Radiation Therapy in the Definitive Management of Oligometastatic Prostate Cancer: The Johns Hopkins Experience

A new perspective on prostate cancer treatment: the interplay between cellular senescence and treatment resistance

The emergence of resistance to prostate cancer (PCa) treatment, particularly to androgen deprivation therapy (ADT), has posed a significant challenge in the field of PCa management. Among the therapeutic options for PCa, radiotherapy, chemotherapy, and hormone therapy are commonly used modalities. However, these therapeutic approaches, while inducing apoptosis in tumor cells, may also trigger stress-induced premature senescence (SIPS). Cellular senescence, an entropy-driven transition from an ordered to a disordered state, ultimately leading to cell growth arrest, exhibits a dual role in PCa treatment. On one hand, senescent tumor cells may withdraw from the cell cycle, thereby reducing tumor growth rate and exerting a positive effect on treatment. On the other hand, senescent tumor cells may secrete a plethora of cytokines, growth factors and proteases that can affect neighboring tumor cells, thereby exerting a negative impact on treatment. This review explores how radiotherapy, chemotherapy, and hormone therapy trigger SIPS and the nuanced impact of senescent tumor cells on PCa treatment. Additionally, we aim to identify novel therapeutic strategies to overcome resistance in PCa treatment, thereby enhancing patient outcomes.

Oligometastatic Prostate Cancer Treated with Stereotactic Body Radiation Therapy: The Role of Three-Dimensional Tumour Volume in Patient Survival

AIMS

The definition of oligometastatic prostate cancer (OPCa) is currently based solely on the maximum number of detectable metastases, as there are no validated biomarkers available. The aim of this study was to identify novel predictive factors for OPCa patients who underwent metastases-directed therapy.

MATERIALS AND METHODS

This monocentre, retrospective study included consecutive OPCa patients with a maximum of five metastases in up to two organs, detected with choline- or PSMA-positron emission tomography, who were treated with metastases-directed stereotactic body radiation therapy. Endpoints were overall survival and progression-free survival, assessed with Kaplan-Meier analysis. Univariate and multivariable Cox regression was carried out to evaluate the association between clinical factors and survival outcomes.

RESULTS

Between 2009 and 2021, 163 patients and 320 metastases were treated with 226 stereotactic body radiation therapy courses. The median three-dimensional metastatic tumour volume was 4.1 cm3, with a range from 0.01 to 233.4 cm3. In total, 87 (53.4%), 21 (12.9%) and 55 (33.7%) metastases were classified as cN1, cM1a and cM1b, respectively. The median follow-up was 28.5 months. The rates of overall survival at 1, 3 and 5 years were 89.5% (95% confidence interval 83.4-93.4), 74.9% (95% confidence interval 66.1-81.7) and 57.2% (95% confidence interval 45.8-67.1), respectively. Multivariable analysis showed that overall survival reduced with the increase in three-dimensional total tumour volume (hazard ratio 1.93, 95% confidence interval 1.06-3.52; P = 0.030) and confirmed a significant difference between cN1 versus cM1a-b disease (hazard ratio 1.81, 95% confidence interval 1.01-3.25; P = 0.046). The cut-off value of total volume correlated with the highest risk of death was 20 cm3 (hazard ratio 2.37, 95% confidence interval 1.34-4.18; P = 0.003). The median progression-free survival was 17.8 months, with 1-, 3- and 5-year rates of 63.7% (95% confidence interval 55.4-70.9), 31.5% (95% confidence interval 22.8-40.6) and 24.7% (95% confidence interval 16.0-34.3).

CONCLUSIONS

This study identified three-dimensional total tumour volume and the site of oligometastases as significant predictors of survival in OPCa patients treated with metastases-directed therapy. These parameters can potentially be used to personalised treatment and improve patient outcome.

Crafting a Personalized Prognostic Model for Malignant Prostate Cancer Patients Using Risk Gene Signatures Discovered through TCGA-PRAD Mining, Machine Learning, and Single-Cell RNA-Sequencing

BACKGROUND

Prostate cancer is a significant clinical issue, particularly for high Gleason score (GS) malignancy patients. Our study aimed to engineer and validate a risk model based on the profiles of high-GS PCa patients for early identification and the prediction of prognosis.

METHODS

We conducted differential gene expression analysis on patient samples from The Cancer Genome Atlas (TCGA) and enriched our understanding of gene functions. Using the least absolute selection and shrinkage operator (LASSO) regression, we established a risk model and validated it using an independent dataset from the International Cancer Genome Consortium (ICGC). Clinical variables were incorporated into a nomogram to predict overall survival (OS), and machine learning was used to explore the risk factor characteristics' impact on PCa prognosis. Our prognostic model was confirmed using various databases, including single-cell RNA-sequencing datasets (scRNA-seq), the Cancer Cell Line Encyclopedia (CCLE), PCa cell lines, and tumor tissues.

RESULTS

We identified 83 differentially expressed genes (DEGs). Furthermore, WASIR1, KRTAP5-1, TLX1, KIF4A, and IQGAP3 were determined to be significant risk factors for OS and progression-free survival (PFS). Based on these five risk factors, we developed a risk model and nomogram for predicting OS and PFS, with a C-index of 0.823 (95% CI, 0.766-0.881) and a 10-year area under the curve (AUC) value of 0.788 (95% CI, 0.633-0.943). Additionally, the 3-year AUC was 0.759 when validating using ICGC. KRTAP5-1 and WASIR1 were found to be the most influential prognosis factors when using the optimized machine learning model. Finally, the established model was interrelated with immune cell infiltration, and the signals were found to be differentially expressed in PCa cells when using scRNA-seq datasets and tissues.

CONCLUSIONS

We engineered an original and novel prognostic model based on five gene signatures through TCGA and machine learning, providing new insights into the risk of scarification and survival prediction for PCa patients in clinical practice.

Uncovering the Secrets of Prostate Cancer's Radiotherapy Resistance: Advances in Mechanism Research

Prostate cancer (PCa) is a critical global public health issue with its incidence on the rise. Radiation therapy holds a primary role in PCa treatment; however, radiation resistance has become increasingly challenging as we uncover more about PCa's pathogenesis. Our review aims to investigate the multifaceted mechanisms underlying radiation therapy resistance in PCa. Specifically, we will examine how various factors, such as cell cycle regulation, DNA damage repair, hypoxic conditions, oxidative stress, testosterone levels, epithelial-mesenchymal transition, and tumor stem cells, contribute to radiation therapy resistance. By exploring these mechanisms, we hope to offer new insights and directions towards overcoming the challenges of radiation therapy resistance in PCa. This can also provide a theoretical basis for the clinical application of novel ultra-high-dose-rate (FLASH) radiotherapy in the era of PCa.

Addition of Metastasis-Directed Therapy to Intermittent Hormone Therapy for Oligometastatic Prostate Cancer: The EXTEND Phase 2 Randomized Clinical Trial

Importance

Despite evidence demonstrating an overall survival benefit with up-front hormone therapy in addition to established synergy between hormone therapy and radiation, the addition of metastasis-directed therapy (MDT) to hormone therapy for oligometastatic prostate cancer, to date, has not been evaluated in a randomized clinical trial.

Objective

To determine in men with oligometastatic prostate cancer whether the addition of MDT to intermittent hormone therapy improves oncologic outcomes and preserves time with eugonadal testosterone compared with intermittent hormone therapy alone.

Design, Setting, Participants

The External Beam Radiation to Eliminate Nominal Metastatic Disease (EXTEND) trial is a phase 2, basket randomized clinical trial for multiple solid tumors testing the addition of MDT to standard-of-care systemic therapy. Men aged 18 years or older with oligometastatic prostate cancer who had 5 or fewer metastases and were treated with hormone therapy for 2 or more months were enrolled to the prostate intermittent hormone therapy basket at multicenter tertiary cancer centers from September 2018 to November 2020. The cutoff date for the primary analysis was January 7, 2022.

Interventions

Patients were randomized 1:1 to MDT, consisting of definitive radiation therapy to all sites of disease and intermittent hormone therapy (combined therapy arm; n = 43) or to hormone therapy only (n = 44). A planned break in hormone therapy occurred 6 months after enrollment, after which hormone therapy was withheld until progression.

Main Outcomes and Measures

The primary end point was disease progression, defined as death or radiographic, clinical, or biochemical progression. A key predefined secondary end point was eugonadal progression-free survival (PFS), defined as the time from achieving a eugonadal testosterone level (≥150 ng/dL; to convert to nanomoles per liter, multiply by 0.0347) until progression. Exploratory measures included quality of life and systemic immune evaluation using flow cytometry and T-cell receptor sequencing.

Results

The study included 87 men (median age, 67 years [IQR, 63-72 years]). Median follow-up was 22.0 months (range, 11.6-39.2 months). Progression-free survival was improved in the combined therapy arm (median not reached) compared with the hormone therapy only arm (median, 15.8 months; 95% CI, 13.6-21.2 months) (hazard ratio, 0.25; 95% CI, 0.12-0.55; P < .001). Eugonadal PFS was also improved with MDT (median not reached) compared with the hormone therapy only (6.1 months; 95% CI, 3.7 months to not estimable) (hazard ratio, 0.32; 95% CI, 0.11-0.91; P = .03). Flow cytometry and T-cell receptor sequencing demonstrated increased markers of T-cell activation, proliferation, and clonal expansion limited to the combined therapy arm.

Conclusions and Relevance

In this randomized clinical trial, PFS and eugonadal PFS were significantly improved with combination treatment compared with hormone treatment only in men with oligometastatic prostate cancer. Combination of MDT with intermittent hormone therapy may allow for excellent disease control while facilitating prolonged eugonadal testosterone intervals.

Trial Registration

ClinicalTrials.gov Identifier: NCT03599765.

LUNAR: a randomized Phase 2 study of 177 Lutetium-PSMA Neoadjuvant to Ablative Radiotherapy for Oligorecurrent Prostate Cancer (clinical trial protocol)

OBJECTIVE

To assess the efficacy of ¹⁷⁷ Lu-PNT2002, a novel radiolabelled small molecule that binds with high affinity to prostate-specific membrane antigen (PSMA), in combination with stereotactic body radiotherapy (SBRT) to all sites of metastasis, vs SBRT alone, in men with oligorecurrent metastatic hormone-sensitive prostate cancer (mHSPC).

PATIENTS AND METHODS

The ¹⁷⁷ Lutetium-PSMA Neoadjuvant to Ablative Radiotherapy for Oligorecurrent Prostate Cancer (LUNAR) trial is an open-label, randomized, stratified, two-arm, single-centre, Phase 2 trial to compare the efficacy and safety of neoadjuvant ¹⁷⁷ Lu-PNT2002 plus SBRT vs SBRT alone in men with oligorecurrent mHSPC. Key eligibility criteria include one to five lesions identified on a PSMA positron emission tomography (PET)/computed tomography (CT) scan centrally reviewed by a board-certified nuclear medicine physician. Key exclusion criteria include castrate-resistant disease, de novo oligometastatic disease and receipt of androgen deprivation therapy (ADT) within 6 months of trial enrolment. The trial aims to enrol 100 patients who will be centrally randomized to one of the two treatment arms, in a 1:1 ratio. Patients in the control arm receive SBRT to all sites of disease. Patients in the experimental arm receive two cycles of neoadjuvant ¹⁷⁷ Lu-PNT2002 (6.8 GBq) 6-8 weeks apart, followed by an interval PSMA PET/CT in 4-6 weeks and dose-adapted SBRT to all sites of disease 1-2 weeks later. The primary endpoint is progression-free survival. Secondary endpoints are radiographic and prostate-specific antigen-based progression, acute and late physician-scored toxicity, patient-reported quality of life, ADT-free survival, time to progression, overall survival, locoregional control, and duration of response. Enrolment in the study commenced in September 2022.

RESULTS AND CONCLUSIONS

The addition of ¹⁷⁷ Lu-PNT2002 to metastasis-directed therapy alone may potentially further forestall disease progression. The results of this Phase 2 trial will determine, for the first time in a randomized fashion, the added benefit of ¹⁷⁷ Lu-PNT2002 to SBRT in patients with oligorecurrent mHSPC.

Survival Outcomes After Radiotherapy for the Treatment of Synchronous Oligometastatic Prostate Cancer

This cohort study assesses biochemical progression-free survival among patients receiving radiotherapy for the treatment of synchronous oligometastatic prostate cancer.

Patient and Treatment Factors Associated with Improved Local Control and Survival in Oligometastatic Bone Disease: Results from a Large Single-Institution Experience Using Stereotactic Body Radiation Therapy

PURPOSE

Limited data exists to guide optimal patient selection and treatment of bone metastases with curative intent despite the increasing application of stereotactic body radiation therapy (SBRT) for oligometastatic (OM) disease control and re-irradiation(ReRT).

METHODS

Clinical characteristics for 434 patients consecutively treated with bone SBRT at a single institution from 3/2011-6/2020 were analyzed by OM, spine, and non-spine bone using Cox regression to determine association with local control (LC), progression-free survival (PFS), and overall survival (OS), and the Kaplan-Meier method to estimate PFS and OS.

RESULTS

Most patients had prostate (39%) or breast/lung (21%) cancer and 1-3 lesions (96%), with 651 lesions (spine 63%) treated for ReRT (12%) or OMD (88%), including synchronous (10%), metachronous (28%), repeat (27%), or induced (23%) states as defined by ESTRO/EORTC criteria. Biologically effective dose (BED₁₀) ≥50 (HR 0.68, CI 0.48-0.96, p<0.03) predicted improved LC among OM lesions and planning target volume (PTV)≥150 cc (HR 1.94, CI 1.02 to 3.70, p<0.04) predicted worse LC for non-spine bone. Prostate histology, performance status (PS) 0-1, and MFI ≥2 year predicted improved PFS and OS (p<0.05). Metachronous, synchronous, or repeat OM had higher PFS and OS (p≤0.001) than induced OM. With median follow-up 25.7 months, 1 and 2-year PFS was 63% and 47% for OM and 36% and 25% for ReRT;1 and 2-yr OS was 87% and 73% for OM, 58% and 43% for ReRT. Acute toxicities included grade 1-2 pain flare (9%) and fatigue (14%). Late toxicities included fracture (1%) for OM and myelopathy (2.5%) or nerve pain (1.2%) for ReRT.

CONCLUSIONS

BED₁₀ ≥ 50 for OM and PTV<150cc for non-spine bone lesions was associated with improved LC. Prostate histology, PS 0-1, MFI≥2 years, and metachronous, synchronous, or repeat presentations per EORTC/ESTRO OM criteria predicted improved PFS and OS among OM patients treated with bone SBRT.

Para-Aortic Radiation Therapy for Oligorecurrent Prostate Cancer

PURPOSE

Oligorecurrent prostate cancer limited to the pelvic lymph nodes (LNs) can be treated with whole pelvis radiotherapy. Radiotherapy may also be beneficial for oligorecurrent prostate cancer in the para-aortic (PA) LNs.

METHODS

We identified a sequential cohort of patients with oligorecurrent prostate cancer to the PA LNs (≤5) treated with elective, conventionally fractionated PA radiotherapy (PA-RT) plus simultaneous integrated boost (SIB) to LN+ disease at our institution from 2015 to 2021. The primary endpoint was progression-free survival (PFS) at 2 years using Kaplan-Meier estimation. PFS was defined as the time from PA-RT to the first event: biochemical failure (PSA 50% above post-treatment nadir and at least 4 ng/mL), escalation of therapy, radiological progression, or death. Secondary endpoints included 2-year biochemical failure-free survival (BFFS), 2-year overall survival (OS) and treatment-related toxicity.

RESULTS

Thirty-four patients were included (median age 66 years), and 82.4% were status post-prostatectomy. The median time from diagnosis to PA-RT was 5.7 years. The median PSA at PA-RT was 3.15 ng/mL (IQR 1.30-5.90). All patients were treated to the PA region with 45-50 Gy in 25 daily fractions. LN+ disease received a SIB to a median dose of 62.5 Gy (range 60-65 Gy). Most received photon-based RT, while 21.1% were treated with proton therapy. Nearly all (97.1%) patients had androgen deprivation therapy (ADT) and 52.9% abiraterone. The median follow-up time from PA-RT was 21.5 months. PFS at 2-years was 83.4% (95% CI: 68.6-100%). Two-year BFFS was 90.4% and OS 100%. There were no grade 3 or higher acute toxicities. There were 10 (29.4%) grade 2 acute toxicities. There were two (5.9%) grade 3 chronic toxicities and 4 (11.8%) chronic grade 2 toxicities.

CONCLUSION

PA-RT for oligorecurrent prostate cancer has low toxicity with very encouraging early disease control. These preliminary results require validation in prospective studies.

Oligometastatic Prostate Cancer: A Comparison between Multimodality Treatment vs. Androgen Deprivation Therapy Alone

Background: We compared multimodality treatment (MMT, defined as robot-assisted radical prostatectomy (RARP) with androgen deprivation therapy (ADT), with or without adjuvant radiotherapy (RT)) vs. ADT alone in oligometastatic prostate cancer (OPC) patients. Methods: From 2010 to 2018, we identified 74 patients affected by cM1a-b OPC (≤5 metastases). Kaplan−Meier (KM) plots depicted cancer-specific mortality (CSM), disease progression, metastatic castration-resistant PC (mCRPC), and time to second-line systemic therapy rates. Multivariable Cox regression models (MCRMs) focused on disease progression and mCRPC. Results: Forty (54.0%) MMT and thirty-four (46.0%) ADT patients were identified. On KM plots, higher CSM (5.9 vs. 37.1%; p = 0.02), mCRPC (24.0 vs. 62.5%; p < 0.01), and second-line systemic therapy (33.3 vs. 62.5%; p < 0.01) rates were recorded in the ADT group. No statistically significant difference was recorded for disease progression. ForMCRMs adjusted for the metastatic site and PSA, a higher mCRPC rate was recorded in the ADT group. No statistically significant difference was recorded for disease progression. Treatment-related adverse events occurred in 5 (12.5%) MMT vs. 15 (44.1%) ADT patients (p < 0.01). Conclusions: MMT was associated with lower CSM, mCRPC, and second-line therapy rates. A lower rate of treatment-related adverse events was recorded for the MMT group.

Radiating the prostate bed in relapsed oligometastatic prostate cancer: How comprehensive should we be?

PURPOSE

A subset of patients with high-risk pathological features at radical prostatectomy recur with oligometastatic disease. The aim of this study is to investigate the rate of prostate bed recurrence, with or without history of prostate bed irradiation (PBRT), in oligometastatic prostate cancer (OMPC) patients after metastasis-directed therapy (MDT).

METHODS

We performed a retrospective analysis of hormone-sensitive OMPC patients treated initially with curative-intent radical prostatectomy followed by disease recurrence and metastasis-directed stereotactic ablative radiotherapy (SABR) at our institution. Prostate bed recurrence rates were compared between patients who had PBRT at any point (i.e., before oligometastatic diagnosis or concurrently with MDT) versus those with no history of PBRT.

RESULTS

Seventy-seven patients were included, and 68.8% had received PBRT. There were no significant differences in baseline characteristics between those who had received and had not received PBRT. There were five prostate bed recurrences following MDT, specifically with a 24-month cumulative incidence of 30.4% in patients who did not have PBRT and 2.4% in those who did (p = 0.03). Three of the five recurrences were isolated to the prostate bed at time of recurrence.

CONCLUSIONS

Relapsed oligometastatic prostate cancer patients who have not received maximal local consolidative therapy to the prostate bed may have higher rates of local failure. Prospective studies are warranted investigating when prostate bed irradiation should be considered for patients after radical prostatectomy who ultimately have oligometastatic prostate cancer.

Spine Stereotactic Body Radiotherapy for Prostate Cancer Metastases and the Impact of Hormone Sensitivity Status on Local Control

BACKGROUND

Stereotactic body radiotherapy (SBRT) is used to deliver ablative dose of radiation to spinal metastases.

OBJECTIVE

To report the first dedicated series of spine SBRT specific to prostate cancer (PCa) metastases with outcomes reported according to hormone sensitivity status.

METHODS

A prospective database was reviewed identifying patients with PCa treated with spine SBRT. This included those with hormone-sensitive PCa (HSPC) and castrate-resistant PCa (CRPC). The primary end point was MRI-based local control (LC).

RESULTS

A total of 183 spine segments in 93 patients were identified; 146 segments had no prior radiation and 37 had been previously radiated; 27 segments were postoperative. The median follow-up was 31 months. At the time of SBRT, 50 patients had HSPC and the remaining 43 had CRPC. The most common fractionation scheme was 24-28 Gy in 2 SBRT fractions (76%). LC rates at 1 and 2 years were 99% and 95% and 94% and 78% for the HSPC and CRPC cohorts, respectively. For patients treated with de novo SBRT, a higher risk of local failure was observed in patients with CRPC (P = .0425). The 1-year and 2-year overall survival rates were significantly longer at 98% and 95% in the HSPC cohort compared with 79% and 65% in the CRPC cohort (P = .0005). The cumulative risk of vertebral compression fracture at 2 years was 10%.

CONCLUSION

Favorable LC rates were observed after spine SBRT for PCa metastases; strategies to improve long-term LC in patients with CRPC require further investigation.

Impact of Progressive Site-Directed Therapy in Oligometastatic Castration-Resistant Prostate Cancer on Subsequent Treatment Response

Simple Summary

Local treatment for oligometastatic hormone-naive prostate cancer has been shown to be effective in phase II trials. As for the efficacy of targeted therapy for oligometastatic castration-resistant prostate cancer, the results of the phase trial are not yet available, but the number of reports showing efficacy by retrospective analysis is increasing. Progressive site-directed therapy has been shown to delay the next intervention and prolong progression-free survival, but its impact on subsequent treatment efficacy and contribution to overall survival has not been reported. The purpose of this retrospective study is to evaluate the impact of progressive site-directed therapy for oligometastatic castration-resistant prostate cancer on the subsequent treatment outcomes. We found that progressive site-directed therapy was associated with better response to subsequent androgen receptor axis-targeted drugs and better overall survival. Progressive site-directed therapy for oligometastatic castration-resistant prostate cancer may improve subsequent oncological outcomes.

Abstract

The purpose of this study was to evaluate the impact of progressive site-directed therapy (PSDT) for oligometastatic castration-resistant prostate cancer (OM-CRPC) on the efficacy of subsequent androgen receptor axis-targeted (ARAT) drugs, and to demonstrate the possibility of prolonging overall survival (OS). We performed a retrospective analysis of 15 OM-CRPC patients who underwent PSDT and subsequently received first-line ARAT drugs (PSDT group) and 13 OM-CRPC patients who were treated with first-line ARAT drugs without PSDT (non-PSDT group). PSDT was performed with the intention of treating all progressing sites detected by whole-body diffusion-weighted MRI with radiotherapy. Thirteen patients (86.7%) treated with PSDT had a decrease in PSA levels, which was at least 50% in 10 (66.7%) patients. The median PSA progression-free survival (PFS) for PSDT was 7.4 months. The median PSA-PFS for ARAT was 27.2 months in patients in the PSDT group and 11.7 months in the non-PSDT group, with a significant difference between the two groups (hazard ratio [HR], 0.28; p = 0.010). The median OS was not reached in the PSDT group and was significantly longer than 44.5 months in the non-PSDT group (HR, 0.11; p = 0.014). In OM-CRPC, PSDT may improve the efficacy of subsequent ARAT and OS.

Evaluating the Role of Stereotactic Body Radiation Therapy With Respect to Androgen Receptor Signaling Inhibitors for Oligometastatic Prostate Cancer

Purpose

Outcomes of stereotactic body radiation therapy (SBRT) with respect to androgen receptor signaling inhibitors (ARSI) have not been characterized for oligometastatic prostate cancer. We sought to characterize prostate specific antigen (PSA) response and progression-free survival (PFS) after SBRT among men who have progressed on ARSI therapy in the oligometastatic castration-resistant setting.

Methods and Materials

A single-institution retrospective analysis was performed for men with ARSI-resistant, oligometastatic, castrate-resistant prostate cancer (omCRPC). Intervention consisted of SBRT. PSA reduction greater than 50% and median PFS (PSA or radiographic progression) as determined by routine care comprised outcome measurements. Cox regression analysis was used to determine factors influencing PFS.

Results

Thirty-five men with ARSI-resistant omCRPC and 65 lesions treated with SBRT were followed for a median of 17.2 months. In 63% of men PSA reduction greater than 50% was achieved. Median PFS was 9.0 months. Incomplete ablation (defined as the presence of untreated lesions after SBRT or receipt of prior palliative radiation therapy doses) was associated with worse PFS (hazard ratio 4.21 [1.74-10.19]; P < .01). For a subgroup of 22 men with complete ablation of metastatic sites with SBRT, the median PFS was 13.1 months. One-year overall survival was 93.1% (95% confidence interval, 84.4-100).

Conclusions

SBRT may augment the efficacy of ARSI in omCRPC, provided that all lesions receive ablative radiation doses. Future prospective study of SBRT for men receiving ARSI is warranted.

Progression-free survival in patients with 68Ga-PSMA-PET-directed SBRT for lymph node oligometastases

BACKGROUND

Prostate cancer oligometastatic disease can be treated using stereotactic body radiotherapy (SBRT) in order to postpone start of systemic treatments such as androgen deprivation therapy (ADT). 68Ga-PSMA-PET/CT imaging allows for diagnosis of oligometastases at lower PSA values. We analysed a cohort of patients with prostate cancer lymph node oligometastases detected on PSMA-PET/CT.

MATERIALS AND METHODS

Ninety patients with metachronous oligometastatic prostate cancer received SBRT for 1-3 lymph node metastases diagnosed on 68Ga-PSMA-PET/CT. The primary end point was progression free survival (PFS), with disease progression defined as occurrence of either target lesion progression, new metastatic lesion or biochemical progression. Secondary outcomes were biochemical PFS (BPFS), ADT-free survival (ADT-FS), toxicity and quality of life (QoL). Baseline patient characteristics were tested for association with PFS and a preliminary risk score was created.

RESULTS

Median follow-up was 21 months (interquartile range 10-31 months). Median PFS and BPFS were 16 and 21 months, respectively. Median ADT-FS was not reached (73% (95%-CI 62-86%) at 24 months). In multivariable analysis, younger age, higher PSA prior to SBRT and extrapelvic location were associated with shorter PFS. Grade 1 fatigue was the most predominant acute toxicity (34%). Highest grade toxicity was grade 2 for acute and late events. QoL analysis showed mild, transient increase in fatigue at 1-4 weeks after SBRT.

CONCLUSION

A median PFS of 16 months was attained after SBRT for patients with PSMA-PET positive oligometastatic lymph nodes from prostate cancer. Higher pre-SBRT PSA, younger age and extrapelvic location were found to be predictors of shorter PFS.

Local Therapies in Oligometastatic and Oligoprogressive Prostate Cancer

Oligometastatic disease was originally defined by Hellman and Weichselbaum as an intermediate-state existing between locally confined and widely disseminated malignancy, whose natural history could be positively impacted with systemic and importantly local therapies such as radiation. Currently oligometastatic prostate cancer (OPCa) is defined clinically by lesion enumeration and several subgroups exist: de novo (synchronous) oligometastatic disease present at initial diagnosis, oligorecurrent (metachronous) disease arising after definitive therapy to the prostate, and oligoprogressive disease where isolated lesions progress in a background of otherwise stable disease. In this review we highlight current knowledge and the potential future of local therapies, such as radiation to the primary prostate and metastasis-directed therapy (MDT), in the disease management of OPCa for all 3 subgroups. In addition, we examine more recent studies classifying the patterns of failure and natural history of OPCa following treatment with local therapies. Finally, while current clinical definitions of OPCa dominate, we introduce studies attempting to elucidate a more biological definition of OPCa to allow for improved selection of patients to treat with local therapies and to better inform precision combination approaches with systemic therapy.

Outcomes of metastasis-directed therapy of bone oligometastatic prostate cancer

Background

The aim of this work was to investigate the outcome of metastasis-directed radiotherapy (MDT) in prostate cancer patients with bone metastases following current ESTRO/EORTC subclassifications for oligometastatic disease.

Methods

Clinical data of 80 consecutive oligometastatic patients with 115 bone lesions receiving MDT between 2011 and 2019 were retrospectively evaluated. Hormone-sensitive (77.5%) and castrate-resistant (22.5%) patients were included. MDT was delivered with conventional fractionated or stereotactic body radiotherapy (SBRT) techniques. Kaplan–Meier method, log rank test, as well as Cox regression were used to calculate local control (LC) and biochemical and clinical progression-free survival (bPFS/cPFS).

Results

At the time of MDT 31% of patients had de-novo synchronous oligometastatic disease, 46% had de-novo metachronous oligorecurrence after primary treatment and 23% had either de-novo oligoprogressive disease, repeat oligometastatic disease or induced oligometastatic disease. The median BED₃ was 93.3 Gy (range 75.8–95.3 Gy). Concomitant ADT was administered in 69% of patients. After a median follow-up of 23 months the median bPFS and cPFS were 16.5 and 21.5 months, respectively. The 2-year LC rate was 98.3%. In multivariate analysis, age ≤ 70 (HR = 2.60, 95% CI 1.20–5.62, p = 0.015) and concomitant ADT (HR = 0.26, 95% CI 0.12–0.58, p = 0.001) significantly correlated with cPFS. Category of oligometastatic disease and hormone-sensitivity were predictive for cPFS in univariate analysis. Of 45 patients with biochemical relapse, nineteen patients (42.2%) had repeat oligometastatic disease. Fourteen patients (31%) underwent a second course of MDT. No patients experienced grade ≥ 3 toxicities.

Conclusions

MDT is safe and offers high local control rates in bone oligometastases of prostate cancer. At 2 years after treatment, more than 2 out of 5 patients are progression-free.

Trial registration Retrospectively registered.

Peripheral androgen blockade in men with castrate-sensitive biochemical recurrent prostate cancer

The aim of the study was to evaluate the feasibility of utilizing peripheral androgen blockade in men with biochemical recurrent castrate-sensitive prostate cancer. A registration study to track outcomes of men with biochemical recurrent castrate-sensitive prostate cancer treated with peripheral androgen blockade utilizing concomitant administration of finasteride and bicalutamide. Men were on intermittent peripheral blockade for a median 20.2 months, continuous peripheral blockade for a median 6.8 months, intermittent triple dose peripheral androgen blockade for a median 10.7 months, and continuous triple dose peripheral androgen blockade for 4.4 months before failing therapy. Six men (21%) had additional therapies during treatment that included metastasis-directed therapy (5/37, 14%), systemic Lu-177 (2/37, 5%), and salvage RT (1/37, 3%). The median time to progression, which includes time from initiation through all therapies to the initiation of ADT, was 37.6 months (IQR 20-74.7). From the start of PAB, median time to castrate resistance was 49.8 months (IQR 40.9-NR). After starting ADT, median time to castrate resistance was 8.8 months (IQR 4.6-17.7). Our data support the exploration of PAB as a treatment option in carefully selected patients who present with biochemical recurrence after failure of definitive local therapy for prostate cancer.

Radiotherapy in the Management of Metastatic Hormone-Sensitive Prostate Cancer: What Is the Standard of Care?

Systemic therapy has historically been the backbone of treatment for patients with metastatic disease. However, recent evidence suggests metastasis-directed therapy in those with oligometastatic disease (≤5 lesions) may improve progression-free and overall survival. Within prostate cancer-specific cohorts, metastasis-directed therapy also appears to delay the time to initiation of androgen deprivation therapy while also generally being associated with a mild toxicity profile and has thus garnered interest as a means to delay systemic therapy. Here we review the evidence surrounding the use of radiation therapy to metastatic sites in patients with metastatic hormone-sensitive prostate cancer.

Oligometastatic and Oligoprogression Disease and Local Therapies in Prostate Cancer

Our understanding of metastatic disease is rapidly advancing, with recent evidence supporting an oligometastatic state currently defined by patients having a limited (typically ≤5) number of metastatic deposits. The optimal management of these patients is also shifting toward increased integration of local therapies, with emerging evidence suggesting metastasis-directed therapy can improve overall survival. Additionally, the use of stereotactic ablative radiation therapy within castration-sensitive oligometastatic prostate cancer cohorts appears to forestall the need to initiate systemic therapy, which has unfavorable side effect profiles, such as androgen deprivation therapy, while itself being associated with little toxicity. We review the literature surrounding the use of metastasis-directed therapy in the treatment of oligometastatic prostate cancer by reviewing the evidence for its use within 3 subgroups: de novo synchronous, oligorecurrent, and oligoprogressive disease.

Long-term clinical outcomes of external beam radiation therapy for oligometastatic prostate cancer: A combination of prostate-targeted treatment and metastasis-directed therapy

OBJECTIVE

To assess the efficacy of combination of prostate-targeted treatment and metastasis-directed therapy for oligometastatic prostate cancer.

METHODS

We retrospectively evaluated the clinical outcomes of synchronously diagnosed oligometastatic prostate cancer patients treated with external beam radiation therapy for the prostate and all metastatic lesions (≤3 lesions) at Kyoto University Hospital between January 2004 and April 2019. The prescribed dose was basically ≥70 Gy for the prostate with or without whole pelvic irradiation, and ≥45 Gy for the metastatic lesions. Clinical outcomes were compared with a contemporary cohort of 55 synchronous oligometastatic prostate cancer patients treated with the standard of care.

RESULTS

In total, 16 consecutive patients with synchronous oligometastatic prostate cancer were analyzed. The median follow-up period was 7.4 years. The 8-year overall survival, prostate cancer-specific survival, biochemical failure-free, clinical failure-free and castration-resistant prostate cancer-free rates were 64.8%, 71.3%, 38.5%, 47.3% and 67.3%, respectively. No grade 3 or higher radiation-induced late toxicities occurred. Patients with prostate-targeted treatment plus metastasis-directed therapy had a significantly higher castration-resistant prostate cancer-free rate than those without prostate-targeted treatment plus metastasis-directed therapy (P = 0.00741).

CONCLUSIONS

Prostate-targeted treatment plus metastasis-directed therapy through external beam radiation therapy can result in favorable long-term disease-free and survival outcomes with acceptable morbidities among synchronous oligometastatic prostate cancer patients. Therefore, this approach may represent a promising treatment strategy for this population. Further investigation is required.

Prognostic Risk Classification for Biochemical Relapse-Free Survival in Oligometastatic Recurrent Prostate Cancer Determined by Choline PET

BACKGROUND

Choline positron emission tomography/computed tomography (PET/CT) is a new imaging technique for the detection of oligometastatic (OM) prostate cancer. The aim of this study was to evaluate the outcomes after initial OM diagnoses; treatment, particularly metastasis-directed therapy (MDT); and determine risk groups.

PATIENTS AND METHODS

This multi-center, retrospective study included patients with hormone-sensitive biological relapse after local treatment with curative intent and with fewer than six choline PET/CT metastases. The primary endpoint was biochemical relapse-free survival (bRFS). Risk groups were based on prostate-specific antigen (PSA) ≥ 0.8 ng/mL and metastatic sites at OM cancer diagnosis.

RESULTS

Between October 2012 and December 2016, 177 patients were included, with a median follow-up of 49.02 months. The median bRFS was 39.74 months. In multivariate analyses, bone metastases and PSA ≥ 0.8 ng/mL were associated with worse bRFS. Four risk groups (I to IV; hazard ratio [HR], 5.92; 95% confidence interval [CI], 1.32-26.61) were observed, with median bRFS not reached for group I (PSA < 0.8 ng/mL; node metastasis [M1a]), a 40.00-month bRFS for group II (PSA ≥ 0.8 ng/mL; M1a), 29.97-month bRFS for group III (bone metastasis [M1b], whatever the PSA level); and 22.70-month bRFS for group IV (PSA > 0.8 ng/mL and visceral metastasis [M1c]). MDT plus androgen deprivation therapy (ADT) improved bRFS over MDT alone (48.36 vs. 34.16 months; HR, 2.12; 95% CI, 1.38-3.26), particularly for group II (HR, 2.09; 95% CI, 1.09-4.00), and reached a limit of significance for group III (HR, ;3.79 95% CI, 0.88- 16.38).

CONCLUSION

Prognostic group classifications were confirmed: PSA < 0.8 ng/mL and M1a showed a better outcome than patients with M1c and PSA ≥ 0.8 ng/mL. These results could facilitate patient selection for prospective clinical trials in OM prostate cancer.

Radiotherapy of oligometastatic prostate cancer: a systematic review

BACKGROUND

Due to improved imaging sensitivity, the term "oligometastatic" prostate cancer disease is diagnosed more often, leading to an increasing interest in metastasis-directed therapy (MDT). There are two types of radiation based MDT applied when treating oligometastatic disease: (1) stereotactic body radiation therapy (SBRT) generally used for bone metastases; or (2) SBRT for isolated nodal oligometastases combined with prophylactic elective nodal radiotherapy. This review aims to summarize current evidence data, which may shed light on the optimal management of this heterogeneous group of patients.

METHODS

A systematic review of the Medline database through PubMed was performed according to PRISMA guidelines. All relevant studies published up to November 2020 were identified and screened. Fifty-six titles were included. Besides outcome parameters, different prognostic and predictive factors were assessed, including site of metastases, time between primary treatment and MDT, use of systemic therapies, hormone sensitivity, as well as pattern of recurrence.

FINDINGS

Evidence consists largely of retrospective case series and no consistent precise definition of oligometastasis exists, however, most investigators seem to acknowledge the need to distinguish between patients presenting with what is frequently called "synchronous" versus "metachronous" oligometastatic disease. Available data on radiotherapy as MDT demonstrate high local control rates and a small but relevant proportion of patients without progressive disease after 2 years. This holds true for both hormone sensitive and castration resistant prostate cancer diseases. The use of 68Ga-PSMA PET/CT for staging increased dramatically. Radiation doses and field sizes varied considerably among the studies. The search for relevant prognostic and predictive factors is ongoing.

CONCLUSIONS

To our best knowledge this review on oligometastatic prostate cancer included the largest number of original articles. It demonstrates the therapeutic potential and challenges of MDT for oligometastatic prostate cancer. Prospective studies are under way and will provide further high-level evidence.

Metastasis-directed therapy and prostate-targeted therapy in oligometastatic prostate cancer: a systematic review

INTRODUCTION

The aim of this review was to summarize the available evidence on the role of metastasis-directed therapy (MDT) and/or prostate-targeted therapy (PTT) in the setting of oligometastatic prostate cancer (PCa).

EVIDENCE ACQUISITION

We searched PubMed, the Web of Science, and the Cochrane Library databases. The following keywords were used: ("prostate cancer" OR "prostate carcinoma" OR "prostate neoplasm" OR "prostate tumor") AND ("oligometastatic" OR "oligometastasis" OR "PSMA") AND ("surgery" OR "prostatectomy" OR "radical prostatectomy" OR "cytoreductive" OR "local treatment" OR "radiotherapy" OR "stereotactic" OR "stereotaxic") AND ("survival" OR "mortality").

EVIDENCE SYNTHESIS

After evaluating the selection criteria, 81 studies were evaluated for our endpoints. We included 22 studies for PTT of synchronous mPCa. There have been no randomized studies on cytoreductive prostatectomy (cRP). Four prospective studies showed that cRP was feasible but did not contribute to a positive effect on overall survival (OS). Regarding PTT-radiotherapy, two randomized controlled phase 3 trials showed that OS was improved in men with a low metastatic burden. Regarding MDT of metachronous lymph node recurrence, we included 29 retrospective studies. For MDT of oligometastases, we included 30 studies. One randomized phase 2 trial showed that androgen deprivation therapy-free survival improved with stereotactic body radiation therapy compared to that with surveillance; however, benefits on OS remain unclear.

CONCLUSIONS

We performed a comprehensive overview of the current literature on MDT and PTT. The feasibility of MDT and PTT is supported by several retrospective studies. Nevertheless, there remains a lack of high-quality trials to prove its survival benefits. Results from ongoing prospective trials data are awaited.

Patterns of Recurrence and Modes of Progression After Metastasis-Directed Therapy in Oligometastatic Castration-Sensitive Prostate Cancer

Purpose:

Metastasis-directed therapy (MDT) is increasingly used in castration-sensitive oligometastatic prostate cancer because it prolongs progression-free survival (PFS) and androgen deprivation free survival. Here we describe patterns of recurrence and identify modes of progression after MDT using SABR.

Methods and Materials:

Two hundred fifty-eight patients with castration-sensitive oligometastatic prostate cancer (≤5 lesions at staging) were retrospectively identified from a multi-institutional database. Descriptive patterns of recurrence and modes of progression were reported. Other outcomes including median time to prostate-specific antigen (PSA) recurrence, time to next intervention, distant metastasis–free survival, overall survival, and biochemical PFS (bPFS) were reported. Survival analysis was performed using the Kaplan-Meier method, and multivariable analysis was performed.

Results:

Median follow-up was 25.2 months, and 50.4% of patients received concurrent androgen deprivation. Median time to PSA recurrence was 15.7 months, time to next intervention was 28.6 months, distant metastasis–free survival was 19.1 months, and bPFS was 16.1 months. Two-year overall survival was 96.8%. On multivariable analysis, factors associated with bPFS included age (hazard ratio [HR], 1.03; P = .04), N1 disease at diagnosis (HR, 2.00; P = .02), M1 disease at diagnosis (HR, 0.44; P = .01), initial PSA at diagnosis (HR, 1.002; P = <.001), use of androgen deprivation therapy (HR, 0.41; P < .001), pre-SABR PSA (HR, 1.02; P = .01), and use of enhanced imaging for staging (HR, 2.81; P = .001). Patterns of progression favored an osseous component at recurrence; in patients initially treated to a bone lesion alone, the vast majority (86.5%) experienced a recurrence that included an osseous site. Patients treated initially to a nodal site alone tended to recur in a node only (64.5%); however, there was also a significant minority with an osseous component of recurrence at progression (32.3%). Modes of progressors were class I (patients with long term control [no recurrence ≥18 months after therapy]) occurring in 40.9%, class II (oligoprogressors [≤3 lesions at recurrence]) occurring in 36% (including 7.9% of patients with PSA recurrence but no metastatic disease), and class III (polyprogressors [>3 lesions]) occurring in 23.1% of patients.

Conclusions:

After MDT, the majority of patients have long-term control or oligoprogression (class I or II). Recurrence tended to occur in osseous sites. These findings, if validated, have implications for future integration of MDT and clinical trial design.

Clinical Outcomes of Stereotactic Body Radiotherapy With Immediate Versus Delayed Hormone Therapy in Men With Oligometastatic Recurrence of Prostate Cancer

AIMS

Stereotactic body radiotherapy (SBRT) with the delayed option of androgen deprivation therapy (ADT) is the current treatment paradigm in men relapsed with oligometastatic prostate cancer based on the outcome of a phase II randomised controlled study. The immediate (concomitant) use of ADT in this clinical setting potentially augments the efficacy of SBRT by improving systemic disease control. The aim of this study was to compare the clinical outcomes of these two treatment strategies.

MATERIALS AND METHODS

Eighty-eight patients with up to three oligometastases and controlled primary disease who had been treated using SBRT with immediate or delayed ADT were included in this retrospective analysis. Progression-free survival (PFS), widespread failure-free survival (WFFS) and freedom from further interventions (FFFI) were assessed using Kaplan-Meier and Cox proportional hazard regression methods. Toxicity was evaluated using Common Terminology Criteria for Adverse Events (CTCAE) v4.0.

RESULTS

Thirty-nine patients (44.3%) were treated with SBRT and immediate ADT (continuous ADT, n = 7; intermittent ADT, n = 32) and 49 (55.7%) with SBRT and delayed ADT. The median follow-up was 24 months (interquartile range 13.5-37.0 months). PFS in the immediate and delayed ADT groups were 26 months and 16 months, respectively (P < 0.007). The median WFFS in the immediate ADT group was not reached compared with 21 months in the delayed ADT group (P = 0.025). The 1- and 2-year FFFI in the immediate ADT group were 88% and 64.1%, respectively, significantly higher than those in the delayed ADT group (63.8% and 30.2%, respectively, P < 0.002). Acute toxicities of grade 1-2 occurred in 17.9% of the immediate ADT group and 18.4% of the delayed ADT group (P = 0.96). Only one case of grade 3 late toxicity (pelvic insufficiency) was identified in this study.

CONCLUSIONS

SBRT with concomitant ADT improves PFS, WFFS and FFFI as compared with SBRT with delayed ADT; this finding needs validation in a prospective, randomised study.

Metastasis-directed Therapy Prolongs Efficacy of Systemic Therapy and Improves Clinical Outcomes in Oligoprogressive Castration-resistant Prostate Cancer

BACKGROUND

Available therapies for castrate-resistant prostate cancer (CRPC) confer minimal survival advantage; thus, there is interest in metastasis-directed therapy (MDT) for oligometastatic or oligoprogressive disease to improve outcomes. Here, we describe outcomes of oligoprogressive CRPC treated with stereotactic ablative radiotherapy (SABR).

OBJECTIVE

To report outcomes of oligoprogressive CRPC treated with MDT using SABR.

DESIGN, SETTING, AND PARTICIPANTS

Patients with oligoprogressive CRPC were retrospectively evaluated, and outcomes following MDT were reported. Outcomes were additionally compared with oligoprogressive CRPC treated with change in systemic therapy alone.

INTERVENTION

SABR to oligoprogressive lesions.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Outcomes of interest were time to prostate-specific antigen (PSA) failure, time to next intervention (TTNI), distant metastasis-free survival (DMFS), and overall survival. Survival analysis was performed using the Kaplan-Meier method, and univariable analysis and multivariable analysis (MVA) were performed.

RESULTS AND LIMITATIONS

A total of 68 patients were included. After MDT, median time to PSA recurrence, TTNI, and DMFS were 9.7, 15.6, and 10.8 months, respectively. A total of 112 lesions were treated, and the cumulative incidences of local failure at 12 and 24 months were 2.1% and 13.8%, respectively. Factors associated with the risk of local recurrence on univariable analysis were age (hazard ratio [HR] 1.07, p =  0.03) and Gleason grade group (HR 2.20, p =  0.07). Compared with change in systemic therapy alone (n = 52), MDT (n = 31) was associated with improved median time to PSA failure (9.7 vs 4.2 months, p =  0.066)), TTNI (14.9 vs 8.8 months, p =  0.025), and DMFS (12.7 vs 8.9 months, p = 0.045), and remained associated with improved outcomes on MVA.

CONCLUSIONS

In a retrospective cohort of oligoprogressive CRPC patients, MDT was associated with favorable outcomes and improved cancer control as compared with change in systemic treatment alone. Future prospective trials are needed to confirm these findings.

PATIENT SUMMARY

In this report, we retrospectively analyzed outcomes of patients with oligoprogressive castrate-resistant prostate cancer treated with radiation therapy to progressing lesions. Our results suggest that treatment of these lesions with radiation therapy can result in sustained periods of disease-free survival and might add benefit in addition to systemic therapy at the time of progression. These results need to be verified in a prospective trial to identify the optimal integration of radiation therapy into metastatic castrate-resistant prostate cancer.

A phase II randomized trial of RAdium-223 dichloride and SABR Versus SABR for oligomEtastatic prostate caNcerS (RAVENS)

BACKGROUND

Metastasis directed therapy (MDT) for patients with oligometastatic disease is associated with improvements in progression free survival (PFS) and overall survival (OS) compared to systemic therapy alone. Additionally, within a prostate-cancer-specific cohort, MDT is able to forestall initiation of androgen deprivation therapy (ADT) in men with hormone-sensitive, oligometastatic prostate cancer (HSOPCa) compared to observation. While MDT appears to be safe and effective in HSOPCa, a large percentage of men will eventually have disease recurrence. Patterns of failure in HSOPCa demonstrate patients tend to have recurrence in the bone following MDT, raising the question of sub-clinically-apparent osseous disease. Radium-223 dichloride is a radiopharmaceutical with structural similarity to calcium, allowing it to be taken up by bone where it emits alpha particles, and therefore might have utility in the treatment of micrometastatic osseous disease. Therefore, the primary goal of the phase II RAVENS trial is to evaluate the efficacy of MDT + radium-223 dichloride in prolonging progression free survival in men with HSOPCa.

METHODS

Patients with HSOPCa and 3 or less metastases with at least 1 bone metastasis will be randomized 1:1 to stereotactic ablative radiation (SABR, also known as stereotactic body radiation therapy (SBRT)) alone vs SABR + radium-223 dichloride with a minimization algorithm to balance assignment by institution, primary intervention, prior hormonal therapy, and PSA doubling time. SABR is delivered in one to five fractions and patients in the SABR + radium-223 dichloride arm will receive six infusions of radium-223 dichloride at four-week intervals. The primary end point is progression free survival. The secondary clinical endpoints include toxicity and quality of life assessments, local control at 12 months, locoregional progression, time to distant progression, time to new metastasis, and duration of response.

DISCUSSION

The RAVENS trial will be the first described phase II, non-blinded, randomized study to compare SABR +/- radium-223 dichloride in patients with HSOPCa and 3 or less metastases with at least one bone metastasis. The primary hypothesis is that SABR + radium-223 dichloride will increase median progression-free survival from 10 months in the SABR arm to 20 months in the SABR + radium-223 dichloride arm.

TRIAL REGISTRATIONS

Clinicaltrials.gov. Identifier: NCT04037358. Date of Registration: July 30, 2019. Date of First Participant Enrolled: August 9, 2019. Date of Last Approved Amendment: October 16, 2019. Protocol Version: Version 5.

Metastasis-directed therapy in castration-refractory prostate cancer (MEDCARE): a non-randomized phase 2 trial

Background

Patients diagnosed with metastatic castration-refractory prostate cancer (mCRPC) rely on a limited number of therapeutic agents resulting in a median survival of 2–3 years. A subgroup of those patients with mCRPC presents with oligoprogressive disease, with a limited number of progressive lesions while other metastases are still controlled by ongoing systemic treatment.

Methods

In this single arm prospective phase II trial, we aim to include 18 patients with oligoprogressive mCRPC (1–3 metastases and/or local recurrence) who will be treated with metastasis-directed therapy to all visible progressive lesions. Progression is based on conventional imaging, as the use of PSMA PET-CT is considered investigational. However all patients will undergo PSMA PET-CT and the images will be blinded until progression. Primary endpoint is the postponement of the start of next-line systemic treatment (NEST) and the additional clinical value of PSMA PET-CT. Recruitment of patients for this trial started in January 2020 and will be completed approximately by December 2020.

Discussion

In this phase 2 trial on oligoprogressive mCRPC, we will investigate the benefit of progression-directed therapy while continuing ongoing systemic treatment. We hypothesize that progression-directed therapy (PDT) with surgery or stereotactic body radiation therapy for these oligoprogressive lesions will postpone the start of next-line systemic treatment and therefore serve as a new or add-on therapy in the spectrum of treatments available for mCRPC. The results of this trial will serve as guidance for a later randomized phase 3 trial. All participants are given an information sheet and are required to give written informed consent. Results will be published in a peer-reviewed journal.

Trial registration

This study is registered at ClinicalTrials.gov: NCT04222634 (December 18th 2019).

Metastasis-directed therapy for oligometastatic urological tumours: still no second-hand news

For patients presenting with limited metastatic disease burden, known as the oligometastatic state of disease, a more aggressive treatment approach targeting the new or progressive metastatic lesions might improve patient outcome, with no or only limited toxicity to be expected from the treatment. This review provides an overview of the existing evidence and on-going trials on oligometastatic disease and metastasis-directed therapy in the field of renal, bladder and prostate cancer.