Combined MTOR and autophagy inhibition: phase I trial of hydroxychloroquine and temsirolimus in patients with advanced solid tumors and melanoma

Abstract

The combination of temsirolimus (TEM), an MTOR inhibitor, and hydroxychloroquine (HCQ), an autophagy inhibitor, augments cell death in preclinical models. This phase 1 dose-escalation study evaluated the maximum tolerated dose (MTD), safety, preliminary activity, pharmacokinetics, and pharmacodynamics of HCQ in combination with TEM in cancer patients. In the dose escalation portion, 27 patients with advanced solid malignancies were enrolled, followed by a cohort expansion at the top dose level in 12 patients with metastatic melanoma. The combination of HCQ and TEM was well tolerated, and grade 3 or 4 toxicity was limited to anorexia (7%), fatigue (7%), and nausea (7%). An MTD was not reached for HCQ, and the recommended phase II dose was HCQ 600 mg twice daily in combination with TEM 25 mg weekly. Other common grade 1 or 2 toxicities included fatigue, anorexia, nausea, stomatitis, rash, and weight loss. No responses were observed; however, 14/21 (67%) patients in the dose escalation and 14/19 (74%) patients with melanoma achieved stable disease. The median progression-free survival in 13 melanoma patients treated with HCQ 1200mg/d in combination with TEM was 3.5 mo. Novel 18-fluorodeoxyglucose positron emission tomography (FDG-PET) measurements predicted clinical outcome and provided further evidence that the addition of HCQ to TEM produced metabolic stress on tumors in patients that experienced clinical benefit. Pharmacodynamic evidence of autophagy inhibition was evident in serial PBMC and tumor biopsies only in patients treated with 1200 mg daily HCQ. This study indicates that TEM and HCQ is safe and tolerable, modulates autophagy in patients, and has significant antitumor activity. Further studies combining MTOR and autophagy inhibitors in cancer patients are warranted.

Keywords: MTOR; autophagy; clinical trial; hydroxychloroquine; melanoma.

Figure 1. Antitumor activity of temsirolimus and hydroxychloroquine. (A) Serial contrast CT (CT) scans of the chest and abdomen in a patient with rapidly progressive melanoma treated with temsirolimus and HCQ. Orange outlines: tumor. (B) Serial [18]-fluordeoxy glucose positron emission tomography (FDG-PET) scans of a melanoma patient with massive tumor burden at baseline, who was able to maintain performance status by achieving stable disease on temsirolimus and hydroxychloroquine. Black signal indicates FDG-avid tumor.

Figure 2. Pharmacodynamic effects of temsirolimus and hydroxychloroquine on autophagic vacuole accumulation in peripheral blood mononuclear cells (PBMC). (A) Mixed-effects model of mean ± SD autophagic vacuoles (AVs)/cell. *P < 0.05. (B) Representative electron micrographs from a patient treated with TEM and TEM + HCQ 600 mg/po bid. Arrows, AVs; scale bar: 2 µm.

Figure 3. Therapy-associated autophagic vacuole accumulation in serial tumor biopsies from melanoma patients. Representative electron micrographs of a melanoma cell from 2 different patients (A and B) at the indicated timepoints. Dotted blue line: border of cytoplasmic membrane of 1 tumor cell. Red arrows, autophagic vacuoles. Yellow arrow, mitochondria.

Figure 4. Changes in FDG-PET uptake in patients treated with temsirolimus and HCQ. (A) Serial FDG-PET images in a patient with metastatic melanoma. Arrow: central necrosis. (B–D) Comparison of FDG-PET parameters in patients with no clinical benefit (RECIST measurements > 0) or clinical benefit (RECIST measurement ≤ 0). (B) SUV_max normalized to baseline. (C) Tumor volume normalized to baseline. (D) Partial volume corrected metabolic volumetric product (cMVP); *P < 0.05.

Figure 5. Pharmacokinetic analysis of HCQ in patients receiving temsirolimus and HCQ. (A) Observed vs. individually predicted concentrations of HCQ based on the population PK model. (B) Estimated peak concentrations (C_max). (C) Estimated trough concentrations (C_min). (D) Estimated average concentrations (C_avg).