Chemotherapy for metastatic castration-sensitive prostate cancer

Real-world clinical outcomes among patients with metastatic castration-sensitive prostate cancer initiating apalutamide

Aim: To describe overall survival, time to castration resistance and castration resistance-free survival in patients with metastatic castration-sensitive prostate cancer (mCSPC) initiating apalutamide in a US oncology network.Patients & methods: Patients with mCSPC initiating apalutamide on or after 17 September 2019 from an electronic health record-derived deidentified database were included. Patients were followed from apalutamide initiation and were censored at the earlier of end of clinical activity or data availability (31 October 2022).Results: At 12 and 24 months, overall survival rates were 91.0 and 88.3%, rates of castration sensitivity were 85.7 and 72.1%, and castration resistance-free survival rates were 80.2 and 65.9%, respectively.Conclusion: Real-world clinical outcomes of patients with mCSPC treated with apalutamide were comparable to results from the phase III TITAN trial.

Pharmaceutical industry funding and chemotherapy trials for prostate cancer: A systematic review

INTRODUCTION

Clinical trials are increasingly supported by industries while previous studies have shown that industry-supported studies have more favorable results than studies with other sources of funding. In the present study, we investigated the association of industrial funding on the results of clinical trials regarding chemotherapy in prostate cancer.

METHODS

A systematic literature search was performed in the Cochrane Library, MEDLINE, and EMBASE to identify clinical trials comparing chemotherapy with treatments such as hormone therapy, surgery, radiotherapy, and placebo in patients with metastatic or non-metastatic prostate cancer. Data were extracted by two reviewers on the financial resources and the positive or negative results of chemotherapy in each study. The quality of articles was evaluated and compared based on Cochrane Critical Appraisal Tool. The trials were divided into two groups; industry funded and those not funded by industry. Association of industry funding and positive outcome was presented as odds ratio.

RESULTS

In this study, out of the 91 studies, 80.2% were funded by pharmaceutical companies and 19.8% were funded by government agencies. The end result of 61.6% of the studies funded by pharmaceutical companies was an increase in survival due to chemotherapy, whereas only 27.8% of the studies sponsored by government agencies reported positive results (P-value=0.010). In fact, industry-funded trials more often presented statistically significant positive results for survival (OR: 4.17; CI, 1.34-12.99). In general, there was no significant difference in the degree of bias between the two groups.

CONCLUSION

According to this study, despite of the similar quality of studies funded by pharmaceutical companies and government agencies, positive results were more common in studies related to pharmaceutical companies. Therefore, this point should be taken into account when making a decision on the best treatment approach.

Clinical proteomics for prostate cancer: understanding prostate cancer pathology and protein biomarkers for improved disease management

Following the introduction of routine Prostate Specific Antigen (PSA) screening in the early 1990's, Prostate Cancer (PCa) is often detected at an early stage. There are also a growing number of treatment options available and so the associated mortality rate is generally low. However, PCa is an extremely complex and heterogenous disease and many patients suffer disease recurrence following initial therapy. Disease recurrence commonly results in metastasis and metastatic PCa has an average survival rate of just 3-5 years. A significant problem in the clinical management of PCa is being able to differentiate between patients who will respond to standard therapies and those who may benefit from more aggressive intervention at an earlier stage. It is also acknowledged that for many men the disease is not life threatenting. Hence, there is a growing desire to identify patients who can be spared the significant side effects associated with PCa treatment until such time (if ever) their disease progresses to the point where treatment is required. To these important clinical needs, current biomarkers and clinical methods for patient stratification and personlised treatment are insufficient. This review provides a comprehensive overview of the complexities of PCa pathology and disease management. In this context it is possible to review current biomarkers and proteomic technologies that will support development of biomarker-driven decision tools to meet current important clinical needs. With such an in-depth understanding of disease pathology, the development of novel clinical biomarkers can proceed in an efficient and effective manner, such that they have a better chance of improving patient outcomes.

Clinical Characterization of Low Prostate-specific Antigen on Prognosis in Patients With Metastatic Castration-naive Prostate Cancer

INTRODUCTION

This study aimed to investigate the effect of low prostate-specific antigen (PSA) on prognosis, as the association of initial PSA level with prognosis in patients with metastatic castration-naive prostate cancer (mCNPC) remains unclear.

PATIENTS AND METHODS

We evaluated 575 patients with mCNPC from 10 hospitals. Patients were stratified into 2 groups according to their initial PSA: PSA < 100 and PSA ≥ 100 groups. We compared castration-resistant prostate cancer (CRPC)-free survival, overall survival (OS), and OS from the CRPC diagnosis between the groups. Multivariate Cox regression analysis was performed to evaluate the effect of initial PSA level on prognosis.

RESULTS

Of the 575 patients, 196 (34%) patients belonged to the PSA < 100 group. No significant difference was found in patients' backgrounds except for PSA, the extent of disease, and high tumor burden between the groups. CRPC-free survival was significantly shorter in the PSA ≥ 100 group than in the PSA < 100 group. However, the OS after CRPC diagnosis was significantly shorter in the PSA < 100 group than that of the PSA ≥ 100 group. Multivariate analyses showed that PSA < 100 ng/mL was an independent factor for OS after CRPC, whereas no significant association was observed in the CRPC-free survival and OS.

CONCLUSIONS

A significant effect of initial PSA < 100 ng/mL on OS after CRPC was observed. PSA < 100 ng/mL might be a poor prognostic factor in patients with mCNPC after CRPC.

Management algorithms for metastatic prostate cancer

INTRODUCTION

Prostate cancer poses a significant lifetime risk to Canadian men. Treatment for metastatic prostatic cancer (mPCa) is an area of ongoing research with a lack of up-to-date clinical guidance. The multidisciplinary Canadian Genitourinary Research Consortium (GURC) determined that additional guidance focusing on management of mPCa was warranted.

METHODS

The most up-to-date guidelines, consensus statements, and emerging phase 3 trials were identified and used to inform development of algorithms by a multidisciplinary genitourinary oncology panel outlining recommendations for the management of mPCa.

RESULTS

A single pan-Canadian guideline and five national and international guidelines or consensus statements published since 2015 were identified, along with two new phase 3 trials and one additional randomized comparison. Iterative GURC discussions led to the development of two mPCa algorithms: the first addressing management of newly diagnosed metastatic castration-sensitive prostate cancer (mCSPC) patients and the second addressing treatment of patients with metastatic castration-resistant prostate cancer (mCRPC). For newly diagnosed mCSPC patients with high-volume/high-risk disease, either docetaxel or abiraterone acetate and prednisone (AAP) added to androgen-deprivation therapy (ADT) is recommended. The addition of radiotherapy to ADT is suggested for those with low-volume disease and/or AAP to ADT for low-volume or low-risk disease. For first-line mCRPC, androgen receptor-axis-targeted (ARAT) therapy is recommended for most patients, while sequencing with docetaxel, radium-223, ARAT therapy, and/or cabazitaxel is recommended for later lines of therapy.

CONCLUSIONS

Two treatment algorithms were developed for the management of mPC and can be used by multidisciplinary specialist teams to guide treatment.

Impact of nadir PSA level and time to nadir during initial androgen deprivation therapy on prognosis in patients with metastatic castration-resistant prostate cancer

PURPOSE

We determine whether the nadir prostate-specific antigen level (PSA nadir) and time to nadir (TTN) during initial androgen deprivation therapy (ADT) are prognostic factors in metastatic castration-resistant prostate cancer (mCRPC) patients.

METHODS

We reviewed the Michinoku Japan Urological Cancer Study Group database, including 321 mCRPC patients. Optimal cutoff values for PSA nadir and TTN on survival were calculated with the receiver operating characteristic (ROC) curve. Patients were stratified into unfavorable (higher PSA nadir and/or shorter TTN) and favorable (lower PSA nadir and longer TTN) groups. The inversed probability of treatment weighing (IPTW)-adjusted Cox proportional hazard model was performed to evaluate the impact of the unfavorable group on overall survival (OS) after CRPC diagnosis.

RESULTS

Median age and follow-up period were 71 years and 35 months, respectively. ROC curve analysis demonstrated cutoffs of PSA nadir > 0.64 ng/mL and TTN < 7 months. The unfavorable group included 248 patients who had significantly shorter OS after mCRPC. The IPTW-adjusted multivariate model revealed that the unfavorable group had a negative impact on OS in mCRPC patients [hazards ratio (HR) 2.98, P < 0.001].

CONCLUSIONS

Higher PSA nadir and shorter TTN during the initial ADT are poor prognostic factors in patients with mCRPC.

Does docetaxel prolong survival of patients with non-metastatic castration-resistant prostate cancer?

BACKGROUND

Guidelines define docetaxel as a first-line therapeutic option for metastatic castration-resistant prostate cancer (mCRPC). However, the role of docetaxel in non-metastatic castration-resistant prostate cancer (nmCRPC) has not been fully investigated. The aim of this retrospective study was to evaluate the potential role of docetaxel in nmCRPC. Clinical outcomes including overall survival were compared between CRPC patients who had docetaxel introduced while in nonmetastatic versus metastatic diseases.

METHODS

A total of 98 CRPC patients had docetaxel therapy. Of these 46 patients received docetaxel for nmCRPC, and 52 had distant metastases. Clinical outcomes from the time of diagnosis of CRPC were compared retrospectively between groups.

RESULTS

The median observation period after the diagnosis of CRPC in these patients was 42 months (range, 3-166). Overall survival (OS) was significantly longer in the nmCRPC group than in the mCRPC group (not reached vs 52.2 months, respectively, P = 0.006). Multivariate analysis showed that longer time to CRPC, docetaxel use in nmCRPC, and use of abiraterone acetate and/or enzalutamide were significant predictors for improved OS (P = 0.04, 0.019 and 0.002, respectively). The incidence and profile of adverse events did not differ significantly between groups.

CONCLUSIONS

Earlier induction of docetaxel in nmCRPC patients may prolong OS. Further prospective studies in more patients will be required to confirm our findings.

No significant impact of response to prior androgen receptor-axis-targeted agents on the efficacy of subsequent docetaxel in patients with metastatic castration-resistant prostate cancer

BACKGROUND

To investigate whether the response to an androgen receptor-axis-targeted (ARAT) agent is associated with the efficacy of subsequent docetaxel in metastatic castration-resistant prostate cancer (mCRPC) patients.

METHODS

This study included 114 consecutive mCRPC patients, comprising 54 and 60 patients who progressed with abiraterone acetate (AA) and enzalutamide (Enz), respectively, before the introduction of docetaxel. The impact of the response to either ARAT agent on the activity of docetaxel was assessed.

RESULTS

Following ARAT therapy, a prostate-specific antigen (PSA) response was observed in 73 of the 114 patients, of whom 33 and 40 received AA and Enz, respectively. In the 114 patients, PSA response to docetaxel was achieved in 48 (42.1%) patients, and median PSA progression-free survival (PFS) and overall survival (OS) with docetaxel were 7.2 and 17.5 months, respectively. No significant difference was noted in PSA response rate, PSA PFS or OS with docetaxel between responders and non-responders to a prior ARAT agent in the overall 114 patients, 54 receiving AA and 60 receiving Enz. Despite the absence of a significant impact of the response to a prior ARAT agent on PSA PFS or OS by univariate analysis, independent prognostic predictors were identified by multivariate analysis, as performance status (PS) for PSA PFS, and PS and visceral metastasis for OS.

CONCLUSIONS

Disease control by docetaxel may not be affected by the response to a prior ARAT agent. Therefore, a prior response to an ARAT agent should not influence the decision on the subsequent introduction of docetaxel for mCRPC patients.

Impact of prior androgen receptor-axis-targeted agents on the clinical activity of subsequent docetaxel in patients with metastatic castration-resistant prostate cancer: comparative assessment between abiraterone acetate and enzalutamide

The objective of this study was to investigate the impact of prior treatment with androgen receptor-axis-targeted (ARAT) agents, abiraterone acetate (AA) and enzalutamide (Enz), on the activity of subsequently introduced docetaxel in patients with metastatic castration-resistant prostate cancer (mCRPC). This study included a total of 114 mCRPC patients consisting of 54 and 60 who progressed following treatment with AA and Enz, respectively, prior to the introduction of docetaxel, and compared oncological outcomes with docetaxel between these two groups. There were no significant differences in the major clinicopathological characteristics before treatment with docetaxel between the AA and Enz groups. The prostate-specific antigen (PSA) response rates to docetaxel in the AA and Enz groups were 40.7 and 43.3%, respectively, with no significant differences in the rates between these two groups. Following the introduction of docetaxel, the median PSA progression-free survival (PFS) and overall survival (OS) in the 114 patients were 7.2 and 17.5 months, respectively. There was no significant difference in the PSA PFS or OS between the AA and Enz groups. Despite the lack of a significant impact of the type of ARAT agent on PSA PFS or OS by univariate analysis, multivariate analyses identified the following independent prognostic predictors: performance status (PS) for PSA PFS and PS and visceral metastasis for OS. Collectively, these findings suggest that the type of ARAT agent may not have a significant impact on disease control by subsequent docetaxel therapy in mCRPC patients.

Phase I/II clinical trial to assess safety and efficacy of intratumoral and subcutaneous injection of HVJ-E in castration-resistant prostate cancer patients

Inactivated Sendai virus particles (hemagglutinating virus of Japan envelope (HVJ-E)) have a novel antitumor effect: HVJ-E fused to prostate cancer cells via cell surface receptor causes apoptosis of prostate cancer cells in vitro and in vivo. HVJ-E also induces antitumor immunity by activating natural killer (NK) cells and cytotoxic T cells and suppressing regulatory T cells in vivo. We conducted an open-label, single-arm, phase I/II clinical trial in patients with castration-resistant prostate cancer (CRPC) to determine the safety and efficacy of intratumoral and subcutaneous injection of HVJ-E. Patients with CRPC who were docetaxel-resistant or could not receive docetaxel treatment were eligible. HVJ-E was injected directly into the prostate on day 1 and subcutaneously on days 5, 8 and 12 in two 28-day treatment cycles using a 3+3 dose-escalation design. The primary end points were to evaluate safety and tolerability of HVJ-E. The secondary end points were to analyze tumor immunity and antitumor effect. The study is registered at UMIN Clinical Trials Registry, number UMIN000006142. Seven patients were enrolled, and six patients received HVJ-E. Grade 2 or 3 adverse events (Common Terminology Criteria for Adverse Events Ver. 4.0) were urinary retention and lymphopenia from which the patients recovered spontaneously. No Grade 4 adverse events were observed. Radiographically, three patients had stable disease in the low-dose group, and one patient had stable disease and two had progressive disease in the high-dose group. The prostate-specific antigen (PSA) declined from 14 to 1.9 ng ml^-1 in one patient in the low-dose group after two cycles of HVJ-E treatment, and the PSA response rate was 16.6%. NK cell activity was elevated from day 12 to day 28 after HVJ-E administration, whereas serum interleukin-6, interferon (IFN)-α, IFN-β and IFN-γ levels were not affected by HVJ-E treatment. Intratumoral and subcutaneous injections of HVJ-E are feasible and PSA response was observed in a subgroup of CRPC patients.

Comparative Assessment of Efficacies Between 2 Alternative Therapeutic Sequences With Novel Androgen Receptor-Axis-Targeted Agents in Patients With Chemotherapy-Naïve Metastatic Castration-Resistant Prostate Cancer

BACKGROUND

The objective of this study was to compare the efficacies of sequential therapies with novel androgen receptor-axis-targeted (ARAT) agents in patients with docetaxel-naïve metastatic castration-resistant prostate cancer (mCRPC).

PATIENTS AND METHODS

This study included 108 consecutive patients with mCRPC who sequentially received abiraterone acetate (AA) and enzalutamide (Enz), in either order, without prior treatment with docetaxel. The combined prostate-specific antigen (PSA) progression-free survival (PFS) was defined as the sum of PFS1 and PFS2, representing PSA PFSs on the first and second ARAT agents, respectively.

RESULTS

Of these patients, 49 and 59 received ARAT therapy with the AA-to-Enz sequence (AA-to-Enz group) and with the reverse sequence (Enz-to-AA group), respectively. No significant differences in the baseline characteristics were noted between the 2 groups. In the overall patient population, the PSA response rate to the second-line ARAT agent (21.3%) was significantly lower than that of the first-line ARAT agent (58.3%). The combined PSA PFS in the AA-to-Enz group (median, 18.4 months) was significantly superior to that of the Enz-to-AA group (median, 12.8 months). Furthermore, multivariate analysis identified the treatment sequence (ie, AA-to-Enz vs. Enz-to-AA group) in addition to performance status as an independent predictor of combined PSA PFS in these patients. However, there was no significant difference in overall survival (OS) between the 2 groups.

CONCLUSIONS

Although cross-resistance between ARAT agents is a common phenomenon in docetaxel-naïve patients with mCRPC, different efficacies were observed favoring the AA-to-Enz rather than Enz-to-AA sequence in this series with respect to combined PSA PFS but not OS.