Hálfdánarson, Þorvarður R.

Purpose Data that guide selection of optimal local ablative therapy for the management localized hepatocellular carcinoma (HCC) are lacking. Because there are limited prospective comparative data for these treatment modalities, we aimed to compare the effectiveness of radiofrequency ablation (RFA) versus stereotactic body radiotherapy (SBRT) by using the National Cancer Database. Methods We conducted an observational study to compare the effectiveness of RFA versus SBRT in nonsurgically managed patients with stage I or II HCC. Overall survival was compared by using propensity score–weighted and propensity score–matched analyses based on patient-, facility-, and tumor-level characteristics. A sensitivity analysis was performed to evaluate the effect of severe fibrosis/cirrhosis. In addition, we performed exploratory analyses to determine the effectiveness of RFA and SBRT in clinically relevant patient subsets. Results Overall, 3,684 (92.6%) and 296 (7.4%) nonsurgically managed patients with stage I or II HCC received RFA or SBRT, respectively. After propensity matching, 5-year overall survival was 29.8% (95% CI, 24.5% to 35.3%) in the RFA group versus 19.3% (95% CI, 13.5% to 25.9%) in the SBRT group ( P < .001). Inverse probability–weighted analysis yielded similar results. The benefit of RFA was consistent across all subgroups examined and was robust to the effects of severe fibrosis/cirrhosis. Conclusion Our study suggests that treatment with RFA yields superior survival compared with SBRT for nonsurgically managed patients with stage I or II HCC. Even though our results are limited by the biases related to the retrospective study design, we believe that, in the absence of a randomized clinical trial, our findings should be considered when recommending local ablative therapy for localized unresectable HCC.

Abstract Expression of DLL3 was examined in additional tumor types, as it was found to be highly expressed in tumor-initiating cells (TIC) in small cell lung cancer (SCLC), where a DLL3-targeted antibody drug conjugate (ADC), rovalpituzumab tesirine (Rova-T; SC16LD6.5; Saunders et al. 2015 Sci Transl Med 7:302ra136)) exerted clinically meaningful anti-tumor effects in a phase I trial (Spigel et al. 2016 Lancet Oncology; In Press). DLL3 expression was profiled by qRT-PCR, ELISA and immunohistochemistry in multiple tumor types. Patient-derived xenografts (PDX) from melanoma and ovarian small cell carcinoma were established and used for efficacy studies to determine the ability of Rova-T to impact tumor growth and TIC frequency. DLL3 expression was seen in metastatic melanoma (55%), low grade gliomas (90%), glioblastoma (70%), medullary thyroid cancer (65%), carcinoids (33%), dispersed neuroendocrine tumors in the pancreas (9%), bladder (57%) and prostate (24%), testicular cancer (90%), and lung adenocarcinomas with neuroendocrine features (80%). Unlike SCLC, where DLL3 does not predict clinical outcome on standard therapies, DLL3 expression negatively correlates with overall survival in melanoma and small cell bladder cancer. In mice bearing DLL3 positive melanoma PDX, treatment with a single dose of Rova-T resulted in effective and durable responses (&gt;100 days), which correlated with a significant impact on TIC frequency. Similarly, in mice bearing DLL3-positive ovarian small cell PDX, a single dose of Rova-T resulted in effective and durable responses (&gt;100 days). Our results show that DLL3 is expressed in many neuroendocrine tumors (lung, ovarian, prostate, bladder, etc), metastatic melanoma, medullary thyroid cancer, low-grade gliomas and glioblastoma. Given pre-clinical results showing efficacy of Rova-T in melanoma and ovarian small cell carcinoma, as well as encouraging clinical data with Rova-T in patients with recurrent/refractory SCLC, clinical evaluation of Rova-T in DLL3-positive melanoma, glioblastoma, medullary thyroid cancer and other high-grade neuroendocrine carcinomas is warranted. A “basket” trial enrolling patients with DLL3-positive solid tumors is now recruiting patients (NCT02709889). Citation Format: Laura R. Saunders, Samuel A. Williams, Sheila Bheddah, Kumiko Isse, Sarah Fong, Marybeth A. Pysz, Himisha Beltran, Loredana Puca, Verena Sailer, Juan M. Mosquera, Yu Yin, Jiaoti Huang, Andrew J. Armstrong, Jorge Garcia, Cristina Magi-Galluzzi, Vadim Koshkin, Petros Grivas, Farhad Kosari, John Cheville, Justin C. Moser, Thomas J. Flotte, Thorvardur Halfdanarson, Aaron Mansfield, Konstantinos N. Leventakos, Julian R. Molina, Douglas W. Ball, Barry D. Nelkin, Jill E. Shea, Courtney L. Scaife, Scott J. Dylla. Expression of DLL3 in metastatic melanoma, glioblastoma and high-grade extrapulmonary neuroendocrine carcinomas as potential indications for rovalpituzumab tesirine (Rova-T; SC16LD6.5), a delta-like protein 3 (DLL3)-targeted antibody drug conjugate (ADC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3093. doi:10.1158/1538-7445.AM2017-3093

791 Background: With the surge of drug development in the past decade, early phase clinical trials (EPCT) have gained value evaluating the potential benefits of new therapies. The inclusion/exclusion criteria in EPCT are usually rigorous and may exclude many patients (pts) commonly seen in clinical practice. Our objective was to identify the most common comorbidities excluded in EPCT for CRC. Methods: ClinicalTrials.gov was queried on December 1stof 2015. We reviewed the characteristics and eligibility criteria of 369 phase I/II interventional drug trials including: experimental arm therapy, location, and exclusion/inclusion criteria. Logistic regressions were completed and exclusion was studied as a binary variable. Results: Of the 369 trials, 68% were phase II and 32% phase I. 46% were conducted in the United States, 30% in Europe, 15% in Asia and 9% in other locations. 74 (20%) trials excluded pts > 70 years of age. 142 (39%) trials required creatinine levels < 1.5 mg/dl, liver enzymes (AST/ALT) < 2.5 and bilirubin < 1.5 of the upper limit of normal. Cytopenia was a significant exclusion factor: 147 (47%) trials required Hgb > 9 g/dl and 218 (59%) excluded pts with platelets < 100,000/dl. In terms of comorbidities, 98 (27%) trials excluded pts with heart failure (NYHA class 3/4), 74 (20%) with atrial fibrillation, 112 (31%) with any anticoagulation therapy and 155 (42%) with positive HIV. Trials located in the US were more likely to exclude pts with Hgb < 9g/dl (OR: 1.5, 95%CI: 1.1-2.3, p < 0.05), immunotherapy trials were more likely to exclude pts on any anticoagulation (OR:1.8, 95%CI: 1.2-2.8, p < 0.007) and targeted therapy trials were more likely to exclude pts with history of DVT/PE or cardiovascular diseases (OR: 3.4, 95%CI: 1.9-5.8, p < 0.0001; OR: 2.3, 95%CI: 1.3-3.8, p < 0.002, respectively). Conclusions: 20% of EPCTs on CRC excluded pts with advanced age, organ dysfunction and common comorbidities. Many of the EPCT reviewed were not inclusive of our aging oncology population who are more likely to have multiple comorbidities. Investigators should review whether sufficient justification exists for every exclusion criterion before their incorporation in future trial protocols.

593 Background: Cancer stem cells or stemness-high cancer cells are considered to be fundamentally important for resistance to therapy, recurrence and metastasis. Napabucasin, a first-in-class cancer stemness inhibitor in clinical development, suppresses cancer stemness by targeting Stat3-driven gene transcription. Preclinical studies suggest that napabucasin sensitizes heterogeneous cancer cells to chemotherapeutics and targeted agents. Methods: This study was performed to assess signs of anti-tumor activity of napabucasin in combination with FOLFIRI +/- Bev in CRC pts. Napabucasin was administered at 240 mg BID. FOLFIRI (5-FU 400 mg/m2 bolus with 2400 mg/m2, irinotecan 180 mg/m2, and leucovorin 400 mg/m2 infusion) +/- Bev 5 mg/kg was administered biweekly until disease progression or other discontinuation criterion. pSTAT3 status of archival tumor tissue was assayed by immunohistochemistry using the H-score with pSTAT3highdefined as ≥ 5% pSTAT3+ cancer cells and tumor stroma staining at ≥ 2+ intensity. Results: 63 CRC pts with an average of >2 prior therapy lines were enrolled. No pharmacokinetic interactions or dose-limiting toxicity was observed. Most common adverse events (AEs) included grade 1/2 diarrhea, nausea, vomiting and fatigue. 25 pts had grade 3 AEs, including diarrhea (14), fatigue (4), dehydration (2), electrolyte imbalance (4), nausea (1) and weight loss (1) resolved with dose reduction and supportive care. Among 63 pts enrolled who received RECIST evaluation, disease control (CR+PR+SD) was observed in 49 pts (86%) with an overall response (CR+PR) of 28% with 1 pt achieving CR. Clinical trial information: NCT02024607. Conclusions: This phase Ib/II study suggests napabucasin may sensitize chemorefractory CRC to FOLFIRI +/- Bev. Encouraging signs of synergistic activity between napabucasin and FOLFIRI was observed in CRC pts regardless of pSTAT3 status.[Table: see text]

420 Background: Advanced biliary cancers respond poorly to chemotherapy and have a dismal survival. Currently gemcitabine-cisplatin (GC) is the standard of care for patients with advanced disease. The efficacy of second line treatment options is not well-defined. We retrospectively evaluated outcomes of patients undergoing second line treatment for advanced biliary cancers at Mayo Clinic. Methods: After obtaining approval from the institutional board review (IRB), we identified 42 patients with advanced and metastatic biliary cancers that progressed after first line (GC) and received second line treatment from 2007-2014. All patients had adequate follow up data. 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 61.5 (range 26-87). The most common regimens used for second line settings were 5-FU-based (69%) followed by gemcitabine-based regimens (19%). The overall response rate (ORR) was 9.1%, while the disease control rate (DCR; stable disease and partial response) was 33%. The median overall survival (mOS) for the entire cohort from first line was 16.8 months (95% CI 12.7-21.7) and the progression-free survival (PFS) was 9.16 months (95% CI 7.3-14.7). From second line start the mOS was 10.4 months (95%; CI 7.3-23.7), and PFS was 2.8 months (95% CI 2.3-4.0). 73% of patients who received second line therapy were alive at 6 months and 50% at 12 months. 25 patients received third line treatment after progression. An univariate and multivariate analysis were performed including age, sex, stage at diagnosis, regimen used, CA19-9 and total body weight loss > 5%, but no significant prognostic factors were identified. Conclusions: Patients with biliary cancers who progress after first line treatment have poor prognosis, but may benefit from second line regimens. 5-FU based regimens were the most commonly used in the second line setting, and 73% of patients who received second line therapy were alive at 6 months.

401 Background: Pancreatic neuroendocrine tumors (PNETs) are rare neoplasms comprising less than 2% of pancreatic tumors. Outcomes of PNETs vary by stage, grade, and clinical presentation. New therapies may have improved outcomes. We present an analysis of the epidemiology and prognosis of patients (pts) with PNETs evaluating a more recent period than previously reported. Methods: Using data from the SEER registry, we identified adults with PNETs between 2000 and 2013. Cases were identified using a combination of ICD-O-3 site and histology codes. The JMP and SEER*STAT 8.3.2 were used for statistical analysis. Overall survival (OS) was analyzed using the Kaplan–Meier method. The prognostic effect of variables was studied using multivariate Cox proportional hazards models. Results: We identified 5993 pts with PNETs. Over the study duration, there was an increase in the annual incidence from 0.3 to 1.2 per 100.000. This was largely explained by the increase in number of pts with localized disease. The OS for the entire cohort was 54 months (95%; CI 50-58) and 5-year OS rates in localized, locally advanced and metastatic disease were 81.7%, 62% and 26% respectively. New therapies were increasingly implemented after 2008 such as sunitinib, everolimus and capecitabine/temozolomide. OS was better for pts diagnosed after 2008 (HR 0.73; 95% CI, 0.69-0.79; P < 0.0001) and this remained significant after excluding pts with localized disease (HR 0.85; 95% CI, 0.78-0.92; P = 0.0002). Factors found to favorably affect OS included younger age, female sex, early stage, low grade, and surgery. In metastatic disease, pts who had surgery had better OS and this was significant after adjusting for possible confounders (HR 0.36; 95% CI, 0.3-0.45). Conclusions: In this large population-based study, we saw an increase in the annual incidence of PNETs mainly due to an increased number of pts with localized disease. The OS has improved over the study duration likely due to both stage migration and new therapies used in advanced disease. Younger age, female gender, low histologic grade, early stage and surgery were found to be factors that favorably affected survival. Surgery was found to be a predictor of better outcomes in metastatic disease.

179 Background: GISTs arise from interstitial cells of Cajal anywhere within the gastrointestinal tract, but those of the esophagus and GEJ are exceedingly rare ( < 1% of cases). Our aim was to characterize clinicopathological features and outcomes of esophageal and GEJ GISTs and compare survival with a population-based registry (SEER). Methods: 28 cases were identified using the Mayo Clinic Cancer Registry from 1997 to 2016, and 378 cases from the SEER 18 registry from 2000 to 2013. Mayo cases were re-reviewed by Mayo pathologists. We analyzed patient characteristics, tumor location, TNM staging, mitotic index, molecular diagnostics, IHC staining, and histomorphology. JMP software was used to calculate time to recurrence (TTR) and overall survival (OS) utilizing Kaplan-Meier and log-rank. Results: At Mayo, 60% of tumors arose in the distal esophagus. Mean tumor size was 5.73 cm. 42% of cases were low grade. None had nodal involvement. Five cases were metastatic at diagnosis, all to the liver. 86.7% had spindle cell morphology. IHC staining was positive for KIT in 92%, followed by CD34 (52%), DOG-1 (24%), and actin (16%). Mutational analysis was done on 10 cases and KIT mutation was found in 8 cases; 2 were wild-type. Two-thirds of patients underwent surgery, mostly esophagectomy. 14 patients received adjuvant imatinib. Median time to diagnosis from symptom onset was 2 months; median time to surgery from diagnosis was 1 month. Of 10 patients with complete follow-up, 2 had recurrences: 1at the anastomotic site and 1 in the liver. Median TTR from surgery was 36.5 months. Median follow-up time was 31.5 months. Median OS from diagnosis for the Mayo cohort was 129.5 months (95% CI 55.7-x). SEER cohort median OS was 81 months (95% CI 63-101), and females had superior OS compared to males (HR 0.67; 95% CI 0.48-0.93, p = 0.016). Conclusions: Patients undergoing surgical resection for esophageal and GEJ GISTs had a favorable prognosis, but recurrences occurred. The superior OS seen in the Mayo cohort suggests early resection and adjuvant imatinib may improve outcomes.

584 Background: Standard therapy for stage II/III rectal cancer includes surgery, radiation, and chemotherapy. Multiple trials demonstrated neoadjuvant chemoradiation (CRT) provides better local control and decreased morbidity compared to adjuvant CRT, though differences in overall survival and long-term QoL have not been demonstrated. We examined impact of treatment (pre-op CRT/post-op CRT/no CRT) on long-term QoL. Methods: CanCORS patients with survey/medical record data diagnosed in 2003-2005 with stage II/III rectal (non-rectosigmoid) cancer had resection and survived > 7 years were included. QoL (SF-36, EQ-5D) measures and defecation problems were derived from surveys at 14 months and 7 years post-diagnosis. Mean scores were adjusted for the following when significant: age, gender, stage, sphincter preservation, comorbidities, and baseline self-reported health status and QoL scores. Results: Of 119 patients, 53% received pre-op CRT, 23% post-op CRT, and 24% no CRT. Of 114 patients with 14-month follow-up, Pre-op CRT and No CRT groups had better EQ-5D adjusted mean scores but worse defecation scale (DS) scores compared to the Post-op CRT group. Of 49 disease-free survivors with 7 years follow-up, there were no differences among groups in QoL scores, but the No CRT group had better DS scores than other groups. Conclusions: No major differences were detected in long-term QoL based on treatment aside from the DS, though sample sizes became small. Regardless of treatment, long term (7y) mental health and vitality were generally comparable to U.S. norms, while physical health and overall health status (EQ-5D) were somewhat lower. [Table: see text]

603 Background: Anal squamous cell carcinoma (Anal SCC) is a rare, HPV-associated malignancy accounting for 2.4% of digestive system cancers. In most cases, these malignancies are detected in the early stages and successfully managed with chemoradiation therapy. Uncommonly, these cancers recur or present with metastases. In this setting, cisplatin and 5-fluorouracil represent the only endorsed regimen. Once beyond standard therapy, few therapeutic options exist for those patients with aggressive disease. The purpose of this study is to identify other novel, potential targets and therapeutic options for this disease, utilizing a multiplatform approach. Methods: 206 anal SCC specimenswere tested via a multiplatform profiling service (Caris Life Sciences, Phoenix, AZ) consisting of gene sequencing (Sanger or next generation sequencing [NGS]), protein expression (immunohistochemistry [IHC]) and gene amplification (CISH or FISH). 6 cases were documented as positive for HPV or HIV; status was not provided on the remaining 200. Results: Key results are shown in the table below, shown as percent change/total cases. Conclusions: Multiplatform tumor profiling identified a low incidence of gene mutations. Protein expression aberrations identified potential treatment options not routinely considered, such as topoisomerase inhibitors and taxanes. Mutations in PIK3CA, Akt1, and FBXW7 as well as PTEN loss indicate potential for targeting the PI3 kinase pathway. Additionally, immunomodulatory agents may be a therapeutic option, based on PD-1 expression levels. Targeting the ErbB-family receptors, namely with anti-EGFR agents or newer generation pan-HER - inhibitors, may represent another option, given EGFR and HER2 amplification as well as EGFR overexpression. It should be mentioned that differences in anal carcinomas whose etiology is of viral origin may present different treatment options based on the driver mutations. [Table: see text]