Chicago—A recent study examined the association of changes in measurable disease via the Response Evaluation Criteria in Solid Tumors (RECIST) with overall survival (OS). The results were discussed during a poster presentation at the ASCO 2015 Annual Meeting by Gregory Russell Pond and colleagues that examined the national trends of prostate-specific antigen (PSA) screening to investigate which patient characteristics were associated with PSA testing [J Clin Oncol. 2015;33; abstract 5057]. The poster was titled Validation of correlation of RECIST changes with survival in metastatic castration-resistant prostate cancer (mCRPC).
Data were collected from the control cohort of the VENICE trial that included 612 patients with mCRPC receiving docetaxel, prednisone, and placebo (DPP). Data on baseline clinical variables and outcomes were used. Cox proportional hazards regression was also used to evaluate the prognostic ability of RECIST changes adjusting for known factors for OS using a 90-day landmark analysis.
The association was validated with 388 patients in the DPP group of the MAINSAIL trial who had RECIST measurements prior to 90 days and survival beyond that.
The researchers found that 363 patients in the VENICE trial had measurable lesions, of whom 296 were included in the analysis; 28 patients (9.5%) had progressive disease prior to 90 days, while 58 patients (19.6%) had unconfirmed partial response.
The hazard ratio (HR) for OS for patients with partial response was 0.64 (95% confidence interval [CI], 0.42-0.99; P=.045) compared with those without partial response. The HR for OS for patients with progressive disease was 1.78 (95% CI, 1.07-2.95; P=.026) compared with those without progressive disease.
Progressive disease was significant after adjusting for PSA changes (HR, 1.85; 95% CI, 1.1-3.12; P=.2), though partial response was not (P=.14).
In addition, the association of partial response (HR, 0.51; 95% CI, 0.22-1.18; P=.12) and progressive disease (HR, 3.51; 95% CI, 1.92-6.43; P<.001) with OS was externally validated via 388 patients in the MAINSAIL trial who had measurable disease.
After adjusting for PSA changes, progressive disease was associated with poor OS (HR, 2.36; 95% CI, 1.11-5.04; P=.026), though partial disease was not (P=.15).
The researchers concluded, “In men with mCRPC receiving first-line docetaxel-based therapy, RECIST changes within 90 days are associated with OS. Given the frequent detection of measurable disease with current imaging and the unclear association of PSA and bone scan changes with outcomes in the setting of new agents, the accrual of patients with measurable tumors in phase  trials to assess RECIST changes may provide a more objective signal of efficacy of new agents.”
Source: Pond GR, Templeton AJ, Petrylak DP, et al. Validation of correlation of RECIST changes with survival in metastatic castration-resistant prostate cancer (mCRPC). Abstract of poster presentation at the American Society of Clinical Oncology 2015 Annual Meeting, Chicago, Illinois, May 30, 2015.