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Up to 25% of patients with metastatic prostate cancer present with germline or somatic DNA damage repair alterations, some of which are associated with aggressive disease and poor outcomes. New data have brought poly(ADP-ribose) polymerase (PARP) inhibitors into sharp focus in the treatment of metastatic castrate-resistant prostate cancer (mCRPC). Olaparib improved survival after at least one new hormonal therapy (NHT) in a cohort of patients harboring BRCA1, BRCA2 or ATM mutations in the PROfound trial, while rucaparib, talazoparib and niraparib demonstrated compelling activity in phase II trials. While patients with prostate cancer and BRCA1 or BRCA2 mutations may derive greatest benefit of PARP inhibition, the magnitude of benefit seems much lower in the context of most other homologous recombination gene mutations. Several PARP inhibitors are currently developed in combination with conventional therapy, including chemotherapy, NHT, and alpha-particle emitters, at different disease stages. Herein, we review the rationale for PARP inhibition in patients with prostate cancer, discuss the impact of PARP inhibitors on outcomes, and explore underlying challenges for future developments.

Few prognostic factors have been identified in patients with metastatic urothelial carcinoma (mUC) treated with immune checkpoint inhibitors (ICIs). The Lung Immune Prognostic Index (LIPI) was associated with clinical outcomes for ICIs in several tumor types. We aim to assess the value of the LIPI in patients with mUC treated with ICIs. A retrospective ICI cohort and a validation cohort (SAUL cohort) included, respectively, patients with mUC treated with ICI in 8 European centers (any line) and patients treated with atezolizumab in a second or further line. A chemotherapy-only cohort was also analyzed. The LIPI score was based on 2 factors, derived neutrophils/(leukocytes minus neutrophils) ratio (dNLR) > 3 and lactate dehydrogenase > upper limit of normal, and defined 3 prognostic groups. The association of LIPI with progression-free survival (PFS) and overall survival (OS) was assessed. In the ICI and SAUL cohorts, 137 and 541 patients were respectively analyzed. In the ICI cohort, mPFS and mOS were 3.6 mo (95% CI; 2.6–6.0) and 13.8 mo (95% CI; 11.5–23.2) whereas in the SAUL cohort the mPFS and mOS were 2.2 mo (95% CI; 2.1–2.3) and 8.7 mo (95% CI; 7.8–9.9) respectively. The LIPI classified the population of these cohorts in good (56%; 52%), intermediate (35%; 36%) and poor (9%; 12%) prognostic groups (values for the ICI and SAUL cohorts respectively). Poor LIPI was associated with a poorer OS in both cohorts: hazard ratio (HR) for the ICI cohort = 2.69 (95% CI; 1.24–5.84, p = 0.035); HR = 2. 89 for the SAUL cohort (CI 95%: 1.93–4.32, p < 0.0001). Similar results were found in the chemo cohort. The LIPI score allows to identify different subgroups in patients with good prognostis according to the Bellmunt score criteria, with a subset of patients with poorer outcomes having an mOS of 3.7 mo compared to the good and intermediate LIPI subgroups with mOS of 17.9 and 7.4 mo, respectively. The LIPI score was associated with survival in mUC patients treated by ICIs. Future prospective studies will be required to test the combination of Bellmunt score and the LIPI score as a more accurate prognosis tool.

Immunotherapy has demonstrated its effectiveness in many cancers. In hepatocellular carcinoma (HCC), promising results shown in the first phase II studies evaluating anti-PD-1 or anti-PD-L1 monotherapies resulted in their approval in the United States. Approval was not obtained in Europe; subsequent randomized studies in first- or second-line treatment did not confirm these initial results. However, first data with immunotherapy plus antiangiogenic treatments or dual immunotherapy combinations were positive. In this context, the combination of bevacizumab and atezolizumab took the lead. The IMbrave150 trial revealed an improved objective response rate (ORR), progression-free survival, and overall survival with this combination versus the previous standard, sorafenib. Subsequent results of dual immunotherapy with the anti-CTLA-4 and anti-PD-1 monotherapies tremelimumab and durvalumab (also superior to sorafenib monotherapy) confirmed the value of using a combination in first-line treatment. These significant therapeutic advances, and the increase in ORR, raise two main questions. Whereas response was very limited with previous treatments, the ORR reported with these new combinations are between 20% and 30%. This raises the question of whether immunotherapy (ICI single agent, combination of ICI with antiangiogenic agent or other antitumoral treatment) can be used in patients beyond those in BCLC group C, the traditional candidate group for systemic therapy. We have thus seen an increasing number of patients previously treated with trans-arterial chemoembolization (BCLC group B) receiving these new treatments, and we develop the results of several studies combining loco-regional therapies and immunotherapy-based systemic treatments. The other major question is that of how and when to use these medical treatments as “adjuvants” to interventional radiology or surgery; the results of several works are discussed for this purpose. In this review, we cover all of these points in a fairly comprehensive manner.

809 Background: Peritoneal carcinomatosis (PC) is a common manifestation in gastro-intestinal (GI) cancers.10-20 % of patients (pts) will present isolated, unresectable peritoneal disease with poor prognosis. In the past years, circulating tumor DNA (ctDNA) has emerged as a novel and less invasive biomarker for molecular diagnosis and disease monitoring. We aimed to evaluate the ability of PC to shed ctDNA into circulation in a cohort of pts with GI cancers and isolated PC treated in our institution. Methods: We reviewed retrospectively the results of liquid biopsies obtained at progression or at diagnosis. Genomic analysis was done using Foundation One liquid CDx panel. Data on demographics, tumor type, clinical outcomes and molecular alterations (MA) have been collected. Results: Out of 400 GI pts tested, 85 with exclusively PC were included in the analysis. The main characteristics were as follows: 45(53%) female, median age of 57 years (IQR: 24-79), majority have received systemic chemotherapy (all were progressive) (n=63, 74%) with median number of previous lines 1 (range: 0-3). Most common tumor types were as follows: gastric (n=24, 28%), colorectal (n=22, 26%) and primary peritoneal (n=20, 24%) cancers. The median index of peritoneal carcinomatosis was 23(IQR: 6-39). The tumor fraction was very low or undetectable in a proportion of 81% (n=69), median Tumor Mutational Burden was 1 mutation per megabase and was not correlated to tumor volume. Gene alterations were found in a proportion of 56% of pts (n=48) but most common alteration were TP 53 (n=22 pts, 26%) and KRAS mutation (n=14 pts, 16%). Targetable MA were identified only in 11 pts (13%) as follows: ATM, ARID1A, BRAFV600E, ERBB2, krasG12C. Three of them were included in a clinical trial. Germline mutations were found in 5 pts: ATM, CDH1, BRCA2, MSH6, BAP1. For colorectal pts known KRAS and BRAF V600E mutations were confirmed in plasma in a proportion of 32% (7 pts out of 22), for pancreatic cancer the KRAS in 17% (3 out of 18) and for gastric cancer, ERBB2 amplification in 5% (1 out of 22 pts). In pts with primary peritoneal disease: pseudomyxoma and mesothelioma, one patient harbored a known germline BAP 1 and kras G12C mutation without other targetable MA. The median survival in MA group was higher compared to non-MA. Conclusions: Isolated Pc and primary peritoneal cancers have distinct clinical and biological characteristics. The clinical utility of ctDNA seems to be limited in isolated PC or primary peritoneal cancers. However, it is not very clear if this to tumor location or to the ability of peritoneum to seed ctDNA.

Until recently, continuing androgen deprivation therapy (ADT) and closely monitoring patients until evolution towards metastatic castration-resistant prostate cancer (CRPC) were recommended in men with non-metastatic CRPC (nmCRPC). Because delaying the development of metastases and symptoms in these patients is a major issue, several trials have investigated next-generation androgen receptor (AR) axis inhibitors such as apalutamide, darolutamide, and enzalutamide in this setting. This review summarizes the recent advances in the management of nmCRPC, highlighting the favourable impact of next-generation AR inhibitors on metastases-free survival, overall survival and other clinically meaningful endpoints.

605 Background: Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of death by cancer worldwide. Mostly diagnosed with locally advanced or metastatic disease, patients lack for treatment options. Gene alterations (GAs) are frequently observed in PDAC, some of them considered as actionable with molecular targeted therapies (MTTs), with potential clinical benefits and improved outcomes. Methods: We conducted a retrospective analysis of all patients, aged ≥18 years, with histologically confirmed PDAC, who underwent tumor molecular profiling between 2010 and 2020 in our institution as part of personalized medicine trials. Overall survival was the primary study endpoint (minimal follow-up after molecular profiling, 6 months). Results: Of 115 eligible patients, molecular profiling was successful in 102 patients (89%). KRAS mutations were the most frequent GAs, mostly G12D. Actionable GAs were found in 29 patients (28%), involving mainly BRCA1/2 (5 [18%]), HER2 (5 [18%]), MTAP (5 [18%]), and FGFR (3 [11%]). Only 12 of these 29 patients (41%, or 10% of the whole population) could receive MTTs accordingly, with a median progression-free survival of 1.6 months. Median OS was 17 months in patients with actionable GAs treated with MTTs (n = 12 [11.8%]), 14 months in patients with actionable GAs not treated with MTTs (n = 17 [16.7%]), and 19 months in patients without actionable GAs treated with standard therapies (n = 73 [71.5%]; p = 0.26). The absence of liver metastases was associated with better OS (HR = 0.471, p = 0.01). The longest duration of response with MTTs was observed in patients with BRCA mutations treated with olaparib. Conclusions: Actionable GAs are found in more than the quarter of patients with advanced PDAC. Overall, targeting actionable GAs with MTTs was not associated with improved OS in this retrospective study. However, selected GA/MTT duets (e.g., BRCA mutations/olaparib) were associated with better outcome.

95 Background: Oxaliplatin, a major drug in metastatic colorectal cancer (MCRC), is responsible for a cumulative and limiting peripheral neuropathy (PN). Hepatic arterial infusion (HAI) chemotherapy, which makes sense in cases of exclusive or predominant liver metastases, increases the intratumor concentration of the administered drug(s) to improve efficacy and limit systemic toxicity. Methods: We compared the frequency and severity of NP in oxaliplatin-naive patients with MCRC included in trials that evaluated treatment with oxaliplatin administered either by HAI (CHOICE, OSCAR, and PACHA-01 trials) or by intravenous (IV) route (FFCD 2000-05 trial). The primary endpoint was the occurrence of clinically significant NP (grade 2-4) according to the cumulative dose of oxaliplatin received. The secondary endpoints were the occurence of severe NP (grade 3-4) and time to onset of NP. Results: 342 patients were included (IV oxaliplatin: 300; HAI: 42). 180 patients in the IV group (60%) and 24 patients in the HAI group (57%) developed clinically significant NP, with no significant difference between the 2 groups (p = 0.85). 95 patients in the IV group (32%) and 8 patients in the HAI group (19%) developed severe NP, with no significant difference between the 2 groups (p = 0.082). NP appeared earlier in the HAI group, with more treatment discontinuations for neurotoxicity. Conclusions: The administration of oxaliplatin HAI rather than IV in the treatment of MCRC does not seem to reduce the incidence, precocity and severity of NP.

A targeted therapy is recommended in case of ERBB2 alteration for breast and gastric carcinomas, but miscellaneous other tumor types are ERBB2-altered at low prevalence. Broadening the administration of HER2 inhibitors across tumor types and genomic alterations could benefit to patients with refractory metastatic tumors. Targeted next-generation-sequencing (tNGS) and comparative genomic hybridization array (CGH) have been performed on fresh tumor biopsies of patients included in the MOSCATO-01 and ongoing MOSCATO-02 trials to administrate HER2 inhibitors in case of ERBB2 pathogenic mutation of amplification. Between December 2011 and January 2017 a molecular analysis was performed for 934 patients (759 CGH and 912 tNGS). A novel ERBB2 alteration has been found in 4.7% (n = 44/934), including 1.5% (n = 14/912) ERBB2 mutations, and 4% (n = 30/759) ERBB2 amplifications. A matched HER2 inhibitor was administrated to 70% (31/44) of patients and consisted in trastuzumab plus chemotherapy for 90% of them (28/31). On the 31 evaluable patients, 1 complete response (CR), 10 partial response (PR) and 2 stable disease (SD) >24 weeks were observed accounting for a clinical benefit rate (CBR) of 42% (n = 13/31, 95% CI 25–61%). Besides breast and oesogastric carcinomas, 19 patients affected by 8 different tumor types had a CBR of 25% for ERBB2 mutations (n = 2/8, 95% CI 3%–65%, with 2 PR) and 64% for ERBB2 amplifications (n = 7/11, 95% CI 31%–89%; with 1 CR, 4 PR, 2 SD). ERBB2 genomic alterations were diffuse across metastatic tumor types and signs of efficacy emerged for HER2 targeted treatments, especially in case of ERBB2 amplifications or a p.S310Y ERBB2 mutation.

Cancer immunotherapy is coming of age; it has prompted a paradigm shift in oncology, in which therapeutic agents are used to target immune cells rather than cancer cells. The first generation of new immunotherapies corresponds to antagonistic antibodies that block specific immune checkpoint molecules cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), programmed cell death protein (PD-1) and its ligand PD-L1. Targeting these checkpoints in patients living with cancer had led to long-lasting tumour responses. By unbalancing the immune system, these new immunotherapies also generate dysimmune toxicities, called immune-related adverse events (IRAEs) that mainly involve the gut, skin, endocrine glands, liver, and lung but can potentially affect any tissue. In view of their undisputed clinical efficacy, anti-CTLA-4 and anti-PD-1 antibodies are entering in the routine oncological practice, and the number of patients exposed to these drugs will increase dramatically in the near future. Although steroids can be used to treat these IRAEs, the associated immunosuppression may compromise the antitumour response. Oncologists must be ready to detect and manage these new types of adverse events. This review focuses on the mechanisms of IRAE generation, putative relationship between dysimmune toxicity and antitumour efficacy, as a basis for management guidelines.

545 Background: Prognostic factors for survival in metastatic urothelial carcinoma (mUC) have been reported in patients (pts) treated with chemotherapy (Bellmunt and al, JCO 2010). However, no biomarkers have been clearly identified in the setting of immune-checkpoint inhibitors (ICI). The Lung immune prognostic index (LIPI) was associated with clinical outcomes for ICI in lung cancer (Mezquita et al, Jama Oncol 2018) and other tumor types (Varga et al, TAT 2019). In this multicenter retrospective study, we correlated LIPI with outcomes in pts with mUC treated with ICI. Methods: Pts with mUC enrolled from May 2013 to July 2018 in 7 high volume centers were analysed. LIPI score includes: LDH > upper limit of normal and neutrophil/[leukocytes minus neutrophils] ratio (dNLR) > 3. The following LIPI subgroups were defined: good prognosis (0), intermediate prognosis (1) and poor prognosis (2 factors). Median (m) progression-free survival (PFS) and median overall survival (OS) were calculated using Kaplan-Meier method, log rank test was used for statistical comparison. Cox model was used for multivariate analysis. Results: To date, 152 mUC pts have been enrolled and preliminary analysis have been performed in 135 pts. Median age was 67 years, 111 (82%) pts were male, 106 pts (79%) had ECOG PS 0-1, 31 pts (23%) had liver metastasis. Median follow-up was 21.1 months (mo) (95% CI; 16.3-24.5), mPFS was 3.6 mo (95% CI; 2.6-6.0) and mOS was 13.8 mo (95% CI; 11.5-23.2). LIPI classified the population in good (56%), intermediate (35%) and poor (9%) prognosis group. In multivariate analysis, estimated mPFS in good, intermediate and poor prognosis were 5.8 mo (95% CI; 2.6-6.0), 3.6 mo (95% CI; 3.3-16.2) and 1.2 mo (95% CI;0.1-NR), respectively (p = 0.001). Estimated mOS in good, intermediate and poor prognosis were 17.3 mo (95% CI; 13.0-36.8), 16.9 mo (95% CI; 6.9-NR) and 5.4 mo (95% CI;2.5-NR), respectively (p = 0.19). OS data will be validated on larger cohort. Conclusions: The LIPI score is associated with clinical outcome to ICI and may be a useful tool for identifying patients who may not benefit from ICI. Validation in independent prospective cohort is ongoing.

239 Background: Corticosteroids have demonstrated activity in men with mCRPC. Previous data suggested that dexamethasone (D) can induce PSA responses when introduced after progression in mCRPC men receiving AR axis targeted drugs and/or prednisone (P). Methods: We prospectively tested P to D switch or D addition at PSA progression in 43 men with mCRPC with PSA progression and stable clinical disease. Baseline characteristics of the patients, time to castration resistance (TTCRPC), response to previous treatment, PSA response during D 0.5 mg/day and biochemical progression-free-survival (bPFS) after D initiation were recorded. Results were assessed using the Fisher’s exact test to compare variables. Results: Data from 43 patients were prospectively collected: 29 (67%) had been treated with abiraterone (AA) + P, 11 (26%) with enzalutamide (ENZ) and 3 (7%) with other treatments. At progression, 27 patients (63%) switched from P to D while continuing AA, 9 (21%) stopped their treatment and began D alone and 7 (21%) received D added to ENZ. Median age was 75 (70-79.5) and median bPFS with previous treatment was 17 months (6.75-22.25). After D initiation, 28% of patients had a PSA decrease ≥ 30% and the median bPFS was 4 months (2-6). The median bPFS was non-statistically different in patients with previous response to AR axis targeted drugs ≥ 6 months (4 [2-6] vs 1 [1-2] months; p-value = 1) and in those with TTCRPC ≥12 months (4 months [2-7.5] vs. 2 [1.5-2]; p-value = 0.3). Eleven patients (26%) had a bPFS ≥ 6 months and 5 (12%) had a bPFS ≥ 12 months. All long D responders (bPFS ≥ 6 months) had a TTCRPC ≥ 12 months, 10/11 patients had a previous PFS ≥ 6 months on AA or ENZ. None of the 2 patients (4.6%) with primary resistance to AA, responded to switch from P to D. Conclusions: D alone or in combination with previous AR axis targeted agents has activity in mCRPC men, with long responders observed amongst those with previous long response to ADT or to next generation AR axis targeting.

Aim: To determine the clinical significance of early PSA response during the first 4 weeks of therapy with next-generation androgen pathway inhibitors (enzalutamide, abiraterone acetate [AA], TAK-700) for metastatic castration-resistance prostate cancer (mCRPC). Methods: Data from patients prospectively recruited in clinical trials were studied. PSA values were obtained at baseline and 28 days (+/- 7d) after treatment initiation. PSA response defined as a decline > 50% from baseline was calculated according to PCWG2 (Scher et al, 2008). The effects of patient, tumor, and treatment characteristics on progression-free survival (PFS) and overall survival (OS) were examined using the Cox model. An independent cohort of patients treated with AA was used as validation population. Results: Early PSA response (EPR) was assessed in 118 patients treated with enzalutamide (AFFIRM and PREVAIL studies), AA (COU-AA-301 and 302 studies) and TAK-700 (C21004 and C21005 study). EPR was associated with longer PFS and OS (P Conclusions: Early PSA response is an independent prognostic factor in patients with mCRPC treated with next-generation androgen pathway inhibitors and may be useful for the therapeutic management of these patients. Disclosure: C. Massard: Consultant for Astellas Lectures for Sanofi, Astellas, Janssen; L. Albiges Sauvin: Advisory board Sanofi; K. Fizazi: Consultant Lectures for si, Astellas, Janssen, Takeda; Y. Loriot: Grant from Sanofi, Astelllas, Consultant for Astellas, Sanofi, Sellgene Lectures for Sanofi, Astellas, Janssen. All other authors have declared no conflicts of interest.