Prognostic and Predictive Role of SPOP Mutations in Prostate Cancer: A Systematic Review and Meta-analysis

CONTEXT

Mutations in the speckle-type POZ (SPOP) gene are frequently identified in prostate cancer (PC); yet, prognostic implications for affected patients remain unclear. Limited consensus exists regarding tailored treatments for SPOP-mutant (SPOPmut) PC.

OBJECTIVE

To elucidate the prognostic and predictive significance of SPOP mutations across distinct PC stages and treatments.

EVIDENCE ACQUISITION

A systematic literature search of PubMed, Embase, and Scopus was conducted up to January 29, 2024. The meta-analysis included studies comparing survival outcomes between SPOPmut and SPOP wild-type (SPOPwt) PC.

EVIDENCE SYNTHESIS

From 669 records, 26 studies (including five abstracts) were analyzed. A meta-analysis of metastasis-free survival in localized (hazard ratio [HR]: 0.72, 95% confidence interval [CI]: 0.59-0.88; p < 0.01) and overall survival (OS) in metastatic PC (HR: 0.64, 95% CI: 0.53-0.76; p < 0.01) showed a favorable prognosis for patients with SPOPmut PC. In metastatic settings, SPOP mutations correlated with improved progression-free survival (PFS) and OS in patients undergoing androgen deprivation therapy ± androgen receptor signaling inhibitor (HR: 0.51, 95% CI: 0.35-0.76, p < 0.01, and HR: 0.60, 95% CI:0.46-0.79, p < 0.01, respectively). In metastatic castration-resistant PC, only abiraterone provided improved PFS and OS to patients with SPOP mutations compared with patients with SPOPwt, but data were limited. SPOP mutations did not correlate with improved PFS (p = 0.80) or OS (p = 0.27) for docetaxel.

CONCLUSIONS

Patients with SPOPmut PC seem to exhibit superior oncological outcomes compared with patients with SPOPwt. Tailored risk stratification and treatment approaches should be explored in such patients.

PATIENT SUMMARY

Speckle-type POZ (SPOP) mutations could be a favorable prognostic factor in patients with prostate cancer (PC) and may also predict better progression-free and overall survival than treatment with hormonal agents. Therefore, less intensified treatments omitting chemotherapy for patients with SPOP-mutant PC should be explored in clinical trials.

The androgen receptor-targeted proteolysis targeting chimera and other alternative therapeutic choices in overcoming the resistance to androgen deprivation treatment in prostate cancer

Androgen receptor (AR) plays a vital role in prostate cancer (PCa), including castration-resistant PCa, by retaining AR signalling. Androgen deprivation treatment (ADT) has been the standard treatment in the past decades. A great number of AR antagonists initially had been found effective in tumour remission; however, most PCa relapsed that caused by pre-translational resistance such as AR mutations to turn antagonist into agonist, and AR variants to bypass the androgen binding. Recently, several alternative therapeutic choices have been proposed. Among them, proteolysis targeting chimera (PROTAC) acts different from traditional drugs that usually function as inhibitors or antagonists, and it degrades oncogenic protein and does not disrupt the transcription of an oncogene. This review first discussed some essential mechanisms of ADT resistance, and then introduced the application of AR-targeted PROTAC in PCa cells, as well as other AR-targeted therapeutic choices.

Role of radiotherapy for high risk localized prostate cancers

Management of high-risk prostate cancers is still a subject of debate, because of the lack of randomized trial comparing surgery and radiotherapy. If external beam radiotherapy is proposed, it must be associated with a long-term androgen deprivation therapy, at least 18-months. Irradiation of pelvic lymph nodes seems to improve distant metastasis-free survival and is so indicated in most of the cases. Moderate hypofractionation is not validated for pelvic lymph nodes irradiation. A combination of external beam radiotherapy and brachytherapy improved biochemical control in randomized trials without impact on survival. But this combination has been evaluated in large retrospective studies and seems to improve specific and overall survivals. An integrated boost on the MRI-defined index lesion is another way of dose escalation and improved also biochemical control. Stereotactic radiotherapy is not a validated option at this moment. For each patient, according to the extension of the disease, age, comorbidities and also his willingness, the best approach must be chosen, ideally in multidisciplinary meeting.

Can local treatment prolong the sensitivity of metastatic prostate cancer to androgen deprivation or even prevent castration resistance?

Purpose

A number of observational clinical studies suggest that prior primary tumor treatment favorably influences the course of metastatic prostate cancer (PCa), but its mechanisms of action are still speculative. Here, we describe the long-lasting sensitivity to various forms of androgen deprivation in patients after radical prostatectomy (RP) for locally advanced PCa as one potential mechanism.

Methods

A consecutive series of 115 radical prostatectomies after inductive therapy for T4 prostate cancer was re-analyzed, and long-term survival, as well as recurrence patterns and responses to different forms of hormonal manipulation, were assessed.

Results

The estimated biochemical response-free, PCa-specific, and overall survival rates after 200 months were 20%, 65%, and 47% with a median overall survival of 156 months. The majority of patients, although not cured of locally advanced PCa (84/115), showed long-term survival after RP. PCa-specific and overall survival rates of these 84 patients with biochemical recurrence were 61% and 44% at 150 months. Long-term sensitivity to ADT was found to be the main reason for the favorable tumor-specific survival in spite of biochemical recurrence.

Conclusions

Sensitivity to primary or secondary hormonal manipulation was the main reason for the long-term survival of patients who had not been cured by surgery only. The results suggest that treatment of the primary tumor-bearing prostate delays castration-resistant PCa and enhances the effect of hormonal therapies in a previously unknown manner. The underlying cellular and molecular mechanisms need to be explored in more detailed analyses, which could profoundly impact treatment concepts of locally advanced and metastatic PCa.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00345-020-03568-3.

The effect of androgen deprivation therapy on 68Ga-PSMA tracer uptake in non-metastatic prostate cancer patients

PURPOSE

To evaluate the effect of neoadjuvant androgen deprivation treatment (ADT) on prostate-specific membrane antigen (PSMA) tracer uptake demonstrated in ⁶⁸Ga-PSMA-positron emission tomography (PET/CT) in non-metastatic hormone-naïve prostate cancer (PC) patients.

MATERIALS AND METHODS

The clinical data of 108 PC patients who received neoadjuvant ADT were retrospectively analyzed. All patients had a baseline ⁶⁸Ga-PSMA-PET/CT scan, and a second scan was delivered median of 2.9 months after the initiation of ADT. The maximum standardized uptake value (SUV_max) of primary tumor (SUV_p) and metastatic lymph nodes (SUV_ln) as well as PSA response were assessed between pre- and post-ADT ⁶⁸Ga-PSMA-PET/CT scans.

RESULTS

There were significant decreases in posttreatment serum PSA, SUV_p, and SUV_ln. A decrease in SUV_p was seen in 91 patients (84%) with a median value of 66% (range, 5-100%), while 17 patients (16%) had no change in or an increase in PSMA tracer uptake with a median value of 24% (range, 0-198%). Patients with Gleason score (GS) of 7 had significantly higher metabolic response rates compared to other patients. The disease progression was significantly higher only in patients with GS > 7 disease compared to GS 7 disease. The PSA response to ADT was the lowest in patients with ISUP high-grade tumors. A total of 16 patients (15%) had progressive disease, and in 9 patients (8%), radiotherapy decisions were modified according to posttreatment ⁶⁸Ga-PSMA-PET/CT scans.

CONCLUSIONS

The current study includes the largest number of patients analyzed to date and demonstrates that ADT causes a significant decrease in serum PSA values and SUV_p and SUV_ln. The authors demonstrate that ⁶⁸Ga-PSMA-PET/CT may be used as a quantitative imaging modality after neoadjuvant ADT in hormone-naïve non-metastatic PC patients.

The effect of androgen deprivation treatment on subsequent risk of bladder cancer diagnosis in male patients treated for prostate cancer

INTRODUCTION

Bladder cancer (BCa) is three-to-four times more common in men than in women. To explain this gender gap, several theories have been proposed, including the impact of androgen hormones. The aim of this study was to investigate the differential impact of androgen deprivation therapy (ADT) on subsequent risk of developing BCa in men with prostate cancer (PCa).

METHODS

A total of 196,914 patients diagnosed with histologically confirmed localized PCa between 2000 and 2009 were identified in the SEER-Medicare insurance program-linked database. Competing-risk regression analyses were performed to assess the risk of developing BCa adjusting for the risk of all-cause mortality. Univariable and multivariable competing-risk regression analyses were performed to test the effect of ADT on BCa incidence for each PCa treatment modality.

RESULTS

Of the 196,914 individuals included in the study, 68,421 (34.7%) received ADT. Median (IQR) follow-up was 59 (29-95) months. Overall, a total of 2495 (1.3%) individuals developed BCa during follow-up. After stratification according to ADT, the 10-year cumulative incidence rate was 1.75% (95% CI 1.65-1.85). In the untreated group, the 10-year cumulative incidence rate was 1.99% (95% CI 1.83-2.15). In multivariable competing-risk regression, the use of ADT was not associated with BCa, after accounting for the risk of dying from any cause (p = 0.1).

CONCLUSION

We failed to identify any impact of ADT on the risk of developing a subsequent BCa even after stratifying according to the type of treatment. Further studies are required to explain the gender gap in BCa incidence and outcomes.

SEOM clinical guidelines for the treatment of metastatic prostate cancer (2017)

Androgen deprivation treatment was the only treatment available for metastatic prostate cancer until recently, with docetaxel as the only treatment with a proven survival benefit in castration-resistant prostate cancer (CRPC). Several drugs have been approved in the castration-resistant disease (sipuleucel-T, cabazitaxel, abiraterone, enzalutamide, radium-223). More recently, docetaxel and abiraterone have been moved to the hormone-sensitive disease setting, achieving better patient survival. The purpose of this article is to define the state of the art in the treatment of prostate carcinoma.

Clinical presentation and predictors of survival related to extent of bone metastasis in 900 prostate cancer patients

OBJECTIVE

The aim of this study was to investigate the impact of bone metastasis on survival and quality of life (QoL) in men with hormone-naïve prostate cancer.

MATERIALS AND METHODS

The study included 900 patients from a randomized trial (No. 5) by the Scandinavian Prostate Cancer Group, comparing parenteral oestrogen with total androgen blockade. Extent of bone metastasis was categorized according to a modified Soloway score: score 1, n = 319; score 2, n = 483; and score 3, n = 98 patients. The primary outcome measurements were mean differences in QoL and overall survival.

RESULTS

QoL rating scales showed a decrease with increasing extent of bone metastasis (p < 0.001). The mean global health status decreased from 64.4 to 50.5 for Soloway score 1 and 3, respectively. Following adjustment for performance status, analgesic consumption, grade of malignancy, alkaline phosphatase, prostate-specific antigen, haemoglobin and global health status, Soloway score 2 and 3 had a 47% [hazard ratio (HR) 1.47, 95% confidence interval (CI) 1.21-1.80] and 78% (HR 1.78 95%, CI 1.32-2.42) increased mortality, respectively, compared to Soloway score 1. Independent predictive factors of mortality were assessed.

CONCLUSIONS

Patient grouping based on three categories of extent of bone metastasis related to performance status, haemoglobin and global health status at presentation, as independent predictors of mortality, may provide improved accuracy of prognosis.

Predictors of early androgen deprivation treatment failure in prostate cancer with bone metastases

Approximately 15% of men with hormone naïve metastatic prostate cancer primarily fail to respond to androgen deprivation treatment (ADT). The reason why the response to ADT differs in this subgroup of men with prostate cancer remains unclear. The aim of this study was to describe the characteristics of these men and to thereby define predictors of early ADT failure in prostate cancer patients with bone metastases. The study was based on 915 men from the prospective randomized multicenter trial (no. 5) conducted by the Scandinavian Prostate Cancer Group comparing parenteral estrogen with total androgen blockade. Early ADT failure was defined as death from metastatic prostate cancer within 12 months after the start of ADT. Multivariate logistic regression models were applied to identify clinical predictors of early ADT failure. Ninety‐four (10.3%) men were primarily nonresponders to ADT. Independent predictors of early ADT failure were poor Eastern Cooperative Oncology Group performance status (PS), analgesic consumption, low hemoglobin, and high Soloway score (extent of disease observed on the scan), in where patients with poor PS and/or high analgesic consumption had a threefold risk of early ADT failure. Not significantly factors related to early ADT failure were age, treatment, cardiovascular comorbidity, T category, grade of malignancy, serum estrogen level, and SHBG at enrolment. We analyzed characteristics of a subgroup of patients who primarily failed to respond to ADT. Four independent clinical predictors of early ADT failure could be defined, and men exhibiting these features should be considered for an alternative treatment.