Real-world comparison of Docetaxel versus new hormonal agents in combination with androgen-deprivation therapy in metastatic hormone-sensitive prostate cancer descrying PSA Nadir ≤ 0.05 ng/ml as marker for treatment response

Abstract

Propose: Using Docetaxel chemotherapy or new hormonal agents (NHT) to intensify upfront systemic therapy resulted in improved survival rates compared to androgen deprivation monotherapy (ADT). Hence, combination therapies have become the new standard of care (SOC) in metastatic hormone-sensitive prostate cancer (mHSPC). However, head-to-head trails comparing different therapies as well as treatment-guiding biomarkers are still lacking. Thus, the aim of the present study was to compare clinical outcomes of Docetaxel versus NHT therapy in the real-world setting as well as to elaborate biomarkers predicting clinical outcome. Methods: We retrospectively assessed overall-survival (OS), progression-free survival 1 and 2 (PFS1/2) and time to progression (TTP) in 42 patients treated by either ADT + NHT or ADT + Docetaxel. In addition, we investigated clinical prognostic biomarkers. Results: Our survival analysis revealed 3-year OS of 89.4% in the NHT group compared to 82.4% in the Docetaxel group. 3-year PFS1 was 59.6% in the NHT group compared to 32.2% in the Docetaxel group and the TTP was 53.8% vs 32.2% (pOS = 0.189; pPFS1 = 0.082; pTTP = 0.055). In addition, castration-resistance occurred more often in the Docetaxel group (78.6% vs 25%, p = 0.004). Interestingly, a PSA-Nadir ≤ 0.05 ng/ml during therapy was associated with increased survival rates (p < 0.001) while PSA levels at primary diagnosis had no influence on therapy outcome. Furthermore, a thyroid-stimulating hormone (TSH) increase during therapy was associated with improved clinical outcome (p = 0.06). Conclusion: We observed a trend towards a higher benefit of NHT as first-line treatment compared to Docetaxel in men with mHSPC. Of note, a PSA-Nadir ≤ 0.05 ng/ml or a TSH-increase during therapy were predictors for therapy response.