The STAMPEDE2 Trial: a Site Survey of Current Patterns of Care, Access to Imaging and Treatment of Metastatic Prostate Cancer

Combination Therapies in Locally Advanced and Metastatic Hormone-sensitive Prostate Cancer

BACKGROUND AND OBJECTIVE

The treatment landscape for advanced prostate cancer has evolved significantly over the past decade. The introduction of docetaxel, androgen receptor pathway inhibitors (ARPIs), poly(ADP-ribose) polymerase inhibitors, and targeted radionuclides has redefined the treatment paradigm, with a focus now on early treatment intensification through combination therapies. This narrative collaborative review summarises the current evidence of combination therapies in locally advanced and metastatic hormone-sensitive prostate cancer (mHSPC).

METHODS

We conducted a literature search up to November 2024. Search terms included "metastatic hormone-sensitive prostate cancer", "metastatic castration-sensitive prostate cancer", "locally advanced prostate cancer", "combination", "intensification", and "de-escalation". Articles were selected by the authors based on their scientific merit, clinical impact, and relevance to provide a summary of the evidence surrounding combination therapy in locally advanced prostate cancer and mHSPC.

KEY FINDINGS AND LIMITATIONS

A doublet approach with an androgen deprivation therapy (ADT) backbone and an ARPI is now considered the standard treatment for mHSPC, with a triplet regimen incorporating docetaxel considered in select subgroups. Similar efforts to improve survival in the high-risk localised and locally advanced disease setting have led to several trials evaluating the benefit of combination therapy in addition to standard-of-care surgery or radiotherapy with ADT. Continued improvements in survival have turned the focus to optimising patient selection for treatment intensification and, in some cases, de-escalation, with the goal of reducing unnecessary overtreatment and minimising harm from long-term treatment toxicity. This is particularly important with the integration of prostate-specific membrane antigen positron emission tomography, which has led to the earlier detection of metastatic disease.

CONCLUSIONS AND CLINICAL IMPLICATIONS

In select subgroups, early treatment intensification with combination therapy leads to improved survival, though it can be associated with long-term toxicity.

Implementing evidence-based strategies for men with biochemically recurrent and advanced prostate cancer: Consensus recommendations from the US Prostate Cancer Conference 2024

Current US clinical practice guidelines for advanced prostate cancer management contain recommendations based on high-level evidence from randomized controlled trials; however, these guidelines do not address the nuanced clinical questions that are unanswered by prospective trials but nonetheless encountered in day-to-day practice. To address these practical questions, the 2024 US Prostate Cancer Conference (USPCC 2024) was created to generate US-focused expert clinical decision-making guidance for circumstances in which level 1 evidence is lacking. At the second annual USPCC meeting (USPCC 2024), a multidisciplinary panel of experts convened to discuss ongoing clinical challenges related to 5 topic areas: biochemical recurrence; metastatic, castration-sensitive prostate cancer; poly [ADP-ribose] polymerase inhibitors; prostate-specific membrane antigen radioligand therapy; and metastatic, castration-resistant prostate cancer. Through a modified Delphi process, 34 consensus recommendations were developed and are intended to provide clinicians who manage prostate cancer with guidance related to the implementation of novel treatments and technologies. In this report, the authors review the areas of consensus identified by the USPCC 2024 experts and evaluate ongoing unmet needs regarding translational application of the current clinical evidence.

Stereotactic ablative radiation therapy in metastatic prostate cancer

PURPOSE OF REVIEW

The evolving role of stereotactic ablative radiation therapy (SABR) as metastasis-directed therapy (MDT) for oligometastatic prostate cancer (omPCa) will be discussed.

RECENT FINDINGS

Oligometastatic disease (OMD) is an intermediate state between localized and wide-spread malignant disease. OMD has recently been spotlighted given the increasing demonstration of clinical benefit from local therapies despite presence of metastatic disease and allure of the curative potential of MDT in select cases. Among the different forms of MDT, SABR has rapidly become a widely adopted treatment modality. Significant efforts in this space have focused on omPCa, owing to its relatively indolent biology, presence of a sensitive and specific serum biomarker and recent advances in molecular imaging. While most studies have evaluated the role of SABR MDT in hormone sensitive omPCa, new emerging clinical data also suggests benefits of SABR MDT for even castration-resistant disease.

SUMMARY

Treating omPCa with SABR MDT appears to generate an efficacy signal with minimal morbidity across both hormone-sensitive and castration-resistant disease. However, additional definitive omPCa trial data are needed. Future research efforts should investigate biomarkers for this heterogeneous disease space and the role of SABR MDT in combination with systemic agents to improve upon standard of care treatments.

The quantitative impact of prostate-specific membrane antigen (PSMA) PET/CT staging in newly diagnosed metastatic prostate cancer and treatment-decision implications

Objectives

To quantify the stage-shift with prostate-specific membrane antigen (PSMA) PET/CT imaging in metastatic prostate cancer and explore treatment implications.

Methods

Single-centre, retrospective analysis of patients with newly diagnosed [18F]PSMA-1007 or [68Ga]Ga-PSMA-11 PET/CT-detected metastatic prostate cancer who had baseline bone scintigraphy between January 2015 and May 2021. Patients were subclassified into oligometastatic and polymetastatic disease utilizing the STAMPEDE2 trial (ISRCTN66357938/NCT06320067) definition. Patient, tumour, and treatment characteristics were collected. PSMA PET/CT concordance with conventional imaging (bone scintigraphy and low-dose CT of PET) was identified by number and site of metastases, and subgroup assigned. Spearman's rank correlation and linear regression modelling determined the association between the imaging modalities.

Results

We analysed 62 patients with a median age was 72 years (range 48-86). On PSMA PET/CT, 31/62 (50%) patients had oligometastatic disease, and 31/62 (50%) had polymetastatic disease. Prostate radiotherapy was delivered in 20/31 (65%) patients with oligometastatic disease and 17/31 (55%) with polymetastatic disease. 23/62 (37%) patients were reclassified as M0 on conventional imaging. PSMA PET/CT had a 2.9-fold increase in detecting bone metastases. Bone metastases concordance was found in 10/50 (20%) by number and 30/33 (91%) by site. PSMA PET/CT had a 2.2-fold increase in detecting nodal metastases. Nodal metastases concordance was found in 5/46 (11%) by number and 25/26 (96%) by site. There was significant positive correlation between PSMA PET/CT and conventional imaging for detecting bone [R 2 = 0.25 (P < 0.001)] and nodal metastases [R 2 = 0.19 (P < 0.001)]. 16/31 (52%) had oligometastatic disease concordance.

Conclusion

The magnitude of PSMA PET/CT-driven stage-shift is highly variable and unpredictable with implications on treatment decisions, future trial design, and potentially clinical outcomes.

Advances in knowledge

The magnitude of "frame-shift" with PSMA PET/CT imaging is highly variable and unpredictable which may unreliably change treatment decisions dependent on image-defined disease extent. Prospective randomized trials are required to determine the relationship between PSMA PET/CT-guided treatment choices and outcomes.