Abstract Purpose Currently available post-hoc TITAN study data indicate favorable cancer-control in metastatic hormone-sensitive prostate cancer (mHSPC) patients treated with apalutamide, even in patients with high metastatic burden, such as ≥ 10 bone metastases. However, these findings have never been validated in real-world setting. Patients and methods We relied on the FRAMCAP (FRAnkfurt Metastatic Cancer database of the Prostate) and stratified apalutamide-treated mHSPC patients according to number of bone metastases (≥ 10 vs. < 10). Primary endpoints were time to metastatic castration-resistant prostate cancer (ttCRPC) and overall survival (OS). Finally, exploratory analyses were made against mHSPC treatment with abiraterone and docetaxel. Results Of 105 apalutamide-treated mHSPC patients, median age was 71 years and median PSA 46 ng/ml. In total, 23% of included patients had ≥ 10 bone metastases. Patients with ≥ 10 bone metastases harbored higher PSA level at treatment start (254 vs. 29 ng/ml) and achieved less PSA response under treatment (PSA nadir 0.64 vs. 0.03 ng/ml, both p < 0.01). Regarding ttCRPC, no statistically significant difference was observed between ≥ 10 vs. < 10 bone metastases with median ttCRPC of 32 vs. 37 months ( p = 0.15). Regarding OS, median OS was significantly shorter for ≥ 10 vs. < 10 bone metastases (29 vs. 64 months, hazard ratio: 2.5, p = 0.02), even after multivariable adjustment for baseline patient and tumor characteristics. In further analyses, apalutamide (32 months) showed numerically longer median ttCRPC compared to abiraterone (18 months) and docetaxel (16 months) in patients with ≥ 10 bone metastases. Conclusion In real-world setting, apalutamide-treated mHSPC patients presenting with a high bone metastatic burden achieve virtually similar ttCRPC outcomes compared to those with a lower metastatic burden. Exploratory comparisons with other first-line doublet mHSPC treatment options indicate a potential advantage of apalutamide. Clinical trial registration Not applicable.
Rehm et al. (Mon,) studied this question.