Definitive radiotherapy for extracranial oligoprogressive metastatic renal cell carcinoma as a strategy to defer systemic therapy escalation.

OBJECTIVE: To study whether delivering definitive radiotherapy (RT) to sites of oligoprogression in metastatic renal cell carcinoma (mRCC) enabled deferral of systemic therapy (ST) changes without compromising disease control or survival. PATIENTS AND METHODS: We identified patients with mRCC who received RT to three or fewer sites of extracranial progressive disease between 2014 and 2019 at a large tertiary cancer centre. Inclusion criteria were: (1) controlled disease for ≥3 months before oligoprogression, (2) all oligoprogression sites treated with a biologically effective dose of ≥100 Gy, and (3) availability of follow-up imaging. Time-to-event end-points were calculated from the start of RT. RESULTS: A total of 72 patients were identified (median follow-up 22 months, 95% confidence interval [CI] 19-32 months), with oligoprogressive lesions in lung/mediastinum (n = 35), spine (n = 30), and non-spine bone (n = 5). The most common systemic therapies before oligoprogression were none (n = 33), tyrosine kinase inhibitor (n = 23), and immunotherapy (n = 13). At 1 year, the local control rate was 96% (95% CI 87-99%); progression-free survival (PFS), 52% (95% CI 40-63%); and overall survival, 91% (95% CI 82-96%). At oligoprogression, ST was escalated (n = 16), maintained (n = 49), or discontinued (n = 7), with corresponding median (95% CI) PFS intervals of 19.7 (8.2-27.2) months, 10.1 (6.9-13.2) months, and 9.8 (2.4-28.9) months, respectively. Of the 49 patients maintained on the same ST at oligoprogression, 21 did not subsequently have ST escalation. CONCLUSION: Patients with oligoprogressive mRCC treated with RT had comparable PFS regardless of ST strategy, suggesting that RT may be a viable approach for delaying ST escalation. Randomised controlled trials comparing treatment of oligoprogression with RT vs ST alone are needed.

Clinical predictors of survival in patients with castration-resistant prostate cancer receiving sipuleucel-T cellular immunotherapy.

BACKGROUND: We evaluated the patterns of progression and determined clinical predictors of survival in patients with castration-resistant prostate cancer (CRPCa) who received sipuleucel-T. METHODS: We retrospectively analyzed 56 consecutive patients with asymptomatic or minimally symptomatic CRPCa treated with sipuleucel-T. Age, number of bone metastases, history of prior systemic treatment, and alkaline phosphatase level (ALP) were tested as predictors of survival in a multivariate Cox proportional hazards regression model. The Kaplan-Meier method was used to estimate event-free probabilities. RESULTS: The 56 patients were a median age of 67 years (range 51-84 years). After sipuleucel-T treatment, 25 patients developed bone progression after a median of 22 months of follow-up (54% of patients were event free at 2 years) and 10% (6/56 patients) developed rapid progression. Eleven deaths were observed after a median of 28 months of follow-up. Forty-eight patients were included in the multivariate analysis for overall survival. The analysis showed that age >70 years (p = 0.012), number of bone metastases >20 (p = 0.018), prior systemic treatment (p = 0.018), and ALP level >90 IU/L (p = 0.010) significantly predicted worse overall survival. Two-year overall survival was 36% among the 16 patients with two or more of these factors and was 93% among the 32 patients with one or none of these factors (p = 0.0004). CONCLUSIONS: CRPCa patients with age (>70 years), increased tumor burden in bone (>20 metastases and/or elevated ALP level), and/or prior systemic treatment are more likely to experience rapid deterioration after sipuleucel-T. These results need to be prospectively validated.