Phase II study of dichloroacetate, an inhibitor of pyruvate dehydrogenase, in combination with chemoradiotherapy for unresected, locally advanced head and neck squamous cell carcinoma.

ABSTRACT

Chemoradiotherapy (CRT) for locally-advanced head and neck squamous cell carcinoma (LA-HSNCC) yields 5-year survival rates near 50% despite causing significant toxicity. Dichloroacetate (DCA), a pyruvate dehydrogenase kinase metabolic inhibitor, reduces tumor lactate production and has been used in cancer therapy previously. The safety of adding this agent to CRT is unknown. Our randomized, placebo-controlled, double-blind phase II study added DCA to cisplatin-based CRT in patients with LA-HNSCC. The primary endpoint was safety by adverse events (AEs). Secondary endpoints compared efficacy via 3-month end-of-treatment response, 5-year progression-free and overall survival. Translational research evaluated pharmacodynamics of serum metabolite response. 45 participants (21 DCA, 24 Placebo) were enrolled from May 2011-April 2014. Higher rates of all-grade drug related fevers (43% vs 8%, p = 0.01) and decreased platelet count (67% vs 33%, p = 0.02) were seen in DCA versus placebo. However, there were no significant differences in grade 3/4 AE rates. Treatment compliance to DCA/placebo, radiation therapy, and cisplatin showed no significant difference between groups. While end-of-treatment complete response rates were significantly higher in the DCA group compared to placebo (71.4% vs 37.5%, p = 0.0362), survival outcomes were not significantly different between groups. Treatment to baseline metabolites demonstrated a significant drop in pyruvate (0.47, p < 0.005) and lactate (0.61, p < 0.005) in the DCA group. Adding DCA to cisplatin-based CRT appears safe with no detrimental effect on survival and expected metabolite changes compared to placebo. This supports further investigation into combining metabolic agents to CRT. Trial registration number NCT01386632, Date of Registration July 1, 2011.