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2029 Background: The HER2 expression switching in circulating tumor cells (CTC) of breast cancer is dynamic and may have prognostic and predictive clinical implications. This study aims to analyse the association between expression of HER2 in CTC of patients with breast cancer brain metastases (BCBM) and brain disease control. Methods: Exploratory analysis of a prospective assessment (NCT02941536) of CTC before (CTC1) and 4–5 weeks after (CTC2) stereotactic radiotherapy/radiosurgery (SRT). CTC were isolated and quantified by a method of isolation by size of tumors and analyzed by immunocytochemistry to evaluate the expression of HER2. Distant brain failure-free survival (DBFFS), the primary endpoint, and overall survival (OS) were estimated by Kaplan-Meier estimator. Log-rank tests were applied in order to compare the survival curves. For multivariate analysis of prognostic factors that affected DBFFS and OS, the Cox proportional model was adjusted. Results: The median age at SRT was 54 (34-70), the diagnosis-specific graded prognostic assessment (DS-GPA) was 1–2 in 17.5% and 2.5–4 in 82.5% and the primary immunophenotype (PIP) was HER2-enriched in 51%, luminal B (LB) in 31% and triple negative (TN) in 18% of the total of 39 patients. CTC were detected in all 39 patients before SRT and the median CTC1 was 2 CTC/mL. After SRT, CTC were detected in 34 of 35 patients (4 deaths between CTC1 and CTC2) and the median CTC2 was 2.33 CTC/mL. HER2 was expressed in CTC1 and/or CTC2 in 9 patients, of which only 2 patients had PIP HER2-enriched. After a median follow-up of 16.6 months, there were 15 patients with distant brain failure and 16 deaths. The median DBFFS and OS were 15.3 and 19.5 months, respectively. Median DBFFS was 7 months in patients with PIP TN and was not reached in PIP LB and HER2-enriched (p = 0.036); 14 months in patients with DS-GPA 1-2 and 7 months with DS-GPA 2.5-4 (p = 0.017); 10 months in patients without HER2 expressed in CTC and not reached in patients with HER2 expressed in CTC (p = 0.012). Median OS was 4.8 months in patients with PIP TN and was not reached in PIP LB and HER2-enriched (p = 0.0026); 19.54 months in patients with DS-GPA 1-2 and 7.6 months with DS-GPA 2.5-4 (p = 0.00088); 17 months in patients without HER2 expressed in CTC and not reached in patients with HER2 expressed in CTC (p = 0.104). On multivariate analysis, DBFFS was superior in patients with PIP HER2-enriched (HR 0.128, 95% CI 0.025–0.534; p = 0.013) and OS was superior in patients with PIP HER2-enriched (HR 0.073, 95% CI 0.018-0.288; p < 0.0001) and LB (HR 0.224, 95% CI 0.062–0.816; p = 0.023). The status of expression of HER2 in CTC was not included in Cox model for DBFFS due to lack of events in patients with HER2 expressed in CTC. Conclusions: The expression of HER2 in CTC was associated with a longer DBFFS and the switching of HER2 expression between PIP and CTC may have impact on prognosis and treatment selection of BCBM.

e17545 Background: Androgen receptor-targeted agents Abiraterone and Enzalutamide (Abi/Ez) prolonged overall survival in metastatic castration resistant prostate cancer (mCRPC). Patients with very-low serum testosterone levels seem to have less benefit from these therapies as well as more aggressive prostate cancer. Methods: A retrospective observational cohort study was conducted to evaluate whether a serum testosterone measured at time of start first-line therapy with Abi/Ez is related to overall survival (OS) and time-to-treatment failure (TTF) in mCRPC patients. Kaplan-Meier survival estimates and Cox-regression models were used for time-to-event analyses. The best cut-off for testosterone was defined using Log-rank statistics (Lausen and Schumacher). X² test and Mann-Whitney U-test were applied to compare categorical and continuous variables, respectively. Logistic regression was used to assess characteristics related to serum testosterone levels. Statistical significance was fixed at 0.05. Results: From May 2012 to February 2017, 100 patients were assessed. Median follow-up was 27.8 months (range 2.23 to 68.26). Pts with a high testosterone level ( > 28.2; n = 20) achieved a significantly higher OS (median 66.0 vs 31.9 mo, testosterone > 28.2 HR: 0.206, 95% CI 0.074 to 0.571, p = 0.002) and TTF (median 30.6 vs 11.8 mo, testosterone > 28.2 HR: 0.408, 95%CI 0.219 to 0.762, p = 0.005) than pts with a low serum testosterone level ( < 28.2; n = 80), regardless of receiving therapy with either Abi (n = 69) or Ez (n = 31). Pts with a higher testosterone level were younger (median 67.7 vs 73.6 years; p = 0.026), had a higher body mass index (BMI) (28.5 vs 25.9, p = 0.023) and a lower PSA at start Abi/Ez (12 vs 26, p = 0.031) than pts with lower values. Age (OR 0.93, 95%CI 0.8 to 0.9, p = 0.021), BMI (OR 1.21, 95%CI 1.1 to 1.4, p = 0.006) and baseline PSA (OR 1.2, 95%CI 1.03 to 1.4, p = 0.020) were significantly associated with testosterone > 28.2. After 4 months of Abi/Ez treatment, PSA decrease > 50% of baseline was seen more frequently in high testosterone levels group than in low testosterone levels pts (90% vs 57.5% of pts, respectively, p = 0.007). Conclusions: Pts with high levels of testosterone ( > 28.2) achieved a better OS and TTF when treated with Abi/Ez in first-line mCRPC than those with low levels. Testosterone can be considered a prognostic and predictive biomarker in this scenario, and could be used in treatment decision for this population.

e22045 Background: Immune checkpoint blockade (ICB) has changed the natural history advanced melanoma (AM) with response rates about 40% and overall survival in 5 years of more than 30%. Interestingly, the site of metastasis may have impact on immune response due to the quantity and quality of immune infiltrate as we have seen in patients (pts) with liver metastasis treated with ICB. We have hypothesized that bone metastasis(BM) represents an immune less responsive site of disease Methods: We conducted a retrospective observational analysis of patients with AM treated with ICB at A.C. Camargo Cancer Center (AC) in São Paulo, Brazil. We analyze the impact of BM on progression-free (PFS) and overall survival (OS) using Kaplan Meier method, log-rank test and time-dependent COX regression model. Results: We analyzed 170 pts with AM treated with anti-PD1 (79%) or anti-PD1 + anti-CTLA4 (21%) between September 2013 and December 2019. Fifty-five percent in first-line, 22.4% second-line and the remaining in third or more lines of therapy. Ninety- four were male (55.3%), median age of 60.5 years (24.8 to 88.3) and 61 (35.9%) pts had BRAF mutation. Among stage IV patients (94%), 52 (32.4%) were M1c, 36 (22.4%) M1d and 46 (27%) had elevated LDH. Forty-two (26%) pts had BM. The overall response rate was 30.9% for pts with BM compared to 57.7% for pts without BM (p:0.004). In a median follow-up of 23.6 months (95% CI: 18.0-29.1), the median PFS and OS for pts with and without BM were 3.8 x 18.8 months (p 0.005) and 19.4months x not achieved (p 0.001), respectively. The 24-month analysis shows an overall survival rate of 38% for patients with BM compared to 62% for the rest of the cohort population. In a multivariate analysis for overall survival, acral melanoma, elevated LDH, ECOG performance status of 1 or 2 and BM were independent adverse prognostic factors (bone metastasis - HR: 2.3; 95%CI: 1.18-4.1; p:0.013). Conclusions: In this analysis, the presence of bone disease seems to be a worse independent prognostic factor for survival. A hypothesis would be the unfavorable bone microenvironment for the action of the immunotherapy.

10046 Background: Immune checkpoint blockade (ICB) has changed the natural history advanced melanoma (AM). Based on phase III trial, which used RECIST criteria, the complete response (CR) rate with anti-PD1 therapy is around 20%. In daily practice, PET/CT is a useful tool to evaluate response to treatment in melanoma patients. Little is known about the number of patients who achieve metabolic CR by PET/CT but with anatomic residual disease and their prognosis. Methods: We conducted a retrospective analysis of patients with AM treated with ICB who achieved metabolic CR by PET/CT but with residual disease on tomography and compared to patients with RECIST CR in a high-volume cancer center. Progression-free (PFS) and overall survival (OS) were obtained by Kaplan Meier method and log-rank test. Results: One hundred seventy pts with AM treated with anti-PD1 (79%) or anti-PD1 + anti- CTLA4 (21%) betweenSeptember 2013 and December 2019 were analyzed. At a median follow-up of 23.6 months, seventy-five (44%) pts achieved CR. RECIST criteria: 22 pts (29.3%) and metabolic CR: 53 pts (70.7%). All patients with metabolic CR had RECIST partial response. The median total time on treatment was 14.8m (95%CI:0.9-42.3). The median time to reach CR was 5.4m (95%CI: 3-39). The median time of treatment after CR was 6.8m (95%CI: 0-21.4). The rate of CR patients off treatment at the moment of this analysis was 69%. The median follow-up after discontinuing treatment was 5.2m. There was no difference in PFS (36 month-rate: 84.4% vs 74%, p:0.64) and OS (36 month-rate: 100% vs 86.3%, p:0.14) between pts with CR based on RECIST or PET-CT, respectively. Median time for PFS and OS have not been reached until the date cut-off. Nine pts have relapsed (12%). Seven of them had residual disease on tomography but with no metabolic active lesion(s) at the time of the end of treatment. Conclusions: Twice more patients achieve complete response considering only metabolic parameters on PET/CT compared to RECIST criteria and they seem to have comparable prognosis.

e22095 Background: The PD-1–blocking antibodies, combination of target therapy and anti-CTLA4 have shown a favorable safety profile with better efficacy than high-dose interferon in the adjuvant setting. However, in Brazil only a minority of patients in private institutions have access to new therapies in adjuvants. Here, we describe the evolution of patients with non metastatic melanoma who received anti-PD1 or target therapy adjuvant or only followed. Methods: This is an observational, descriptive, retrospective cohort, which included patients diagnosed with cutaneous, mucous or acral melanoma (operated stage III or stage IVa) submitted or not they undergoing adjuvant chemotherapy between January 2013 and December 2019 at AC, São Paulo, Brazil. Results: We evaluated 82 patients with a median age of 54 years, 62.2% of the patients were male, the majority, 81.1%, white. In 29.3% had primary ulceration and presence of satellites was observed in 18.3% and the average Breslow value of the cases was 3,3mm. We found that 18.3% of patients were classified as stage IIIA, 4.9% IIIB, 22% IIIC, 8.5% IIID and 9.8% stage IV operated. The 44.6% of patients completed 1 year of adjuvant treatment. Related to the presence of ulceration, we observed a progression-free survival of 36.3 months for cases with ulceration versus 47.1 months for cases with absent ulceration, ( p= 0.449). Patients with satellite presence had a progression-free survival of 29.9 months versus 49.1 months for cases of missing satellite, ( p= 0.118). Patients who underwent lymph node dissection had a progression-free survival of 50.3 versus 36.4 months, those who did not undergo ( p= 0.201). Patients who completed 1 year of adjuvant therapy achieved a recurrence-free survival of 66.1 versus 27.9 months who did not complete, ( p= 0.003). Considering the tumor staging, patients classified T1a-T2a had a progression-free survival of 59.8 months, T2b-T3b of 42 months and those grouped as T4a, T4b, of 29.9 months, ( p = 0.021). The median progression-free survival was 44 months, 40.6 months for patients who received adjuvant treatment versus 27.2 months for those who did not ( p = 0.271) with a reduced risk of progression in the order of 33% for patients who received adjuvant. Conclusions: The presence of ulceration, satellites and advanced T staging were associated with a worse outcome with a greater chance of recurrence. Emptying of the lymph node chain, receiving adjuvant treatment and completing 1 year of adjuvant treatment were directly associated with improved survival

e17538 Background: mCRPC phenotype involves androgen-receptor signalling mechanisms that support the use of abiraterone/enzalutamide (Abi/Ez). These therapies improve overall survival (OS) and quality-of-life, with a favourable safety profile. There is no validated data defining the best drug or sequence to be used. Methods: A retrospective study evaluated if a nomogram helps the decision-making of first-line for mCRPC. The nomogram evaluated time-to-treatment failure (TTF) from Abi/Ez and Docetaxel (Doc) treatment and had C-índex of 0.726. Time from start of androgen deprivation therapy to Abi/Ez or Doc, pain, Gleason score, testosterone and the lowest PSA in castration-sensitive scenario were analysed. All patients (pts) in Doc group used second-line Abi/Ez. The outcomes were: to evaluate whether the nomogram scores were associated with TTF/OS in Abi/Ez population; to compare OS between Abi/Ez and Doc poor prognostic (PP) groups based on the nomogram scores. Kaplan-Meier and Cox-regression models were used for time-to-event analyses. The cut-off was defined by Log-Rank. Statistical significance was fixed at 0.05. Results: From May/12 to Feb/20, 123 pts were assessed (79 received first-line Abi/Ez and 44 Doc). Median follow-up was 25.7 months (1.6 to 93.7). Nomogram scores based on Abi/Ez treatment (medium score of 65, 0-225) were statistically associated with OS (HR 1.02, 95% CI 1.01-1.02, p < 0.001) and TTF (HR 1.02, 95% CI 1.02-1.03, p < 0.001). 79 pts who received Abi/Enz were stratified as having good (GP) (score < 46), intermediate (IP) (score 46-112) and PP (score > 112), and it was associated with 75%, 25-75% and 25% probability to 1-year free from treatment failure, respectively. Pts with GP (n = 24) had a median TTF of 29.8m (15.4-44.2), IP (n = 44) 9.8m (4.1-15.4) and PP (n = 11), 4m (2.5-5.5), p = < 0.001. Pts with GP achieved higher TTF than IP (HR 2.3 95% CI 1.3-4.2 p = 0.005) and PP (HR 8.9 95% CI 3.8-20.6 p < 0.001). The results were similar for OS, once the median for GP was 54.0m (30.5-77.6); IP 34.8m (32.2-37.5); and PP 13.6m (9.3-17.9), p = 0.023 (GP versus IP: HR 2.1 95% CI 1.01-4.4 p = 0.046; GP vs PP: HR 3.6 95%CI 1.4-9.6 p = 0.011). Pts with a higher score and PP from Abi/Ez group were compared with Doc pts at first-line (n = 44), showing worse OS (HR 2.4 95%CI 1.03-5.6 p = 0.042) when treated with Abi/Ez. Conclusions: The nomograns scores showed good correlation with TTF/OS. In PP groups, treatment with Doc was associated with better OS than Abi/Ez, suggesting a possible tool on the first-line decision making.

202 Background: Survival outcomes for metastatic castration resistant prostate cancer (mCRPC) patients (pts) have greatly improved following the approval of Docetaxel and abiraterone(Abi)/enzalutamide(Ez). However, it is not clear who is likely to benefit more from these therapies in real life clinical practice. Methods: A retrospective cohort study was performed with mCRPC pts treated with Abi/Ez in pre-Docetaxel setting. Primary endpoint: to identify predictive biomarkers of long time to treatment failure (TTF), develop a nomogram and convert it into a web app. Secondary endpoint: to correlate biomarkers with overall survival (OS). Kaplan Meier survival estimates and Cox Regression models were used for time-to-event analyses. Statistical analysis was made with R software. All statistical tests were two-sided and statistical significance was fixed at 0.05. Results: From May2012 to October2017, 117 pts were assessed, 81 received Abi and 36 Ez. Median follow-up of 21 months (mo), estimated median TTF was 12.8mo (95%CI 9.98-15.7) for the total population. Predictive biomarkers for TTF included in the first nomogram model were time from start of androgen deprivation therapy (tADT) to start of Abi/Ez, pain at baseline, Gleason score, baseline testosterone and lower PSA nadir in castration sensitive prostate cancer (CSPC). The second nomogram model included pain and Gleason plus neutrophil counts, tADT to CRPC and baseline PSA at CRPC. C-index: 0.726 and 0.731 respectively, providing a reliable prediction of long-term benefit with Abi/Ez in this setting. All these characteristics were significantly associated with OS. Conclusions: The two nomogram achieved a good internal validation and can work as a tool to the decision-making process of the best strategy to first-line therapy in mCRPC pts.[Table: see text]

6061 Background: The prognostic impact of CTCs in LAHNSCC is yet to be determined, with conflicting results in previous trials, the majority utilizing cytokeratin dependent techniques for identification and counting of CTCs. The primary objective of this study is to determine the detection rates using the ISET method, and the prognostic role of CTCs in LAHNSCC patients (pts) treated with a curative intent. Methods: In this prospective study, peripheral blood samples of pts with non-metastatic LAHNSCC, stages III/IV, were analyzed for CTCs using the ISET method, in two scenarios: curative surgical resection and adjuvant radiotherapy (CTCs before RT) and candidates for a non-surgical strategy (unresectable or organ preservation) either with upfront RT concurrent with chemotherapy (CT) or cetuximab (CTCs before RT), or preceded by induction CT (CTCs before ICT). Results: Eighty-three pts were included, the majority males (83%), with oropharynx primary (50%) and submitted to ICT (40%). The detection rate of baseline CTCs was 94% (78/83), and CTCs counts were significantly correlated with survival. For each increase of 1 CTC at baseline there was a relative increase of 18% in the risk of death (HR = 1.18; 95%CI: 1.06-1.31; p < 0.001), 16% in the risk of progression (HR = 1.16; 95%CI: 1.04-1.28; p = 0.004) and a reduction of 26% in the odds of complete response to treatment (non-surgical group only - OR = 0.74; 95%CI: 0.58-0.95; p = 0.022). Using the maximum of the standardized log-rank statistic proposed by Lausen and Schumacher we establish cut off points for overall survival (OS) and progression-free survival (PFS). Pts with CTCs < 6.5/ml had an estimated 2y OS of 85.6% versus 22.9% for CTCs ≥ 6.5/ml (HR = 0.18; 95%CI: 0.06-0.49; P < 0.0001) and pts with CTCs ≤ 3.8/ml had an estimated 2y PFS of 71.8% versus 37% for CTCs > 3.8/ml (HR = 0.32; 95%CI:0.15-0.67; p = 0.001). Conclusions: The detection rate of baseline CTCs using the ISET method was very high in LAHNSCC and the counts of CTCs were strongly correlated with survival and response to treatment.

e566 Background: Cabazitaxel is an approved second-line treatment in metastatic castration-resistant prostate cancer therapy with a significant survival benefit compared to mitoxantrone. There are few data about cabazitaxel's toxicity in patients not selected. Objective: Evaluate the efficacy and toxicity among younger (< 70 years) and older (> 70 years) population. Methods: We selected 62 patients with metastatic castration resistant prostate cancer treated in AC Camargo Cancer Center from January 2011 to July 2015. 58 patients fulfilled the study criteria: diagnosis of adenocarcinoma prostate cancer, at least one session of cabazitaxel, with more than 18 years old. Results: We had in our sample 33 patients less than 70 years and 25 over 70 years. The initial dose of cabazitaxel was 25 mg/m2 in 75.8% of patients < 70 years and 52% in > 70 years patients. The use of granulocytics growing factor was observed in 64% of the older patients and more than 80% of this indication was in primary profilaxis. There were five deaths associated to the treatment, 4 lung infection and 1 kidney failure. The worst grade of adverse event up to 30 days after last administration was grade 2, including hematological and non-hematological events, both with no statistical significance between the groups. However, there was a greater number of febrile neutropenia in elderly people (28% versus 6%) with a statistical significance between < 70 e > 70 years (p 0.031). OS was 13,7 months (IC 9.16 – 18.2) and PFS was 4,6 months (IC 3.43 – 5.73). OS among the two groups was lower in < 70 years reaching 9,3 months (IC 2.06-16.5) versus 22.2 months (IC 4.86-39.50 ), p= 0.073. As well, PFS in < 70 years was 3.8 months (IC 3.26-4.36) versus 4.6 months (IC 2.4-14.1), p = 0.02. Conclusions: Treatment with cabazitaxel is tolerable, with manageable adverse events in a real-world patient population. In our cohort, elderly population (> 70 years) had more febrile neutropenia, suggesting dose reduction in this population, indication of granulocytic growing factor as primary profilaxis, close monitoring, and adequate patient counseling.

e17013Background: To evaluate the impact of the extension of radiotherapy field cranially towards para-aortic lymph nodes (EF-RT) in advanced cervical cancer. Methods: A systematic search of data-b...