Safety and efficacy of cabazitaxel in Japanese patients with castration-resistant prostate cancer

Current Evidence on Cabazitaxel for Prostate Cancer Therapy: A Narrative Review

The incidence of prostate cancer (PC) has recently increased in Japan. Androgen deprivation therapy (ADT) has been a key treatment in patients with castration-sensitive PC (CSPC); however, resistance typically emerges through multiple mechanisms, leading to metastatic castration-resistant PC (mCRPC). Taxane-based therapy (i.e., docetaxel, cabazitaxel) has been standard care in patients with mCRPC. New evidence supporting the addition of androgen receptor signaling inhibitors (ARSIs, e.g., enzalutamide, abiraterone) to docetaxel and ADT for patients with metastatic CSPC (mCSPC) raises questions about the role of taxane-based therapies and their optimal sequencing, as well as how to identify patients who may benefit from taxane-based therapy. Here we review the evidence on taxane-based therapy, including cabazitaxel, in the treatment of PC, with a focus on clinical and real-world evidence from Japan. Cabazitaxel has proven effective for patients with mCRPC who have a history of ARSI and docetaxel use, and it is preferable to a second alternative ARSI, as indicated in the CARD study. The safety profile of cabazitaxel (particularly, the incidence of neutropenia) can be managed through prophylactic use of granulocyte colony-stimulating factor, as well as a lower dosage and possibly variation of the dosage interval. However, a certain dose intensity is required because neutropenia has been identified as a potential prognostic indicator for treatment effectiveness. In the ARSI era for mCSPC, evidence on mCRPC treatment sequencing is limited. A better understanding of PC biology and the collection of real-world data is essential for effective treatment and improved safety-benefit outcomes.

Efficacy of cabazitaxel in patients with metastatic castration-resistant prostate cancer: A single-center study in Japan

OBJECTIVES

Cabazitaxel is a next-generation taxane that can prolong overall survival after docetaxel treatment in patients with metastatic castration-resistant prostate cancer. However, the efficacy of cabazitaxel varies among these patients. The clinical indicators of the prognosis after cabazitaxel treatment were analyzed.

METHODS

A retrospective review of patients who received cabazitaxel between February 2015 and June 2021 was performed. All patients had metastatic castration-resistant prostate cancer. Prognostic factors for prostate-specific antigen progression-free and overall survival were analyzed by Cox proportional-hazards analysis and the log-rank test.

RESULTS

The study comprised 57 patients who received cabazitaxel (median 4 cycles, range 1-27) at a starting dose of 15-25 mg/m² . The median age and follow-up duration were 70 years and 9.2 months. The median prostate-specific antigen progression-free survival and overall survival were 2.6 and 10.5 months, respectively. Univariate analysis showed that previous androgen receptor-axis-targeted therapy before cabazitaxel treatment was the only significant risk factor (hazard ratio 2.784, p = 0.022) for prostate-specific antigen progression-free survival. Multivariate analysis for overall survival revealed that poor performance status (≥1) (hazard ratio 2.107, p = 0.039), low hemoglobin (hazard ratio 0.142, p = 0.010), and high neutrophil-lymphocyte ratio (hazard ratio 9.150, p = 0.032) at baseline were significantly associated with a poor prognosis.

CONCLUSIONS

Previous androgen receptor-axis-targeted therapy was the only risk factor for biochemical progression. Poor performance status, anemia, and high neutrophil-lymphocyte ratio were risk factors for poor prognosis in patients with metastatic castration-resistant prostate cancer treated with cabazitaxel. These risk factors seem useful for identifying patients with survival benefit from cabazitaxel treatment.

Efficacy of cabazitaxel and androgen splicing variant-7 status in circulating tumor cells in Asian patients with metastatic castration-resistant prostate cancer

Androgen receptor splice variant-7 (AR-V7) expression in circulating tumor cells (CTCs) in metastatic castration-resistant prostate cancer (mCRPC) is associated with abiraterone and enzalutamide resistance. We determine whether cabazitaxel (CBZ) is equally effective in AR-V7-positive and -negative CRPC and whether AR-V7-positive patients retain CBZ sensitivity. This is the first prospective, open-label, Asian validation study of CBZ in Japanese patients with mCRPC after docetaxel (n = 48; four CBZ cycles; 2017-2020, Juntendo University Hospitals). Primary endpoint was prostate-specific antigen response rate (PSA-RR); secondary endpoints included overall survival (OS), bone scan index (BSI) PSA-RR (≥ 50% decline from baseline) for CTC-/ARV7-, CTC+ /ARV7-, and CTC +/ARV7+ groups. PSA-RR ≥ - 30% was 38% (18/48) and ≥ - 50% was 26% (12/48). BSI-change rate ≥ - 30% was 19% (9/41) and ≥ - 50% was 17% (8/41). Median OS was 13.7(12.2-18.9) months. PSA decline in early CBZ treatment associated with OS (p = 0.00173). BSI decline associated with OS (p = 0.0194). PSA-RR(≥ 50%) was 43%(6/14) in CTC-/ARV7-, 19%(5/26) in CTC+ ARV7-, and 12%(1/8) in CTC+/ARV7+ ( p > 0.05). AR-V7 in CTCs at baseline not associated with OS. AR-V7 was not associated with CBZ resistance in CTCs. Reductions in BSI and PSA in early stages of CBZ treatment may predict OS.

Sarcopenia and Visceral Metastasis at Cabazitaxel Initiation Predict Prognosis in Patients With Castration-resistant Prostate Cancer Receiving Cabazitaxel Chemotherapy

BACKGROUND/AIM

Cabazitaxel is recommended as first-line treatment after docetaxel for metastatic castration-resistant prostate cancer. However, the efficacy, adverse events and prognostic factors associated with cabazitaxel are unclear.

PATIENTS AND METHODS

This single-centre retrospective study including 30 patients with CRPC treated with cabazitaxel between 2014 and 2020 investigated efficacy, outcomes and prognostic factors.

RESULTS

Fourteen patients had visceral metastases. The median cabazitaxel dose was 20 mg/m² The prostate-specific antigen response rate, time to prostate-specific antigen response, and overall survival were 13.3%, 3.48 months, and 7.92 months, respectively. The rates of grade 3 or more neutropenia and febrile neutropenia were 20% and 6.7%, respectively. By multivariate analysis, sarcopenia and visceral metastasis at the time of cabazitaxel initiation were independent and significant factors conferring a poor prognosis.

CONCLUSION

The early introduction of cabazitaxel, prior to the development of sarcopenia and visceral metastasis, might contribute to improved prognosis in CRPC.

Utility of prophylactic antibiotics for preventing febrile neutropenia during cabazitaxel therapy for castration-resistant prostate cancer

The aim was to investigate the efficacy of prophylactic antibiotics for the prevention of febrile neutropenia (FN) during cabazitaxel therapy for castration-resistant prostate cancer (CRPC) with G-CSF. We retrospectively studied 443 cycles of cabazitaxel therapy given to 56 patients with CRPC at Keio University Hospital between May 2012 and August 2018. Statistical analysis was conducted to determine whether the combination of prophylactic G-CSF and antibiotics was more effective in preventing FN, compared with prophylactic G-CSF alone. Prophylactic PEG-G-CSF or G-CSF was administered in all 443 cycles. Only fluoroquinolones were used as prophylactic antibiotics and were administered in 328 cycles (74.0%). FN occurred in 5 cycles (1.1%). Prophylactic antibiotics were administered in 327 cycles (74.6%) in the FN-negative group and in only 1 cycle (20.0%) in the FN-positive group. Chi-square test indicated the incidence of FN was significantly lower in the group that received prophylactic antibiotics compared with the group that did not receive prophylactic antibiotics (P = 0.017). Compared with prophylactic G-CSF alone, prophylactic G-CSF and antibiotics significantly suppressed the occurrence of FN.

Cabazitaxel versus abiraterone or enzalutamide in metastatic castration-resistant prostate cancer: post hoc analysis of the CARD study excluding chemohormonal therapy for castrate-naive disease

Background

In the CARD study (NCT02485691), cabazitaxel significantly improved clinical outcomes versus abiraterone or enzalutamide in patients with metastatic castration-resistant prostate cancer previously treated with docetaxel and the alternative androgen-signalling-targeted inhibitor. However, some patients received docetaxel or the prior alternative androgen-signalling-targeted inhibitor in the metastatic hormone-sensitive (mHSPC) setting. Therefore, the CARD results cannot be directly translated to a Japanese population.

Methods

Patients (N = 255) received cabazitaxel (25 mg/m² IV Q3W, prednisone, G-CSF) versus abiraterone (1000 mg PO, prednisone) or enzalutamide (160 mg PO) after prior docetaxel and progression ≤12 months on the alternative androgen-signalling-targeted inhibitor. Patients who received combination therapy for mHSPC were excluded (n = 33) as docetaxel is not approved in this setting in Japan.

Results

A total of 222 patients (median age 70 years) were included in this subanalysis. Median number of cycles was higher for cabazitaxel versus androgen-signalling-targeted inhibitors (7 versus 4). Clinical outcomes favoured cabazitaxel over abiraterone or enzalutamide including, radiographic progression-free survival (rPFS; median 8.2 versus 3.4 months; P < 0.0001), overall survival (OS; 13.9 versus 11.8 months; P = 0.0102), PFS (4.4 versus 2.7 months; P < 0.0001), confirmed prostate-specific antigen response (37.0 versus 14.4%; P = 0.0006) and objective tumour response (38.9 versus 11.4%; P = 0.0036). For cabazitaxel versus androgen-signalling-targeted inhibitor, grade ≥ 3 adverse events occurred in 55% versus 44% of patients, with adverse events leading to death on study in 2.7% versus 5.7%.

Conclusions

Cabazitaxel significantly improved outcomes including rPFS and OS versus abiraterone or enzalutamide and are reflective of the Japanese patient population. Cabazitaxel should be considered the preferred treatment option over abiraterone or enzalutamide in this setting.

Efficacy and safety of cabazitaxel therapy in elderly (≥75 years) patients with castration-resistant prostate cancer: A multiinstitutional study

Background

There is little data on the outcome of cabazitaxel (CBZ) treatment of elderly patients with castration-resistant prostate cancer (CRPC). This study assessed the efficacy and safety of CBZ chemotherapy in patients with CRPC aged 75 years or older in a multiinstitutional study.

Methods

We retrospectively reviewed the 74 patients with CRPC treated with CBZ enrolled in 10 institutions. Clinicopathological backgrounds, prognosis including prostate-specific antigen decline, time to treatment failure, progression-free survival, overall survival, and safety profiles were compared between younger (<75 years) and elder (≥75 years) patients.

Results

In total, 74 patients were enrolled; 50 patients were younger than 75 years and 24 were ≥75 years. Clinicopathological characteristics were comparable between younger and elder patients, with the exception of serum albumin values at the time of CBZ treatment. The median prostate-specific antigen decline in younger and elder men was −8.8% and −32.3% from baseline, respectively. The median time to treatment failure, progression-free survival, and overall survival for younger and elder men were 0.24 and 0.33 years, 0.23 and 0.43 years, and 0.69 and 1.17 years, respectively. In addition, safety profiles were comparable between younger and elder patients.

Conclusions

This multiinstitutional study suggests that patients with CRPC aged 75 years or older eligible for CBZ treatment can be treated safely and with noninferior efficacy compared with those younger than 75 years.