Impact of prostate radiotherapy on survival outcomes in clinically node-positive prostate cancer: A multicentre retrospective analysis

PURPOSE

To evaluate clinical outcomes for cN1M0 prostate cancer treated with varied modalities.

MATERIALS AND METHODS

Men with radiological stage cN1M0 prostate cancer on conventional imaging, treated from 2011-2019 with various modalities across four centres in the UK were included. Demographics, tumour grade and stage, and treatment details were collected. Biochemical and radiological progression-free survival (bPFS, rPFS) and overall survival (OS) were estimated using Kaplan Meier analyses. Potential factors impacting survival were tested with univariable log-rank test and multivariable Cox-proportional hazards model.

RESULTS

Total 337 men with cN1M0 prostate cancer were included, 47% having Gleason grade group 5 disease. Treatment modalities included androgen deprivation therapy (ADT) in 98.9% men, either alone (19%) or in combinations including prostate radiotherapy (70%), pelvic nodal radiotherapy (38%), docetaxel (22%), or surgery (7%). At median follow up of 50 months, 5-year bPFS, rPFS, and OS were 62.7%, 71.0%, and 75.8% respectively. Prostate radiotherapy was associated with significantly higher bPFS (74.1% vs 34.2%), rPFS (80.7% vs 44.3%) and OS (86.7% vs 56.2%) at five years (log rank p < 0.001 each). On multivariable analysis including age, Gleason grade group, tumour stage, ADT duration, docetaxel, and nodal radiotherapy, benefit of prostate radiotherapy persisted for bPFS [HR 0.33 (95% CI 0.18-0.62)], rPFS [HR 0.25 (0.12-0.51)], and OS [HR 0.27 (0.13-0.58)] (p < 0.001 each). Impact of nodal radiotherapy or docetaxel was not established due to small subgroups.

CONCLUSION

Addition of prostate radiotherapy to ADT in cN1M0 prostate cancer yielded improved disease control and overall survival independent of other tumour and treatment factors.

Real world prospective evaluation of clinical outcomes in patients with non-metastatic castrate resistant prostate cancer treated with darolutamide

335

Background: The RECORD Study is a real world data, prospective evaluation of clinical outcomes in patients with nmCRPC treated with Darolutamide. This study will increase the understanding of treatment response and management and in particular inform regarding use of next generation imaging in this setting. Methods: Patient data from 9 UK centres was collected based on the recommendation of NICE for Darolutamide as an option for the treatment of non-metastatic castrate resistant prostate cancer (nmCRPC) from November 2020. Data cut-off was 15 September 2022. The study is ongoing. Results: 87 patients were analysed with a median age of 78 (range 61-92). Median pre-treatment PSA and PSA doubling time (PSAdT) were 13 (range 1.99-110.6) mg/L and 5.05 (range 0.6 - 10) months. 42 patients (49.4%) had pre-treatment PSAdT of <6 months and 43 (50.6%) patients had PSAdT of ≥6 months (2 patients had no pre-treatment PSAdT data). 6 patients (6.90%) had next generation imaging prior to initiation of Darolutamide. Median duration of treatment on Darolutamide was 17 months for patients with pre-treatment PSAdT <6 months but median duration had not been reached for patients with pre-treatment PSAdT ≥6 months after 24 months of treatment, a significant difference p=0.018 (HR=0.385, 95% CI 0.17-0.88). 30 patients have come off treatment so far (34.5%); 21 (70%) for disease progression, 5 (16%) for a medical cause unrelated to the drug (e.g. COVID infection, reduced performance status secondary to pre-existing Parkinson's), 3 (10%) for unacceptable toxicity (rash, Grade3 fatigue, muscle aches, memory issues), and 1 patient died (unrelated). Conclusions: In the RECORD study, predominantly the diagnosis of nmCRPC is based on conventional imaging. The majority of patients respond and tolerate Darolutamide well, comparable with the ARAMIS trial. There is a significant difference between time on Darolutamide for those with pre-treatment PSAdT of <6 months compared with ≥6 months. Further long-term toxicity, MFS and OS data will continue to be collected prospectively within the study.

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.

Identification of a microbiome signature predicting immune checkpoint inhibitor outcomes across multiple cancer types in the MITRE study

TPS2665

Background: The gut microbiome is implicated as a biomarker of response to immune checkpoint inhibitors (ICIs), based on preclinical mouse models and preliminary observations in limited patient series. Furthermore, early reports suggest faecal microbial transfer may have therapeutic potential, converting ICI non-responders to responders. So far, identification of specific responsible bacterial taxa has been inconsistent between published studies, which limits future application. By culturing and metagenomic sequencing of stool sample bacteria, our group has identified a unique microbiome signature, which appears to be predictive of response to ICIs across all key published series as well as our own melanoma patient series (Robinson M et al, J Immunother Cancer 2020;8(suppl 3):A404). Because the patient numbers in all published series remain low, we are now further exploring and validating this microbiome signature in a larger scale study across several different cancer types. Methods: MITRE (Microbiome Immunotherapy Toxicity and Response Evaluation) is a UK NIHR portfolio multi-centre prospective study funded jointly by Cancer Research UK and Microbiotica (NCT04107168). Up to 1800 patients receiving ICIs will be recruited over a 5-year period. In the first stage, 300 patients with advanced melanoma (cohort 1: anti-PD1 monotherapy, cohort 2: anti-PD1+anti-CTLA-4 combination), renal cancer (cohort 3: anti-PD(L)1+kinase inhibitor, cohort 4: anti-PD1+anti-CTLA-4 combination) and non-small cell lung cancer (cohort 5: anti-PD(L)1 monotherapy, cohort 6: anti-PD(L)1+chemotherapy+anti-angiogenic) are being recruited, 50 patients to each cohort. A cohort-specific, simulation-based power calculation will then be performed, guiding subsequent recruitment. Stool and blood are collected prior to treatment, at 3, 6 and 12 months, or disease progression (whichever is sooner), as well as after any grade >3 immune-related adverse events. Patients collect and freeze their own stool samples which are cultured and subjected to shotgun metagenomic sequencing. Plasma, whole blood, buffy coat, RNA and PBMCs are being stored, for correlative studies. Any tumour, or organ biopsies, taken prior to and during treatment are also being collected. Clinical data collection includes treatment, disease response (using RECIST criteria) and toxicity. The primary outcome measure is 1 year progression-free survival. Patients are also asked to invite a household member to be part of the study control group. Recruitment started in July 2020. The Covid-19 pandemic hindered recruitment last year, but the protocol was amended to incorporate a Covid-19 substudy (to document testing, infection and vaccination) and adapt processes for remote trial delivery as much as possible. As of February 2021, 7 sites have opened, 17 patients and 5 household controls have been recruited. Clinical trial information: NCT04107168.

In Vitro Evaluation of Notch Inhibition to Enhance Efficacy of Radiation Therapy in Melanoma

Purpose

The scope of radiation therapy is limited in melanoma. Using in vitro melanoma models, we investigated a Notch signaling inhibitor as a radiosensitizer to explore its potential to improve the efficacy of radiation therapy to widen the clinical application of radiation therapy in melanoma.

Methods and Materials

Melanoma cell lines A375, SKMEL28, and G361 were grown using standard tissue culture methods. Radiation was delivered with a clinical x-ray unit, and a gamma secretase inhibitor RO4929097 was used to inhibit Notch signaling. Cell viability signal was used to calculate Loewe's combination index to assess the interaction between radiation and RO4929097 and also the effect of scheduling of radiation and RO4929097 on synergy. Clonogenic assays were used to assess the clonogenic potential. An in vitro 3-dimensional culture model, γ-H2AX, and notch intracellular domain assays were used to interrogate potential underlying biological mechanisms of this approach. Scratch and transwell migration assays were used to assess cell migration.

Results

A375 and SKMEL28 cell lines showed consistent synergy for most single radiation doses examined, with a tendency for better synergy with the radiation-first schedule (irradiation performed 24 hours before RO4929097 exposure). Clonogenic assays showed dose-dependent reduction in colony numbers. Both radiation and RO4929097 reduced the size of melanospheres grown in 3-dimensional culture in vitro, where RO4929097 demonstrated a significant effect on the size of A375 and SKMEL28 melanospheres, indicating potential modulation of stem cell phenotype. Radiation induced γ-H2AX foci signal levels were reduced after exposure to RO4929097 with a tendency toward reduction in notch intracellular domain levels for all 3 cell lines. RO4929097 impaired both de novo and radiation-enhanced cell migration.

Conclusions

We demonstrate Notch signaling inhibition with RO4929097 as a promising strategy to potentially improve the efficacy of radiation therapy in melanoma. This strategy warrants further validation in vivo.

Additional Treatments to the Local tumour for metastatic prostate cancer-Assessment of Novel Treatment Algorithms (IP2-ATLANTA): protocol for a multicentre, phase II randomised controlled trial

INTRODUCTION

Survival in men diagnosed with de novo synchronous metastatic prostate cancer has increased following the use of upfront systemic treatment, using chemotherapy and other novel androgen receptor targeted agents, in addition to standard androgen deprivation therapy (ADT). Local cytoreductive and metastasis-directed interventions are hypothesised to confer additional survival benefit. In this setting, IP2-ATLANTA will explore progression-free survival (PFS) outcomes with the addition of sequential multimodal local and metastasis-directed treatments compared with standard care alone.

METHODS

A phase II, prospective, multicentre, three-arm randomised controlled trial incorporating an embedded feasibility pilot. All men with new histologically diagnosed, hormone-sensitive, metastatic prostate cancer, within 4 months of commencing ADT and of performance status 0 to 2 are eligible. Patients will be randomised to Control (standard of care (SOC)) OR Intervention 1 (minimally invasive ablative therapy to prostate±pelvic lymph node dissection (PLND)) OR Intervention 2 (cytoreductive radical prostatectomy±PLND OR prostate radiotherapy±pelvic lymph node radiotherapy (PLNRT)). Metastatic burden will be prespecified using the Chemohormonal Therapy Versus Androgen Ablation Randomized Trial for Extensive Disease (CHAARTED) definition. Men with low burden disease in intervention arms are eligible for metastasis-directed therapy, in the form of stereotactic ablative body radiotherapy (SABR) or surgery. Standard systemic therapy will be administered in all arms with ADT±upfront systemic chemotherapy or androgen receptor agents. Patients will be followed-up for a minimum of 2 years.

PRIMARY OUTCOME

PFS. Secondary outcomes include predictive factors for PFS and overall survival; urinary, sexual and rectal side effects. Embedded feasibility sample size is 80, with 918 patients required in the main phase II component. Study recruitment commenced in April 2019, with planned follow-up completed by April 2024.

ETHICS AND DISSEMINATION

Approved by the Health Research Authority (HRA) Research Ethics Committee Wales-5 (19/WA0005). Study results will be submitted for publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03763253; ISCRTN58401737.

Initial experience of the adjuvant treatments to the local tumor for metastatic prostate cancer: Assessment of novel treatment algorithms, a multicenter, phase II randomized controlled trial (IP2-ATLANTA)

TPS5600

Background: Local cytoreductive and metastasis-directed interventions are hypothesised to confer additional survival benefit beyond standard systemic therapy in patients with de novo synchronous metastatic prostate cancer. There is accumulating prospective evidence for local cytoreductive therapy. In particular, the phase III study STAMPEDE which demonstrated improved overall survival in a low burden subgroup of men following cytoreductive radiotherapy. Cytoreductive prostatectomy and minimally invasive ablative therapies (MIAT) are now subject to similar trial evaluation. IP2-ATLANTA will evaluate progression-free and overall survival outcomes with the addition of sequential multi-modal local and metastasis-directed treatments in patients with newly diagnosed metastatic prostate cancer compared to standard care alone. Methods: Phase II, multicentre, three-arm randomised controlled trial using a positive comparator arm ( n=918 ). An internal pilot ( n=80) feasibility phase is incorporated. All men with new histologically diagnosed, hormone sensitive, metastatic prostate cancer, within three months of commencing ADT and of PS 0-2 are eligible. Patients are randomised (1:1:1) to: Control (Standard of Care) OR Intervention 1 (Minimally invasive ablative therapy to the prostate +/- pelvic lymph node dissection [PLND]) OR Intervention 2 (prostate radiotherapy +/- lymph nodes OR Radical prostatectomy +/- PLND). Metastatic burden pre-specified by CHAARTED definition. Men with low-burden disease in intervention arms are eligible for metastasis-directed therapy (stereotactic ablative radiotherapy [SABR] or surgery). Standard systemic therapy given in all arms (incl. docetaxel). Follow-up: min. 2-years; max. 4 years. Primary outcome: progression-free survival (PFS). Secondary outcomes: Overall survival; urinary, sexual & rectal side-effects; patient reported outcome measures. HRA ethical approval (Ref: 19/WA0005). To date, 28/80 (35%) patients have been recruited and randomised across 9 open sites in the internal pilot. Median recruitment rate is 85.7% (IQR 55–86). Internal pilot recruitment expected to be complete by April 2020. IP2-ATLANTA addresses an important research gap in the role of local and metastasis-directed therapy in men with newly diagnosed metastatic prostate cancer. Clinical trial information: NCT03763253 .