Is There a Benefit of Combining Immunotherapy and Radiotherapy in Bladder Cancer?

Immune checkpoint inhibitors have transformed the management of patients with metastatic urothelial cancer, by leading to long-term response and prolongation of survival in a subset of patients. Unfortunately, only one in five patients with metastatic urothelial cancer responds to anti-programmed death ligand-1 ([AQ1]anti-PD-1) monotherapy. Preclinical and early clinical evidence indicates that radiotherapy not only acts locally, but also exerts systemic anti-tumour effects by modulating the immune system. It is hypothesised that combining checkpoint inhibitors with radiotherapy might enhance an anti-tumour immune response and increase response rates. So far, a handful of early phase clinical trials have been performed seeking to answer this question in urothelial cancer patients. The current review summarises the available preclinical and clinical evidence on radiotherapy/immunotherapy combinations in locally advanced and metastatic bladder cancer and suggests future avenues worthy of exploration.

Positron Emission Tomography and Whole-body Magnetic Resonance Imaging for Metastasis-directed Therapy in Hormone-sensitive Oligometastatic Prostate Cancer After Primary Radical Treatment: A Systematic Review

CONTEXT

Next-generation imaging includes positron emission tomography (PET) imaging and whole-body magnetic resonance imaging (wbMRI) including diffusion-weighted imaging. Accurate quantification of oligometastatic disease using next-generation imaging is important to define the role and value of metastasis-directed therapy (MDT).

OBJECTIVE

To perform a review of next-generation imaging modalities in the detection of recurrent oligometastatic hormone-sensitive prostate cancer in men who received prior radical treatment for localized disease.

EVIDENCE ACQUISITION

MEDLINE, Scopus, Cochrane Libraries, and Web of Science databases were systematically searched for studies reporting next-generation imaging and oncological outcomes. An expert panel of urologists, radiation oncologists, radiologists, and nuclear medicine physicians performed a nonsystematic review of strengths and limitations of currently available imaging options for detecting the presence and extent of recurrent oligometastatic disease.

EVIDENCE SYNTHESIS

From 370 articles identified, three clinical trials and 21 observational studies met the following inclusion criteria: metachronous oligometastatic recurrence after radical treatment for prostate cancer, MDT, and hormone-sensitive patients. Androgen deprivation therapy (ADT) was allowed before MDT. Next-generation imaging modalities included PET/computed tomography and/or PET/MRI with the following tracers: choline (n = 1), NaF (n = 1), and prostate-specific membrane antigen (PSMA; n = 1) for clinical trials; choline (n = 7) or PSMA (n = 11) or both (n = 3) for observational studies. The number of metastases ranged from two to five lesions in most studies. In PSMA-based studies, progression-free survival ranged from 19% to 100%, whereas in studies employing choline, progression-free survival ranged from 16% to 93%. Overall, ADT-free survival ranged from 48% to 79%, while local control was reported as 75-100% and prostate-specific antigen response as 23-94%. Among the different PET tracers and wbMRI, PSMA PET is emerging as the most accurate imaging technique in defining the oligometastatic status.

CONCLUSIONS

PSMA and choline PET contribute to guiding MDT in men with hormone-sensitive oligometastatic prostate cancer. Further studies are warranted to ascertain their role and optimize the timing of imaging for such patients.

PATIENT SUMMARY

We looked at the evidence regarding the use of modern imaging techniques to direct additional treatments in men with early spread of prostate cancer after they receive their initial radical treatment. We found that next-generation imaging, in particular prostate-specific membrane antigen and choline positron emission tomography, can successfully guide metastasis-directed therapies, and further trials should evaluate which modalities are best suited to improve outcomes for our patients.

Dose-intensified versus conventional dose-salvage radiotherapy for biochemically recurrent prostate cancer after prostatectomy: Six-year outcomes of the SAKK 09/10 randomized phase III trial

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Background: Salvage radiotherapy (RT) is often utilized in case of biochemical progression after radical prostatectomy (RP). Here we report the outcomes of the European SAKK 09/10 randomized phase 3 trial with the aim to compare effectiveness and tolerability of conventional vs. dose-intensified salvage RT. Methods: SAKK 09/10 is an open-label, multicenter, randomized phase 3 trial performed in 24 centers in Switzerland, Germany and Belgium. Men with biochemical progression (two consecutive rises with the final PSA > 0.1 ng/mL or three consecutive rises) after RP with a PSA nadir of ≤ 0.4 ng/mL, with a PSA ≤ 2 ng/mL at randomization and without clinical evidence of macroscopic disease were recruited. Patients were randomly assigned to either conventional dose RT (64 Gy in 32 fractions) or dose-intensified RT (70 Gy in 35 fractions) directed to the prostate bed. Three-dimensional conformal RTor intensity-modulated RT/rotational techniques were used. The primary endpoint was freedom from biochemical progression (PSA ≥ 0.4 ng/mL and rising). Secondary endpoints included clinical progression-free survival, time to hormonal treatment, overall survival, acute and late toxicity (according to the NCI CTCAE v4.0) and quality of life (according to the EORTC QLQ-C30 and PR25). The trial was registered under NCT01272050 in clinicaltrials.gov. Results: Between 02/2011 and 04/2014, 350 patients were randomly assigned to 64 Gy (n = 175) or 70 Gy (n = 175), of whom 344 aged between 48 to 75 years were assessable for the intention-to-treat population. The median PSA at randomization was 0.3 ng/mL (range, 0.03-1.61 ng/mL). At the time of data cutoff (July 3, 2020), the median follow-up was 6.2 years (IQR 5.5-7.2) and a total of 138 biochemical progression events occurred. The estimated freedom from biochemical progression rate at 6 years was 62.3% (95% CI 54.2-69.4%) and 61.3% (95% CI 53.4-68.3%) for the 64 Gy and the 70 Gy arm, respectively, and the hazard ratio adjusted by stratification factors was 1.14 (95% CI 0.82-1.60; log-rank p = 0.44). No significant difference was found for clinical progression-free survival, time to hormonal treatment and overall survival between the two arms, respectively. Late grade 2 and 3 genitourinary toxicity was observed in 35 (21.2%) and 13 (7.9%) patients treated with 64 Gy, and in 46 (26.3%) and 7 (4%) patients with 70 Gy (p = 0.81). Lategrade 2 and 3 gastrointestinal toxicity was observed in 12 (7.3%) and 7 (4.2%) patients with 64 Gy, and in 35 (20%) and 4 (2.3%) patients with 70 Gy(p = 0.009). Quality of life data will be presented. Conclusions: Dose-intensified salvage RT to the prostate bed was not superior to conventional dose RT. However, dose-intensified salvage RT was associated with higher frequencies of late grade ≥ 2 gastrointestinal toxicity. Clinical trial information: NCT01272050.

A modified Delphi study to develop a practical guide for selecting patients with prostate cancer for active surveillance

Background

Active surveillance (AS) is a management option for men diagnosed with lower risk prostate cancer. There is wide variation in all aspects of AS internationally, from patient selection to investigations and follow-up intervals, and a lack of clear evidence on the optimal approach to AS. This study aimed to provide guidance for clinicians from an international panel of prostate cancer experts.

Methods

A modified Delphi approach was undertaken, utilising two rounds of online questionnaires followed by a face-to-face workshop. Participants indicated their level of agreement with statements relating to patient selection for AS via online questionnaires on a 7-point Likert scale. Factors not achieving agreement were iteratively developed between the two rounds of questionnaires. Draft statements were presented at the face-to-face workshop for discussion and consensus building.

Results

12 prostate cancer experts (9 urologists, 2 academics, 1 radiation oncologist) participated in this study from a range of geographical regions (4 USA, 4 Europe, 4 Australia). Complete agreement on statements presented to the participants was 29.4% after Round One and 69.0% after Round Two. Following robust discussions at the face-to-face workshop, agreement was reached on the remaining statements. PSA, PSA density, Multiparametric MRI, and systematic biopsy (with or without targeted biopsy) were identified as minimum diagnostic tests required upon which to select patients to recommend AS as a treatment option for prostate cancer. Patient factors and clinical parameters that identified patients appropriate to potentially receive AS were agreed. Genetic and genomic testing was not recommended for use in clinical decision-making regarding AS.

Conclusions

The lack of consistency in the practice of AS for men with lower risk prostate cancer between and within countries was reflected in this modified Delphi study. There are, however, areas of common practice and agreement from which clinicians practicing in the current environment can use to inform their clinical practice to achieve the best outcomes for patients.

Adoption of single fraction radiotherapy for uncomplicated bone metastases in a tertiary centre

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Single fraction radiotherapy is feasible for uncomplicated bone metastases.

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Four-week mortality was similar between single fraction and multiple fraction.

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Our paper has the highest rate of reported single fraction radiotherapy in literature.

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Re-irradiation were higher for single fraction radiotherapy in uncomplicated bone metastases.

Background

Single-fraction radiotherapy (SFRT) offers equal pain relief for uncomplicated painful bone metastases as compared to multiple-fraction radiotherapy (MFRT). Despite this evidence, the adoption of SFRT has been poor with published rates of SFRT for uncomplicated bone metastases ranging from <10% to 70%. We aimed to evaluate the adoption of SFRT and its evolution over time following the more formal endorsement of the international guidelines in our centre starting from 2013.

Materials and methods

We performed a retrospective review of fractionation schedules at our centre for painful uncomplicated bone metastases from January 2013 until December 2017. Only patients treated with 1 × 8 Gy (SFRT-group) or 10 × 3 Gy (MFRT-group) were included. We excluded other fractionation schedules, primary cancer of the bone and post-operative radiotherapy. Uncomplicated was defined as painful but not associated with impending fracture, existing fracture or existing neurological compression. Temporal trends in SFRT/MFRT usage and overall survival were investigated. We performed a lesion-based patterns of care analysis and a patient-based survival analysis. Mann-Whitney U and Chi-square test were used to assess differences between fractionation schedules and temporal trends in prescription, with Kaplan-Meier estimates used for survival analysis (p-value <0.05 considered significant).

Results

Overall, 352 patients and 594 uncomplicated bone metastases met inclusion criteria. Patient characteristics were comparable between SFRT and MFRT, except for age. Overall, SFRT was used in 92% of all metastases compared to 8% for MFRT. SFRT rates increased throughout the study period from 85% in 2013 to 95% in 2017 (p = 0.06). Re-irradiation rates were higher in patients treated with SFRT (14%) as compared to MFRT (4%) (p = 0.046). Four-week mortality and median overall survival did not differ significantly between SFRT and MFRT (17% vs 18%, p = 0.8 and 25 weeks vs 38 weeks, p = 0.97, respectively).

Conclusions

Adherence to the international guidelines for SFRT for uncomplicated bone metastasis was high and increased over time to 95%, which is the highest reported rate in literature.

Plasma ctDNA is a tumor tissue surrogate and enables clinical-genomic stratification of metastatic bladder cancer

Molecular stratification can improve the management of advanced cancers, but requires relevant tumor samples. Metastatic urothelial carcinoma (mUC) is poised to benefit given a recent expansion of treatment options and its high genomic heterogeneity. We profile minimally-invasive plasma circulating tumor DNA (ctDNA) samples from 104 mUC patients, and compare to same-patient tumor tissue obtained during invasive surgery. Patient ctDNA abundance is independently prognostic for overall survival in patients initiating first-line systemic therapy. Importantly, ctDNA analysis reproduces the somatic driver genome as described from tissue-based cohorts. Furthermore, mutation concordance between ctDNA and matched tumor tissue is 83.4%, enabling benchmarking of proposed clinical biomarkers. While 90% of mutations are identified across serial ctDNA samples, concordance for serial tumor tissue is significantly lower. Overall, our exploratory analysis demonstrates that genomic profiling of ctDNA in mUC is reliable and practical, and mitigates against disease undersampling inherent to studying archival primary tumor foci. We urge the incorporation of cell-free DNA profiling into molecularly-guided clinical trials for mUC.

Safety and Survival Rates Associated With Ablative Stereotactic Radiotherapy for Patients With Oligometastatic Cancer: A Systematic Review and Meta-analysis

Importance

The oligometastatic paradigm postulates that patients with a limited number of metastases can be treated with ablative local therapy to each site of disease with curative intent. Stereotactic ablative radiotherapy (SABR) is a radiation technique that has become widely used in this setting. However, prospective data are limited and are mainly from single institutional studies.

Objective

To conduct a meta-analysis to characterize the safety and clinical benefit of SABR in oligometastatic cancer.

Data Sources

A comprehensive search was conducted in PubMed/MEDLINE, Embase, Cochrane Database of Systematic Reviews, and Cumulative Index to Nursing and Allied Health Literature on December 23, 2019, that included prospective clinical trials and review articles that were published within the past 15 years.

Study Selection

Inclusion criteria were single-arm or multiarm prospective trials including patients with oligometastatic cancer (ie, ≤5 sites of extracranial disease), and SABR was administered in less than or equal to 8 fractions with greater than or equal to 5 Gy/fraction.

Data Extraction and Synthesis

The Population, Intervention, Control, Outcomes and Study Design; Preferred Reporting Items for Systematic Reviews and Meta-analyses; and Meta-analysis of Observational Studies in Epidemiology methods were used to identify eligible studies. Study eligibility and data extraction were reviewed by 3 authors independently. Random-effects meta-analyses using the Knapp-Hartung correction, arcsine transformation, and restricted maximum likelihood method were conducted.

Main Outcomes and Measures

Safety (acute and late grade 3-5 toxic effects) and clinical benefit (1-year local control, 1-year overall survival, and 1-year progression-free survival).

Results

Twenty-one studies comprising 943 patients and 1290 oligometastases were included. Median age was 63.8 years (interquartile range, 59.6-66.1 years) and median follow-up was 16.9 months (interquartile range, 13.7-24.5 months). The most common primary sites were prostate (22.9%), colorectal (16.6%), breast (13.1%), and lung (12.8%). The estimate for acute grade 3 to 5 toxic effect rates under the random-effects models was 1.2% (95% CI, 0%-3.8%; I2 = 50%; 95% CI, 3%-74%; and τ = 0.20%; 95% CI, 0.00%-1.43%), and the estimate for late grade 3 to 5 toxic effects was 1.7% (95% CI, 0.2%-4.6%; I2 = 54%; 95% CI, 11%-76%; and τ = 0.25%; 0.01%-1.00%). The random-effects estimate for 1-year local control was 94.7% (95% CI, 88.6%-98.6%; I2 = 90%; 95% CI, 86%-94%; and τ = 0.81%; 95% CI, 0.36%-2.38%]). The estimate for 1-year overall survival was 85.4% (95% CI, 77.1%-92.0%; I2 = 82%; 95% CI, 71%-88%; and τ = 0.72%; 95% CI, 0.30%-2.09%) and 51.4% (95% CI, 42.7%-60.1%; I2 = 58%; 95% CI, 17%-78%; and τ = 0.20%; 95% CI, 0.02%-1.21%) for 1-year progression-free survival.

Conclusions and Relevance

In this meta-analysis, SABR appears to be relatively safe in patients with oligometastatic cancer with clinically acceptable rates of acute and late grade 3 to 5 toxic effects less than 13% and with clinically acceptable rates of 1-year local control overall survival, and progression-free survival. These findings are hypothesis generating and require validation by ongoing and planned prospective clinical trials.

Trans-ancestry genome-wide association meta-analysis of prostate cancer identifies new susceptibility loci and informs genetic risk prediction

Prostate cancer is a highly heritable disease with large disparities in incidence rates across ancestry populations. We conducted a multiancestry meta-analysis of prostate cancer genome-wide association studies (107,247 cases and 127,006 controls) and identified 86 new genetic risk variants independently associated with prostate cancer risk, bringing the total to 269 known risk variants. The top genetic risk score (GRS) decile was associated with odds ratios that ranged from 5.06 (95% confidence interval (CI), 4.84-5.29) for men of European ancestry to 3.74 (95% CI, 3.36-4.17) for men of African ancestry. Men of African ancestry were estimated to have a mean GRS that was 2.18-times higher (95% CI, 2.14-2.22), and men of East Asian ancestry 0.73-times lower (95% CI, 0.71-0.76), than men of European ancestry. These findings support the role of germline variation contributing to population differences in prostate cancer risk, with the GRS offering an approach for personalized risk prediction.

The Multicenter, Randomized, Phase 2 PEACE V-STORM Trial: Defining the Best Salvage Treatment for Oligorecurrent Nodal Prostate Cancer Metastases

Optimal local treatment for nodal oligorecurrent prostate cancer is unknown. The randomized phase 2 PEACE V-STORM trial will explore the best treatment approach in this setting. Early results on the acute toxicity profile are projected to be published in quarter 3, 2021.

Radiomics to predict outcomes and abscopal response of patients with cancer treated with immunotherapy combined with radiotherapy using a validated signature of CD8 cells

BACKGROUND

Combining radiotherapy (RT) with immuno-oncology (IO) therapy (IORT) may enhance IO-induced antitumor response. Quantitative imaging biomarkers can be used to provide prognosis, predict tumor response in a non-invasive fashion and improve patient selection for IORT. A biologically inspired CD8 T-cells-associated radiomics signature has been developed on previous cohorts. We evaluated here whether this CD8 radiomic signature is associated with lesion response, whether it may help to assess disease spatial heterogeneity for predicting outcomes of patients treated with IORT. We also evaluated differences between irradiated and non-irradiated lesions.

METHODS

Clinical data from patients with advanced solid tumors in six independent clinical studies of IORT were investigated. Immunotherapy consisted of 4 different drugs (antiprogrammed death-ligand 1 or anticytotoxic T-lymphocyte-associated protein 4 in monotherapy). Most patients received stereotactic RT to one lesion. Irradiated and non-irradiated lesions were delineated from baseline and the first evaluation CT scans. Radiomic features were extracted from contrast-enhanced CT images and the CD8 radiomics signature was applied. A responding lesion was defined by a decrease in lesion size of at least 30%. Dispersion metrices of the radiomics signature were estimated to evaluate the impact of tumor heterogeneity in patient's response.

RESULTS

A total of 94 patients involving multiple lesions (100 irradiated and 189 non-irradiated lesions) were considered for a statistical interpretation. Lesions with high CD8 radiomics score at baseline were associated with significantly higher tumor response (area under the receiving operating characteristic curve (AUC)=0.63, p=0.0020). Entropy of the radiomics scores distribution on all lesions was shown to be associated with progression-free survival (HR=1.67, p=0.040), out-of-field abscopal response (AUC=0.70, p=0.014) and overall survival (HR=2.08, p=0.023), which remained significant in a multivariate analysis including clinical and biological variables.

CONCLUSIONS

These results enhance the predictive value of the biologically inspired CD8 radiomics score and suggests that tumor heterogeneity should be systematically considered in patients treated with IORT. This CD8 radiomics signature may help select patients who are most likely to benefit from IORT.

A Deep Learning Approach Validates Genetic Risk Factors for Late Toxicity After Prostate Cancer Radiotherapy in a REQUITE Multi-National Cohort

Background: REQUITE (validating pREdictive models and biomarkers of radiotherapy toxicity to reduce side effects and improve QUalITy of lifE in cancer survivors) is an international prospective cohort study. The purpose of this project was to analyse a cohort of patients recruited into REQUITE using a deep learning algorithm to identify patient-specific features associated with the development of toxicity, and test the approach by attempting to validate previously published genetic risk factors. Methods: The study involved REQUITE prostate cancer patients treated with external beam radiotherapy who had complete 2-year follow-up. We used five separate late toxicity endpoints: ≥grade 1 late rectal bleeding, ≥grade 2 urinary frequency, ≥grade 1 haematuria, ≥ grade 2 nocturia, ≥ grade 1 decreased urinary stream. Forty-three single nucleotide polymorphisms (SNPs) already reported in the literature to be associated with the toxicity endpoints were included in the analysis. No SNP had been studied before in the REQUITE cohort. Deep Sparse AutoEncoders (DSAE) were trained to recognize features (SNPs) identifying patients with no toxicity and tested on a different independent mixed population including patients without and with toxicity. Results: One thousand, four hundred and one patients were included, and toxicity rates were: rectal bleeding 11.7%, urinary frequency 4%, haematuria 5.5%, nocturia 7.8%, decreased urinary stream 17.1%. Twenty-four of the 43 SNPs that were associated with the toxicity endpoints were validated as identifying patients with toxicity. Twenty of the 24 SNPs were associated with the same toxicity endpoint as reported in the literature: 9 SNPs for urinary symptoms and 11 SNPs for overall toxicity. The other 4 SNPs were associated with a different endpoint. Conclusion: Deep learning algorithms can validate SNPs associated with toxicity after radiotherapy for prostate cancer. The method should be studied further to identify polygenic SNP risk signatures for radiotherapy toxicity. The signatures could then be included in integrated normal tissue complication probability models and tested for their ability to personalize radiotherapy treatment planning.

Radiotherapy treatment volumes for oligorecurrent nodal prostate cancer: a systematic review

BACKGROUND

Radiotherapy is an emerging treatment strategy for nodal oligorecurrent prostate cancer (PCa) patients. However, large heterogeneities exist in the RT regimens used, with series reporting the use of elective nodal radiotherapy (ENRT) strategies and others the delivery of focal treatments to the relapsing nodes with Stereotactic Body Radiotherapy (SBRT). In this systematic review of the literature we compared the oncological outcomes and toxicity of the different RT regimens for nodal oligorecurrent PCa patients, with the aim of defining the optimal RT target volume in this setting.

METHODS

We performed a systemic search on the Pubmed database to identify articles reporting on the use of ENRT or SBRT for oligometastatic PCa with nodal recurrence.

RESULTS

Twenty-two articles were analyzed, including four prospective phase II trials (3 with SBRT and 1 with ENRT). Focal SBRT, delivered with an involved node, involved site, and involved field modality, was the most commonly used strategy with 2-year progression-free survival (PFS) rates ranging from 16 to 58% and a very low toxicity profile. Improved PFS rates were observed with ENRT strategies (52-80% at 3 years) compared to focal SBRT, despite a slightly higher toxicity rate. One ongoing randomized phase II trial is comparing both modalities in patients with nodal oligorecurrent PCa.

CONCLUSIONS

With a large variability in patterns of practice, the optimal RT strategy remains to be determined in the setting of nodal oligorecurrent PCa. Ongoing randomized trials and advances in translational research will help to shed light on the best management for these patients. .

Management of Patients with Node-positive Prostate Cancer at Radical Prostatectomy and Pelvic Lymph Node Dissection: A Systematic Review

CONTEXT

Optimal management of prostate cancer (PCa) patients with lymph node invasion at radical prostatectomy and pelvic lymph node dissection still remains unclear.

OBJECTIVE

To assess the effectiveness of postoperative treatment strategies for pathologically node-positive PCa patients. The secondary aim was to identify the most relevant prognostic factors to guide the management of pN1 patients.

EVIDENCE ACQUISITION

A systematic review was performed in January 2020 using Medline, Embase, and other databases. A total of 5063 articles were screened, and 26 studies including 12 537 men were selected for data synthesis and included in the current review according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) recommendations.

EVIDENCE SYNTHESIS

Ten-year biochemical recurrence (BCR)-free, clinical recurrence-free, cancer-specific (CSS), and overall (OS) survival rates ranged from 28% to 56%, 70% to 92%, 72% to 98%, and 60% to 87.6%, respectively. A total of seven, five, and six studies assessed the oncological outcomes of observation, adjuvant radiotherapy (aRT), or adjuvant androgen deprivation therapy (ADT), respectively. Initial observation followed by salvage therapies at the time of recurrence represents a safe option in selected patients with a low disease burden. The use of aRT with or without ADT might improve survival in men with locally advanced disease and a higher number of positive nodes. Risk stratification according to pathological Gleason score, number of positive nodes, pathological stage, and surgical margins status is the key to risk stratification and selection of the optimal postoperative therapy. Limitations of this systematic review are the retrospective design of the studies included and the lack of data on adverse events.

CONCLUSIONS

While the majority of men with pN1 disease would experience BCR after surgery, long-term disease-free survival has been reported in selected patients. Management options to improve oncological outcomes include observation versus adjuvant therapies such as aRT and/or ADT. Disease characteristics should be used to select the optimal postoperative management for pN1 PCa patients.

PATIENT SUMMARY

Finding node-positive prostate cancer after a radical prostatectomy often leads to high postoperative prostate-specific antigen levels and is overall a poor prognostic factor. However, this does not necessarily translate into poor survival for all men. Management can be tailored to the severity of disease and options include observation, androgen deprivation therapy, and/or radiotherapy.

When What You See Is Not Always What You Get: Raising the Bar of Evidence for New Diagnostic Imaging Modalities

Even though prostate-specific membrane antigen (PSMA)-positron emission tomography (PET)-computed tomography (CT) is more accurate than conventional imaging in prostate cancer patients, its impact on patient-relevant outcomes is unknown. We argue that more evidence is required before using PSMA-PET-CT as the standard of care for staging.

Abstract PR08: The genomic landscape of metastatic urothelial carcinoma from circulating tumor DNA

The recent expansion of treatment options for patients with metastatic urothelial carcinoma (mUC) has emphasized the need for molecular biomarkers in this setting. However, knowledge of the somatic genome landscape in mUC is limited; large-scale sequencing efforts have relied on primary tumor tissue from muscle-invasive bladder cancer (MIBC), revealing a molecularly heterogeneous disease characterized in particular by high somatic mutation rates. Putative prognostic and predictive biomarkers described from primary tissue need validation in metastatic tumors. Given the challenge of obtaining metastatic tissue, we sought to utilize circulating tumor DNA (ctDNA) to characterize the somatic landscape in mUC. We collected 162 whole-blood samples from 90 mUC patients. Targeted next-generation sequencing was performed on cell-free DNA (cfDNA) and matched leukocyte DNA utilizing a custom 50-gene panel. Somatic alteration frequencies in our metastatic cohort were compared to those reported for primary MIBC by TCGA (Cell 2017, n=412), with data obtained via cBioPortal. Our cohort of 90 mUC patients included 14% with upper tract disease. The median cfDNA sequencing depth was 986x, with ctDNA detectable in at least one blood collection for 81% (73/90) of mUC patients. In 10/73 patients, the estimated tumor mutation burden was ≥30 mutations per Mb. TP53 was the most frequently mutated gene (46/73 ctDNA-positive patients). Chromatin modifiers were also frequently altered: ARID1A 27%, and 25% for KDM6A and KMT2D. Genes mutated in the PI3K pathway included PIK3CA (22%), PTEN (5.5%), and PIK3R1 (1.4%). FGFR3 mutations were identified in 8.2% of patients. ERBB2 mutations were present in 12.3% of patients, and amplification was detected in eight patients. Thus, the metastatic somatic landscape closely resembles primary disease; however, comparison to TCGA dataset revealed mutations in TP53 and FGFR1 were enriched for in the metastatic setting (TP53: 63.0% vs. 48.1%, p = 0.022; FGFR1: 5.5% vs. 1.5%, p = 0.049; two-sided Fisher's exact test). Profiling of ctDNA from a large mUC cohort suggests a relatively similar somatic landscape to primary MIBC. However, alterations in key driver genes are potentially over- or underrepresented in metastatic disease, which has prognostic implications. In mUC, ctDNA profiling is a powerful alternative to metastatic tissue biopsy.

This abstract is also being presented as Poster B19.

Citation Format: Gillian R. Vandekerkhove, Matti Annala, Jean-Michel Lavoie, Nora Sundahl, Simon Walz, Takeshi Sano, Andrew Murtha, Tilman Todenhöfer, Piet Ost, Kim N. Chi, Peter C. Black, Bernhard Eigl, Alexander W. Wyatt. The genomic landscape of metastatic urothelial carcinoma from circulating tumor DNA [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2019 May 18-21; Denver, CO. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(15_Suppl):Abstract nr PR08.

Comparative analysis of somatic variant calling on matched FF and FFPE WGS samples

Background

Research grade Fresh Frozen (FF) DNA material is not yet routinely collected in clinical practice. Many hospitals, however, collect and store Formalin Fixed Paraffin Embedded (FFPE) tumor samples. Consequently, the sample size of whole genome cancer cohort studies could be increased tremendously by including FFPE samples, although the presence of artefacts might obfuscate the variant calling. To assess whether FFPE material can be used for cohort studies, we performed an in-depth comparison of somatic SNVs called on matching FF and FFPE Whole Genome Sequence (WGS) samples extracted from the same tumor.

Methods

Four variant callers (i.e. Strelka2, Mutect2, VarScan2 and Shimmer) were used to call somatic variants on matching FF and FFPE WGS samples from a metastatic prostate tumor. Using the variants identified by these callers, we developed a heuristic to maximize the overlap between the FF and its FFPE counterpart in terms of sensitivity and precision. The proposed variant calling approach was then validated on nine matched primary samples. Finally, we assessed what fraction of the discrepancy could be attributed to intra-tumor heterogeneity (ITH), by comparing the overlap in clonal and subclonal somatic variants.

Results

We first compared variants between an FF and an FFPE sample from a metastatic prostate tumor, showing that on average 50% of the calls in the FF are recovered in the FFPE sample, with notable differences between callers. Combining the variants of the different callers using a simple heuristic, increases both the precision and the sensitivity of the variant calling. Validating the heuristic on nine additional matched FF-FFPE samples, resulted in an average F1-score of 0.58 and an outperformance of any of the individual callers. In addition, we could show that part of the discrepancy between the FF and the FFPE samples can be attributed to ITH.

Conclusion

This study illustrates that when using the correct variant calling strategy, the majority of clonal SNVs can be recovered in an FFPE sample with high precision and sensitivity. These results suggest that somatic variants derived from WGS of FFPE material can be used in cohort studies.

The ProBio trial: molecular biomarkers for advancing personalized treatment decision in patients with metastatic castration-resistant prostate cancer

BACKGROUND

Multiple therapies exist for patients with metastatic castration-resistant prostate cancer (mCRPC). However, their improvement on progression-free survival (PFS) remains modest, potentially explained by tumor molecular heterogeneity. Several prognostic molecular biomarkers have been identified for mCRPC that may have predictive potential to guide treatment selection and prolong PFS. We designed a platform trial to test this hypothesis.

METHODS

The Prostate-Biomarker (ProBio) study is a multi-center, outcome-adaptive, multi-arm, biomarker-driven platform trial for tailoring treatment decisions for men with mCRPC. Treatment decisions in the experimental arms are based on biomarker signatures defined as mutations in certain genes/pathways suggested in the scientific literature to be important for treatment response in mCRPC. The biomarker signatures are determined by targeted sequencing of circulating tumor and germline DNA using a panel specifically designed for mCRPC.

DISCUSSION

Patients are stratified based on the sequencing results and randomized to either current clinical practice (control), where the treating physician decides treatment, or to molecularly driven treatment selection based on the biomarker profile. Outcome-adaptive randomization is implemented to early identify promising treatments for a biomarker signature. Biomarker signature-treatment combinations graduate from the platform when they demonstrate 85% probability of improving PFS compared to the control arm. Graduated combinations are further evaluated in a seamless confirmatory trial with fixed randomization. The platform design allows for new drugs and biomarkers to be introduced in the study.

CONCLUSIONS

The ProBio design allows promising treatment-biomarker combinations to quickly graduate from the platform and be confirmed for rapid implementation in clinical care.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT03903835. Date of registration: April 4, 2019. Status: Recruiting.

Health-related quality of life overview after different curative treatment options in muscle-invasive bladder cancer: an umbrella review

PURPOSE

This umbrella review aims to evaluate the quality, summarize and compare the conclusions of systematic reviews investigating the impact of curative treatment options on health-related quality of life (HRQoL) in muscle-invasive bladder cancer (MIBC).

METHODS

The Cochrane Library, MEDLINE, Embase and Web of Science were searched independently by two authors from inception until 06 January 2020. Systematic reviews and meta-analyses assessing the impact of any curative treatment option on HRQol in MIBC patients were eligible. Risk of bias was assessed using the AMSTAR 2 tool.

RESULTS

Thirty-two reviews were included. Robot-assisted RC with extracorporeal urinary diversion and open RC have similar HRQoL (n = 10). Evidence for pelvic organ-sparing RC was too limited (n = 2). Patients with a neobladder showed better overall and physical HRQoL outcomes, but worse urinary function in comparison with ileal conduit (n = 17). Bladder-preserving radiochemotherapy showed slightly better urinary and sexual but worse gastro-intestinal HRQoL outcomes in comparison with RC patients (n = 6). Quality of the reviews was low in more than 50% of the available reviews and most of the studies included in the reviews were nonrandomized studies.

CONCLUSION

This umbrella review gives a comprehensive overview of the available evidence to date.