542 Background: Cisplatin-based chemotherapy remains the perioperative treatment in muscle-invasive bladder carcinoma (MIBC). Recent evidence suggests that immune checkpoint inhibitors could be incorporated in this setting. Olaparib is a PARP inhibitor with well-established activity in HRD tumor. Results from trials assessing the combination of durvalumab and olaparib suggest a synergistic effect. However, a molecular characterization is crucial to warrant a rational development. Methods: A phase II clinical trial was designed to assess the impact of neoadjuvant treatment with the combination of durvalumab plus olaparib in the molecular profile of MIBC (NCT03534492; SOGUG-2017-A-IEC(VEJ)-2). Efficacy and safety were secondary objectives. Subjects with cT2-T4a MIBC aimed for cystectomy were treated during 6 to 8 weeks pre-cystectomy. Diagnostic and surgical samples, pre and postreatment blood samples have been collected for the molecular analysis. We present results regarding efficacy and safety. Results: From November 2018 to October 2019 28 patients have been enrolled. 52%/48% of patients had PS 0/1. Median age was 70. TNM stage was: pT2 in 73,6% patients, pT3 in 10.6%, pT4 in 15.8% and 10.6% presented nodal spread. 13 patients have completed neoadjuvant treatment so far and 12 have undergone cystectomy. A wound dehiscence and one death related to surgical procedures were postoperative complications. Pathological complete response rate is 44,5%. Radiological evaluation is ongoing. 10 serious adverse events non-treatment related have been communicated. Any grade of toxicity has been reported in 91% of patients but adverse events grade 3-4 was detected in only 8.3% of cases. Grade 1 pruritus was the unique IR adverse event described in one patient. PARP inhibitors-related adverse events were grade 1 nausea and vomiting (25%), and grade 1 anemia (25%). Conclusions: Preliminary clinical data suggest that Durvalumab in combination with Olaparib could be active and well-tolerated neoadjuvant treatment of MIBC. Molecular characterization and biomarker discovery will be presented separately. Clinical trial information: NCT03534492.

Background: Covid-19 pandemic by the new coronavirus SARS-Cov-2 has produced devastating effects on the health care system, affecting also cancer patient care. Data about COVID-19 infection in cancer patients are scarce, and they point out a higher risk of complications due to the viral infection in this population. Moreover, cancer treatments could increase viral complications, specially those treatments based on the use of immunotherapy with checkpoints antibodies. There are no clinical data about the safety of immune check point antibodies in cancer patients when they become infected by SARS-CoV-2. As checkpoint inhibitors, mainly anti PD-1 and anti CTLA-4 antibodies, are an effective treatment for most melanoma patients, avoiding their use during the pandemic could lead to a decrease in the chances of curing melanoma. Methods: In Spain we have started a national registry of melanoma patients infected by SARS-Cov-2 since April 1st, 2020. A retrospective analysis of patients included in the Spanish registery has been performed weekly since the activation of the study. Interim analysis shows unexpected findings about cancer treatment safety in SARS-Cov-2 infected melanoma patients, so a rapid communication to the scientific community is mandatory Results: Fifty patients have been included as of May 17th, 2020. Median age is 69 years (range 6 to 94 years), 27 (54%) patients are males and 36 (70%) patients have stage IV melanoma. Twenty-two (44%) patients were on active anticancer treatment with anti PD-1 antibodies, 16 (32%) patients were on treatment with BRAF plus MEK inhibitors and 12 (24%) patients were not on active cancer treatment. COVID-19 episode has been resolved in 43 cases, including 30 (70%) patients cured, four (9%) patients that have died due to melanoma progression, and nine (21%) patients that have died from COVID-19. Mortality rates from COVID-19 according to melanoma treatment type were 16%, 15% and 36% for patients on immunotherapy, targeted drugs, and for those that were not undergoing active cancer treatment, respectively. Conclusion: These preliminary findings show that the risk of death in those patients undergoing treatment with anti PD-1 antibodies does not exceed the global risk of death in this population. These results could be relevant in order to select melanoma therapy during the COVID-19 pandemic

TPS503 Background: Perioperative treatment of muscle-invasive bladder carcinoma (MIBC) remains cisplatin-based chemotherapy, but recent evidences suggest that immune checkpoint inhibitors could be incorporated in this setting. Durvalumab is a PD-L1 blocking antibody active in advanced urothelial carcinoma pretreated with platinum-containing chemotherapy and currently under evaluation in first-line, both as monotherapy and in combination with tremelimumab. Olaparib is a PARP inhibitor especially important in tumors with deficiencies in DNA repair mechanisms. Preliminary results from combination trials suggest that these drugs could have synergistic effect dependent on an immunogenic modulation related with STING pathway, and an increase of neoantigens. Unexpected toxicities have not been described. Methods: Design: Open label phase II single arm clinical trial. Primary Objective: To assess the impact of neoadjuvant treatment with durvalumab plus olaparib in the molecular profile of MIBC. Secondary Objectives: Efficacy (Radiological and pathological responses); Safety. Exploratory objective: To identify predictive and prognostic biomarkers. Key correlative studies: Independent central pathologist for histological review and assessment of immunohistochemistry for PD1, PD-L1 and PD-L2; Genomic characterization (WES) and Expression assessment (RNAseq) of the tumors pre and post treatment; Assessment of soluble biomarkers and their evolution during the treatment: flow cytometry for immune cells; immunoassays for cytokines; HLA genotyping. Treatment: Durvalumab 1500 mg iv Q4W & Olaparib 150 mg bid orally during 6 to a maximum of 8 weeks pre-cystectomy. Recruitment: 29 patients. Collaborating institutions: 10 (members of Spanish Oncology Genitourinary Group). Key Inclusion Criteria: Subjects with histological confirmation of T2-T4a MIBC aimed for cystectomy without neoadjuvant chemotherapy; Available samples for correlative studies; Adequate medullary, renal and hepatic function. Key Exclusion Criteria: Use of immunosuppressive medication; Documented autoimmune disorders. Clinical trial information: NCT03534492.

mTOR pathway inhibitors are important drugs for the treatment of advanced renal cell carcinoma (RCC). However, no valid predictive markers have been identified to guide treatment selection and identify patients who are sensitive to these drugs. Mutations activating the mTOR pathway have been suggested to predict response; however, their predictive value is still unclear. Here, we present the genomic and functional characterization of a patient with metastatic clear cell RCC (ccRCC) who experienced a partial response to temsirolimus after a poor response to 2 previous lines of treatment. At the time of publication, the patient was disease-free 8 years after temsirolimus treatment. Multiregion whole-exome sequencing (WES) on 3 regions of the primary tumor, 1 metastasis, and blood revealed tumor mutations in driver genes in ccRCC: a missense mutation in (p.W88L), a loss-of-function mutation in (p.E454Rfs*15), and a novel missense mutation in (p.Y1974H). The mutation was present in all tumor regions, with similar allele frequency as the mutation, and in vitro functional assessment of the variant demonstrated that it increased mTORC1 activity. Consistently, immunohistochemistry in the tumor samples demonstrated increased levels of phospho-S6. In conclusion, multiregion WES identified a novel mutation acquired early during tumor development as the event leading to a high sensitivity to temsirolimus treatment. This study supports tumor multiregion sequencing to detect truncal mutations in the mTOR pathway to identify patients sensitive to mTOR inhibitors.

The mammalian target of rapamycin (mTOR) pathway inhibitors are key drugs for the treatment of many tumor types, however, there are no predictive biomarkers in clinical use. Here, we performed a molecular and immunohistochemical characterization of key mTOR pathway components in a series of 105 renal cell carcinoma patients treated with rapalogs, aimed at identifying markers of treatment response. Mutational analysis in MTOR, TSC1 and TSC2 was performed through targeted next‐generation sequencing (NGS), and immunohistochemistry (IHC) was performed for PTEN, pAKT, pS6K1, pS6 and p21. Among patients with NGS data, 11 of 87 (13%) had mTOR pathway mutations (8 in MTOR, 1 in TSC1 and 2 in TSC2). When comparing the molecular data to the response of the patients, we found that partial response was more frequent in cases with mTOR pathway mutations than in those without mutations (odds ratio [OR] = 0.08, 95% confidence interval [CI] = 0.008–0.79, p = 0.030 univariate; p = 0.038 multivariable). Regarding IHC, negative PTEN staining was detected in 58% of the tumors, and it was more frequent in rapalog responder patients (OR = 0.24, 95% CI = 0.065–0.86, p = 0.029 univariate; p = 0.029 multivariable). Mutations and PTEN IHC were not mutually exclusive events and its combination improved response prediction (OR = 0.16, 95% CI = 0.04–0.62, p = 0.008 univariate; p = 0.013 multivariable). The staining of other proteins did not show and association with response and no association with PFS was observed in unselected patients. In conclusion, our findings suggest that mTOR pathway mutations, negative PTEN IHC and their combination are potential markers of rapalog response.