Sanhueza, Cristobal T.

AbstractObjectiveElevated serum chromogranin A (CGA) is associated with intrinsic or treatment‐related neuroendocrine differentiation (NED) in men with metastatic castration‐resistant prostate cancer (mCRPC). Fluctuations in serum CGA during treatment of mCRPC have had conflicting results. We analyzed the impact of (i) rising serum CGA and (ii) baseline CGA/PSA ratio during treatment to identify associations with abiraterone acetate (AA) therapy.MethodsBetween June 2013 and August 2015, 92 men with mCRPC were enrolled in a prospective trial with uniform serum CGA processing performed before initiating abiraterone acetate/prednisone (AA/P) and serially after 12 weeks of AA/P treatments. Serum CGA was measured using a homogenous automated immunofluorescent assay. Patients receiving proton pump inhibitors or with abnormal renal function were excluded due to possible false elevations of serum CGA (n = 21 excluded), therefore 71 patients were analyzed. All patients underwent a composite response assessment at 12‐weeks. Kaplan–Meier estimates and Cox Regression models were used to calculate the association with time‐to‐treatment failure analyses and overall survival.ResultsAn increase in chromogranin was associated with a lower risk of treatment failure (hazard ratio [HR]: 0.52, p = 0.0181). The median CGA/PSA ratio was 7.8 (2.6–16.0) and an elevated pretreatment CGA/PSA ratio above the median was associated with a lower risk of treatment failure (HR: 0.54 p value = 0.0185). An increase in CGA was not found to be associated with OS (HR: 0.71, 95% CI: 0.42–1.21, p = 0.207). An elevated baseline CGA/PSA ratio was not associated with OS (HR: 0.62, 95% CI: 0.37–1.03, p = 0.062). An increase in PSA after 12 weeks of treatment was associated with an increased risk of treatment failure (HR: 4.14, CI: 2.21–7.73, p = < 0.0001) and worse OS (HR: 2.93, CI: 1.57–4.45, p = < 0.0001).ConclusionsWe show that an increasing chromogranin on AA/P and an elevated baseline CGA/PSA in patients with mCRPC were associated with a favorable response to AA/P with no changes in survival. There may be limited clinical utility in serum CGA testing to evaluate for lethal NED as AA/P did not induce lethal NED in this cohort. This highlights that not all patients with an increasing CGA have a worse OS.

Abstract Purpose: This phase Ib/2 trial investigated pembrolizumab-containing trimodality therapy in patients with gastroesophageal junction (GEJ) adenocarcinoma. Patients and Methods: Patients with GEJ adenocarcinoma (cT1–3NanyM0) received neoadjuvant pembrolizumab-containing chemoradiation (CROSS regimen) followed by surgical resection and adjuvant pembrolizumab. The primary endpoints were tolerability in the first 16 patients and pathologic complete response [pCR (ypT0N0)]. Secondary endpoints included progression-free survival (PFS) and overall survival (OS). An independent propensity-score-matched cohort (treated with CROSS without immunotherapy) was used for comparison. Exploratory analyses included immune biomarkers in the tumor microenvironment (TME) and plasma. Results: We enrolled 31 eligible patients, of whom 29 received all expected doses of neoadjuvant pembrolizumab and 28 underwent R0 resection. Safety endpoints were met. The primary efficacy endpoint was not met [7/31 (22.6%) achieved pCR]. Patients with high [i.e., combined positive score (CPS) ≥ 10] baseline expression of programmed death (PD)-L1 in the TME had a significantly higher pCR rate than those with low expression [50.0% (4/8) vs. 13.6% (3/22); P = 0.046]. Patients with high PD-L1 expression also experienced longer PFS and OS than propensity-score-matched patients. Among trial patients with PD-L1 CPS &lt; 10, unprespecified analysis explored whether extracellular vesicles (EV) could identify further responders: an elevated plasma level of PD-L1–expressing EVs was significantly associated with higher pCR. Conclusions: Adding pembrolizumab to trimodality therapy showed acceptable tolerability but did not meet the pre-specified pCR endpoint. Exploratory analyses suggested that high PD-L1 expression in the TME and/or on EVs may identify patients most likely to achieve tumor response.

452 Background: Surgical resection is the only curative treatment for patients with gallbladder cancer, despite surgical advances many patients ultimately develop recurrent disease. Management of resected gallbladder cancer mostly relies on single-arm trials and retrospective observations. The purpose of our study is to assess the role of adjuvant therapy in stage I-III gallbladder cancer patients who have undergone surgical resection. Methods: Clinical data were collected on 251 patients who underwent surgical resection for stage I-III gallbladder cancer and presented to Mayo clinic from January 2000-December 2015. Patients were then classified into adjuvant treatment group and surveillance only group. Overall survival and recurrence were compared between the two groups. Results: 78 (31.1%) patients received adjuvant therapy while 173 patients were observed only. Patients who received adjuvant tended to be younger (63.0[SD 11] vs 66.2 [SD 13.1]), have higher stage, and underwent extended surgery. Most patients received chemoradiotherapy (55) with 5-Fluorouracil (67.3%) and capecitabine (25.5%) as radiosensitizing agents. 21 patients received additional adjuvant chemotherapy. 27% of patients received chemotherapy as the sole adjuvant treatment. The most common chemo regimens included gemcitabine (52.3%) and gemcitabine plus cisplatin combination (23.8%). On multivariate analysis patients > 65 years(HR 1.53 [1.07-2.19], p = 0.02), males (HR 1.7 [1.2-2.4], p = 0.003), positive margins (2.77 [1.69-4.38], p < 0.01), and stage III (HR 1.91 [1.35-2.70], p < 0.01) had worse overall survival. Patients who underwent extended radical resection (HR 0.73 [0.51-1.05], p = 0.09) had better overall survival. Adjuvant therapy had no statistical significant effect on overall survival (HR 1.10 [0.75-1.59], p = 0.63 or disease free survival (HR 1.05 [0.69-1.59], p = 0.81) on overall population. However, in stage IIIB, patients receiving adjuvant therapy had better overall survival (HR 0.51 [0.25-1.01], p = 0.05) and disease free survival (HR 0.45 [0.19-1.09], p = 0.06). Conclusions: In our study, adjuvant treatment, especially chemoradiation therapy, was only beneficial in patients with stage IIIb gallbladder cancer patients.

450 Background: The standard treatment for patients with gallbladder cancer is a combination of gemcitabine and cisplatin based on ABC-02 trial. However, there are no guidelines regarding treatment after first-line therapy. We retrospectively analyzed the efficacy and overall survival of different second-line regimens. Methods: We identified 203 patients with advanced gallbladder cancer who received palliative treatment between January 2000 and December 2015 at Mayo Clinic, Rochester. RECIST criteria was used to assess response. Results: 68 patients received second-line chemotherapy. Median age was 63 years (range: 32-86) and majority were males (60.6%). The median time from the diagnosis to the start of the second line chemotherapy was 8 (1-120) months. The most common used second-line chemotherapy were FOLFOX (14), gemcitabine alone (10), single agent fluoropyrimidine (11), gemcitabine with capecitabine (5), and capecitabine with oxaliplatin (4). There were 30 patients that received 5-fluorouracil based regimens, 20 patients received gemcitabine-based regimen, 3 patients received taxane-based regimen, and 15 patients received other types of chemotherapy. Median progression free survival and overall survival was 2.1 (1.8-2.7) and 16.7 (13.2-21.3) months respectively. There were 10 (52%), 11 (37%), 2 (67%), 5 (33%) with partial response and stable disease in 5-fluorouracil-based, gemcitabine-based, taxane-based, and others, respectively. There were no difference in PFS, with median PFS of 2.5, 2.0, 2.8 and 2.3 months, respectively (p=0.43). The overall survival were 15.7 (8.9-40.2), 15.0 (10.7-21.3), 40.3 (22.0-47.0), and 20.4 (9.2-30.7) months, respectively (p=0.83). There were 27 patients that received single agent chemotherapy and 41 patients that received combined regimen. There were 17 (42%) patients and 13 (48%) patients with partial response or stable disease in single and combined regimen. There were no differences in progression free survival and overall survival between single and multi agent chemotherapy. Conclusions: In this largest single institution study, second-line chemotherapy regimens for gallbladder cancer provided benefit in select patients and there is an urgent need to develop more active therapeutic regimens.

5058 Background: The detection of full length AR (AR-FL) or AR variants (AR-Vs) in blood and association with outcomes in mCRPC is unknown. We compared whole blood mRNA expression of AR-FL and AR-Vs to circulating tumor cells (CTCs) for predicting OS and time to treatment failure (TTF). Methods: We isolated RNA from whole blood collected in PAXgene RNA tubes and concurrent metastatic tissue biopsy from 51 men with mCRPC prior to initiation of abiraterone acetate in a prospective clinical trial (NCT#01953640). Whole transcriptome sequencing (RNAseq) was performed on blood samples and paired biopsies to detect AR-FL, ARV1, ARV3, ARV7, ARV8, AR12, ARV14, and ARV45. Reads were aligned to the GRCh38 reference genome with the spliced-alignment TopHat2 package. The Pearson correlation coefficient was calculated between AR-FL in blood and matched bone biopsy. CTCs were determined using the CELLSEARCH assay. Cox proportional hazard regression analysis was performed on AR-FL, each AR-V, and CTCs for association with OS and TTF. We compared the area under the curve (AUC) using CTCs alone to a multivariable model that included AR-Vs for predicting OS. Results: The median follow up was 3.0 years, (range 0.3-3.5); the median CTC count was 3 (range 0-372); 34/53 men were deceased. Blood based AR-FL or AR-Vs were detected in 50/53 patients with following distribution: AR-FL (41/53), ARV3 (9/53), ARV45 (8/53), ARV12 (4/53), ARV14 (4/53), ARV7 (2/53), and ARV8 (2/53). Whole blood AR-FL transcripts were highly correlated to paired bone biopsy (r2= 0.76). Elevated transcripts of either ARV12 or ARV14 were associated with decreased OS [hazard ratio (HR) 3.46, p = 0.006]. CTC count ≥5 was associated with poorer OS [HR 3.42, p = 0.02] and shorter TTF [HR 3.52, p = < 0.001]. Adjusting for CTC counts, in a multivariate model, blood AR12 expression was associated with poor OS [HR = 6.33, p = 0.009]. AR12 and CTCs trended toward improved AUC compared to CTC alone (0.78 vs 0.71, p = 0.07). Conclusions: AR-FL and AR-Vs are detectable in whole blood and are highly correlated with metastatic bone AR-FL expression. AR-Vs may add to prognostication in mCRPC and further validation is needed. Clinical trial information: NCT#01953640.

e15797 Background: Duodenal adenocarcinoma is a rare tumor representing approximately 0.3% of all gastrointestinal tract cancers. Prognostic factors in relation to survival outcomes for these patients are sporadically reported in the medical literature. We aimed to evaluate outcomes of patients with duodenal adenocarcinoma who underwent pancreaticojejunostomy treated at Mayo Clinic Rochester from January 1, 2006 to December 31, 2016. Methods: Clinicopathological data of 52 duodenal cancer patients were collected. JMP software was used for statistical analysis. Kaplan-Meier method and log-rank tests were used for survival analysis, and multivariate cox proportional hazards model was used to evaluate the prognostic effect of pertinent clinical variables. All tests were two sided and a P value of < 0.05 was considered significant. Results: The median age at diagnosis was 65.9 years (range 39-81). The median overall survival was 51 months (95% CI 31.3-105.4) and the median progression free survival was 30.4 months with median follow up of 73.4 months. There were 3, 9, 21, and 19 patients with stage I, II, III, and IV disease, respectively. Depth of tumor invasion (p = 0.0156) and lymph node metastasis (p = 0.0441) were associated with overall survival on multivariate analysis. Advanced clinical staging influenced overall survival in univariate analysis, but lost prognostic significance in multivariate analysis. Age, gender, surgical technique, presence of metastases, tumor size, number of lymph nodes removed, location of duodenal segment involvement, and adjuvant treatment had no significant impact on overall survival. Laparoscopic approach did not influence survival but was associated with less hospital days (p = 0.0437). Conclusions: Depth of tumor invasion and lymph node status were associated with improved overall survival in patients with duodenal adenocarcinoma. Laparoscopic procedure decreased the hospital stay without affecting outcomes.

e15757 Background: SPN is a rare neoplasia of the pancreas, defined by the World Health Organization (WHO) as an epithelial low-grade malignant neoplasm, with a high-grade malignant transformation potential. Literature in this subject is scarce and limited only to small retrospective series. Methods: This is a retrospective study aiming to characterize patients with the diagnosis of SPN at Mayo Clinic between 1992 and 2016. Demographics, clinical and pathological features, recurrence rate and overall survival were recorded. Malignant SPN was defined as per the WHO 2010 classification (Perineural invasion, angioinvasion or deep tissue invasion) and compared to Benign SPN. Results: 44 patients with SPN were identified. 39 patients (88.6%) were female. Median age at diagnosis was 27.5 (Range: 13-64). The most frequent presentation was abdominal pain (52.6%), whereas 36.8% were diagnosed based on incidental imaging findings. Majority (60.4%) of the tumors were located at the pancreatic tail, and 48.5% were solid-cystic lesions. Vascular and lymph node involvement were infrequent. 15 cases (30.23%) were classified as malignant. Tumor size was associated with malignant behavior (Table). Three patients had a metastatic presentation. All but 1 patient were treated with surgery. R1 resection was more frequent in malignant SPN, and 2 patients experienced disease recurrence. Two Stage IV patients were treated with surgery and experienced long term survival, one of them without evidence of disease. There was only 1 death recorded. Conclusions: SNP presents predominantly on young women. The prognosis is excellent even in presence of malignant features, and a complete surgery remains as the main treatment. [Table: see text]

e15703 Background: The aim of this study is to identify prognostic factors and effects of adjuvant therapy for patients with ampullary adenocarcinoma who had pancreatoduodenectomy. Methods: A cohort of 123 consecutive patients underwent pancreatoduodenectomy for ampullary adenocarcinoma from January 1, 2006, through August 31, 2016 at Mayo Clinic in Rochester, MN. Only patients with ampullary carcinoma by pathology review were included and were histologically classified as pancreaticobiliary or intestinal subtypes. Median follow-up duration was 41.0 months. Patient survival and its correlation with patient and tumor variables were tested by univariate and multivariate analysis. Results: Pancreatoduodenectomy was curative-intent in 120 out of 123 patients. All 123 patients underwent radical surgery, 32 patients (26.0%) had laparoscopic pancreatoduodenectomy. Among 123 patients, there were 76 men (61.8%).Median age at diagnosis was 67.2 years. 54 patients (45%) without metastatic disease upon surgery had adjuvant therapy (35 patients had chemotherapy only while 19 patient also had radiation). Median overall survival (OS) was 91.8 months. Poor performance status at disease diagnosis (ECOG > = 1), old age ( > = 70 years), primary tumor infiltration (T), lymph node metastasis (N), and advanced disease stage (TNM) had a significant negative impact on survival (p < 0.05 by univariate analysis). Gender, diabetes at disease diagnosis, laparoscopic surgery approach, number of lymph nodes removed, number of positive lymph nodes, and tumor size did not influence survival. In multivariate analysis, ECOG score > = 1, adjuvant treatment, primary tumor infiltration (T) and lymph node metastasis (N) remained statistically significant. Adjuvant therapy was independently associated with improved disease free survival (P = 0.0388) and overall survival (p = 0.030) for patients with advanced disease (stage IIB and above). Conclusions: Poor performance status and advanced disease stage are associated with decreased survival in patients with ampullary adenocarcinoma. Patients with advanced disease should be considered for adjuvant chemotherapy.

e15030 Background: Deficiencies in the DNA mismatch repair (dMMR) system cause errors during DNA replication, which in turn give rise to microsatellite instability (MSI-H). MSI-H in mCRC is rare and its prognostic and predictive impact on outcome is unclear. This cohort study aims to investigate the prognostic and predictive value of MSI-H in metastatic CRC prior to the immune therapy era. Methods: 75 MSI-H mCRC patients (pts) and 75 matched (age, gender, disease sidedness, metachronous) MSS mCRC pts were identified from 1268 mCRC who had MSI/MMR test results at Mayo Clinic Rochester between 1/1992 and 7/2016. A retrospective review was conducted by using data from electronic medical records (EMR). Statistical analyses utilized Kaplan-Meier method, Log-rank test, and Cox proportional hazards models. Results: In the MSI-H group, there were 39 male (52%) and 36 female (48%) pts. Median age at metastatic disease diagnosis was 54.7 years. 35 patients presented with stage IV CRC. Primary tumors location: 38 right side, 11 transverse colon, 15 left side, 11 rectum. The MSS group was well matched (3 mismatches for gender and 1 mismatch for metachronous metastatic disease). Median overall survivals (OS) were 28.1 and 37.4 months for MSI-H and MSS pts, respectively ( p= 0.098). 98.7% MSS pts and 94.7% MSI-H pts had Fluoropyrimidine-based chemotherapy for metastatic disease and there was no median OS difference between these two groups (37.4 vs. 32.3 months p= 0.91). 43 MSI-H and 39 MSS pts had metastasectomy including ablation ( p= 0.51) with longer median OS (82.0 and 69.9 months, p= 0.90) compared to pts without metastasectomy (13.9 and 19.7 months, p= 0.15). Age < 65, metastasectomy, asymptomatic metastatic lesions, BRAF wild type, and multiple metastasectomy were associated with better survival in univariate analysis. Only metastasectomy remained statistically significant in multivariate analysis ( p< 0.0001). Conclusions: MSI-H mCRC do not appear to have improved prognosis compared with MSS cancers, in fact, there is a trend toward inferior outcome. In both groups, metastasectomy including multiple metastasectomy should be considered to optimize OS.

Abstract Background Deficiencies in the DNA mismatch repair system cause errors during DNA replication, which in turn give rise to microsatellite instability (MSI). The impact of MSI on survival in metastatic colorectal cancer (mCRC) is unclear. This cohort study aims to investigate the prognostic and predictive value of MSI in mCRC prior to the immune therapy era. Materials and Methods A total of 75 MSI-high (MSI-H) mCRC patients (pts) and 75 matched (age, gender, disease sidedness, metachronous/synchronous) microsatellite-stable (MSS) mCRC pts were identified from 1,268 mCRC pts who had MSI/mismatch repair test results at Mayo Clinic Rochester between January 1992 and July 2016. A retrospective review was conducted by using data from electronic medical records. Statistical analyses utilized the Kaplan-Meier method, log-rank test, and Cox proportional hazards models. Results The MSS group was well matched to the MSI-H group based on age, gender, location, and chronicity of metastatic disease. MSI-H mCRC pts had earlier disease recurrence (median time from initial diagnosis to metastatic disease diagnosis, MSI-H group 12.9 vs. MSS group 20.9 months, p = .034). Median overall survival (OS) was 28.1 and 37.4 months for MSI-H and MSS pts, respectively (p = .99). In total, 94.7% of MSI-H pts and 98.7% of MSS pts had fluoropyrimidine-based chemotherapy for metastatic disease, and there was no difference in OS between these two groups (32.3 vs. 37.4 months, p = .91). Forty-three MSI-H and thirty-nine MSS pts had metastasectomy and/or ablation of metastases (p = .51) with longer median OS compared with pts without metastasectomy (MSI-H: 82.0 vs. 13.9, p &lt; .001; MSS: 69.9 vs. 19.7, p &lt; .001). Age &lt;65 years, BRAF wild type, and metastasectomy were associated with better OS in univariate analysis. Only metastasectomy remained statistically significant in multivariate analysis (p &lt; .001). Conclusion In mCRC, patients with MSI-H tumors have similar, but numerically shorter, median overall survival compared with those with MSS tumors. In both groups, metastasectomy and ablation of metastatic disease should be considered to optimize OS. Implications for Practice This study clearly demonstrated the survival benefits that aggressive metastasectomy provides in selected microsatellite instability-high metastatic colorectal cancer patients. This could be meaningful practice-changing information that has been long awaited.