Modulation of autophagy: a Phase II study of vorinostat plus hydroxychloroquine versus regorafenib in chemotherapy-refractory metastatic colorectal cancer (mCRC)

Background In metastatic colorectal cancer (mCRC), regorafenib (RGF), a multi-kinase inhibitor with angiogenic inhibition has modest effects on survival. We reported that autophagy modulation using hydroxychloroquine (HCQ), enhances the anticancer activity of the histone deacetylase inhibitor, vorinostat (VOR), in mCRC, is well tolerated, and has comparable activity to RGF. Thus, we conducted a prospective study of VOR/HCQ versus RGF in mCRC. Methods This is a randomised, controlled trial of VOR 400 mg and HCQ 600 mg orally daily versus RGF 160 mg orally daily (3 weeks on/1 week off), every 4 weeks, in patients with mCRC. Primary endpoint: median progression-free survival (mPFS). Secondary endpoints: median overall survival (mOS); adverse events; pharmacodynamic analyses. Results From 2/2015-10/2017, 42 patients were randomised to VOR/HCQ and RGF. Median age was 58.4 years. mPFS on VOR/HCQ was 1.9 months versus 4.35 months with RGF (P = 0.032). There was no difference in mOS (P = 0.9). Treatment was tolerated in both arms. In both arms, there was improved anti-tumour immunity. Conclusions VOR/HCQ had an inferior PFS when compared to RGF, although there was an increase in anti-tumour immunity in mCRC. VOR/HCQ has a favourable safety profile, and immune or tumour biomarkers may be used to identify clinical benefit of autophagy modulation in mCRC.