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Background There is a considerable need to incorporate biomarkers of resistance to new antiandrogen agents in the management of castration-resistant prostate cancer (CRPC). Methods We conducted a phase II trial of enzalutamide in first-line chemo-naïve asymptomatic or minimally symptomatic mCRPC and analyzed the prognostic value of TMPRSS2-ERG and other biomarkers, including circulating tumor cells (CTCs), androgen receptor splice variant (AR-V7) in CTCs and plasma Androgen Receptor copy number gain (AR-gain). These biomarkers were correlated with treatment response and survival outcomes and developed a clinical–molecular prognostic model using penalized cox-proportional hazard model. This model was validated in an independent cohort. Results Ninety-eight patients were included. TMPRSS2-ERG fusion gene was detected in 32 patients with no differences observed in efficacy outcomes. CTC detection was associated with worse outcome and AR-V7 in CTCs was associated with increased rate of progression as best response. Plasma AR gain was strongly associated with an adverse outcome, with worse median prostate specific antigen (PSA)-PFS (4.2 vs. 14.7 m; p

502 Background: Urothelial carcinoma (UC) commonly affects patients (pts) who are ineligible for full doses of cisplatin-based chemotherapy (CT) due to bad performance status, advanced age, or renal impairment. The combination of split-dose cisplatin with ATZ might be a feasible treatment for pts with UC who are unfit for full doses of cisplatin. Methods: The phase II SOGUG-AUREA clinical trial recruited treatment-naive pts in advanced or metastatic settings considered unfit for full dose of platinum-based CT. Pts received a split dose of cisplatin (35 mg/m2) and gemcitabine (1000 mg/m2) days 1 and 8 (up to 6 cycles) in combination with 3-weekly ATZ 1200 mg in D1 intravenously until progression, unacceptable toxicity, or absence of clinical benefit. Here we present the early results from the confirmed objective response rate (ORR) according to RECIST 1.1, the primary endpoint for efficacy, progression-free survival (PFS), overall survival (OS) and safety. Results: Between Jan 2021 and Mar 2022, 82 pts were screened, 66 pts were enrolled and received at least one dose of study treatment. Baseline characteristics are outlined in the table. The median duration of ATZ treatment was 4.4 months (m) (95%CI: 4.1-4.6). The confirmed ORR was 40.9%, with 5 (7.6%) pts having CR and 22 (33.3%) PR. The median duration of the response was 7 m (95%CI: 4.9-10.4). The clinical benefit rate (CBR) was 53%, and SD (maintained > 6m) was reported in 8 (12.1%) pts. Eight (12.1%) pts were not evaluable for response due to exitus previous to disease evaluation (9.1%), non measurable target lesions (1.5%) or withdrawal (1.5%). With a median follow-up of 9.3 m (range: 0.6-18.1), the median PFS was 6.9 m (95%CI: 6.4-9.2), with a 6-m PFS rate of 67.1% (95% CI: 56.5-79.7). The reasons for platinum ineligibility did not correlate with PFS. The 6-m OS rate was 78.2% (95%CI: 68.6-89). Most frequent grade 3-4 toxicities were neutrophil count decreased (24.2%), anemia (21.5%) and platelet count decreased (13.6%). Conclusions: ATZ with split doses of CT was safely administered in a population of frail pts with mUC who were unfit for CT showing promising preliminary survival outcomes in terms of response. Final survival results are awaited. Clinical trial information: NCT04602078 . [Table: see text]

96 Background: Radium-223 represents an option for symptomatic metastatic castration-resistant prostate cancer (mCRPC) after demonstrated an overall survival improvement in the ALSYMPCA trial. Radium-223 real-life experiences are scarce, particularly after the results of the ERA-223 trial. To describe Radium-223 outcomes in real life practice, and specifically those related with bone health, sequence of treatment, and prognostic factors. Methods: Multicenter retrospective study of a cohort of 143 patients with mCRPC treated with Radium-223 in either the second line or third line of therapy or beyond in the context of routine clinical practice between 11 March 2013 and 26 July 2022, in seven Galician hospitals. Survival estimates were calculated by the Kaplan-Meier method, and groups were compared with the log-rank test. The Cox proportional hazards regression model was used to evaluate factors independently associated with OS. Between March 11, 2013, and July 26, 2022, 143 patients were enrolled from 5 Galician hospitals. With a median follow-up of 9.68 months. All patients signed an informed consent form agreeing to participate in this observational study, that was approved by the Galician Ethics Committee, registration code 2018/282. Results: Baseline patient and disease characteristics are summarized. Median follow-up was 9.68 months. Median overall survival (OS) was 12 months (95% CI 9.7 – 16.0). Best OS outcomes were achieved in second and third line, 18 months (95% CI 12.0 – 26.0) and 9.4 months (95% CI 8.0 – 12.0) months, respectively. Among those baseline clinic-analytical factors analyzed, only alkaline phosphatase level >354 UI/L was correlated with a worse OS (HR 2.56 (95% CI 1.39 – 4.72; p=0.003) and the number of cycles of Radium-223 received (HR 0.63 (95% CI 0.54 – 0.73; p

e23135 Background: Breakthrough cancer pain (BTcP) is one of the most common symptoms related with the disease and its treatment. Its management differs from that of chronic pain but there is not a wide consensus about fundamental aspects of BTcP definition, diagnosis, follow-up, and management. The objective of this study promoted by ECO Foundation, is to reach a consensus on the follow-up of patients with BTcP under opioid treatment. Methods: This work was conducted using a modified Delphi method organized in two rounds and involving a panel of 84 medical oncologists. A questionnaire of 66 items was developed. The items proposed to reach a consensus included the following topics: 1) When to perform the first and subsequent BTcP treatment evaluations; 2) What to assess at the first follow-up visit and how; and 3) What to assess in the following visits and how. Results: After two rounds, a consensus was reached on 80.3% of the items proposed. The main agreements reached include: The first follow-up visit should preferably be face-to-face; increase the number of visits after detecting poor control of BTcP; assess pain control episodes of BTcP in the first and following visits; adjust treatment dose of opioids due to poor control of BTcP; and adopt measures to prevent aberrant opioid-induced behaviors when treating BTcP in patients with cancer. Conclusions: This Delphi consensus highlights the different points of view of medical oncologists regarding the follow-up of patients with BTcP under opioids treatment. Nonetheless, the conclusions reached can facilitate optimizing monitoring of these patients and promote long-term effectiveness of BTcP control.

Bladder cancer is the fourth most common cancer in men and the ninth most common in women in the Western world. The management of bladder carcinoma requires a multidisciplinary approach. Optimal treatment depends on several factors, including histology, stage, patient status, and possible comorbidities. Here we review recent findings on the treatment of muscle-invasive bladder carcinoma, advanced urothelial carcinoma, upper tract urothelial carcinoma, non-urothelial carcinoma, and urologic complications arising from the disease or treatment. In addition, we present the recommendations of the Spanish Oncology Genitourinary Group for the treatment of these diseases, based on a focused analysis of clinical management and the potential of current research, including recent findings on the potential benefit of immunotherapy. In recent years, whole-genome approaches have provided new predictive biomarkers and promising molecular targets that could lead to precision medicine in bladder cancer. Moreover, the involvement of other specialists in addition to urologists will ensure not only appropriate therapeutic decisions but also adequate follow-up for response evaluation and management of complications. It is crucial, however, to apply recent molecular findings and implement clinical guidelines as soon as possible in order to maximize therapeutic gains and improve patient prognosis.

4588 Background: Combined-modality treatments are bladder-preserving alternatives for patients (pts) who are not candidates for radical cystectomy by medical reasons, refusal, or patient´s choice. Immune therapies seem to potentiate tumor-specific immune response induced by radiotherapy (RT). Combination of RT with anti-PD-1/PD-L1 therapy appears safe and there are signs of promising activity. The aim of this study is to assess the efficacy and safety of atezolizumab (ATZ) concurrent with external beam radiotherapy (EBRT) for the treatment of muscle-invasive bladder cancer (MIBC) with bladder preservation intent. Here we present an interim analysis. Methods: This is an open, multicenter, and phase II trial, sponsored by SOGUG, in pts with confirmed diagnosis of MIBC in clinical stages cT2-T4a N0 M0 who are not candidates for radical cystectomy. Treatment consists of 6 doses of ATZ 1200 mg IV every 3 weeks, starting on day 1 of EBRT, and 60 Gy of RT in 30 fractions over 6 weeks at 2 Gy/day. The primary endpoint of the study is pathological complete response (pCR) defined as a response of grade 5 according to Miller and Payne criteria, 1 to 2 months after the last dose of ATZ. A planned interim analysis has been performed (data cut-off date: November 2021) on the primary endpoint to avoid exposure to ineffective treatment according to the minimax two-stages Simon’s design (stopping rule: 9 out of the first 13 evaluable pts should achieve pCR). Incidence of adverse events (AE) and serious AE (SAE) has been also secondarily assessed. Results: From September 2019 to November 2021, 39 pts were screened, of whom 13 were excluded due to non-compliance with eligibility criteria. Thus, the evaluable population consisted of 26 pts. The safety analysis was performed in 22 pts who had received at least one dose of ATZ. 14 pts were assessed pathologically and, thus, included in interim efficacy analysis (median age: 78.6 years; clinical stage: 71.4% T2a, 14.3% T2b, 7.1% T3a, 7.1% T3b). All 14 pts had achieved pCR at the cut-off date. 20/22 (91%) pts experienced at least one AE, with asthenia (11 pts), diarrhea (9 pts), and urinary tract infection (4 pts) being the most common. 9 SAEs were reported in 7 (32%) pts (bacteriemia, COVID-19 infection, depressed LVEF, unknown origin fever, hepatic toxicity, kidney failure, rectorrhagia, respiratory infection, and urinary sepsis). 6 (27%) pts suffered AEs leading to treatment discontinuation. No AEs leading to death occurred. 17 pts with available data on survival were alive at the cut-off date. Conclusions: Interim results suggest that ATZ combined with EBRT is a feasible and effective treatment in terms of pCR, with a manageable safety profile. The final results from this trial will provide information about its effects on clinical outcome, including survival and updated safety findings. Clinical trial information: NCT04186013.

Aim Cabazitaxel (CBZ), a novel tubulin-binding taxane, improves overall survival in metastatic castration-resistant prostate cancer (mCRPC) that progresses during or after docetaxel treatment. We have designed a phase II study to evaluate the efficacy and safety of CBZ as a weekly schedule for ‘unfit’ mCRPC patients after docetaxel failure. Methods In this single arm phase II study. CBZ was weekly administered in 1-hour infusion on days 1, 8, 15 and 22, every 5 weeks at 10 mg/m2 to eligible ‘unfit’ patients; oral prednisone (5 mg) was administered twice a day. Circulating tumour cells (CTCs) were also collected. New treatment scheme was considered effective if at least 65% of patients met a clinical benefit criteria based on prostate-specific antigen (PSA)-progression-free survival (PFS) values at week 12. Results Seventy patients (median age: 73.9 years) were enrolled; overall, 71.4% had an Eastern Cooperative Oncology Group Performance Status (ECOG-PS) of 2; and 84%, 16% and 11% had bone, liver and lung metastases, respectively. Objective partial response or stable disease was achieved in 61% of patients, while PSA responses of ≥50% and ≥80% were observed in 34.8% and 10.6%, respectively. The median PSA-PFS was 4.8 months; and 68.6% of patients had no progression at week 12. The most frequent grade 3/4 toxicities were neutropenia (2.8%), leukopenia (5.7%) and thrombocytopaenia (9%); no cases of febrile neutropenia were reported. Early CTC response was significantly correlated with PSA-PFS. Conclusions CBZ/prednisone administered weekly to ‘unfit’ mCRPC patients appears to be as effective as classical standard 3-week scheme (TROPIC study) but with significantly lower toxicities and better tolerance. Early CTC response appears to be valuable as an early end-point of therapeutic efficacy.

TPS4589 Background: First-line cisplatin-based chemotherapy (70 mg/m2) is the standard of care for LA/mUC patients (pts). However, about 50% will be ineligible for Cisplatin according to Galsky´s criteria. Moreover, a significant proportion of cisplatin-fit pts will receive carboplatin based on physician criteria. s-GC represents a feasible alternative in such situations, and could improve response rate compared to carboplatin regimens. Atezo is a programmed death-ligand 1 (PD-L1) inhibitor that is approved as first line treatment for cisplatin-ineligible LA/mUC pts with PD-L1 expression ≥5% (Ventana SP142). We present the study design of a phase II single arm trial of Atezo +s-GC in previously untreated pts with LA/mUC (NCT04602078). Methods: This single arm, open-label, multicenter study evaluates the efficacy and safety of Atezo +s-GC in previously untreated pts with LA/mUC. 66 pts will be enrolled and receive s-GC x 6 cycles (Cisplatin 35mg/m2 + Gemcitabine 1000mg/m2 on days 1 and 8 Q3W) and Atezo (1200 mg IV Q3W), followed by Atezo (1200 mg IV Q3W) until disease progression, toxicity or absence of clinical benefit. Eligibility criteria include histologically confirmed unresectable LA/mUC, measurable disease per RECIST 1.1 and adequate organ and marrow. Pts must be unfit for full cisplatin dose based on: age > 70 years, PS ECOG 0-2, creatinine Clearance >30 and 12 months prior to inclusion), prior autoimmune disease and uncontrolled significant illnesses. The primary endpoint is ORR per RECIST 1.1 assessed by investigator; the secondary endpoints are DoR, OS, PFS and safety. Biomarker analysis, including PD-L1 expression and microbiome relationship, will be an exploratory objective. The first two patients were enrolled in February 2021. Clinical trial information: NCT04602078.

Prostate cancer is the most frequent cancer amongst men. Until recently, only two therapeutic options, initial androgen-deprivation therapy in patients without castration-resistant prostate cancer, with addition of docetaxel when the disease becomes castration-resistant, were considered as standard. In the last years, new drugs (abiraterone, enzalutamide, Ra-223, Sipuleucel) have been developed for prostate cancer treatment with important advantages in safety and efficacy. Results from the recent Chaarted study, in patients that received docetaxel for the hormone sensitive disease, have contributed to change the initial treatment approach in metastatic prostate cancer, in order to adapt the best sequence for each patient. Those results have been supported by the Stampede trial. Stampede survival data showed not only a benefit in overall survival of adding docetaxel initially, but also a prolonged time to first skeletal related event. Now it is discussed in which setting the available drugs should be administered. This review article summarizes the treatment options for patients treated with docetaxel initially for hormone sensitive prostate cancer after developing progressive disease, and offers an algorithm proposal for treatment.

371 Background: Inflammation plays a key role in the pathophysiology of many diseases, including cancer. Systemic inflammatory factors have been validated as indicators of ongoing systemic inflammation that could be predictive markers of poor prognosis for oncological outcomes. However, it is unknown the prognostic impact of systemic inflammation markers in patients with GEP-NETs treated with PRRT. Methods: We conducted an observational, retrospective, multicentric study of 40 patients with GEP-NET treated with PRRT belonging to GGNET (Galician Research Group on Neuroendocrine Tumors) network at Nuclear Medicine Department of Santiago de Compostela University Hospital (Spain). The systemic inflammatory markers were calculated as follows: NLR = neutrophil count/lymphocyte count, PLR = platelet count/lymphocyte count, MLR= monocyte count/lymphocyte count, ALB= albumin levels and dNLR = neutrophil count/ (leucocytes count – neutrophils count). For the calculation of the different ratios, baseline analysis and after the second dose were used. The cut-off values were determined as the median of each values, correlating them with progression-free survival (PFS). Results: Data from 40 patients (pts) treated between 2016 and 2020 were recorded. Median age was 63.5 years (range 41-85) and 55% were male. Baseline ECOG PS 0/1/2 was 15 (37.5%)/16 (40%)/9 (22.5%). Tumor location was intestinal 26 pts (65%), pancreas 11 pts (27.5%) and unknown origin 3 pts (7.5%). 15 pts (37.5%) were functioning. Tumor grade G1/G2/G3 were 17 pts (42.5%)/ 20 pts (50%)/ 3 pts (7.5%), and Ki 67 20%/unknown were 11 pts (27.5%)/ 21 pts (52.5%)/ 3 pts (7.5%)/ 5 pts (12.5%), respectively. The most frequent site of metastasis was liver 32 pts (80%), lymph nodes 19 pts (47.5%), peritoneum 11 pts (27.5%) and bone 10 pts (25%). Surgery: 22 pts (55%) primary tumor surgery and 8 pts (20%) metastasectomy. Previous systemic treatments included somatostatin analogs (SSA) 40 pts (100%), everolimus 26 pts (65%) and sunitnib 11 pts (27.5%), others 7 pts (17.5%). The baseline cutoff-values for NLR was 2.61, for PLR 110.14, for MLR 0.31, for ALB 4.2. and for dNLR 1.71. The cutoff-values after the 2nd dose for NLR was 2.3, for PLR 2.15, for MLR 0.3, for ALB 4.2 and for dNLR 1.48. With a median follow up of 21 months, 14 pts (35%) had died. Median PFS was 27.2 m (95% CI 16.0-38.4m) and OS was not reached (NR). Pts with baseline higher NLR (>2.61 vs. 1.71 vs.

Neuroendocrine tumors (NETs) belong to a heterogeneous family of rare tumors with very broad and complex clinical behavior. Due to their heterogeneity, the lack of specific symptoms and the absence of sensitive methods for early detection, patients are usually diagnosed when the disease is in an advanced state for which curative treatments are scarce. In most cases, these few treatments try to prolong the survival of patients, maintaining the quality of life. The identification of biomarkers could help to improve early diagnosis and to choose the most suitable therapeutic strategy. This paper provides a review of the current histopathological diagnostic approaches for lung NET subtypes, including the predictive and prognostic factors, to help in the early diagnosis of this disease.

TPS601 Background: Radical cystectomy (RC) is the standard of care for patients with T2-T4a MIBC. Organ-preserving treatment is an alternative for patients who wish to attempt bladder preservation therapy or are ineligible for cystectomy. This includes maximal transurethral resection of bladder tumour, external beam radiation therapy (EBRT) and concurrent chemotherapy. The 5 and 10 year OS and disease specific survival (DSS) rates in contemporary RC series are comparable to that reported in bladder-preserving series. Due to EBRT can mediate inmunoestimulatory effects and that radiotherapy has been used in combination with different treatment regimens, a considerable interest has been attracted by combinatorial regimens involving EBRT plus checkpoint inhibitors. The purpose of the present study is to explore feasibility and activity of the combination of atezolizumab associated with EBRT after TURBT in the treatment of localized MIBC with preservation intent. Methods: The primary endpoint of this study is to assess the efficacy of atezolizumab concurrent with EBRT in terms of pathological complete response. The secondary endpoints include OS, DSS, disease free survival, bladder intact disease-free survival, number of patients (pts) with muscle invasive and non-muscle invasive local failure, the rate of distance metastases, the rate of pts with bladder preserved, the rate of immediate or late salvage cystectomy and safety profile and tolerability of the combination. Biomarkers will be evaluated as exploratory endpoints. Elegibility criteria include pts with histologically-confirmed diagnosis of MIBC in clinical stages T2-4a N0 M0, who are not candidates for radical cystectomy by medical reasons, refusal or patient’s choice, unfit for cisplatin and PS (ECOG) 0-2. Pts will receive atezolizumab 1.200 mg by IV infusion on Day1 of each cycle every 3 weeks for a total of 6 treatment courses, concurrent with EBRT 60 Gy in 30 fractions over 6 weeks at 2 Gy/day. With 35 evaluable pts and a pCR of 80%, the 95%CI of the estimation would be 0.62–0.92. The study will be stopped if we do not achieve at least 9 pCR among the first 13 evaluable pts. Otherwise, the study will continue until 39 pts. Clinical trial information: 2018-004348-47.

5040 Background: TMPRSS2-ERG fusion gene is a common driver of prostate cancer. The PREMIERE study is a phase II, single arm open-label, multicentre, clinical trial designed to analyse the predictive/prognostic value of TMPRSS2-ERG in first-line chemo-naïve mCRPC patients treated with enzalutamide. Methods: We centrally evaluated TMPRSS2-ERG in diagnostic samples using PCR, FISH and IHC for ERG. Among exploratory biomarkers we included plasma DNA, AR copy number by ddPCR and CTC by AdnaTest. PCWG2 criteria were used for outcome evaluation. We correlated TMPRSS2-ERGand other exploratory biomarkers with mCRPC outcomes. Results: Ninety eight patients with median age 77 y (range 59-95), ECOG 0/1 (54/46%) with mts located in bone (82%), LN (48%) and visceral (17%). With a median FU of 37.3 months, PSA response was PSA50: 82% and PSA90: 53%; median PSA-PFS was 13.7m (95%CI 10.2-19.0), Rad-PFS 26.7m (95%CI: 22.0-NA) and OS 37.5m (95%IC: 33.7-NA). TMPRSS2-ERG was detected in 32 pts (33%), AR gain in 11 pts and CTCs in 35 pts. No differences were observed based on TMPRSS2-ERG status for PSA response (PSA50: 81% vs 83%; p=0.8), PSA-PFS (median 12.8 vs 14.7m; HR 0.98; 95%CI 0.58-1.67; p=0.95), Rad-PFS (median 28.4 vs 26.4m; HR 1.02; 95% 0.53-1.96, p=0.95) or OS (median 36.9 vs 38.1m; HR 1.23; 95%CI 0.69-2.21, p=0.48). Plasma AR gain was associated with worse PSA-PFS (median 4.2 vs 14.7 m; p

176 Background: Cabazitaxel (CBZ) improves overall survival in mCRPC that progresses during or after docetaxel treatment. CABASEM is a phase II study to evaluate the efficacy and safety of a weekly schedule of CBZ for 'unfit' (ECOG2, previous neutropenic fever with docetaxel, or radiotherapy to

Review [Abstract] Radionuclides have been widely used for cancer treatment. Recently, new research about radium-223 dichloride has been conducted in prostate cancer, which reveals that it is the first radiopharmaceutical to demonstrate an improvement in overall survival and time to first symptomatic skeletal event in patients with castration resistant prostate cancer with symptomatic bone metastases. This fact has created a new paradigm in the treatment of prostate cancer landscape, where only chemotherapy and hormone therapy had a role, while β-emitters had been confined exclusively to the role of pain relief with no impact on survival. The aim of this review is to outline current treatment approaches for advanced prostate cancer with a focus on the role of radium-223 dichloride, reviewing patients' profile that make them suitable to therapy and chances for further studies.

5016 Background: Building on previous discoveries studying AR status in plasma (Carreira S, Sci Transl Med 2014, Romanel A, Sci Transl Med 2015) and following a road-map for biomarker development, we aimed to clinically qualify AR status in chemotherapy-naïve mCRPC using an optimized multiplex droplet digital PCR (ddPCR) assay (Condeduca et al.;ASCO2017;Abstract#). Methods: Between February and November 2015, 98 asymptomatic or oligo-symptomatic chemotherapy-naïve mCRPC patients were recruited in 16 Spanish hospitals. Tissue and blood samples were required at study entry. Although initially designed to study the predictive value of TMPRSS2-ETS, data emerging after the trial was initiated led the group to prioritize alternative predefined exploratory biomarkers, including plasma ARand CTC characterization (Grande E. ESMO 2016 & Font A. et al; ASCO2017; Abstract #). Outcome measures included PSA-progression-free survival (sPFS), radiographic progression-free survival (rPFS) and overall survival (OS). Cox regression was used for survival analyses and Fisher’s exact test for PSA response. Results: Ninety-four patients had plasma DNA available for analysis. At baseline, AR gain was present in 11 pts (12%) and CTCs in 35 (37%). AR gain in CTC-positive and negative patients was 20% and 7%, respectively. At first interim analysis and with a median follow-up of 10.6 months, detection of AR gain was associated with worse sPFS (median, 3.60 versus 15.5 m, HR, 4.33; 95% CI 1.94-9.68; P < 0.001), rPFS (median, 3.90 m versus not reached HR, 8.06; 95% CI, 3.26-19.93; P < 0.001) and OS (medians not reached, HR, 11.08; 95% CI, 2.16-56.95; P = 0.004). These results were independently associated in multivariate analysis including cfDNA and CTCs for all described endpoints. AR gain patients were less likely to have a ≥50% decline in PSA (OR, 4.93; 95% CI, 1.30-18.75; P = 0.025). Conclusions: Detection of AR gain in plasma using a robust multiplex ddPCR method predicts an adverse outcome in chemotherapy-naïve mCRPC. Further prospective randomized studies are warranted. Clinical trial information: NCT02288936.

5052 Background: Circulating tumor cells (CTCs) enumeration using CellSearch correlates with clinical outcome in prostate cancer, but is limited for gene expression analysis. AdnaTest ProstateCancer is a commercially available CTC immune-enrichment and PCR-related detection method that allows gene expression studies (Antonarakis E, NEJM 2014). It has demonstrated incremental detection of CTCs in patients with no CTCs identified by CellSearch (Samoila A, ASCO 2013) but needs to be clinically qualified. There is a strong need for studies to assess the association with the clinical outcome in CRPC. Methods: Between February and November 2015, 98 asymptomatic or oligo-symptomatic chemotherapy-naïve mCRPC pts were recruited in 16 institutions. Although initially designed to study the predictive value of TMPRSS2-ETS, data emerging after the trial was initiated led the group to prioritize alternative predefined exploratory biomarkers, including plasma AR (Grande E, ASC0 2017 #) and CTC characterization (Grande E, ESMO 2016). Outcome measures included PSA-PFS (sPFS), radiographic PFS (rPFS) and OS. Cox regression was used for survival analyses and Fisher’s exact test for PSA response. Results: Ninety-eight patients had CTC blood samples available. CTCs were detected at baseline, 12 weeks and progression in 36% (35/98), 27% (26/95) and 78% (32/41), respectively. The CTC conversion rate (positive to negative after 12 w) was 43% (15/35). All CTC conversions had ≥50% decline in PSA (15/15) whereas only 35% (7/20) of pts with persistent CTCs. At first interim analysis, with a median follow-up of 10.6 months, detection of CTCs at baseline was associated with worse sPFS (median, 7.59 m versus NR, HR, 3.67; 95% CI 1.90-7.10; P < 0.001), rPFS (median, 12.9 m versus NR; HR, 7.61; 95% CI, 2.80-20.64; P < 0.001) and OS (medians NR, HR, 9.51; 95% CI, 1.11-81.52; P = 0.0398). CTC positive pts were less likely to have a ≥90% decline in PSA (OR, 2.88; 95% CI, 1.13-7.72; P = 0.02). Conclusions: CTC detection using AdnaTest is associated with an adverse outcome in chemotherapy-naïve asymptomatic or oligo-symptomatic mCRPC pts. Clinical trial information: NCT02288936.

[Abstract] Enzalutamide (MDV3100), an androgen receptor-signalling inhibitor, represents the most recent compound added to the therapeutic armamentarium for the treatment of metastatic castration-resistant prostate cancer (mCRPC) who progressed to docetaxel. The anti-tumour activity and safety of enzalutamide has been demonstrated in a phase III clinical trial, showing a benefit in overall survival, which was the primary endpoint. There are no head-to-head studies comparing the different treatment options in this subset of patients. In this article, most relevant data published in the literature have been reviewed, with special attention to the therapeutic alternatives currently available for postdocexatel mCRPC patients, emphasising the mechanisms of action of the different drugs, efficacy and quality of life-related aspects.

A 75-year-old-man, with a 2-month history of abdominal pain, underwent a standard diagnostic workup that included a CT scan that showed a large right renal mass and subcentimeter nodes in the right and left lung lobes. In December 2003, the patient underwent right nephrectomy with adrenalectomy and a diagnosis of renal cell carcinoma (pT3N0M0 stage) was made. No further treatment was proposed and patient was followed up regularly. In October 2006, the annual gastrointestinal endoscopy showed asymptomatic multilobulated and polypoid masses in the gastric fundus and gastric body that corresponded to metastasis of the renal carcinoma that had been resected three years ago. Surgical treatment was refused and oral treatment with sunitinib (50 mg/day consecutively for 4 weeks followed by 2 weeks off) was initiated. Patient completed one cycle and development of acute toxicity (grade 3 asthenia, anorexia and mucositis) led to treatment interruption. After recovering from acute toxicity, the patient was proposed to reinitiate treatment with dose reduction, but he refused any medical treatment. At the follow-up visit, three months later, the gastrointestinal endoscopy showed four unspecific 2 mm nodules without malignant evidence. The whole-body CT did not reveal any other abnormality except for the known lung nodes. PET scan six months after treatment confirmed complete gastric response.

e20612Background: Nivolumab is an immune checkpoint inhibitor antibody and it has demonstrated durable responses and tolerability in pretreated patients with advanced NSCLC. This is an observationa...

A 63-year-old male, ex-smoker since 2000 underwent left radical nephrectomy in June 2004 after being diagnosed with stage II, pT3bN0M0 clear cell carcinoma. In June 2006, a control CT showed a nodule in the superior lobe, on a peripheral location, and another nodule in the base of the right lung. The patient underwent atypical resections of both nodules, confirming the presence of metastatic disease. In August 2006 the patient started treatment with sunitinib (50 mg/day for 4 weeks, with 2 weeks of rest). A total of nine cycles were administered. Periodic monitoring showed good tolerance, only presenting grade 2 erythrodisesthesia and grade 2 thrombocytopenia. CT studies performed every three cycles showed no evidence of disease recurrence. The last cycle was administered in September 2007 and PET imaging confirmed the absence of recurrence. With the patient s consent, treatment was interrupted and periodic radiological and clinical examinations were performed. The patient remained asymptomatic until March 2008 when a control CT revealed an objective progression of the disease at the left lung and mediastinum level. Treatment with sunitinib was restarted at the same doses, completing a total of three cycles, achieving a complete response. The patient is still under treatment.

TPS5073 Background: Enzalutamide (E) is a newly authorized drug for metastatic CRPC. E inhibits binding of androgens to androgen receptors, nuclear translocation of activated receptors and DNA tran...

167 Background: Cabazitaxel (C), a novel taxane developed to overcome D resistance, showed an overall survival improvement after D in metastatic castration-resistant prostate cancer (mCRPC) in a three-weekly schedule. Its main toxicity is hematological, especially in unfit patients. We aimed to evaluate efficacy and safety of weekly C/prednisone (P) schedule in "unfit" mCRPC previously treated with D. Methods: Unfit pts defined as ECOG 2, dose reduction due to febrile neutropenia during D treatment or radiation therapy affecting more than 25% of bone marrow reserve, with mCRPC progressing after D treatment with adequate bone marrow, liver and kidney functions were included. C 10 mg/m2 was administered on days 1, 8, 15 and 22 of 5-week cycles with P (5 mg b.i.d.). Radiological and PSA response were evaluated according to the PCWG2 (Scher H, 2008) criteria and toxicity according NCI-CTC AE. Results: To date 70 pts have been enrolled and data are available for 66. Median age was 73 y (range 54-84), 67% pts had ECOG 2, 87% had bone, 14% liver and 11% lung metastases. Half of pts had Gleason >7. Treatment: 271 cycles (median: 3; range: 1-12); 1002 weekly infusions (median 11; range 1-48). Median dose intensity was 93%. Eighteen of 55 pts (32.7%) achieve ≥50% PSA response and 5 (9.1%) ≥80% PSA response. Radiological response was evaluable in 56 pts. PR was observed in 4 pt (7.1%) and SD in 29 pts (51.8%). Median PFS was 3.9 months. Median OS was 14.2 months. Most frequent toxicities of all grades as % of pts were: anemia (71.2%), asthenia (43.9%), thrombocytopenia (15.1%), leukopenia (24.2%), diarrhea (27.3%), nauseas (18.2%), neutropenia (12.1%), peripheral neuropathy (7.6%), and anorexia (18.2%). Grade 3-4: thrombocytopenia (4.5%), anemia (6%), neutropenia (3.0%), asthenia (10.6%), diarrhea (1.5%), anorexia (1.5%), No grade IV diarrhea nor febrile neutropenia were observed. Conclusions: Weekly cabazitaxel (10 mg/m2) plus prednisone administered to unfit pts seems a highly effective treatment and safe, with no grade 4 neutropenia, diarrhea or febrile neutropenia reported. Clinical trial information: NCT01518283.

e16034 Background: Docetaxel (D) is standard first-line chemotherapy in patients (pts) with mCRPC. Cabazitaxel (C), a novel taxane developed to overcome D resistance, showed an overall survival imp...

190 Background: Docetaxel (D) is standard first-line chemotherapy in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC). Cabazitaxel (C), a novel taxane developed to overcome D resistance, showed an overall survival improvement in second line CRPC in a three-weekly dose schedule. Its main toxicity is hematological, especially in unfit patients. We aimed to evaluate efficacy and safety of weekly C/pred. in "unfit" mCRPC previously treated with D. Methods: Unfit pts (ECOG 2, dose reduction due to febrile neutropenia during treatment with D or radiation therapy affecting more than 25% of bone marrow reserve) with advanced CRPC progressing after D treatment with ECOG

e16014 Background: Docetaxel (D) is standard first-line chemotherapy in patients (pts) with metastatic castration-resistant prostate cancer (CRPC). Cabazitaxel (C), a novel taxane developed to overcome D resistance, showed an overall survival improvement in second line CRPC in a three-weekly dose schedule. Its main toxicity is hematological with a risk of febrile neutropenia, especially in unfit patients. We aimed to evaluate efficacy and safety of weekly C/prednisone in "unfit" metastatic CRPC previously treated with D. Methods: Unfit pts (ECOG 2, dose reduction due to febrile neutropenia during treatment with D or radiation therapy affecting more than 25% of bone marrow reserve) with advanced CRPC progressing after D treatment with ECOG

e15620 Background: VFL is the standard chemotherapy in second-line advanced TCCU in Europe (EMA approval 21/09/2009). We set up a multicenter retrospective study to evaluate the efficacy and toxicity of VFL in patients (pts) with advanced TCCU after platinum failure within the framework of routine practice. Methods: Descriptive and retrospective study in pts who had demonstrated prior progression to a platinum-containing chemotherapy regimen at 7 centers. VFL standard dose (280-320/m2 every three weeks) was administered until progression or unacceptable toxicity. Objective response was evaluated according to RECIST criteria v.1.1. Results: Between April 2010 and December 2012, a total of 45 pts with median age of 68 years (range 47-83) were analyzed. Main characteristics: ECOG 0-1-2 in 7pts (15.6%), 33pts (73.3%), 5pts (11.1%). Mean creatinine clearance was 59 ml/min. Primary sites of disease were bladder 39pts (86.7%), renal pelvis 5pts (11.1%) and prostatic urethra 1pt (2.2%). All pts had previously received platinum-based chemotherapy as a first-line treatment (cisplatin in 45% of pts). Metastatic locations were: 27pts (60%) lymph nodes, 18pts (40%) lung, 13pts (29%) bone and 10pts (22%) liver. The median number of cycles of VFL was 5 (1-18). All pts were assessed for response, one (2.2%) patient presented complete response (CR), 11pts (24.4%) partial response (PR), 18pts (40%) stable disease (SD) and 15pts (33.4%) progressive disease (PD). Median progression-free survival was 4 months (95% CI, 2.2-5.7). Median overall survival (OS) was 11 months (95% CI, 3.5-18). OS at 6 months was 45%. Liver metastasis was the main prognostic factor for OS (p=0.04). Grade 3/4 adverse events included neutropenia 6pts (13%), constipation 4pts (9%), abdominal pain 4pts (9%) and nausea/vomiting 3pts (6%). Conclusions: This retrospective analysis confirm VFL as an active agent in pts progressing after platinum-based combination for advanced TCCU in a daily clinical practice in Spain. As ESMO (Bellmunt J, 2011) and Spanish (Castellano D, 2012) guidelines recommend vinflunine, it should be offered in this setting or alternatively, treatment within a clinical trial.

e15077 Background: Renal cell carcinomas (RCC) constitute a morphologically and genetically heterogeneous tumor.Wnt proteins are a large family of secreted glycoproteins that activate intracellular signal transduction pathways to control a wide variety of cellular processes such as determination of cell fate, proliferation, migration, and polarity.Wnt signalling may be playing a central role during RCC development. Methods: To characterize Wnt signalling activity in RCC, we gathered 48 tumor samples from patients diagnosed with metastatic RCC between years 2006 and 2011. Expression levels of Wnt family members (Wnt1, Wnt2, Wnt3a, Wnt4, Wnt5a, Wnt7a, and Wnt9a) were examined by real-time PCR and immunohistochemistry in tumor and normal tissue from removed kidneys. Results: Wnt1 and Wnt5a were up-regulated in clear cell RCC being their relative expression 2.4.103 (Wnt1) and 4.102 (Wnt5a) times higher in renal tumor tissue than in normal tissue. One-way ANOVA test showed Wnt3a and Wnt4 as the best protein markers to distinguish clear cell RCC (F=3.95, p=0.010 and F=3.05, p=0.029, respectively). Wnt1 and Wnt7a were over-expressed in those cases which had undergone nefrectomy (Mann-Whitney U test p=0.065 and p=0.056 respectively). Finally, Wnt2 protein level was associated with those patients with high risk prognosis (Kruskal-Wallis test p=0.001). Conclusions: Our results indicate that Wnt3a and Wnt4 are potentially useful immunohistochemical markers for the differential diagnosis between clear cell RCC and other subtypes of RCC and also suggest a role for Wnt2 as a high risk prognosis marker.

e15067 Background:A multicenter retrospective analysis was performed in patients (pts) with metastatic RCC treated with sunitinib who achieved long-term PFS defined as ≥18 months. Methods: 46 pts (87% male) treated with sunitinib in first (74%) or subsequent lines were included. Median age was 59 years, most common histology was clear cell (93.5%), 89% had undergone prior nephrectomy, 28.3% were metastatic at diagnosis and 58.7% presented one site of metastasis, 28.3% two sites and 13% three or more and 12 (26%) had bone metastases. Good, medium, and poor prognosis (MKSCC) was presented in 30.4%, 67.4% and 2.2% of pts respectively. Median time from diagnosis to sunitinib treatment was 2.23 years and median duration of therapy was 27 months. At the time of analysis 37% were still receiving sunitinib. Reasons for discontinuation were progressive disease (83%), toxicity (10.3%) and death (3.4%). Results: Incidence of adverse events was as expected, with asthenia, hand food syndrome (HFS), hypertension, and mucositis as main toxicities. Efficacy results are described in the table. No significant differences in PFS with prior or nonprior history of hypertension, diabetes, or hyperlipidemia were observed. The emergence of drug-related toxicities, lack of bone metastasis, and being nonmetastatic at the time of diagnosis were independenly associated with a trend towards an improvement in PFS (p=NS)(see table). Conclusions: A comparison with a sunitinib-refractory population is planned and will provide additional information about prognostic biomarkers for long term response. [Table: see text]

e15076 Background: The characterization of factors involved in the etiology of renal cell carcinoma (RCC) may lead to the identification of new targets for therapy and prognostic markers. Recent data indicate that Notch family members can be expressed by malignant RCC cells and this expression may have potential use as a strong prognostic factor. The aim of this study was to investigate the potential of Notch family members as prognostic markers for stage IV patients. Methods: We analyzed, by means of immunohistochemistry and quantitative polymerase chain reaction, protein and mRNA levels of 4 Notch family members in tumor specimens obtained from 48 patients with stage IV RCC. Clinicopathological data for these patients were evaluated. A 34% of the population had hypertension, 7.3% had hypothyroidism, 19.5% were diabetic, 7.7% prediabetic, and 22% showed hyperlipidemia. RCC specimens included clear cell RCC: 34; papillary: 3; mixed: 1; undifferentiated: 1; hypernephroma: 1.The association among biomarkers and clinicopathological factors were explored using One-Way ANOVA test and non-parametric statistics, Mann-Whitney U and Kruskal-Wallis tests. Results: Relative expression of Nocth3 and Notch4 transcript levels were elevated 25-fold in clear cell RCC tumors when compared with normal kidney tissues. Notch1 and Notch2 were overexpressed at protein level in clear cell RCC (p>0.05). Those renal tumors with right localization showed highest levels of Notch4 protein (p=0.096). Notch2 overexpression was associated with patients who had undergone nefrectomy (p=0.038). Finally, Bonferroni post-hoc statistic test showed us a statistically significant association (p = 0.020) between Nocth1 protein expression levels and patients with medium risk prognosis. Conclusions: These results show a deregulated expression of Notch receptors in RCC and suggest a role for this pathway in the progression of this tumoral pathology.

e18146 Background: Efficacy of oral erlotinib has been conclusively established in 2nd line setting (BR.21 and TRUST studies) and the outcomes are similar to those provided by other approved chemotherapeutical agents (TITAN study). Higher responses rates have been found in p with Asian ethnicity, adenocarcinoma, women and never smokers, where predictive EGFR mutations occur more frequently; even though erlotinib has a significant effect on survival in all subgroups of patients. This observational study evaluates the efficacy of 2nd line erlotinib in unselected p with nsNSCLC in 4 Galician institutions. Methods: Unselected p with advanced nsNSCLC were treated with 150 mg/day of erlotinib as 2nd line therapy until unacceptable toxicity or progressive disease. EGFR mutational status was retrospectively tested when feasible, and serum carcinoembryonic antigen (CEA) monitored during the treatment period. Results: Baseline characteristics of 45 p included at the time of this analysis: mean age of 61.7 yrs. (range: 38-83); 80% male; 73.3% adenocarcinoma; 71.1% stage IV; 7/69/24% PS ECOG 0/1/2; 29/33/38 % never/current/former smokers. EGFR activating mutation testing was performed in 24 p (53%) and 2 positive cases were found (8%), both with metastatic adenocarcinoma (stage IV). The median PFS was 3.3 (95% CI: 1.6-5.1) and the median OS 10 months (95% CI: 7.5-12.5). Among p without EGFR mutations, erlotinib conferred a median OS of 8.1 months (95% CI: 1.4-14.9). Out of 31 p evaluable, radiologic response was achieved in 7 p (22.6%), for an overall disease control rate of 45.2 %. No unexpected toxicities were reported: 60 % of p experienced cutaneous toxicity (6.6 % grade ¾), 22.2% asthenia (4.4% grade ¾) and 17.8% diarrhea (2.2% grade ¾). Only 3 p discontinued due to adverse events. Conclusions: This study confirms the efficacy and safety of 2nd line erlotinib in a clinical practice scenario and the outcomes in p with non-squamous NSCLC are equivalent to those reported with the chemotherapy for salvage therapy. Moreover, the absence of mutations does not preclude the benefit from the drug. Updated data of the study will be presented.

e18040 Background: NSCLC is primarily a disease of older people with a median age of approximately 70 years (y) at diagnosis. Platinum combination chemotherapy (CT) has shown to be more effective than single agents but it is associated with more toxicity. Erlotinib is an EGFR TK inhibitor with a favourable toxicity profile and its oral administration makes it suitable to treat elderly p. No much is known about its efficacy and toxicities in this subpopulation, often under-represented in clinical trials. This Galician study aims to evaluate the efficacy and safety of erlotinib as 1st-line treatment (Tx) for elderly p with advanced nsNSCLC. Methods: Elderly p (≥70 years old) with stage IIIB/IV nsNSCLC were included in this prospective observational study. Erlotinib was orally administered at a dose of 150 mg daily until disease progression or intolerable toxicity. PFS (primary objective) and OS were measured from time of diagnosis. Results:A total of 31 p were enrolled. Baseline characteristics: Mean age 78 y (range 70-85); female 67.7%; adenocarcinoma (including BAC) 90.3%; never/current/former smokers (%): 54.8/16.1/22.6 (6.5% unknown), stage IV 84%; ECOG PS 0/1/2 (%): 6.4/45.2/48.4. The median PFS was 6.4 and the median OS was 9.9 months. Out of 26 evaluable p, 8 had PR and 8 SD, for an ORR of 30.8% and a DCR of 61.6%. The most common adverse event was skin rash, 38.7% (9.6% grade 3-4), diarrhoea, 25.8% (3.2% gr. 3-4) and asthenia, 19.3% (no gr 3-4 were reported). 5 p (16.1%) needed dose reduction and 3 p withdrew the Tx due to grade 3 diarrhoea, eye perforation and esofaghitis, respectively. EGFR mutational status was available for 10 p (32.2%); 4 p harboured activating mutations: 3 p achieved PR and 1 p SD. SLP of 31 (ongoing), 22.4 (ongoing), 13.6 and 9.8 months. Conclusions: These results in real-life settings confirm that erlotinib is an active and well tolerated agent as frontline Tx in elderly p (≥70) in nsNSCLC. Response rate is similar to that achieved with CT in younger people; benefit in PFS is modest, but median OS is acceptable, taking into account that half of the p had a PS of 2 EGFR mutation testing should be strongly encouraged among elderly p.