Indirect treatment comparison of cabazitaxel for patients with metastatic castrate-resistant prostate cancer who have been previously treated with a docetaxel-containing regimen

Comparison of Systemic Treatments for Metastatic Castration-Resistant Prostate Cancer After Docetaxel Failure: A Systematic Review and Network Meta-analysis

Background: Lacking head-to-head trial, the optimal treatment for patients with metastatic castration-resistant prostate cancer (mCRPC) after docetaxel failure is unclear. This study is to compare the efficacy and safety of systemic treatments in patients who progressed after docetaxel to aid clinical decision-making.

Methods: Databases including MEDLINE, EMBASE, and the Cochrane Library were searched from inception to June 15th, 2021. The outcomes of interest include overall survival (OS), biochemical progression-free survival (bPFS), and serious adverse events (SAEs). The Cochrane risk of bias tools were used to assess study quality. Indirect comparisons of competing treatments were performed via Bayesian network meta-analysis.

Results: Five trials with 3,862 patients comparing four treatments (abiraterone, enzalutamide, cabazitaxel, and radium-223) were identified. All the four treatments were associated with improved OS and bPFS relative to best supportive care. Among them, enzalutamide (hazard ratio [HR] = 0.58, 95% credible interval [Crl]: 0.49–0.69) had the highest probability of ranking first in terms of OS, followed by cabazitaxel (HR = 0.70, 95% Crl: 0.59–0.83), radium-223 (HR = 0.71, 95% Crl: 0.56–0.90) and abiraterone (HR = 0.73, 95% Crl: 0.63–0.84). Similarly, enzalutamide (HR = 0.25, 95% Crl: 0.20–0.31) showed the greatest improvement of bPFS, followed by abiraterone (HR = 0.60, 95% Crl: 0.51–0.71) and cabazitaxel (HR = 0.75, 95% Crl: 0.63–0.89). In terms of safety, treatments ranked from the safest to the least safe were radium-223 (OR = 0.58, 95% Crl: 0.20–1.68), enzalutamide (OR = 0.80, 95% Crl: 0.28–2.29), abiraterone (OR = 0.94, 95% Crl: 0.39–2.27) and cabazitaxel (OR = 2.50, 95% Crl: 0.84–7.44).

Conclusion: For patients with mCRPC who progressed after docetaxel, enzalutamide may offer the most significant survival benefits and satisfying safety. Cabazitaxel is effective in post-docetaxel settings but associated with a high risk of SAEs. Although network meta-analysis provides indirect comparisons and ranking probabilities, the results should be treated with caution as it cannot replace randomized direct comparison.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020223040, identifier CRD42020223040.

Induction of Endoplasmic Reticulum Stress-Mediated Apoptosis by Aminosteroid RM-581 Efficiently Blocks the Growth of PC-3 Cancer Cells and Tumors Resistant or Not to Docetaxel

Aminosteroid derivative RM-581 was previously identified as an endoplasmic-reticulum (ER) stress inducer with potent in vitro and in vivo anticancer activities. We report its evaluation in androgen-independent prostate cancer (PC-3) cells. RM-581 efficiently blocks PC-3 cell proliferation with stronger activity than that of a selection of known antineoplastic agents. This later also showed a synergistic effect with docetaxel, able to block the proliferation of docetaxel-resistant PC-3 cells and, contrary to docetaxel, did not induce cell resistance. RM-581 induced an increase in the expression level of ER stress-related markers of apoptosis, potentially triggered by the presence of RM-581 in the ER of PC-3 cells. These in vitro results were then successfully translated in vivo in a PC-3 xenograft tumor model in nude mice, showing superior blockade than that of docetaxel. RM-581 was also able to stop the progression of PC-3 cells when they had become resistant to docetaxel treatment. Concomitantly, we observed a decrease in gene markers of mevalonate and fatty acid pathways, and intratumoral levels of cholesterol by 19% and fatty acids by 22%. Overall, this work demonstrates the potential of an ER stress inducer as an anticancer agent for the treatment of prostate cancers that are refractory to commonly used chemotherapy treatments.

Overall Survival Among Chemotherapy-Naive Patients With Castration-Resistant Prostate Cancer Under Abiraterone Versus Enzalutamide: A Direct Comparison Based on a 2014-2018 French Population Study (the SPEAR Cohort)

Abiraterone acetate (ABI) and enzalutamide (ENZ) are considered to be clinically relevant comparators among chemotherapy-naive patients with castration-resistant prostate cancer. No clinical trials comparing overall survival with ABI versus ENZ in a head-to-head approach have been published so far. A few observational studies with low power suggested a potential benefit of ENZ. We used the French National Health Data System to compare overall survival of new users of ABI and ENZ among chemotherapy-naive patients with castration-resistant prostate cancer in 2014-2017, followed through 2018 (the SPEAR cohort, a 2014-2018 cohort study). With an intent-to-treat approach, a survival analysis was performed, estimating hazard ratios for overall survival with the inverse probability weighted Cox model method. Among 10,308 new users, 64% were treated with ABI and 36% with ENZ. The crude mortality rate was 25.2 per 100 person-years (95% confidence interval (CI): 24.4, 26.0) for ABI and 23.7 per 100 person-years (95% CI: 22.6, 24.9) for ENZ. In the weighted analysis, ENZ was associated with better overall survival compared with ABI (hazard ratio = 0.90 (95% CI: 0.85, 0.96) with a median overall survival of 31.7 months for ABI and 34.2 months for ENZ). When restricting to 2015-2017 new users, the effect estimate shifted up to a hazard ratio of 0.93 (95% CI: 0.86, 1.01).

Efficacy and safety of abiraterone acetate plus prednisone vs. cabazitaxel as a subsequent treatment after first-line docetaxel in metastatic castration-resistant prostate cancer: results from a prospective observational study (CAPRO)

BACKGROUND

To describe the patterns of second-line treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) after docetaxel treatment in a Spanish population, to identify the factors associated with those patterns, and to compare the efficacy and safety of the treatments most frequently administered.

METHODS

Observational, prospective study conducted in patients with histologically or cytologically confirmed prostate adenocarcinoma; documented metastatic castration-resistant disease; progression after first-line, docetaxel-based chemotherapy with or without other agents.

RESULTS

Of the 150 patients recruited into the study, 100 patients were prescribed abiraterone acetate plus prednisone (AAP), 44 patients received cabazitaxel plus prednisone (CP), and 6 patients received other treatments. Age (odds ratio [OR] 1.06, 95% [confidence interval] CI 1.01 to 1.11) and not elevated lactate dehydrogenase (LDH) levels (OR 0.33, 95% CI 0.14 to 0.76) were independently associated with the administration of AAP. Treatment with AAP was associated with significantly longer clinical/radiographic progression-free survival (hazard ratio [HR] 0.57, 95% CI 0.38 to 0.85) and overall survival (OS; HR 0.40, 95% CI 0.21 to 0.76) compared to CP, while no significant differences between the treatments were found regarding biochemical progression-free survival (PFS; HR 0.78 [95% CI 0.49 to 1.24]). However, in a post-hoc Cox regression analysis adjusted for potential confounders there were not differences between AAP and CP in any of the time-to-event outcomes, including overall survival. We observed no new safety signals related to either regimen.

CONCLUSION

Second-line AAP for patients with mCRPC is the most common treatment strategy after progression with a docetaxel-based regimen. When controlling for potential confounders, patients receiving this treatment showed no differences in PFS and OS in comparison to those receiving CP, although these latter results should be confirmed in randomized controlled trials.