A phase II study investigating the re-induction of endocrine sensitivity following chemotherapy in androgen-independent prostate cancer

The Use of Transdermal Estrogen in Castrate-resistant, Steroid-refractory Prostate Cancer

BACKGROUND

Androgen-deprivation therapy is the mainstay of treatment for metastatic prostate cancer. Corticosteroids and estrogens are also useful agents in castration-resistant prostate cancer (CRPC). However, oral estrogens are associated with thromboembolic events, which limits their use, and transdermal estrogens may offer a safer alternative. This study was carried out to determine the safety and effectiveness of transdermal estrogens in CRPC.

PATIENTS AND METHODS

Forty-one patients with CRPC and steroid-resistant prostate cancer were eligible for this dose-escalation study of transdermal estradiol. A starting dose of 50 mcg/24 hours was applied and increased if prostate-specific antigen (PSA) rose > 5 ng/mL in steps to 300 mcg/24 hours. The primary endpoint was PSA response, and secondary outcomes included incidence of thromboembolic events and progression-free survival. Patients who progressed were offered diethylstilbestrol.

RESULTS

Five (13%) of 40 patients had > 50% PSA reduction for at least 1 month at any transdermal estradiol dose. No venous-thromboembolic events were observed, and responses plateaued at 200 mcg/24 hours. A correlation between PSA response and rising sex hormone binding globulin was seen. Fifty percent of patients subsequently responded to low-dose diethylstilbestrol.

CONCLUSION

Transdermal estradiol appears to be a low toxicity treatment option to control CRPC after failure of steroid therapy. Modulation of sex hormone binding globulin by transdermal estradiol may be one mechanism of action of estrogens on CRPC. Oral estrogens remain effective after the use of transdermal estradiol.

Importance of androgen-deprivation therapy during enzalutamide treatment in men with metastatic castration-resistant prostate cancer following chemotherapy: results from retrospective, multicenter data

BACKGROUND

Enzalutamide can significantly prolong the survival of patients with metastatic castration-resistant prostate cancer (mCRPC). However, there is a paucity of evidence on continuing androgen-deprivation therapy (ADT) for mCRPC. Here, we analyzed the effect of concomitant ADT during enzalutamide treatment in men with mCRPC following chemotherapy.

METHODS

We retrospectively reviewed the medical records of 232 patients with mCRPC who received oral enzalutamide (160 mg per day) following chemotherapy at 9 tertiary centers in Korea between 2014 and 2016. The primary endpoint was overall survival, while secondary endpoints included time to prostate-specific antigen (PSA) progression and radiographic progression-free survival.

RESULTS

The median age of the patients was 71 years (interquartile range, 64-75 years). The proportion of patients in a grade group ≥4 was 77.6%. The rate of concomitant ADT was 29.3%, and the all-cause mortality rate was 27.1% (n = 63). Median overall survival, time to PSA progression, and radiographic progression-free survival were 24.0, 8.0, and 10.0 months, respectively. Notably, concomitant ADT showed a significant association with longer overall survival (median duration not reached vs. 18.2 months; p = 0.008). After adjusting for confounding factors, concomitant ADT was still associated with longer overall survival (hazard ratio, 0.35; 95% confidence interval, 0.17-0.72).

CONCLUSION

Concomitant ADT during enzalutamide treatment may improve the survival of patients with mCRPC following chemotherapy.

Androgen deprivation therapy in castrate-resistant prostate cancer: how important is GnRH agonist backbone therapy?

BACKGROUND

A growing number of treatment options exist to treat metastatic castrate-resistant prostate cancer (mCRPC), and with these newer options, many questions about optimising treatment remain unanswered. One recommendation that may potentially be overlooked by practitioners is that androgen deprivation therapy (ADT) should be maintained when CRPC develops and when treatment with any of the newer agents is initiated.

AIM

However, to emphasise this recommendation, it is valuable to interrogate the evidence for maintaining ADT in different clinical situations.

OUTCOME

This statement, reflecting the views of the authors, provides a discussion of this evidence and the rationale behind the recommendation that ADT should be continued in CRPC.

Diethylstilboestrol for the treatment of prostate cancer: past, present and future

The aim of this review was to discuss the most recent data from current trials of diethylstilboestrol (DES) to identify its present role in advanced prostate cancer treatment as new hormonal therapies emerge. The most relevant clinical studies using DES in castration-refractory prostate cancer (CRPC) were identified from the literature. The safety, efficacy, outcomes and mechanisms of action are summarized. In the age of chemotherapy this review highlights the efficacy of oestrogen therapy in CRPC. The optimal point in the therapeutic pathway at which DES should be prescribed remains to be established.

Drug rechallenge and treatment beyond progression--implications for drug resistance

The established dogma in oncology for managing recurrent or refractory disease dictates that therapy is changed at disease progression, because the cancer is assumed to have become drug-resistant. Drug resistance, whether pre-existing or acquired, is largely thought to be a stable and heritable process; thus, reuse of therapeutic agents that have failed is generally contraindicated. Over the past few decades, clinical evidence has suggested a role for unstable, non-heritable mechanisms of acquired drug resistance pertaining to chemotherapy and targeted agents. There are many examples of circumstances where patients respond to reintroduction of the same therapy (drug rechallenge) after a drug holiday following disease relapse or progression during therapy. Additional, albeit limited, evidence suggests that, in certain circumstances, continuing a therapy beyond disease progression can also have antitumour activity. In this Review, we describe the anticancer agents used in these treatment strategies and discuss the potential mechanisms explaining the apparent tumour re-sensitization with reintroduced or continued therapy. The extensive number of malignancies and drugs that challenge the custom of permanently switching to different drugs at each line of therapy warrants a more in-depth examination of the definitions of disease progression and drug resistance and the resulting implications for patient care.

Drug rechallenge and treatment beyond progression--implications for drug resistance

The established dogma in oncology for managing recurrent or refractory disease dictates that therapy is changed at disease progression, because the cancer is assumed to have become drug-resistant. Drug resistance, whether pre-existing or acquired, is largely thought to be a stable and heritable process; thus, reuse of therapeutic agents that have failed is generally contraindicated. Over the past few decades, clinical evidence has suggested a role for unstable, non-heritable mechanisms of acquired drug resistance pertaining to chemotherapy and targeted agents. There are many examples of circumstances where patients respond to reintroduction of the same therapy (drug rechallenge) after a drug holiday following disease relapse or progression during therapy. Additional, albeit limited, evidence suggests that, in certain circumstances, continuing a therapy beyond disease progression can also have antitumour activity. In this Review, we describe the anticancer agents used in these treatment strategies and discuss the potential mechanisms explaining the apparent tumour re-sensitization with reintroduced or continued therapy. The extensive number of malignancies and drugs that challenge the custom of permanently switching to different drugs at each line of therapy warrants a more in-depth examination of the definitions of disease progression and drug resistance and the resulting implications for patient care.

Does androgen-ablation therapy (AAT) associated autophagy have a pro-survival effect in LNCaP human prostate cancer cells?

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Androgen-ablation therapy (AAT) and chemotherapy are commonly used to treat incurable prostate cancer. To improve outcome, there is major on-going research to develop more effective treatments with less toxicity. Autophagy has been suggested from previous studies to play a potential role in cell survival and may be associated with resistance to chemotherapy. Autophagy is known to be upregulated by nutrient starvation or AAT in prostate cancer. However, its functional impact is not fully known. The present study describes the potential synergism between the blockade of autophagy and AAT alone or AAT combined with taxane chemotherapy. Hence, future combined treatment options are warranted to further investigate the clinical impact of autophagy suppression as a treatment strategy.

OBJECTIVE

To study the cellular effects of the anti-androgen bicalutamide on autophagy and its potential impact on response to androgen-ablation therapy (AAT) alone or combined with docetaxel chemotherapy in human prostate cancer LNCaP cells.

MATERIALS AND METHODS

LNCaP cells were treated with bicalutamide ± docetaxel, and cellular effects were assayed: lipidated LC3 (a microtubule-associated protein) for autophagy and its trafficking to fuse with lysosome; flow cytometry using propidium iodide or caspase 3 for cell death; and sulforhodamine B assay for cell growth.

RESULTS

Bicalutamide treatment enhanced autophagy in LNCaP cells with increased level of autophagosome coupled with an altered cellular morphology reminiscent of neuroendocrine differentiation. Consistent with the literature on the interaction between androgen receptor activation and taxane chemotherapy, bicalutamide diminished docetaxel mediated cytotoxicity. Significantly, pharmacological inhibition of autophagy with 3-methyladenine significantly enhanced the efficacy cell kill mediated by AAT ± docetaxel.

CONCLUSION

Autophagy associated with bicalutamide treatment in LNCaP cells may have a pro-survival effect and strategy to modulate autophagy may have a potential therapeutic value.

Whole blood stem cell reinfusion and escalated dose melphalan in castration-resistant prostate cancer: a phase 1 study

PURPOSE

Nontaxane-based chemotherapeutic options in castrate-resistant prostate cancer (CRPC) are limited despite the long natural history of the disease. We carried out a phase 1 dose-escalation study of the alkylating agent melphalan with autologous stem cell transplantation, comparing rapid changes in circulating tumor cells (CTC) and prostate-specific antigen (PSA) as a measure of response.

EXPERIMENTAL DESIGN

Cohorts of individuals with advanced CRPC received high-dose intravenous melphalan, and autologous blood was returned to patients during treatment. The efficacy endpoints were the PSA reduction rate, CTC response, survival parameters, toxicity and whether reinduction of endocrine sensitivity occurred.

RESULTS

Twenty-four patients were recruited. Dose escalation was feasible with the highest dose cohort being reached. Of 23 individuals evaluable for response, 16 had a PSA response of more than 30%; of 11 patients with soft tissue disease, 4 achieved a partial response and 7 had stable disease. Patients with CTC counts that decreased to less than 5 within 2 weeks from the start of therapy had a longer overall survival (30.6 months vs. 15.3 months, P = 0.03) Treatment was associated with myelosuppression and frequent hospitalizations. In 20 patients after the study, hormone therapy was reintroduced when PSA increased again; response rates were high.

CONCLUSIONS

Autologous transplantation following high-dose alkylating agent chemotherapy induces responses but proved toxic, although dose escalation proved possible. The possibility of using CTCs to identify responders at two weeks may be used to justify such an intensive approach. Many individuals went on to further respond to both docetaxel and hormonal therapy.

Role of androgen deprivation treatment in patients with castration-resistant prostate cancer, receiving docetaxel-based chemotherapy

OBJECTIVES

To assess the impact of continued androgen deprivation therapy (ADT) in patients with castration-resistant prostate cancer (CRPC) receiving first-line docetaxel-based chemotherapy.

METHODS

A retrospective review was performed on 78 patients fulfilling the criteria for CRPC who were treated with docetaxel-based chemotherapy over 5 years.

RESULTS

Thirty-nine patients received concurrent ADT (ADT group), whereas 39 patients discontinued ADT (No-ADT group). PSA response rates were 66.7% for ADT patients and 48.7% for No-ADT patients (P = 0.27). The median progression-free survival and overall survival were 5.0 months and 24.8 months for ADT patients and 4.9 months and 22.1 months for No-ADT patients, respectively (P = 0.57, P = 0.94). Follow-up testosterone levels were available in 13 patients of the No-ADT group and none of them recovered a normal serum testosterone level over a median follow-up duration of 8.3 months from ADT discontinuation. ADT was recommenced in 21 of 39 patients in the No-ADT group and, of these, 6 (29%) achieved a PSA response.

CONCLUSION

Clinical outcomes were not significantly different when patients with CRPC received concurrent ADT, or were not so treated, when receiving first-line docetaxel-based chemotherapy. Despite ADT withdrawal, serum testosterone level did not recover to the noncastrated level during the period of chemotherapy, and reinduction of hormone sensitivity occurred in about one-quarter of patients.

Second-line chemotherapy in metastatic docetaxel-resistant prostate cancer: a review

The results of cytotoxic therapy in the second-line setting of metastatic castration-resistant prostate cancer have demonstrated that disease is poorly controlled after taxane resistance with a time to progression of 3 months or less. Many trials of second-line chemotherapy have been disappointing. However, most of patients with docetaxel-pretreated castration-resistant disease receive a second-line chemotherapy. Molecular mechanism of castration resistance and docetaxel resistance is resumed, and clinical trials of second-line chemotherapy after docetaxel progression are reviewed. Reintroduction of docetaxel after a drug-free interval is an active treatment in docetaxel-pretreated patients, and only recently a prospective study documented a survival benefit of 2.4 months after second-line taxane-based chemotherapy of metastatic docetaxel-resistant prostate cancer. Although a second-line chemotherapy with a taxane could improve overall survival, a change of biology of castration-resistant prostate cancer after docetaxel is suggested, as inferred by the renewed hormonal sensitivity, whose role on survival remains unknown, and from the activity of antiangiogenic drugs.

A multi-centre randomised phase III trial of Dexamethasone vs Dexamethasone and diethylstilbestrol in castration-resistant prostate cancer: immediate vs deferred Diethylstilbestrol

Background:

The role of further hormone therapy in castration-resistant prostate cancer (CRPC) remains unclear. We performed a multi-centre randomised phase III study comparing the use of Dexamethasone, Aspirin, and immediate addition of Diethylstilbestrol (DAiS) vs Dexamethasone, Aspirin, and deferred (until disease progression) addition of Diethylstilbestrol (DAdS).

Methods:

From 2001 to 2008, 270 men with chemotherapy-naive CRPC were randomly assigned, in a 1 : 1 ratio, to receive either DAiS or DAdS. They were stratified for performance status, presence of bone metastases, and previous normalisation of prostate-specific antigen (PSA) to androgen deprivation. The study end points were the proportion of patients achieving a 50% PSA response, progression-free survival (PFS), overall survival, and quality of life. Intention-to-treat analysis was carried out. The effect of treatment was studied first by Kaplan–Meier curves and log-rank test, and finally through multivariable stratified Cox's proportional hazards model adjusting for the effects of possible baseline prognostic factors. Quality of life was analysed using multivariate analysis of variance.

Results:

At study entry, the median age was 76 years (inter-quartile range: 70–80 years), the median PSA was 79 ng ml⁻¹, and 76% of the cohort had metastatic disease. The response rates for DAiS (68%) and DAdS (64%) were not significantly different (P=0.49). Similar to the response rate, neither the PFS (median=8.1 months for both arms) nor the overall survival (19.4 vs 18.8 months) differed significantly between the DAiS and DAdS groups (P>0.20). However, the response rate for the DAiS (68%) was significantly higher than the response rate of DA (before adding Diethylstilbestrol) (50%) (P=0.002). Similarly, the median time to progression for DAiS (8.6 months) was significantly longer than that of DA (4.5 months) (P<0.001). Multivariable analysis showed that patients with previous haemoglobin ⩾11 g dl⁻¹ decreased the risk of death significantly (hazard ratio: 0.44, 95% CI: 0.25–0.77). Patients treated with previous anti-androgens alone had more than 5 times more risk of death compared with patients treated with gonadorelin analogues throughout their castration-sensitive phase. Treatment sequencing did not affect the quality of life but pre-treatment performance status did. The incidence of veno–thromboembolic events was 22% (n=28) in DAiS and 11% (n=14) in the DA arm (P=0.02). Painful gynaecomastia occurred in only 1% on DA, whereas in 40% on DAiS (P=0.001).

Conclusion:

Dexamethasone and immediate Diethylstilbestrol resulted in neither higher PSA response rate nor higher PFS compared with Dexamethasone with deferred Diethylstilbestrol. There was no suggestion of significantly improved overall survival or quality of life. Given the significantly higher toxicity of Diethylstilbestrol, deferring Diethylstilbestrol until failure of Dexamethasone is the preferred strategy when using these agents in CRPC.

Leptomeningeal metastases from prostate cancer: an emerging clinical conundrum

Leptomeningeal metastases from solid tumors are relatively uncommon events with dismal prognosis. They can be seen mainly in patients with breast and lung cancer, and malignant melanoma, but have also been described in a variety of other tumor types. Leptomeningeal carcinomatosis from prostate cancer is an extremely rare complication, but as patients' survival is prolonged due to more effective treatments, it is expected that more patients will present with leptomeningeal involvement in advanced stages of the disease. In these cases high levels of prostate-specific antigen can be found in the cerebrospinal fluid. This comprehensive review presents the recent findings from the literature.

[Physiopathological mechanism of hot flushes-perspiration induced by androgen deprivation in prostate carcinoma]

Hot flushes and perspiration are common problems during androgen deprivation therapy for prostate carcinoma, and largely contribute to worsen patient quality of life. Different hypotheses have been proposed to explain the underlying physiopathological mechanisms, though all are very complex, basically because of the multiple causal factors involved. The present review offers a pondered and updated perspective of the origin of hot flushes-perspiration in such patients. Negative feedback of the plasma sexual hormones upon the hypothalamic secretion of noradrenalin and serotonin appears to be the main cause. Likewise, the direct action of such mechanisms upon the LH-RH producing hypothalamic center located close to the thermoregulatory center, together with shortening of the thermoneutral interval, would also play a role. Improved understanding of the causal mechanism may help improve the treatment of such symptoms.