Effects of enobosarm on muscle wasting and physical function in patients with cancer: a double-blind, randomised controlled phase 2 trial

Abstract

Background: Cancer-induced muscle wasting begins early in the course of a patient's malignant disease, resulting in declining physical function and other detrimental clinical consequences. This randomised, double-blind, placebo-controlled phase 2 trial assessed the efficacy and safety of enobosarm, a selective androgen receptor modulator, in patients with cancer.

Methods: We enrolled male (>45 years) and female (postmenopausal) patients with cancer who were not obese and who had at least 2% weight loss in the previous 6 months. Participants were randomly assigned (1:1:1 ratio, by computer generated list, block size three, stratified by cancer type) to receive once-daily oral enobosarm 1 mg, 3 mg, or placebo for up to 113 days at US and Argentinian oncology clinics. The sponsor, study personnel, and participants were masked to assignment. The primary endpoint was change in total lean body mass from baseline, assessed by dual-energy x-ray absorptiometry. Efficacy analyses were done only in patients who had a baseline and an on-treatment assessment in the protocol-specified window of within 10 days before baseline or first study drug, and within 10 days of day 113 or end of study (evaluable efficacy population). Adverse events and other safety measurements were assessed in the intention-to-treat (safety) population. This trial is registered with ClinicalTrials.gov, number NCT00467844.

Findings: Enrolment started on July 3, 2007, and the last patient completed the trial on Aug 1, 2008. 159 patients were analysed for safety (placebo, n=52; enobosarm 1 mg, n=53; enobosarm 3 mg, n=54). The evaluable efficacy population included 100 participants (placebo, n=34; enobosarm 1 mg, n=32; enobosarm 3 mg, n=34). Compared with baseline, significant increases in total lean body mass by day 113 or end of study were noted in both enobosarm groups (enobosarm 1 mg median 1·5 kg, range -2·1 to 12·6, p=0·0012; enodosarm 3 mg 1·0 kg, -4·8 to 11·5, p=0·046). Change in total lean body mass within the placebo group (median 0·02 kg, range -5·8 to 6·7) was not significant (p=0·88). The most common serious adverse events were malignant neoplasm progression (eight of 52 [15%] with placebo vs five of 53 [9%] with enobosarm 1 mg vs seven of 54 [13%] with enobosarm 3 mg), pneumonia (two [4%] vs two [4%] vs three [6%]), and febrile neutropenia (three [6%vs one [2%] vs none). None of these events were deemed related to study drug.

Interpretation: Cancer cachexia is an unmet medical need and our data suggest that use of enobosarm might lead to improvements in lean body mass, without the toxic effects associated with androgens and progestational agents.

Funding: GTx.

Copyright © 2013 Elsevier Ltd. All rights reserved.

Figures

Figure 1. Trial profile

Because of the prevalence of end-stage cancer in this study, 27 deaths occurred; nine discontinued because of death, 16 died after study discontinuation, and two died after study completion. *Removals were done before unmasking of primary investigators. †Two participants in the enobosarm 3 mg group were included in the efficacy analysis but did not complete the trial (one withdrew consent, one because of non-compliance).

Figure 2. Mean absolute change from baseline to day 113 or end of study in stair climb time and power

These analyses were done for patients for whom efficacy data were evaluable; no adjustments have been made for missing data. Error bars represent 1 SE.