A pilot study of the pan-class I PI3K inhibitor buparlisib in combination with cetuximab in patients with recurrent or metastatic head and neck cancer

Background: This study assessed the maximum tolerated dose (MTD) of the PI3K inhibitor buparlisib given concurrently with cetuximab in recurrent and metastatic (R/M) head and neck squamous cell carcinoma (HNSCC). Methods: Twelve patients with R/M HNSCC were enrolled. Patients were given oral buparlisib starting day 7 and daily thereafter. The dose of buparlisib was escalated in a 3 + 3 design followed by a dose expansion cohort of 6 patients. The MTD of buparlisib per protocol was 100 mg daily with cetuximab given intravenously every 14 days starting day 0. Results: Ten patients had ≥2 previous treatment regimens (11 with prior cetuximab). There were no dose limiting toxicities observed during dose escalation. One patient achieved a partial response and 4 achieved stable disease. Conclusion: Based on this pilot study, buparlisib at 100 mg daily plus cetuximab proved to be well-tolerated. Patients previously treated with cetuximab monotherapy showed benefit from this combination.