Tolerability, safety and feasibility of metformin combined with chemoradiotherapy in patients with locally advanced cervical cancer: A phase II, randomized study.

Abstract

Background and purpose: Locally advanced cervical cancer is treated with chemoradiotherapy. The treatment-related morbidity is high. Tumor hypoxia has prognostic impact and represents a valid, interventional target. This phase II study investigated efficacy of the antidiabetic drug metformin to modify hypoxia according to established biomarkers. Preliminary results including tolerability, safety and feasibility are reported here.

Patients and methods: Patients were included in a 1:1 randomized, open-label design, comparing standard chemoradiotherapy ± metformin. Metformin 850 mg twice daily was administered 1 week before and during chemoradiotherapy. Magnetic resonance images (MRI) and tumor biopsies were collected at baseline, after 1 week of metformin treatment, and at brachytherapy for biomarker assessments. Tolerability and safety were determined by treatment completion rates and frequency of adverse events (AEs). Safety was further evaluated by possible increase in MRI-based hypoxia during the first week of metformin. Feasibility was determined by proportion of completed study interventions and imaging and biopsy procedures.

Results: In total, 18 and 23 patients were allocated to the intervention and control arm, respectively. Eighteen and 15 patients completed metformin treatment for 1 and 5 weeks. Frequency of AEs ≥ grade 3 was not significantly different between study arms. Most AEs were gastrointestinal toxicities. Tumors with increase in hypoxia during the first week were all below the defined safety limit. A total of 98% of scheduled MR series and biopsies were collected with satisfactory quality.

Interpretation: Addition of metformin to chemoradiotherapy is tolerable and safe. Serial sampling of MRI and tumor biopsies for hypoxia biomarker assessment is feasible.