Clinical perspectives from ongoing trials in oligometastatic or oligorecurrent prostate cancer: an analysis of clinical trials registries

A Phase II Trial of Stereotactic Body Radiation Therapy and Androgen Deprivation for Oligometastases in Prostate Cancer (SBRT-SG 05)

PURPOSE

SBRT-Spanish Group-05 (ClinicalTrials.gov.Identifier: NCT02192788) is a collaborative (SBRT-SG, Grupo de Investigación Clínica en Oncología Radioterápica, and Sociedad Española de Oncología Radioterápica) prospective multicenter phase II trial testing stereotactic body radiation therapy (SBRT) and androgen deprivation therapy (ADT) in patients with oligorecurrent prostate cancer.

METHODS AND MATERIALS

Two cohorts of patients with prostate cancer in an oligorecurrent stage (hormone-sensitive in the principal cohort and castration-resistant in the exploratory cohort) were assigned to receive ADT and SBRT for at least 24 months from the time of the enrollment. Concomitant treatment with chemotherapy, abiraterone, or enzalutamide was not allowed. Oncologic outcomes were assessed in both cohorts. Toxicity was prospectively analyzed.

RESULTS

From 2014 to 2019, 81 patients with a total of 126 lesions from 14 centers met the inclusion criteria, 14 of whom were castration-resistant. With a median follow-up of 40 months (12-58 months), 3-year local recurrence-free survival was 92.5% (95% CI, 79.9%-96.3%) and 85.7% (95% CI, 48.2%-95.6%) in the principal and exploratory cohorts, respectively. In the principal cohort, biochemical relapse-free survival and metastasis progression-free survival at 1, 2, and 3 years were 91% (95% CI, 81%-95.8%), 73.7% (95% CI, 61.1%-82.8%), 50.6% (95% CI, 36.2%-63.3%), and 92% (95% CI, 83%-97%), 81% (95% CI, 70%-89%), and 67% (95% CI, 53%-77%), respectively. In the exploratory cohort, metastasis progression-free survival at 1, 2, and 3 years was 64% (95% CI, 34%-83%), 43% (95% CI, 18%-66%), and 26% (95% CI, 7%-51%), respectively. None of the patients developed grade III or higher toxicity or symptoms related to local progression, and only 2 (2.4%) patients developed grade II toxicity.

CONCLUSIONS

The combination of SBRT and ADT is safe and shows favorable clinical outcomes in patients with hormone-sensitive and castration-resistant prostate cancer. Validation studies are needed in patients with castration-resistant prostate cancer.

Unravelling oligometastatic disease from the perspective of radiation and medical oncology. Part II: prostate cancer and colorectal cancer

Oligometastatic disease (OMD) defines a status of cancer that is intermediate between localized and widely spread metastatic disease, and can be treated with curative intent. While imaging diagnostic tools have considerably improved in recent years, unidentified micrometastases can still escape from current detection techniques allowing disease to progress. The variety of OMD scenarios are mainly defined by the number of metastases, the biological and molecular tumour profiles, and the timing of the development of metastases. Increasing knowledge has contributed to the earlier and improved detection of OMD, underlining the importance of an early disease control. Based on increasing detection rates of OMD in the current real clinical practice and the lack of standardized evidence-based guidelines to treat this cancer status, a board of experts from the Spanish Societies of Radiation Oncology (SEOR) and Medical Oncology (SEOM) organized a series of sessions to update the current state-of-the-art on OMD from a multidisciplinary perspective, and to discuss how results from clinical studies may translate into promising treatment options. This experts' review series summarizes what is known and what it is pending clarification in the context of OMD in the scenarios of Non-Small Cell Lung Cancer and Breast Cancer (Part I), and Prostate Cancer and Colorectal Cancer (Part II), aiming to offer specialists a pragmatic framework that might contribute to the improved management of patients.

Oligometastatic Prostate Cancer: Current Status and Future Challenges

In accordance with the spectrum theory of metastatic disease, an oligometastatic clinical state has been proposed as an intermediary step along the natural history of cancer with few (typically 1-3) metastatic lesions identifiable on imaging that may be amenable to metastasis-directed therapy. Effective therapy of oligometastatic disease is anticipated to impact cancer evolution by delaying progression and improving patient outcome at a minimal or acceptable cost of toxicity. There has been increasing recognition of oligometastatic disease in prostate cancer with the advent of new-generation imaging agents, most notably the recently approved PET radiotracers based on targeting prostate-specific membrane antigen. Early clinical trials with metastasis-directed therapy of oligometastases have provided evidence for delaying the employment of systematic therapy and improving outcome in selected patients. Despite these encouraging results, much needs to be investigated and learned about the underlying biology of the oligometastatic state along the evolutionary clinical course of prostate cancer, the identification of relevant imaging and nonimaging predictive and prognostic biomarkers, and the development of treatment strategies to optimize short-term and long-term patient outcome. We provide a review of the current status and the lingering challenges of this rapidly evolving clinical space in prostate cancer.

Cytoreductive surgery in patients with oligometastatic prostate cancer. Systematic review of the scientific literature

INTRODUCTION

Interest in oligometastatic prostate cancer has spiked due to the emergence of new evidence regarding more specific and accurate imaging, and the wider use of minimally invasive techniques. Nevertheless, the optimal management of this pathology is yet to be determined.

OBJECTIVE

Assess the efficacy and safety of cytoreductive surgery in patients suffering from oligometastatic prostate cancer.

EVIDENCE GATHERING

Systematic review of the scientific literature (01/01/2010-31/12/2021) within the MedLine, Embase, Cochrane Library, Cinahl, Scopus, Spanish Healthcare Technology Assessment Agencies (AETS, Agencias de Evaluación de Tecnologías Sanitarias) and ClinicalTrials.gov databases. The keywords used were prostatectomy, prostatic neoplasm, radical prostatectomy; the free search terms were prostatectomy and oligometastatic prostate. The inclusion criteria comprised studies on patients with oligometastatic prostate cancer who had been operated on using radical cytoreductive prostatectomy.

EVIDENCE SYNTHESIS

The systematic review included 4 observational studies, 2 clinical trials, and 2 case series, of moderate quality. The results observed suggest that oligometastatic prostate cancer patients who had undergone cytoreductive prostate surgery obtained a benefit in terms of efficacy. Conversely, the majority of these studies showed a reduction in the number of localized complications, when compared to the best systemic treatments.

CONCLUSIONS

Cytoreductive surgery in this group of patients is a safe procedure that reduces the incidence of localized complications and that presents promising results with regard to survival rates. To date, the lack of prospective trials limits the use of this therapeutic option to experimental environments.

Stereotactic body radiation therapy in patients with metachronous oligorecurrent prostate cancer: A single-center experience

INTRODUCTION AND OBJECTIVE

Metachronous oligorecurrence in prostate cancer (PCa) occurs in patients with localized disease who, after failed radical treatment, develop oligometastases. Metastasis-directed stereotactic radiotherapy (SBRT) aims to delay androgen deprivation therapy. In this study, we report our experience to elucidate the role of SBRT in a selected population of patients with metachronous oligorecurrence.

MATERIAL AND METHODS

Retrospective analysis of patients treated with SBRT for oligorecurrent PCa between November 2015 and December 2020. We detailed clinicopathological characteristics at disease onset (age, PSA, stage, primary treatment), clinical scenario at diagnosis of oligorecurrence (PSA, PSA velocity, metastases characteristics), progression-free survival, castration resistance-free survival, dose, and toxicity of SBRT.

RESULTS

Thirty-eight SBRT treatments were applied to 13 lymph node and 25 bone metastases in a total of 28 patients. After a follow-up of 34.57 months (21.17-57.59), 17 patients had radiological progression of the disease and 11 presented castration resistant PCa. PFS and CRFS were 21.93 and 44.13 months, respectively. Only 2 patients presented grade 1 toxicity.

CONCLUSIONS

In patients with metachronous oligorecurrent PCa, SBRT constitutes a safe and effective treatment that allows delaying the onset of androgen deprivation therapy and the time to castration resistance, assuming low levels of toxicity.

A Systematic Review of Patients' Values, Preferences, and Expectations for the Treatment of Metastatic Prostate Cancer

CONTEXT

Advances in systemic agents have increased overall survival for men diagnosed with metastatic prostate cancer. Additional cytoreductive prostate treatments and metastasis-directed therapies are under evaluation. These confer toxicity but may offer incremental survival benefits. Thus, an understanding of patients' values and treatment preferences is important for counselling, decision-making, and guideline development.

OBJECTIVE

To perform a systematic review of patients' values, preferences, and expectations regarding treatment of metastatic prostate cancer.

EVIDENCE ACQUISITION

The MEDLINE, Embase, and CINAHL databases were systematically searched for qualitative and preference elucidation studies reporting on patients' preferences for treatment of metastatic prostate cancer. Certainty of evidence was assessed using Grading of Recommendation, Assessment, Development and Evaluation (GRADE) or GRADE Confidence in the Evidence from Reviews of Qualitative Research (CERQual). The protocol was registered on PROSPERO as CRD42020201420.

EVIDENCE SYNTHESIS

A total of 1491 participants from 15 studies met the prespecified eligibility for inclusion. The study designs included were discrete choice experiments (n = 5), mixed methods (n = 3), and qualitative methods (n = 7). Disease states reported per study were: metastatic castration-resistant prostate cancer in nine studies (60.0%), metastatic hormone-sensitive prostate cancer in two studies (13.3%), and a mixed cohort in four studies (26.6%). In quantitative preference elicitation studies, patients consistently valued treatment effectiveness and delay in time to symptoms as the two top-ranked treatment attributes (low or very low certainty). Patients were willing to trade off treatment-related toxicity for potential oncological benefits (low certainty). In qualitative studies, thematic analysis revealed cancer progression and/or survival, pain, and fatigue as key components in treatment decisions (low or very low certainty). Patients continue to value oncological benefits in making decisions on treatments under qualitative assessment.

CONCLUSIONS

There is limited understanding of how patients make treatment and trade-off decisions following a diagnosis of metastatic prostate cancer. For appropriate investment in emerging cytoreductive local tumour and metastasis-directed therapies, we should seek to better understand how this cohort weighs the oncological benefits against the risks.

PATIENT SUMMARY

We looked at how men with advanced (metastatic) prostate cancer make treatment decisions. We found that little is known about patients' preferences for current and proposed new treatments. Further studies are required to understand how patients make decisions to help guide the integration of new treatments into the standard of care.

Metastatic prostate cancer men's attitudes towards treatment of the local tumour and metastasis evaluative research (IP5-MATTER): protocol for a prospective, multicentre discrete choice experiment study

INTRODUCTION

Systemic therapy with androgen deprivation therapy (ADT) and intensification with agents such as docetaxel, abiraterone acetate and enzalutamide has resulted in improved overall survival in men with de novo synchronous metastatic hormone-sensitive prostate cancer (mHSPC). Novel local cytoreductive treatments and metastasis-directed therapy are now being evaluated. Such interventions may provide added survival benefit or delay the requirement for further systemic agents and associated toxicity but can confer additional harm. Understanding men's preferences for treatment options in this disease state is crucial for patients, clinicians, carers and future healthcare service providers.

METHODS

Using a prospective, multicentre discrete choice experiment (DCE), we aim to determine the attributes associated with treatment that are most important to men with mHSPC. Furthermore, we plan to determine men's preferences for, and trade-offs between, the attributes (survival and side effects) of different treatment options including systemic therapy, local cytoreductive approaches (external beam radiotherapy, cytoreductive radical prostatectomy or minimally invasive ablative therapy) and metastases-directed therapies (metastasectomy or stereotactic ablative body radiotherapy). All men with newly diagnosed mHSPC within 4 months of commencing ADT and WHO performance status 0-2 are eligible. Men who have previously consented to a cytoreductive treatment or have developed castrate-resistant disease will be excluded. This study includes a qualitative analysis component, with patients (n=15) and healthcare professionals (n=5), to identify and define the key attributes associated with treatment options that would warrant trade-off evaluation in a DCE. The main phase component planned recruitment is 300 patients over 1 year, commencing in January 2021, with planned study completion in March 2022.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Health Research Authority East of England, Cambridgeshire and Hertfordshire Research Ethics Committee (Reference: 20/EE/0194). Project information will be reported on the publicly available Imperial College London website and the Heath Economics Research Unit (HERU website including the HERU Blog). We will use the social media accounts of IP5-MATTER, Imperial Prostate London, HERU and the individual researchers to disseminate key findings following publication. Findings from the study will be presented at national/international conferences and peer-reviewed journals. Authorship policy will follow the recommendations of the International Committee of Medical Journal Editors.

TRIAL REGISTRATION NUMBER

NCT04590976.

Current usage of stereotactic body radiotherapy for oligometastatic prostate cancer in Korea: patterns of care survey (KROG 19-08)

Background

Growing evidence suggests that metastasis-directed therapy and/or prostate-directed therapy may benefit patients with oligometastatic prostate cancer (OMPC). Stereotactic body radiotherapy (SBRT) is increasingly used to treat oligometastases in various cancers. The purpose of this study was to investigate the current patterns of curative-intent SBRT for OMPC in Korea.

Methods

A 20-item questionnaire was sent to 326 radiation oncologists in 93 institutions in Korea. Only 1 physician per institution was required to complete the survey. Subsequently, the second survey consisting of 3 clinical scenarios was sent to 64 physicians with clinical experience in SBRT: case 1, cT4N0M1 (direct invasion to two pelvic bones); case 2, cT2N0M1 (three bone metastases); and case 3, solitary spine metastasis after radical prostatectomy.

Results

Seventy-six physicians from 93 institutions (82%) answered the first survey. The multidisciplinary team approach was practiced in 16 institutions (21%). Most physicians (75%) agreed on the definition of oligometastases as limited lesions and/or organs ≤5: 25% agreed with low-volume disease according to CHAARTED trial. During the last year, 49 physicians (64%) treated OMPC patients with curative intent. Sixty four physicians (84%) had a clinical experience with SBRT: 48 (75%) stated that both dose and fraction number should be considered when defining SBRT, whereas others (25%) stated that only fraction size should be considered. Fifty-five faculties (86%) answered the second survey. Physicians agreed with oligometastases in 89% for case 1, in 80% for case 2, and in 100% for case 3. The rate of SBRT application was the highest in case 3 (70%).

Conclusions

There was diversity in the patterns of SBRT for OMPC in Korea. Additional prospective studies are necessary to strengthen evidence regarding role of SBRT in OMPC.

Combining 68Ga-PSMA-PET/CT-Directed and Elective Radiation Therapy Improves Outcome in Oligorecurrent Prostate Cancer: A Retrospective Multicenter Study

Background

In case of oligo-recurrent prostate cancer (PC) following prostatectomy, ⁶⁸Ga-PSMA-PET/CT can be used to detect a specific site of recurrence and to initiate metastasis-directed radiation therapy (MDT). However, large heterogeneities exist concerning doses, treatment fields and radiation techniques, with some studies reporting focal radiotherapy (RT) to PSMA-PET/CT positive lesions only and other studies using elective RT strategies. We aimed to compare oncological outcomes and toxicity between PET/CT-directed RT (PDRT) and PDRT plus elective RT (eRT; i.e. prostate bed, pelvic or paraaortal nodes) in a large retrospective multicenter study.

Methods

Data of 394 patients with oligo-recurrent ⁶⁸Ga-PSMA-PET/CT-positive PC treated between 04/2013 and 01/2018 in six different academic institutions were evaluated. Primary endpoint was biochemical-recurrence-free survival (bRFS). bRFS was analyzed using Kaplan-Meier survival curves and log rank testing. Uni- and multivariate analyses were performed to determine influence of treatment parameters.

Results

In 204 patients (51.8%) RT was directed only to lesions seen on ⁶⁸Ga-PSMA-PET/CT (PDRT), 190 patients (48.2%) received PDRT plus eRT. PDRT plus eRT was associated with a significantly improved 3-year bRFS compared to PDRT alone (53 vs. 37%; p = 0.001) and remained an independent factor in multivariate analysis (p = 0.006, HR 0.29, 95% CI 0.12-0.68). This effect was more pronounced in the subgroup of patients who were treated with PDRT and elective prostate bed radiotherapy (ePBRT) with a 3-year bRFS of 61% versus 22% (p <0.001). Acute and late toxicity grade ≥3 was 0.8% and 3% after PDRT plus eRT versus no toxicity grade ≥3 after PDRT alone.

Conclusions

In this large cohort of patients with oligo-recurrent prostate cancer, elective irradiation of the pelvic lymphatics and the prostatic bed significantly improved bRFS when added to ⁶⁸Ga-PSMA-PET/CT-guided focal radiotherapy. These findings need to be evaluated in a randomized controlled trial.

Stereotactic body radiotherapy for oligometastatic castration sensitive prostate cancer using 1.5 T MRI-Linac: preliminary data on feasibility and acute patient-reported outcomes

OBJECTIVES

To report preliminary data on feasibility and patient-reported outcomes following PSMA-PET/CT guided SBRT by means of 1.5 T MRI-Linac.

METHODS AND MATERIALS

Between October 2019 and April 2020, twenty consecutive castration sensitive oligorecurrent prostate cancer patients were enrolled in an ethical committee approved prospective observational study (Protocol n. XXXX) and treated with PSMA-PET/CT guided SBRT by means of 1.5 T MRI-Linac (Unity, Elekta AB, Stockholm, Sweden). The mean delivered dose was 35 Gy in 5 fractions. Clinicians reported toxicity was prospectively collected according to Common Terminology Criteria for Adverse Events v5.0. Quality of life (QoL) assessment was performed using EORTC-QLQ C30 questionnaires administered at baseline, end of treatment and at first follow-up.

RESULTS

Twenty-five lesions in 20 castration sensitive oligorecurrent patients were treated: the most commonly treated anatomic sites were nodal (n = 16) and pelvic bone (n = 9). Median PSA-value preMRI guided SBRT was 1.16 ng/mL (range, 0.27-8.9), whereas median PSA value at first follow-up after SBRT was 0.44 ng/mL (range, 0.06-8.15). At first follow-up, for 16 patients showing detectable PSA, PSMA-PET/CT was performed detecting, respectively, in 6 cases partial response and in 10 cases complete response. In the remaining cases, PSA-value was undetectable after SBRT. Radiotherapy treatment was safe and well tolerated according to the PROMs. No acute G2 or higher toxicities were recorded.

CONCLUSIONS

The current series represent the largest one exploring the feasibility and patient-reported outcomes following PSMA-PET/CT guided SBRT by means of 1.5 T MRI-Linac. The preliminary findings here reported are encouraging in terms of effectiveness and tolerability.

Oligorecurrent prostate cancer treated with metastases-directed therapy or standard of care: a single-center experience

BACKGROUND

The optimal treatment for oligorecurrent prostate cancer (PCa) is a matter of debate. We aimed to assess oncologic outcomes of patients treated with metastasis-directed therapy (MDT) vs. androgen deprivation therapy (ADT) for oligorecurrent PCa.

METHODS

We analyzed data from patients with oligorecurrent PCa treated with ADT (n = 121), salvage lymph node dissection (sLND) (n = 191) or external beam RT (EBRT) (n = 178). Radiological recurrence (RAR) was defined as a positive positron emission tomography imaging after MDT or ADT. Second-line systemic therapies (SST) were defined as any systemic therapy administered for progression. Oncologic outcomes were evaluated separately for patients with node-only or bone metastases. Kaplan-Meier method was used to assess time to RAR, SST, and cancer-specific mortality (CSM). Predictors of RAR, SST, and castration-resistant PCa (CRPCa) were assessed with Cox regression analyses.

RESULTS

Overall, 74 (22.6%), 63 (19.2%), and 191 (58.2%) patients were treated with ADT, EBRT, and sLND for lymph node-only recurrence. Both sLND (HR 0.56, 95% CI 0.33-0.94) and EBRT (HR 0.46, 95% CI 0.25-0.85) were associated with better RAR than ADT. Similarly, sLND (HR 0.25, 95% CI 0.13-0.50) and EBRT (HR 0.41, 95% CI 0.19-0.87) were associated with longer SST, as compared with ADT. Similar results were found for CRPCa status. Oncologic outcomes were similar between sLND and EBRT. MDT was not associated with survival benefit in patients with bone metastases as compared with ADT.

CONCLUSIONS

sLND and EBRT were associated with better RAR, SST, and CRPCa-free survival as compared with ADT in patients with oligometastatic PCa nodal recurrence. No difference in survival outcomes was observed between sLND and EBRT. MDT was not associated with survival benefit in patients with bone metastases, as compared with ADT.

The role of surgery in high risk and advanced prostate cancer: A narrative review

Patients with high-risk and advanced prostate cancer require safe and efficacious therapies likely to offer a survival advantage while minimizing the treatment-related toxicities. Improvements in the surgical technology, diagnostic modalities, radiological staging, and risk stratification have made surgery for high-risk and advanced prostate cancer a safe and feasible option. In this review, we outline the role of radical prostatectomy in high-risk localized, locally advanced, and metastatic prostate cancer. We overview available data evaluating the use of surgery in the context of a multi-modal approach and highlight ongoing trials in this area. Furthermore, the role of surgery as a non-systemic modality for metastasis-directed therapy (MDT) is also described. Emerging imaging modalities enabling more accurate staging and longer follow-up of clinical trials for prognostic endpoints are anticipated to help identify patient cohorts and treatment strategies, where the use of surgical treatments is likely to provide oncological benefits and acceptable toxicity.

Prostate-specific Membrane Antigen PET: Therapy Response Assessment in Metastatic Prostate Cancer

Therapy response assessment is a critical step in cancer management, leading clinicians to optimize the use of therapeutic options during the course of the disease. Imaging is a pivotal biomarker for therapy response evaluation in oncology and has gained wider use through the development of reproducible data-based guidelines, of which the Response Evaluation Criteria in Solid Tumors is the most successful example. Disease-specific criteria have also been proposed, and the Prostate Cancer Working Group 3 criteria are the mainstay for prostate cancer (PC). However, conventional imaging evaluation in metastatic PC has several limitations, including (a) the inability to detect small-volume disease, (b) the high prevalence of bone (nonmeasurable) lesions at imaging, and (c) the established role of serum prostate-specific antigen (PSA) levels as the biomarker of choice for response assessment and disease progression. In addition, there are an increasing number of newer treatment options with various effects on imaging features. Prostate-specific membrane antigen (PSMA) PET has improved patient selection for newer treatments, such as metastasis-directed therapy (MDT) or radionuclide therapy. The role of PSMA PET in response assessment for many metastatic PC therapeutic options (MDT, androgen deprivation therapy, chemotherapy, radionuclide therapy, and immunotherapy) is an evolving issue, with emerging data showing good correlation with PSA levels and clinical outcome. However, there are specific implications of each therapy (especially androgen deprivation therapy and immunotherapy) on PSMA expression by PC cells, leading to potential pitfalls and inaccuracies that must be known by radiologists. Despite some limitations, PSMA PET is addressing gaps left by conventional imaging methods (eg, CT and bone scanning) and nonimaging biomarkers (PSA levels) in metastatic PC therapy response assessment, a role that can be improved with advances like refinement of interpretation criteria and whole-body tumor burden quantification.^© RSNA, 2020See discussion on this article by Barwick and Castellucci.

A systematic scoping review of multidisciplinary cancer team and decision-making in the management of men with advanced prostate cancer

PURPOSE

The early diagnosis of prostate cancer and subsequent access to the treatment options helps to achieve optimal cancer outcomes. As the treatment options for patients with advanced prostate cancer continues to evolve, patients need to access a multidisciplinary team (MDT) meeting to receive best-practice care.

METHODS

In this paper a MEDLINE review was performed to assess clinical decision making in the context of MDT discussions for patients with advanced prostate cancer.

RESULTS

From 441 returned articles and abstracts, 50 articles were assessed for eligibility and 16 articles included for analysis. Sixteen articles were identified, 9 of the 16 articles used quantitative methodology including three retrospective analysis of clinical registry data, patient medical records and/or MDT meeting notes and three cross-sectional surveys. Other study designs included one observation study and one study using a combination of qualitative and quantitative methodologies and one mini-review. There were also four editorials included in the review and two consensus statements.

CONCLUSION

This paper highlights the important role the inter-disciplinary MDT has on shared decision making for men with advanced prostate cancer. The application of MDT care is a rapidly growing trend in uro-oncology and an efficient MDT service requires further research to assess its efficiency so that it may expand through all aspect of uro-oncology.