Effects of cabozantinib on pain and narcotic use in patients with castration-resistant prostate cancer: Results from a phase 2 nonrandomized expansion cohort - Abstract

BACKGROUND: Pain negatively affects quality of life for cancer patients.

Preliminary data in metastatic castration-resistant prostate cancer (mCRPC) suggested a benefit of the oral tyrosine kinase inhibitor cabozantinib to pain palliation.

OBJECTIVE: Prospective evaluation of cabozantinib's benefits on pain and narcotic use in mCRPC.

DESIGN, SETTING, AND PARTICIPANTS: This was a nonrandomized expansion (NRE) cohort (n=144) of a phase 2 randomized discontinuation trial in docetaxel-refractory mCRPC patients. Pain and interference of symptoms with sleep and general activity were electronically self-reported daily for 7-d intervals at baseline and regularly scheduled throughout the study. Mean per-patient scores were calculated for each interval. Narcotic use was recorded daily during the same intervals.

INTERVENTION: Open-label cabozantinib (100mg or 40mg).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The following stringent response definition was used: clinically meaningful pain reduction (≥30% improvement in mean scores from baseline) confirmed at a later interval without concomitant increases in narcotics. Only patients with moderate or severe baseline pain were analyzed.

RESULTS AND LIMITATIONS: Sixty-five patients with moderate or severe baseline pain were evaluable. Of these, 27 (42%) experienced pain palliation according to the stringent response definition. Thirty-seven patients (57%) had clinically meaningful pain relief at two consecutive intervals, reported ≥6 wk apart in the majority. Forty-four patients (68%) had palliation at one or more intervals; 36 (55%) decreased narcotics use during one or more intervals. Clinically meaningful pain reduction was associated with significant (p ≤ 0.001) improvements in sleep quality and general activity. A limitation of this study was its open-label design.

CONCLUSIONS: Cabozantinib demonstrated clinically meaningful pain palliation, reduced or eliminated patients' narcotic use, and improved patient functioning, thus meriting prospective validation in phase 3 studies.

PATIENT SUMMARY: We evaluated the potential of cabozantinib to improve symptoms in patients with metastatic prostate cancer that no longer responds to standard therapies. We saw a promising reduction in pain and reduced need for narcotic painkillers. Larger, well-controlled trials are necessary to confirm these findings.

Written by:
Basch EM, Autio KA, Smith MR, Bennett AV, Weitzman AL, Scheffold C, Sweeney C, Rathkopf DE, Smith DC, George DJ, Higano CS, Harzstark AL, Sartor AO, Gordon MS, Vogelzang NJ, de Bono JS, Haas NB, Corn PG, Schimmoller F, Scher HI.   Are you the author?
Institution(s): See publishing journal.

Reference: Eur Urol. 2014 Feb 20. pii: S0302-2838(14)00132-8.
doi: 10.1016/j.eururo.2014.02.013

PubMed Abstract
PMID: 24631409

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