Results: The analysis includes 850 patients. The median survival was 8.7 months (PC) versus 11.7 months (PCB) for males (p = 0.001) and 13.1 months (PC) versus 13.3 months (PCB) for females (p = 0.87). Progression-free survival and response rate on the PCB arm were 6.3 months and 29% for males and 6.2 months and 41% for females (p > 0.05). Progression-free survival and response rate on the PC arm were 4.3 months and 16% for males and 5.3 months and 14% for females (p > 0.05). No significant demographic differences were seen between the two arms for males, whereas fewer females on the PCB arm had liver metastasis (PCB 11.7% versus PC 23.2%, p = 0.003). Adverse events with a sex difference on the PCB arm included severe hypertension (males: 4.2%, females: 9.9%, p = 0.02), constipation (males: 1.4%, females: 4.7%, p = 0.05), and abdominal pain (males: 0.9%, females: 5.2%, p = 0.01). In the proportional hazards model adjusting for the other factors, the test for a sex by treatment interaction was not significant (p = 0.09).

Conclusions: Multiple factors may contribute to the apparent sex-specific differences in efficacy of bevacizumab noted in this study.