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Table S1: BROCA-HR gene list Table S2: Best Response, TTP, OS in Patients with HR-DDR Defects

Protocol

Purpose:PARP inhibitors synergize with topoisomerase inhibitors, and veliparib plus modified (m) FOLFIRI (no 5-FU bolus) had preliminary activity in metastatic pancreatic cancers. This study evaluated the safety and efficacy of second-line treatment with veliparib and mFOLFIRI versus FOLFIRI (control) for metastatic pancreatic cancer.Patients and Methods:This randomized phase II clinical trial led by the SWOG Cancer Research Network enrolled patients between September 1, 2016 and December 13, 2017. The median follow-up was 9 months (IQR 1–27). BRCA1/2 and homologous recombination DNA damage repair (HR-DDR) genetic defects were tested in blood and tumor biopsies. Patients received veliparib 200 mg twice daily, days 1–7 with mFOLFIRI days 3–5, or FOLFIRI in 14-day cycles.Results:After 123 of planned 143 patients were accrued, an interim futility analysis indicated that the veliparib arm was unlikely to be superior to control, and the study was halted. Median overall survival (OS) was 5.4 versus 6.5 months (HR, 1.23; P = 0.28), and median progression-free survival (PFS) was 2.1 versus 2.9 months (HR, 1.39; P = 0.09) with veliparib versus control. Grade 3/4 toxicities were more common with veliparib (69% vs. 58%, P = 0.23). For cancers with HR-DDR defects versus wild-type, median PFS and OS were 7.3 versus 2.5 months (P = 0.05) and 10.1 versus 5.9 months (P = 0.17), respectively, with FOLFIRI, and 2.0 versus 2.1 months (P = 0.62) and 7.4 versus 5.1 months (P = 0.10), respectively, with veliparib plus mFOLFIRI.Conclusions:Veliparib plus mFOLFIRI did not improve survival for metastatic pancreatic cancer. FOLFIRI should be further studied in pancreatic cancers with HR-DDR defects.

Purpose: PARP inhibitors synergize with topoisomerase inhibitors, and veliparib plus modified (m) FOLFIRI (no 5-FU bolus) had preliminary activity in metastatic pancreatic cancers. This study evaluated the safety and efficacy of second-line treatment with veliparib and mFOLFIRI versus FOLFIRI (control) for metastatic pancreatic cancer. Patients and Methods: This randomized phase II clinical trial led by the SWOG Cancer Research Network enrolled patients between September 1, 2016 and December 13, 2017. The median follow-up was 9 months (IQR 1–27). BRCA1/2 and homologous recombination DNA damage repair (HR-DDR) genetic defects were tested in blood and tumor biopsies. Patients received veliparib 200 mg twice daily, days 1–7 with mFOLFIRI days 3–5, or FOLFIRI in 14-day cycles. Results: After 123 of planned 143 patients were accrued, an interim futility analysis indicated that the veliparib arm was unlikely to be superior to control, and the study was halted. Median overall survival (OS) was 5.4 versus 6.5 months (HR, 1.23; P = 0.28), and median progression-free survival (PFS) was 2.1 versus 2.9 months (HR, 1.39; P = 0.09) with veliparib versus control. Grade 3/4 toxicities were more common with veliparib (69% vs. 58%, P = 0.23). For cancers with HR-DDR defects versus wild-type, median PFS and OS were 7.3 versus 2.5 months (P = 0.05) and 10.1 versus 5.9 months (P = 0.17), respectively, with FOLFIRI, and 2.0 versus 2.1 months (P = 0.62) and 7.4 versus 5.1 months (P = 0.10), respectively, with veliparib plus mFOLFIRI. Conclusions: Veliparib plus mFOLFIRI did not improve survival for metastatic pancreatic cancer. FOLFIRI should be further studied in pancreatic cancers with HR-DDR defects.

Lessons Learned Background Cediranib, a vascular endothelial growth factor receptor inhibitor, suppresses expression of BRCA1/2 and RAD51 inducing homologous recombination DNA repair deficiency (HRD) in several cancer cell lines and xenograft models [1]. Olaparib provides a clinical benefit in patients with metastatic pancreatic adenocarcinoma (mPDAC) with germline BRCA mutation (gBRCAmt) [2]. We hypothesized that cediranib induces HRD in the absence of gBRCAmt and synergizes with olaparib, resulting in an objective response in patients with mPDAC. Methods Patients with mPDAC with at least one prior systemic chemotherapy were enrolled. Patients with known gBRCAmt were excluded. Patients took cediranib 30 mg daily and olaparib 200 mg twice daily, orally. The primary endpoint was objective response (OR) rate. Results Nineteen patients received the study drugs. Seven patients came off treatment before the first restaging scan: six because of clinical progression and one because of an adverse event. No OR was observed. Six patients had stable disease (SD) as a best overall response. The median duration of SD was 3.1 months. The median overall survival was 3.4 months. Common treatment-related adverse events were fatigue, hypertension, and diarrhea. Conclusion Cediranib and olaparib combination did not result in clinically meaningful activity in patients with mPDAC without gBRCAmt.

Altered metabolism is a hallmark of cancer. In addition to glucose, glutamine is an important nutrient for cellular growth and proliferation. Non-invasive imaging via positron emission tomography (PET) may help facilitate precision treatment of cancer through patient selection and monitoring of treatment response. L-[5-11C]-glutamine (11C-glutamine) is a PET tracer designed to study glutamine uptake and metabolism. The aim of this first-in-human study was to evaluate the radiologic safety and biodistribution of 11C-glutamine for oncologic PET imaging. Methods: Nine patients with confirmed metastatic colorectal cancer underwent PET/computed tomography (CT) imaging. Patients received 337.97 ± 44.08 MBq of 11C-glutamine. Dynamic PET acquisitions centered over the abdomen or thorax were initiated simultaneously with intravenous tracer administration. Following the dynamic acquisition, a whole-body PET/CT was acquired. Volume-of-interest analyses were carried out to obtain estimates of organ-based absorbed doses of radiation. Results:11C-glutamine was well-tolerated in all patients with no observed safety concerns. Organs with the highest radiation exposure included the bladder, pancreas, and liver. The estimated effective dose was 4.46E-03 ± 7.67E-04 mSv/MBq. Accumulation of 11C-glutamine was elevated and visualized in lung, brain, bone, and liver metastases, suggesting utility for cancer imaging. Conclusion: PET using 11C-glutamine appears safe for human use and allows non-invasive visualization of metastatic colon cancer lesions in multiple organs. Further studies are needed to elucidate its potential for other cancers and for monitoring response to treatment.

PURPOSE Nivolumab received US Food and Drug Administration approval as a single agent or in combination with ipilimumab in patients with microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) metastatic colorectal cancer (mCRC) that progressed following treatment with a fluoropyrimidine, oxaliplatin, and irinotecan based on CheckMate 142. Presented are results of nivolumab plus low-dose ipilimumab in the first-line therapy cohort from the phase II CheckMate 142 study. PATIENTS AND METHODS Patients with no prior treatment in the metastatic setting for MSI-H/dMMR CRC were treated with nivolumab every 2 weeks plus low-dose ipilimumab every 6 weeks until disease progression. The primary end point was objective response rate (investigator assessment; RECIST v1.1). RESULTS Median age of treated patients was 66 years (N = 45). Median follow-up was 29.0 months. Objective response rate and disease control rate were 69% (95% CI, 53 to 82) and 84% (95% CI, 70.5 to 93.5), respectively, with 13% complete response rate. Median duration of response was not reached; 74% of responders had ongoing responses at data cutoff. Median progression-free survival and median overall survival were not reached with minimum follow-up of 24.2 months (24-month rates, 74% and 79%, respectively). Clinical benefit was observed regardless of baseline demographic and tumor characteristics, including BRAF or KRAS mutation status. In a post hoc analysis, of 14 patients who discontinued treatment and did not receive subsequent therapy, 10 remained progression-free. Patient-reported outcomes were stable over the treatment period. Grade 3-4 treatment-related adverse events occurred in 22% of patients; 13% discontinued because of any-grade treatment-related adverse events. CONCLUSION Nivolumab plus low-dose ipilimumab demonstrated robust and durable clinical benefit and was well tolerated as a first-line treatment for MSI-H/dMMR mCRC. Based on these promising data, randomized studies are warranted.

Introduction Immune-related adverse event (IRAE) onset may represent a clinical biomarker for anti-programmed cell death protein 1 (PD-1) antibody response based on emerging evidence from patients with various advanced malignancies. This phenomenon has not been previously reported in a multidisease cohort of patients with gastrointestinal (GI) cancer with Food and Drug Administration (FDA)-approved indications to receive immune checkpoint inhibitor therapy. Materials and Methods The study was a multicenter retrospective cohort analysis of 76 patients with GI cancer who had received anti-PD-1 antibodies for FDA-approved indications. The primary and secondary outcomes of the study were progression-free survival (PFS) and overall survival (OS) in patients based upon IRAE presence, respectively. PFS and OS were estimated by the Kaplan-Meier method; a Cox proportional-hazards model adjusted for IRAE onset, patient age, and enrolling institution was used to analyze outcomes. Results Median PFS and OS were prolonged in patients who experienced IRAEs compared with those who did not experience them (PFS: not reached [NR] vs. 3.9 months [hazard ratio (HR) 0.13, 95% confidence interval (CI) 0.05–0.3, p < .001]; OS: NR vs. 7.4 months [HR 0.11, 95% CI 0.03–0.36, p < .001]). Among patients who experienced IRAEs, there were no significant differences in PFS and OS by either initial IRAE severity, management, or time to onset. Conclusion Patients with gastrointestinal cancer who experienced IRAEs while on anti-PD-1 antibodies demonstrated significant improvements in PFS and OS compared with their counterparts who did not develop IRAEs. Although these findings add to results from studies in other tumor types, larger prospective studies are needed prior to clinical adoption of IRAE onset as a biomarker for immune checkpoint inhibitor response. Implications for Practice Predictive clinical biomarkers for immune checkpoint inhibitor response have been understudied in the field of immuno-oncology. Immune-related adverse event onset appears to be one such biomarker. Across tumor types, immune-related adverse event onset has been associated with response to anti-programmed cell death protein 1 (PD-1) antibodies. The results of this study demonstrate this for the first time in patients with gastrointestinal cancer receiving anti-PD-1 antibodies. Before immune-related adverse event onset can be adopted clinically as a predictive biomarker for immune checkpoint inhibitor response, however, larger prospective studies are needed to better understand the nuances between immune-related adverse event characteristics (severity, site, management, timing of onset) and immune checkpoint inhibitor effectiveness.

Older patients make up the majority of patients with pancreatic cancer, with a median age of 71 years at diagnosis. However, older patients are underrepresented in clinical trials in pancreatic cancer. This study investigates trends in age distribution of patients enrolled in clinical trials for advanced pancreatic cancer over time, and examines outcomes and toxicity in older patient subgroups from two studies conducted by Eastern Cooperative Oncology Group and American College of Radiology Imaging Network (ECOG-ACRIN) in this disease.16,042 patients from 38 phase III clinical trials for locally advanced or metastatic pancreatic adenocarcinoma published between 1997 and 2016 were identified and included in this analysis. Outcomes and toxicity by age were examined in two of the trials, ECOG-ACRIN trials E2297 and E6201, which included a total of 1146 patients.The median age across the trials was 62.7 years; median ages for individual trials ranged from 57 years to 66 years. Weighted linear regression showed no significant change in median age over time. Combined analysis of the two ECOG-ACRIN trials demonstrated higher rates of fatigue, thrombocytopenia, and infection in those ≥75 years compared with those75 years, but despite this showed no difference in overall survival (OS) or progression-free survival (PFS) (OS: 5.7 vs. 5.6 months and PFS: 2.8 vs 3.5 months).Enrollment of older adults in phase III pancreatic cancer clinical trials has not increased over time, despite increasing number of older patients seen in clinic. Increased efforts are needed to enhance enrollment of older patients in clinical trials, and to promote trials specifically for older patients, in order to improve the evidence base for treating this patient population.

SummaryVantictumab is a fully human monoclonal antibody that inhibits Wnt pathway signaling through binding FZD1, 2, 5, 7, and 8 receptors. This phase Ib study evaluated vantictumab in combination with nab-paclitaxel and gemcitabine in patients with untreated metastatic pancreatic adenocarcinoma. Patients received vantictumab at escalating doses in combination with standard dosing of nab-paclitaxel and gemcitabine according to a 3 + 3 design. A total of 31 patients were treated in 5 dosing cohorts. Fragility fractures attributed to vantictumab occurred in 2 patients in Cohort 2 (7 mg/kg every 2 weeks), and this maximum administered dose (MAD) on study was considered unsafe. The dosing schedule was revised to every 4 weeks for Cohorts 3 through 5, with additional bone safety parameters added. Sequential dosing of vantictumab followed by nab-paclitaxel and gemcitabine was also explored. No fragility fractures attributed to vantictumab occurred in these cohorts; pathologic fracture not attributed to vantictumab was documented in 2 patients. The study was ultimately terminated due to concerns around bone-related safety, and thus the maximum tolerated dose (MTD) of the combination was not determined. The MAD of vantictumab according to the revised dosing schedule was 5 mg/kg (n = 16).

Pancreatic cancer is the fourth leading cause of cancer-related death among men and women in the United States. A major challenge in treatment remains patients’ advanced disease at diagnosis. The NCCN Guidelines for Pancreatic Adenocarcinoma provides recommendations for the diagnosis, evaluation, treatment, and follow-up for patients with pancreatic cancer. Although survival rates remain relatively unchanged, newer modalities of treatment, including targeted therapies, provide hope for improving patient outcomes. Sections of the manuscript have been updated to be concordant with the most recent update to the guidelines. This manuscript focuses on the available systemic therapy approaches, specifically the treatment options for locally advanced and metastatic disease.

4154 Background: Pancreatic cancer is a formidable malignancy, with an estimated 62,000 new cases in 2022 and approximately 50,000 deaths. Five-year overall survival remains low at 11%; 14.4% for locally advanced disease. Nearly one-third of newly diagnosed patients (pts) present with locally advanced pancreatic cancer (LAPC) and only a minority of pts ( 65% of pts receiving care at an academic program; 95% living in or near a metro area, and nearly 60% living < 20 miles of their primary treatment center (p

4136 Background: Mesothelin (MSLN) is overexpressed in 80-85% of pancreatic adenocarcinomas (PDAC). Anetumab ravtansine (AR) is a fully human anti-MSLN immunoglobulin G1 antibody conjugated to the anti-tubulin maytansinoid DM4. Through NCI-ETCTN, the North American Star Consortium conducted a phase I study to evaluate the safety/tolerability of AR in various combinations in patients (pts) with PDAC. Here, we report preliminary results of the escalation part. Methods: Pts with advanced PDAC after at least one line of treatment were included. AR was combined with nivolumab (ARM1), nivolumab/ipilimumab (ARM 2), or nivolumab plus gemcitabine (Gem) (ARM3), using an integrated biomarker analysis. Two dose levels (DL) of AR were evaluated, DL1=5.5mg/kg and DL2=6.5mg/kg (established RP2D). Key eligibility criterion was MSLN expression in >5% of tumor cells by immunohistochemistry. Pts with prior anti-PD1/anti-CTLA4 treatment were excluded but treatment with prior Gem was allowed. Mandatory blood and paired tumor samples were collected for investigation of the immune microenvironment, genomic/transcriptomic changes and for an in-depth description of AR pharmacokinetics. Results: Data cut-off date was 22/01/2022. A total of n=33 pts were enrolled, n=11 (ARM 1), n=13 (ARM 2) and n=9 (ARM3). Median age of pts was 66 (40-83), 33% of PS=0 and 66% of PS=1. Twenty-six pts (79%) had previously been exposed to Gem. Median number of prior lines of treatment was 3 (1-7). Twenty-eight patients were evaluable for DLT. Grade (G)3/4 TRAEs: 0% in ARM1DL1, 5.3% in ARM1DL2, 0% in ARM2DL1, 16.9% in ARM2DL2, 8.6% in ARM3DL1 and 19.5% in ARM3DL2. There were 2 dose-limiting toxicities in ARM2DL2, one G3 upper gastrointestinal haemorrhage, possibly related to AR, and one G3 thrombocytopenia and G3 anaemia, definitely related to AR. Ocular toxicity events were G1/2 blurred vision in 5/33 (15%) and G1 xerophthalmia in 1/33 (3%), related to both AR and anti-PD1; G2 keratitis in 1/33 (3%), related to AR only. Only G1 peripheral neuropathy was observed in 4/33 (12%) pts. Efficacy data is presented in the table. In ARM3, the range of tumor measurement (ΤΜ) change was ΔTM=–16.8% to +16.2% and 3/8 (36%) pts with SD had previously been exposed to Gem. Conclusions: Based on the observed disease control rate and acceptable toleratbility, ARM3 (both DL1 and DL2) will be tested in the expansion part. A further 20 patients will be recruited for dose confirmation and comprehensive biomarker evaluation. Pharmacokinetic/pharmacodynamic analysis is under way. Clinical trial information: NCT03816358. [Table: see text]

3510 Background: NIVO ± IPI is approved in previously treated pts with MSI-H/dMMR mCRC in the US, EU, and Japan, based on findings from the phase 2 CheckMate 142 study (NCT02060188). NCCN guidelines include NIVO + IPI as an initial therapy option for pts with MSI-H/dMMR mCRC. Results from a ~5-year follow-up from CheckMate 142 cohorts 1–3 (C1–3) are reported here. Methods: In this non-randomized, multicohort study, pts with MSI-H/dMMR mCRC were treated as follows: C1 (2L+; NIVO 3 mg/kg Q2W), C2 (2L+; NIVO 3 mg/kg + IPI 1 mg/kg Q3W [4 doses], followed by NIVO 3 mg/kg Q2W) and C3 (1L; NIVO 3 mg/kg Q2W + IPI 1 mg/kg Q6W), until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR) by investigator assessment (INV) per RECIST v1.1. Other key endpoints were disease control rate (DCR), duration of response (DOR), progression-free survival (PFS), all by INV and blinded independent central review; overall survival (OS), and safety. Results: In C1 (N = 74), C2 (N = 119), and C3 (N = 45), median (range) follow-up (time from first dose to data cutoff) was 70.0 (66.2–88.7), 64.0 (60.0–75.8), and 52.4 (47.6–57.1) months (mo), respectively. ORR (95% CI) by INV was 39% (28–51), 65% (55–73), and 71% (56–84; Table) and progressive disease (PD) rates were 26%, 12%, and 16% in C1, C2, and C3, respectively. Median DOR was not reached in the 3 cohorts. The 48-mo PFS rates were 36%, 54%, and 51% and 48-mo OS rates were 49%, 71%, and 72% in C1, C2, and C3, respectively (Table). PFS and OS rates with up to 60 mo of follow-up will be presented. Safety data are shown in the table. Conclusions: With extended follow-up of ~5 years, NIVO ± IPI continued to demonstrate durable OS and PFS benefit, with no new safety signals. These updated data further support current treatment recommendations for 2L+ NIVO ± IPI and 1L NIVO + IPI for pts with MSI-H/dMMR mCRC. Clinical trial information: NCT02060188. [Table: see text]

3559 Background: Colorectal cancer remains a significant source of morbidity and mortality within the United States, causing nearly 53,000 deaths in 2021. For unresectable pts, the estimated 5-year survival rate is 14%. Given recent advances in treatment, 50% of pts with mCRC will receive third-line therapy or greater, making optimization of therapy in these settings pivotal. Trifluridine-tipiracil (TAS-102) is FDA approved for third-line or greater in mCRC per the RECOURSE Trial. Standard dosing is 35 mg/m2 twice daily (maximum = 80 mg/day) on Days 1-5 and Days 8-12 of 28-day cycles. This dosing schedule is associated with Grade 3-4 neutropenia (38%), requiring treatment delays (53%), dose reductions (14%) and G-CSF support (9%). To reduce this toxicity while maintaining efficacy, we studied an alternative biweekly dosing (Days 1-5 and Days 15-19 of 28-day cycles). Methods: A retrospective analysis was completed (2019-2021) at Vanderbilt-Ingram Cancer Center in pts with refractory mCRC and appendiceal cancer (CA) who completed > 12 days of TAS-102 therapy. Diagnostic imaging was completed every 8-12 weeks. Patient data was evaluated for lines of prior therapy, ECOG performance status (PS), the addition of bevacizumab, and CTCAE grade of treatment-related myelotoxicity. Evaluation of progression-free survival (PFS) was performed only in mCRC pts. Results: 24 pts met the criteria, with a mCRC:appendiceal CA ratio of 20:4 and Male:Female 13:11. Median age 61.5 yrs (range 31-80); median number of prior therapies 3; median ECOG PS of 1; and median duration of therapy 73.5 days. Hematologic toxicities: Neutropenia 30% [Grade 3 (13%), Grade 4 (0%)]; anemia 17.4% [Grade 3 (8.7%), Grade 4 (0%)]; thrombocytopenia 4.3% [Grade 3/4 (0%)]. No pts required G-CSF. One patient required a treatment-related dose delay (neutropenia), and 2 pts required dose reductions (fatigue). In mCRC pts, the median PFS was 2.3 months. To date, 7 mCRC pts remain on treatment (range: 38-385). Conclusions: In our retrospective cohort analysis, TAS-102 biweekly dosing schedule (35 mg/m2 twice daily; Days 1-5 and Days 15-19 of 28-day cycles) for pts with refractory mCRC and appendiceal CA reduced Grade 3 myelotoxicity without Grade 4 toxicities, while preserving PFS in pts with mCRC. With an improved toxicity profile, this alternative TAS -102 dosing schedule may be a more favorable option for future combination studies. Additional prospective data are needed to validate these findings. To our knowledge, this is the first analysis of biweekly TAS-102 in a US patient population.

We developed a clinical score (CS) at Vanderbilt Ingram Cancer Center (VICC) that we hoped would predict outcomes for patients with progressive well-differentiated neuroendocrine tumors (NETs) receiving therapy with Lutetium-177 (177Lu)-DOTATATE. Patients under consideration for 177Lu-DOTATATE between March 1, 2016 and March 17, 2020 at VICC were assigned a CS prospectively. The CS included 5 categories: available treatments for tumor type outside of 177Lu-DOTATATE, prior systemic treatments, patient symptoms, tumor burden in critical organs and presence of peritoneal carcinomatosis. The primary outcome of the analysis was progression-free survival (PFS). To evaluate the effect of the CS on PFS, a multivariable Cox regression analysis was performed adjusting for tumor grade, primary tumor location, and the interaction between 177Lu-DOTATATE doses received (zero, 1–2, 3–4) and CS. A total of 91 patients and 31 patients received 3–4 doses and zero doses of 177Lu-DOTATATE, respectively. On multivariable analysis, in patients treated with 3–4 doses of 177Lu-DOTATATE, for each 1-point increase in CS, the estimated hazard ratio (HR) for PFS was 2.0 (95% CI 1.61–2.48). On multivariable analysis, in patients who received zero doses of 177Lu-DOTATATE, for each 1-point increase in CS, the estimated HR for PFS was 1.22 (95% CI 0.91–1.65). Among patients treated with 3–4 doses of 177Lu-DOTATATE, those with lower CS experienced improved PFS with the treatment compared to patients with higher CS. This PFS difference, based upon CS, was not observed in patients who did not receive 177Lu-DOTATATE, suggesting the predictive utility of the score.

58 Background: In the phase 2 CheckMate 142 trial, NIVO + low-dose IPI had robust, durable clinical benefit and was well tolerated as 1L therapy for MSI-H/dMMR mCRC (median follow-up, 29.0 months [range, 24.2–33.7]) (Lenz et al. J Clin Oncol 2020;38:Abstract 4040; NCT02060188). Objective response rate (ORR) per investigator (INV) was achieved in 69% of pts (95% CI, 53–82); progressive disease rate was 13%. Median progression-free survival (PFS) and overall survival (OS) were not reached. Median duration of treatment was 19.1 months (95% CI, 11.1–29.0). Grade 3–4 treatment-related adverse events (TRAEs) occurred in 22% of pts. We present the post hoc subgroup analyses of efficacy and safety outcomes in pts from the same follow-up based on demographics and baseline disease characteristics. Methods: Pts with MSI-H/dMMR mCRC and no prior treatment for metastatic disease received NIVO 3 mg/kg Q2W + low-dose IPI 1 mg/kg Q6W until disease progression or discontinuation. ORR (primary endpoint, RECIST v1.1) and PFS were assessed per INV. Post hoc subgroup analyses of efficacy (by ECOG performance status [PS], stage at initial diagnosis, primary tumor location, and BRAF/KRAS mutation status) and safety (by age and ECOG PS) are presented. Results: Among 45 treated pts, efficacy (Table) and safety were generally consistent across evaluated subgroups. ORR was similar in pt subgroups by BRAF/ KRAS mutation status, stage at initial diagnosis, primary tumor location, and ECOG PS (Table). Median PFS and OS were not reached (NR) in evaluated subgroups after a minimum follow-up of 24.2 months (Table). Incidence of grade 3–4 TRAEs for subgroups by age and ECOG PS were consistent with the overall population. Conclusions: NIVO + low-dose IPI demonstrated robust, durable clinical benefit; was well tolerated with 2-year follow-up; and was consistent in evaluated subgroups in 1L MSI-H/dMMR mCRC. Clinical trial information: NCT02060188. [Table: see text]

Metastatic (and locally advanced) pancreatic adenocarcinoma (mPDA) represents a major challenge for the oncology community given the rising mortality burden from the disease and the preponderance of patients diagnosed with unresectable disease. Although systemic therapies have become more potent with the development of fluorouracil, irinotecan, and oxaliplatin (FOLFIRINOX) and gemcitabine plus nab-paclitaxel as first-line treatments, the median overall survival for patients treated with either of these regimens remains just above 1 year. A significant need exists to build upon the effectiveness of first-line regimens, incorporate tolerable maintenance treatments, and add effective later-line options for patients with this disease. We believe every newly diagnosed mPDA patient should undergo next-generation sequencing (NGS) testing, preferably from tumor tissue, to assess for the presence of DNA damage repair (DDR) defects, microsatellite instability, and other possible actionable molecular alterations (such as neurotrophic tropomysin receptor kinase (NTRK) fusions, anaplastic lymphoma kinase (ALK) rearrangements, or human epidermal growth factor receptor 2 (HER2) amplification). Existing clinical data suggests that patients, whose tumors harbor DDR defects, benefit from treatment with platinum-based chemotherapy and poly (ADP-ribose) polymerase (PARP) inhibitors. Preclinically, inhibitors of other critical players in DDR such as ataxia-telangiectasia and Rad3 related (ATR), ataxia-telangiectasia mutated (ATM), DNA-dependent protein kinase (DNA-PK), and WEE1 have demonstrated promising anti-tumor activity in PDA cell lines and xenografts. How to move forward the preclinical promise of these newer DDR-targeting therapies into rational clinical trial combinations and sequence PARP inhibitors in relation to platinum chemotherapy remain areas of tremendous clinical research interest. We believe clinical trials should be considered early for mPDA patients, in all treatment lines, so that novel therapies may be added to the treatment armamentarium for patients with this disease. Beyond NGS testing from tumor tissue, we believe it is important to consider germline genetic testing for all patients diagnosed with PDA given recent data suggesting a much stronger hereditary component of the disease than previously understood, and the potential screening implications for family members.

Purpose: The recombinant fusion protein ipafricept blocks Wnt signaling, and in combination with gemcitabine and nab-paclitaxel caused tumor regression in xenografts. This phase Ib study evaluated the combination of ipafricept with nab-paclitaxel + gemcitabine in patients with untreated metastatic pancreatic adenocarcinoma (mPDAC). Patients and Methods: Dose escalation started with standard dose nab-paclitaxel + gemcitabine and ipafricept (3.5 mg/kg days 1, 15). Because of fragility fractures seen with different anti-Wnt agents, following cohorts had ≥6 patients treated with ipafricept 3 to 5 mg/kg on day 1, and included bone marker monitoring and prophylactic bisphosphonates as indicated. On the basis of preclinical data, sequential dosing was evaluated in cohort 4 (ipafricept day 1 followed nab-paclitaxel + gemcitabine day 3). Objectives included safety, MTD, recommended phase II dose, pharmacokinetics, immunogenicity, pharmacodynamics, and efficacy. Results: A total of 26 patients were enrolled, five in cohort 1 and seven each in cohorts 2–4. ipafricept-related adverse events (AEs) of any grade included fatigue, nausea, vomiting, anorexia, and pyrexia. ipafricept-related AEs grade ≥3 included two events of aspartate aminotransferase elevation, and one each of nausea, rash, vomiting, and leucopenia. No dose-limiting toxicities or fragility fractures were observed. Nine patients (34.6%) had partial response, 12 (46.2%) stable disease as best response, with clinical benefit rate of 81%. Median progression-free survival was 5.9 m [95% confidence interval (CI), 3.4–18.4], median overall survival was 9.7 m (95% CI, 7.0–14). The study was terminated by the sponsor due to bone-related toxicity within this therapeutic program and concerns for commercial viability. One patient remains on therapy under compassionate use. Conclusions: Ipafricept can be administered with nab-paclitaxel + gemcitabine with reasonable tolerance. Wnt pathway remains a therapeutic target of interest in mPDAC.

Objectives Heat shock protein 90 regulates multiple signaling proteins involved in key pathways of pancreatic cancer pathogenesis. Ganetespib binds to heat shock protein 90 and interferes with its binding to client proteins thus leading to inactivation and degradation of the signaling proteins that promote cancer progression. This phase II study was designed to evaluate the efficacy of ganetespib in patients with refractory metastatic pancreatic cancer (rMPC). Methods Patients with rMPC received 175 mg/m ganetespib intravenously once weekly for 3 weeks in 4-week cycles. Primary endpoint was disease control rate at 8 weeks, with a goal of 70%. Secondary endpoints were progression-free survival, overall survival, and safety. Simon's 2-stage design was used to assess futility and efficacy. Ganetespib was considered inactive if ≤8 patients among the first 15 treated had disease control after 8 weeks of treatment. Results Fourteen patients were treated on study. Grade 3 treatment-related toxicities were diarrhea, abdominal pain, fatigue, nausea, vomiting, and hyponatremia. Disease control rate at 8 weeks was 28.6%, and median progression-free survival and overall survival were 1.58 months and 4.57 months, respectively. Early stopping rules for lack of clinical efficacy led to study closure. Conclusions Single-agent ganetespib was tolerable with only modest disease control in rMPC. This disease is resistant to chemotherapy, and given the emerging data in lung and rectal cancers, as well as in pancreatic cancer cell lines, suggesting improved activity of ganetespib in combination with cytotoxic agents, studies combining this agent with chemotherapy in rMPC are more likely to yield success.

Pancreatic adenocarcinoma remains a major therapeutic challenge, as the poor (

Objectives The programmed death 1 (PD-1) pathway is upregulated in the immune microenvironment of many cancers. In this study, we examined the PD-1 pathway and the immune microenvironment of small intestinal adenocarcinomas by immunohistochemistry. Methods From our department pathology archives we identified 42 small intestinal adenocarcinomas from between 2000 and 2015, with blocks available for IHC studies. Tumors were immunohistochemically stained for CD3, CD4, CD8, CD20, PD-1, and programmed death ligand 1 (PD-L1) expression. Results PD-1 was expressed by intratumoral and peritumoral lymphocytes in 35 of 42 (83%) cases. PD-L1 expression on tumor cells and immune cells was observed in seven of 42 (17%), and 18 of 42 (43%) cases, respectively. PD-L1 was mainly expressed by histiocytes capping cancerous glands/nests at the invasive front or by most tumor cells in medullary carcinomas. All the PD-L1+ tumors also expressed PD-1. The tumors expressing PD-L1 contained more CD3+, CD4+, and CD8+ T cells, but showed a lower CD4+/CD8+ ratio than those without expression of PD-L1. Conclusions PD-1 and PD-L1 are highly expressed by most small intestinal adenocarcinomas. Blockage of the PD-1 pathway should be evaluated in the treatment of small intestinal adenocarcinomas.

Lessons Learned This trial evaluating a novel plant extract, PBI-05204, did not meet its primary endpoint of overall survival but did show signals of efficacy in heavily pretreated mPDA. PBI-05204 was generally well tolerated, with the most common side effects related to treatment being vomiting (23.7%), nausea (18.4%), decreased appetite (18.4%), and diarrhea (15.8%). Additional trials are needed to explore the role of PBI-05204 in cancer treatment. Background Survival for metastatic pancreatic ductal adenocarcinoma (mPDA) is dismal, and novel agents are needed. PBI-05204 is a modified supercritical carbon dioxide extract of Nerium oleander leaves. Oleandrin, the extract's major cytotoxic component, is a cardiac glycoside that has demonstrated antitumor activity in various tumor cell lines with a mechanism involving inhibition of Akt phosphorylation and through downregulation of mTOR. Methods A phase II, single-arm, open-label study to determine the efficacy of PBI-05204 in patients with refractory mPDA therapy was conducted. The primary endpoint was overall survival (OS), with the hypothesis that 50% of patients would be alive at 4.5 months. Secondary objectives included safety, progression-free survival (PFS), and overall response rate. Patients received oral PBI-05204 daily until progressive disease (PD), unacceptable toxicity, or patient withdrawal. Radiographic response was assessed every two cycles. Results Forty-two patients were enrolled, and 38 were analyzed. Ten patients were alive at 4.5 months (26.3%) with a median PFS of 56 days. One objective response (2.6%) was observed for 162 days. Grade ≥ 3 treatment-emergent adverse events occurred in 63.2% of patients with the most common being fatigue, vomiting, nausea, decreased appetite, and diarrhea. Conclusion PBI-05204 did not meet its primary endpoint for OS in this study. Recent preclinical data indicate a role for PBI-05204 against glioblastoma multiforme when combined with chemotherapy and radiotherapy. A randomized phase II trial is currently being designed.

11 Background: In the phase 2 CheckMate 142 trial, nivolumab plus low-dose ipilimumab provided robust and durable clinical benefit and was well tolerated as first-line therapy for microsatellite instability-high/DNA mismatch repair deficient (MSI-H/dMMR) metastatic colorectal cancer (mCRC) (Lenz et al. Ann Oncol 2018;29:LBA18). Longer follow-up data will be presented. Methods: Patients with MSI-H/dMMR mCRC and no prior treatment for metastatic disease received nivolumab 3 mg/kg every 2 weeks plus low-dose ipilimumab 1 mg/kg every 6 weeks until disease progression or discontinuation. The primary endpoint was investigator-assessed objective response rate (ORR). Results: For all 45 patients (median follow-up was 13.8 months), ORR was 60% (95% CI 44.3–74.3). Responses were consistent with the overall population across subgroups including age, Eastern Cooperative Oncology Group (ECOG) performance status, prior adjuvant/neoadjuvant therapy, and mutation status (Table). Seven patients (16%) had grade 3–4 treatment-related adverse events; 3 (7%) had any grade treatment-related adverse events leading to discontinuation. Updated response, survival, and safety data after a longer follow-up (median 19.9 months) will be presented. Conclusions: Nivolumab plus low-dose ipilimumab demonstrated robust and durable clinical benefit and was well tolerated. Evaluated subgroups had responses consistent with the overall population. Nivolumab plus low-dose ipilimumab may represent a new first-line treatment option for patients with MSI-H/dMMR mCRC. Clinical trial information: NCT02060188. [Table: see text]

Purpose: The RAS/RAF/MEK/ERK signaling pathway is critical to the development of colorectal cancers, and KRAS, NRAS, and BRAF mutations foster resistance to radiation. We performed a phase I trial to determine the safety of trametinib, a potent MEK1/2 inhibitor, with 5-fluorouracil (5-FU) chemoradiation therapy (CRT) in patients with locally advanced rectal cancer (LARC). Patients and Methods: Patients with stage II/III rectal cancer were enrolled on a phase I study with 3+3 study design, with an expansion cohort of 9 patients at the MTD. Following a 5-day trametinib lead-in, with pre- and posttreatment tumor biopsies, patients received trametinib and CRT, surgery, and adjuvant chemotherapy. Trametinib was given orally daily at 3 dose levels: 0.5 mg, 1 mg, and 2 mg. CRT consisted of infusional 5-FU 225 mg/m2/day and radiation dose of 28 daily fractions of 1.8 Gy (total 50.4 Gy). The primary endpoint was to identify the MTD and recommended phase II dose. IHC staining for phosphorylated ERK (pERK) and genomic profiling was performed on the tumor samples. Results: Patients were enrolled to all dose levels, and 18 patients were evaluable for toxicities and responses. Treatment was well tolerated, and there was one dose-limiting toxicity of diarrhea, which was attributed to CRT rather than trametinib. At the 2 mg dose level, 25% had pathologic complete response. IHC staining confirmed dose-dependent decrease in pERK with increasing trametinib doses. Conclusions: The combination of trametinib with 5-FU CRT is safe and well tolerated, and may warrant additional study in a phase II trial, perhaps in a RAS/RAF-mutant selected population.

Purpose: This two-part phase Ib trial determined the maximum tolerated dose (MTD) of the combination of trifluridine/tipiracil (FTD/TPI) and irinotecan in patients with advanced gastrointestinal tumors, and evaluated the safety, pharmacokinetics, and antitumor activity of the FTD/TPI, irinotecan, and bevacizumab triplet combination in previously treated metastatic colorectal cancer (mCRC). Patients and Methods: Dose escalation (3+3 design) in advanced gastrointestinal tumors was followed by expansion in mCRC. During dose escalation, patients received FTD/TPI (20–35 mg/m2 twice daily; days 1–5 of a 14-day cycle) and irinotecan (120–180 mg/m2; day 1). During expansion, the MTD of FTD/TPI and irinotecan plus bevacizumab (5 mg/kg; day 1) was administered. Results: Fifty patients (26 across six dose-escalation cohorts and 24 in the expansion phase) were enrolled. Two dose-limiting toxicities (fatigue and neutropenia) were observed in the dose-escalation phase, and MTD was defined as FTD/TPI 25 mg/m2 twice daily plus irinotecan 180 mg/m2. In the expansion phase, 83% (20/24) experienced any-cause grade ≥3 adverse events (AEs) with the triplet combination, most frequently neutropenia (42%), leukopenia (25%), and diarrhea (12%). AEs of any-cause led to dosing interruptions, modifications, and discontinuations in 29%, 17%, and 4% of patients, respectively. No treatment-related deaths occurred. Three patients (12%) experienced partial responses and 16 (67%) patients had stable disease lasting >4 months. The median progression-free survival was 7.9 months (95% confidence interval, 5.1–13.4 months). Conclusions: Tolerability and activity observed in this phase I trial support further investigation of the FTD/TPI–irinotecan–bevacizumab combination in previously treated mCRC.

3521 Background: In the phase 2 CheckMate 142 trial, NIVO + low-dose IPI provided robust and durable clinical benefit and was well tolerated as 1L therapy for MSI-H/dMMR mCRC (Lenz et al. Ann Oncol 2018;29:LBA18). Longer follow-up data will be presented. Methods: Patients with MSI-H/dMMR mCRC and no prior treatment for metastatic disease received NIVO 3 mg/kg every 2 weeks + low-dose IPI 1 mg/kg every 6 weeks until disease progression or discontinuation. The primary endpoint was investigator-assessed objective response rate (ORR). Results: For all 45 patients (median follow-up was 13.8 months), ORR was 60% (95% CI 44.3–74.3). Responses were consistent with the overall population across subgroups including age, Eastern Cooperative Oncology Group (ECOG) performance status, prior adjuvant/neoadjuvant therapy, and mutation status (Table). Seven patients (16%) had grade 3–4 treatment-related adverse events (TRAEs); 3 (7%) had any grade TRAEs leading to discontinuation. Updated response, survival, and safety data after a longer follow-up (median 19.9 months) will be presented. Conclusions: NIVO + low-dose IPI demonstrated robust and durable clinical benefit and was well tolerated. Evaluated subgroups had responses consistent with the overall population. NIVO + low-dose IPI may represent a new 1L treatment option for patients with MSI-H/dMMR mCRC. Clinical trial information: NCT02060188. [Table: see text]

4109 Background: Questions remain regarding when to sequence PRRT and how to categorize pts being considered for the treatment (tx). We previously developed a CS (comprised of 5 categories: available non-PRRT tx for tumor type, prior systemic tx, pt symptoms, tumor burden in critical organs and peritoneal carcinomatosis presence) at Vanderbilt Ingram Cancer Center (VICC) for pts being considered for PRRT to help answer these questions and demonstrated the score to be associated with progression-free survival (PFS) in pts receiving PRRT. Herein, we present the performance of the CS in a validation cohort (VC) and combined cohort (CC). Methods: Our original cohort (OC) included pts with progressive WD NETs (N = 122) under consideration for PRRT between 3/1/2016-3/17/2020 at VICC while our VC included pts under consideration for PRRT (N = 126) between 1/25/2017-11/18/2019 at Ochsner Medical Center (OMC) (N = 51), Markey Cancer Center (MCC) (N = 51) and Rush Medical Center (RMC) (N = 24). All pts in the OC were prospectively scored while pts in the VC were scored retrospectively, with the CS-assigning investigator blinded to patient outcomes. The primary outcome PFS, was estimated by the Kaplan‐Meier method; a Cox proportional‐hazards model adjusting for primary tumor site, tumor grade and number of PRRT doses administered (0, 1-2 or 3-4) was used to analyze effect of CS. Overall survival (OS) was a key secondary outcome. Results: In our VC, on multivariable (MV) analysis, for each 2-point increase in CS, the hazard ratio (HR) for PFS was 2.58 (95% confidence interval (CI) 1.62-4.11). On MV analysis, for each 2-point increase in CS, the HR for OS was 3.89 (95% CI 1.8-4.83). We combined the OC and VC for this analysis in order to increase the predictive power of our originally developed Cox proportional-hazards models. In our CC, of the 248 total pts, median pt age, CS and number of prior tx were 63.3 years, 4 (range 0-8) and 1 (range 0-7), respectively. The most represented primary tumor sites were small intestinal (N = 136), pancreatic (N = 58), unknown primary (N = 26) and lung (N = 14). A total of 140, 82 and 26 pts received 3-4, 0 or 1-2 doses of PRRT, respectively. On MV analysis, for each 2-point increase in CS, the HR for PFS was 2.52 (95% CI 1.90-3.35). On MV analysis, for each 2-point increase in CS, the HR for OS was 3.48 (95% CI 2.33-5.18). No interaction between PRRT doses administered and CS was observed. Conclusions: Increases in CS were strongly associated with worsening PFS and OS in our VC and CC, validating findings from our OC. Although we cannot determine whether the CS specifically predicts PRRT response or is prognostic based upon these data, it is the first presented clinical metric which can categorize pts with WD NETs under consideration for PRRT and estimate anticipated benefit from PRRT for pts.

8563 Background: Cediranib, a pan-vascular endothelial growth factor receptor tyrosine kinase inhibitor, suppresses expression of homologous recombination DNA repair (HRR) genes and increases sensitivity of tumors to a poly-(ADP-ribose) polymerase (PARP) inhibitor in vitro and in vivo models of breast and ovarian cancer. Olaparib, a PARP inhibitor, demonstrated clinical efficacy in patients with advanced solid tumor with a deleterious mutation in HRR genes. We hypothesized that cediranib induces HRR deficient phenotype by suppressing expression of HRR genes and cediranib and olaparib combination (C+O) results in an objectives response in patients with HRR proficient (HRP) advanced solid tumors. Herein, we report the biomarker data from analyses of targeted sequencing of 84 DNA repair (DR) genes with BROCA-HR assay in patients with metastatic small cell lung cancer (mSCLC). Methods: This multi-institutional phase 2 trial enrolled patients with mSCLC previously treated with a platinum-based chemotherapy. Patients received cediranib 30mg orally (po) daily plus olaparib 200mg po twice daily until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR) by RECIST v1.1. A tumor biopsy was obtained from the patients with safely accessible metastatic tumor. HRR deficiency (HRD) was defined as presence of a deleterious mutation in any of the 10 key HRR-related genes per BROCA-HR assay including: ATM, BARD1, BRCA1, BRCA2, BRIP1, CDK12 (somatic mutations only), NBN, PALB2, RAD51C, or RAD51D. Otherwise, the tumors were defined as HRR proficiency (HRP). Results: A total of 25 patients with SCLC received the study treatment. Fourteen patients had available tumor biopsy samples and/or germline available for BROCA-HR. One patient (7%) was determined to have a HRD tumor by a presence of PALB2 mutation. This patient had stable disease as a best overall response but came off study due to unequivocal clinical progression. Thirteen patients (93%) had a HRP tumor. Six of these (46%) patients had PR. Median PFS in patients with HPR tumors was 122 days. The most common gene alterations detected by BROCA-HR assay was TP53 (93%) and RB1 (79%). Other DR gene alterations noted from our study samples were MRE11, CKD12 PALB2, ERCC4, FANCB, and BAP1. Conclusions: HRD was infrequent in our mSCLC samples. C+O resulted in objective responses in 46% of mSCLC patients with HRP tumors. Mutations in TP53 and RB1 were the most common gene alterations. Further investigation in warranted to confirm this observation. Clinical trial information: NCT02498613.

363 Background: Despite the benefit of PRRT for patients with WD NETs, questions remain regarding sequencing and optimal patient selection for the treatment. We developed a CS at Vanderbilt Ingram Cancer Center (VICC) that we hoped would predict outcomes for patients with WD NETs receiving PRRT. Methods: Patients with progressive WD NETs (N = 146) under consideration for PRRT with Lu 177-dotatate between 3/1/2016-3/17/2020 at VICC (N = 122) and Rush Medical Center (RMC) (N = 24) were scored. The CS included 5 categories: available non-PRRT treatments for tumor type, prior systemic treatments, patient symptoms, tumor burden in critical organs and peritoneal carcinomatosis presence. All categories were scored from 0-2 except the peritoneal carcinomatosis category which was scored from 0-1; scoring criteria were determined by the VICC NET tumor board. All patients at VICC were prospectively scored, while patients from RMC were scored retrospectively with the investigator blinded to patient outcomes. The primary outcome, progression-free survival (PFS) was estimated by the Kaplan‐Meier method; a Cox proportional‐hazards model adjusting primary tumor site, tumor grade and number of PRRT doses administered (none, 1-2 doses or 3-4 doses) was used to analyze effect of CS. Results: Median patient age was 62.7 while median CS was 5 (range 1-8); the most common primary tumor sites were small intestinal (N = 81) and pancreatic (N = 37). A total of 101 patients and 31 patients received 3-4 doses and no doses of PRRT, respectively. On multivariable analysis, in patients treated with 3-4 doses of PRRT, for each 2-point increase in CS, the estimated hazard ratio (HR) for PFS was 3.26 (95% confidence interval (CI) 2.05-5.19). On multivariable analysis, in patients who received no doses of PRRT, for each 2-point increase in CS, the estimated HR for PFS was 1.37 (95% CI .78-2.41). Conclusions: Among patients treated with 3-4 doses PRRT, those with lower CS had better PFS with the treatment compared to patients with higher CS. This PFS difference, based upon CS, was not observed in patients who did not receive PRRT, suggesting the predictive utility of the CS for patients with WD NETs receiving PRRT with Lu 177-dotatate. Though the CS needs to be validated, it is the first of its kind reported.

Background: Gln metabolism plays a critical role in cancer. In CRC, the epidermal growth factor receptor (EGFR) and Gln cooperate to provide signal transduction and fuel for mitogen activated protein kinase-dependent cell growth. Our preclinical data illustrate that Gln abrogates EGFR inhibition and blockade of Gln metabolism restores EGFR sensitivity, forming the basis of a phase I/II clinical trial exploring dual EGFR and Gln metabolism in mCRC (NCT03263429). As a biomarker correlate, we are performing dual tracer PET imaging of Gln flux (11C-Gln) and Gln to glutamate conversion (18F-FSPG). We hypothesize that tumors dependent on Gln will exhibit high 11C-Gln uptake at baseline, while inhibition of Gln metabolism will reduce 18F-FSPG uptake. Notably, this is the first-in-human study with 11C-Gln. Methods: Adult patients (pts) with previously treated anti-EGFR, RAS WT, mCRC are enrolling and receive panitumumab (6 mg/kg Day 1 and 15) and CB-839 (800 mg twice daily) in 28-day treatment cycles. 11C-Gln and 18F-FSPG scans are performed at baseline and Cycle 1 Day 28. Lesion to blood pool ratio (LBR) is calculated for each target lesion and compared with change in tumor size as measured by RECIST 1.1 after 2 cycles of therapy. Results: The study is ongoing. To date, we have collected pre- and post-therapy PET data on 4 pts; individual lesion data for 2 pts are presented in the table. A mixed response with 11C-Gln uptake was observed for Pt #1, which could reflect different underlying lesion pathology; varying degree of lesion size change was also observed in this patient. The greatest decrease in 18F-FSPG uptake corresponded to the lesion with the smallest growth. For Pt #2, 11C-Gln uptake at baseline was highest in the lesion with the largest decrease in tumor size at Day 56; 18F-FSPG uptake was greatly reduced in all lesions, which corresponded to decreases in tumor size. Best overall response was progressive disease and partial response for Pt #1 and #2, respectively. Gln PET as a function of lesion response11C-Gln18F-FSPG% Change in lesion size at Day 56Baseline LBRDay 28 LBR% ChangeBaseline LBRDay 28 LBR% ChangePatient#1L lung nodule+44%2.171.93-11.1%2.001.06-47.0%Posterior hepatic lobe+6%5.404.27-20.9%6.422.84-55.8%Segment IVA liver+107%5.114.88-4.5%5.583.90-30.1%Adrenal mass+152%3.504.4727.7%2.862.84-0.7%Patient#2R infrahilar pulmonary metastasis-15%2.471.74-29.6%3.131.72-45.0%L pulmonary metastasis-15%0.750.784.0%0.960.82-14.6%Hepatic Metastasis #1-100%8.976.81-24.1%7.003.50-50.0% Conclusions: Quantitative biomarkers that predict response early in the course of therapy are a means to achieve the promise of precision medicine. Our preliminary clinical imaging data suggest that the employed investigational PET molecular imaging tracers have potential for prioritizing patients for combined EGFR/Gln targeted therapy and to predict response early in the treatment course. Additional PET data for all pts and summary statistics will be presented. Citation Format: Jennifer Gray Whisenant, Gary Smith, Allison Cohen, Kristen K. Ciombor, Dana Cardin, Cathy Eng, Laura Goff, Satya Das, Tiffany Hickman, Anna Fisher, Adria Payne, Robert Coffey, G. Dan Ayers, Jordan D. Berlin, H. Charles Manning. Molecular imaging of glutamine (Gln) metabolism in RAS wildtype (WT) metastatic colorectal cancer (mCRC) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4260.

Preclinical studies have shown synergy between everolimus, an mTOR inhibitor, radiation, and platinum agents. We conducted a phase IB trial to determine the recommended phase II dose of everolimus with carboplatin and radiation.Patients with stage II/III esophageal cancer were enrolled. Following 2 cycles of Capecitabine/Oxaliplatin (XELOX), patients with no disease progression, received 50.4 Gy in 28 fractions and concurrent weekly carboplatin (area under the curve=2), with escalating doses of everolimus. A standard 3+3 dose escalation design was used.Nineteen patients were enrolled. Two patients were screen failures and 4 were removed due to poor tolerance to XELOX (n=2) or disease progression (n=2). All treated patients had adenocarcinoma. Median age was 58 (44 to 71 y) and 85% were male patients. One patient at dose level 1 was replaced due to ongoing anxiety. One of 6 patients had a dose-limiting toxicity of bowel ischemia that was fatal. At dose level 2, two of 6 patients had a dose-limiting toxicity (fever with neutropenia and nausea). The recommended phase II dose of everolimus was 2.5 mg QOD. Grade ≥3 toxicities included lymphopenia (11%), nausea (10%), low white blood cell (8.0%) vomiting (5.5%), decreased neutrophils (4.0%). All patients achieved an R0 resection with a pathologic response rate of 40% and a pathologic complete response (ypCR) rate of 23%. The 2-year progression-free survival and overall survival were 50% and 49.6%, respectively.The recommended phase II dose of everolimus with concurrent weekly carboplatin and radiation is 2.5 mg QOD.

4040 Background: In the phase 2 CheckMate 142 trial, NIVO + low-dose IPI had robust, durable clinical benefit and was well tolerated as 1L therapy for MSI-H/dMMR mCRC (median follow-up 13.8 months [mo; range, 9–19]; Lenz et al. Ann Oncol 2018;29:LBA18). Longer follow-up is presented here. Methods: Patients (pts) with MSI-H/dMMR mCRC and no prior treatment for metastatic disease received NIVO 3 mg/kg Q2W + low-dose IPI 1 mg/kg Q6W until disease progression or discontinuation. The primary endpoint was investigator-assessed (INV) objective response rate (ORR) per RECIST v1.1. Results: In 45 pts with median follow-up of 29.0 mo, ORR (95% CI) increased to 69% (53–82) (Table) from 60% (44.3–74.3); complete response (CR) rate increased to 13% from 7%. The concordance rate of INV and blinded independent central review was 89%. Median duration of response (DOR) was not reached (Table). Median progression-free survival (PFS) and overall survival (OS) were not reached, and 24-mo rates were 74% and 79%, respectively (Table). Nineteen pts discontinued study treatment without subsequent therapy. An analysis of tumor response post discontinuation will be presented. Ten (22%) pts had grade 3–4 treatment-related adverse events (TRAEs); 3 (7%) had grade 3–4 TRAEs leading to discontinuation. Conclusions: NIVO + low-dose IPI continued to show robust, durable clinical benefit with a deepening of response, and was well tolerated with no new safety signals identified with longer follow-up. NIVO + low-dose IPI may represent a new 1L therapy option for pts with MSI-H/dMMR mCRC. Clinical trial information: NTC02060188 . [Table: see text]

Managing patients with metastatic pancreatic adenocarcinoma (mPDA) is a challenging proposition for any treating oncologist. Although the potency of first-line therapies has improved with the approvals of FOLFIRINOX and gemcitabine plus nab-paclitaxel, many patients are unable to derive significant benefit from later lines of therapy upon progression. Enrollment on clinical trials remains among the best options for patients with mPDA in all lines of therapy. At our institution, we routinely check for microsatellite instability (MSI-H) and perform next-generation sequencing (NGS) at the time of diagnosis in all good performance status mPDA patients. Although MSI-H status is only found in 1% of patients with mPDA, given pembrolizumab’s tissue-agnostic approval for MSI-H tumors in later-line settings, it is a viable option when deciding on subsequent lines of therapy. Any use of immune therapy in mPDA is investigational outside the MSI-H setting. NGS can identify BRCA or other DNA damage response (DDR) defects in patients which can predict sensitivity to platinum-based therapies and influence choice of both initial and later lines of therapy. It can also identify rare actionable genomic alterations such as HER2 (2%) and TRK fusions (0.1%) and offer patients the option of enrollment on clinical trials with agents targeting these or other identified alterations. We believe enrolling mPDA patients on clinical trials with immune-modulating agents is critical to determine if there are other patient subsets, outside of the MSI-H setting, who would benefit from these approaches. Immunotherapy’s general tolerability and potential to generate durable responses make it particularly appealing for mPDA patients. Although single-modality immunotherapy such as checkpoint inhibitors or vaccines have not demonstrated efficacy in this disease, combinatorial strategies targeting unique aspects of PDA including the tumor micro-environment and desmoplastic stroma have shown preclinical or early-phase success. Validating these treatments with later-phase prospective studies is essential to making immunotherapy a routine component of the treatment armamentarium for mPDA patients.

Ductal adenocarcinoma and its variants account for most pancreatic malignancies. High-quality multiphase imaging can help to preoperatively distinguish between patients eligible for resection with curative intent and those with unresectable disease. Systemic therapy is used in the neoadjuvant or adjuvant pancreatic cancer setting, as well as in the management of locally advanced unresectable and metastatic disease. Clinical trials are critical for making progress in treatment of pancreatic cancer. The NCCN Guidelines for Pancreatic Adenocarcinoma focus on diagnosis and treatment with systemic therapy, radiation therapy, and surgical resection.

Pancreatic ductal adenocarcinoma is one of the deadliest solid tumor malignancies and is projected to become a leading cause of cancer-related death in coming years. Improving quality of life and survival amongst these patients will require new ideas and novel therapies in a multidisciplinary approach. This review will cover the most recent advances in the comprehensive treatment of pancreatic cancer and place them within a historical context when necessary. Treatment of all disease stages will be discussed, but the focus is on systemic therapy as novel drugs and new treatment combinations enter the clinic. This will include more aggressive chemotherapy in earlier disease stages, approved uses for immunotherapy, and targetable mutations. In addition, negative trials of importance and controversial topics will be noted.

797 Background: SBA is rare and often grouped with, and treated like, large intestinal adenocarcinomas. However, SBA has a very different microenvironment and could respond differently to the same therapies, potentially lowering efficacy. Also no standard treatments exist due to the lack of prospective randomized trials. We presented data at GI ASCO 2016 that suggested SBAs might benefit from targeting the PD-1/PD-L1 axis based on strong PD-L1 staining in ~50% of SBAs tested. Thus, we designed a pilot phase 2 trial to study safety and efficacy of avelumab in SBA. Methods: Patients (pts) with advanced (not amenable to surgery) or metastatic disease were eligible; ampullary tumors were considered part of the duodenum and allowed. Pts with prior PD-1/PD-L1 were excluded. Avelumab (10 mg/kg) was given every 2 weeks in 14-day cycles, and imaging was performed every 8 weeks. Primary endpoint was response rate (RR). Enrollment of 25 pts were planned, and avelumab would be considered active if ≥4 responses (RR≥16%) were observed (80% power, a = 5%). Secondary endpoints included disease-control rate (DCR) and progression-free survival (PFS). Results: Eight SBA pts (5 small intestine; 3 ampullary) were enrolled, with a majority (88%) being male and a median age of 61 years. Median time on treatment was 3.4 months; 1 patient is still on study with an ongoing partial response (PR). Of 7 efficacy-evaluable patients, 2 had a PR for a RR of 29%; DCR was 71% (5/7). Median PFS was 8.0 months. Most frequent, related adverse events were fatigue (38%), elevated alkaline phosphatase (25%), and infusion related reaction (25%), all ≤G2; a G3 (not serious) hypokalemia and a G4 (serious) diabetic ketoacidosis occurred in 1 pt each. Conclusions: Avelumab was considered safe, and antitumor activity was observed as evidenced by a 29% RR and 71% DCR. Despite this benefit, accrual was slower than expected and the study was closed early due to feasibility. A general clinical observation is that more pts are receiving immunotherapy off-label as the availability of these agents increases. This was a likely contributor to slow accrual, in addition to disease rarity. Analysis of PD-L1 expression, MSI status, and other immune cell markers is planned and will be compared to response. Clinical trial information: NCT03000179 .

698 Background: Survival statistics for mPDA are dismal and with limited treatment options novel agents are needed to improve disease outcomes. PBI-05204 (Phoenix Biotechnology, Inc., San Antonio, TX) is a modified supercritical carbon dioxide extract of Nerium oleander leaves. Oleandrin, the extract’s major cytotoxic component, has demonstrated anti-tumor activity in various tumor cell lines. In a human PDA orthotopic model, this preparation reduced tumor burden as monotherapy. Pharmacodynamic studies suggest that PBI-05204’s mechanism of action is through inhibition of the PI3k/Akt/mTOR pathway. Methods: A phase II single-arm, open-label study to determine the efficacy of PBI-05204 in patients (pts) with mPDA refractory to standard therapy was conducted. The primary endpoint was overall survival (OS) with the hypothesis that 50% of pts would be alive at 4.5 months. Secondary objectives included safety, progression-free survival (PFS), and overall response rate. Pts received oral PBI-05204 daily until progressive disease (PD), unacceptable toxicity, or pt withdrawal. Radiographic response was assessed every two cycles. Results: Forty-one pts were enrolled; two never received treatment and one was found to have a neuroendocrine tumor after pathological re-evaluation, leaving 38 pts for analysis. Median age at time of enrollment was 65.0 years. The median time from initial diagnosis to treatment was 16.9 months. The primary reason for withdrawal was PD (45.2%). Ten pts were alive at 4.5 months (26.3%) with a mPFS of 56 days (corresponding to first restaging). One objective response (2.6%) was observed for 162 days. Grade ≥3 treatment-emergent adverse events occurred in 63.2% of pts with the most common attributed to drug (all grades) being fatigue (36.8%), vomiting (23.7%), nausea (18.4%), decreased appetite (18.4%), and diarrhea (15.8%). Conclusions: PBI-05204 did not meet its primary endpoint for OS in this study. Recent preclinical data indicate an efficacious role for PBI-05204 against glioblastoma multiforme when combined with chemotherapy, such as temozolomide, and radiotherapy. A randomized Phase II trial is currently being designed. Clinical trial information: NCT02329717.

4014 Background: PC is characterized by DNA Damage Repair (DDR) deficiencies, including in BRCA1/2, ATM, and FANC genes. Given preclinical synergism between veliparib with irinotecan, safety and preliminary efficacy, we designed a randomized phase II study of mFOLFIRI (no 5-FU bolus) + veliparib vs FOLFIRI alone for 2nd line mPC patients (pts). Methods: Eligible pts had mPC, adequate organ function, ECOG PS 0-1, and 1 prior non-irinotecan systemic therapy.143 pts were to be randomized (1:1) to veliparib vs control. Primary endpoint was overall survival (OS). All pts had blood and tumor biopsies at baseline to assess germline and somatic BRCA1/2 mutations (integrated), and homologous recombination (HR) or DDR biomarkers (exploratory). Results: 123 pts were accrued between 09/2016 to 12/2017, and 108 were included in this analysis. 117 pts were biomarker evaluable: 109 blood/106 tumors. 11 cancers (9%) had HR deficiency (HRD), including 4 germline ( BRCA1, BRCA2, ATM) and 7 somatic mutations ( BRCA2, PALB2, ATM, CDK12). Additional 24 cancers (20%) had germline (n = 11, e.g., FANC, BLM, SLX4, CHEK2) or somatic mutations (n = 13, e.g., FANC, BLM, POLD1, RIF1, MSH2, MSH6) in other DNA repair genes, not classified as HRD. A planned interim futility analysis at 35% of expected PFS events determined the veliparib arm was unlikely to be superior to control. Most common grade 3/4 treatment related toxicities were neutropenia (33% vs 20%), fatigue (19% vs 4%), and nausea (11% vs 4%), for veliparib vs control. Treatment exposure was similar for veliparib vs control: median 4 cycles (range 1-31 vs 1-32). Median OS was 5.1 vs 5.9 mos (HR 1.3, 95%CI 0.9-2.0, p = 0.21), and median PFS was 2.1 vs 2.9 mos (HR 1.5, 95%CI 1.0-2.2, p = 0.05) for veliparib vs control arms, respectively. Correlations of gene mutations and signatures with efficacy outcomes will be presented. Conclusions: Nearly 30% of mPC pts had DNA repair gene abnormalities, including 9% with HRD. Veliparib increased toxicity and did not improve OS when added to mFOLFIRI in biomarker unselected pts. BRCA1/2 and DDR biomarkers will be correlated with efficacy to inform patient selection for future PARP inhibitor clinical trials. Clinical trial information: NCT02890355.

3031 Background: AurA is a key regulator of cell division, including mitotic spindle assembly. However, elevated levels of AurA have been reported to abrogate the mitotic spindle checkpoint activated by taxanes leading to treatment resistance. Preclinical studies of TAS-119 + P showed enhanced antitumor activity and suggested an optimal timing window of the combination. Study objective was to assess the safety of TAS-119 + P in adult patients (pts) with advanced solid tumors. Methods: Dose escalation used a 3+3 design to determine the maximum tolerated dose (MTD); 7 dose levels (DLs) were explored, starting with 25 mg TAS-119 BID dosed 4 days/week (d/wk) and weekly 90 mg/m2 P for 3 weeks of a 4 week cycle (DL1). Plasma samples were collected during cycle 1 to evaluate pharmacokinetics. In expansion, pts with advanced breast/ovarian cancers were treated at the MTD. Results: Dose escalation enrolled 26 pts with various cancers, the majority being pancreas, colon, and ovarian; 2 pts were not evaluable for DLT assessment and replaced. A DLT (neutropenia and elevated AST) was observed in 2/3 pts in DL1. Dosing was modified to 25 mg TAS-119 BID 2 d/wk and P 70 mg/m2 (DL2) and no DLTs were observed. Zero DLTs were observed in the next 4 doses: 70 mg/m2 P + TAS-119 2 d/wk at 50 mg BID (DL3) or 75 mg BID (DL4), or 80 mg/m2 P + TAS-119 at 75 mg BID 2 d/wk (DL5) or 75 mg BID 3 d/wk (DL6). TAS-119 was escalated to 100 mg BID 3 d/wk (DL7) and 3 DLTs (n=1, elevated ALT; n=1, diarrhea and mucositis) occurred in 2/3 pts. Three additional pts were then enrolled at DL6 to confirm the MTD. One breast and 2 ovarian pts were enrolled in expansion before the trial was suspended by the company. Toxicities observed in ≥30% of pts were diarrhea, nausea, and fatigue (most ≤Gr2). Plasma TAS-119 exposure increased dose-proportionally in 2 d/wk and 3 d/wk schedules; no impact of TAS-119 on PK of paclitaxel was found. The disease control rate was 59% (17/29); 4 of these pts had a partial response. Conclusions: The combination had a manageable toxicity profile at the MTD of 80 mg/m2 P + TAS-119 at 75 mg BID 3 d/wk. Preliminary clinical activity was seen in 59% of pts, including tumor responses in a majority (4/7) of pts with ovarian/fallopian tube cancers. Clinical trial information: NCT02134067.

4116 Background: Despite the therapeutic promise of ICIs for patients (pts) with some advanced malignancies, they are FDA-approved for only a few GI cancer pts. In NSCLC, melanoma and urothelial carcinoma, there is emerging data that pts who experience IRAEs while on ICIs have improved outcomes compared with pts who do not. This association in GI cancer pts has not been reported. Methods: We retrospectively analyzed outcomes for metastatic GI cancer pts receiving ICIs for FDA-approved indications (later-line MSI-H tumors, 2nd line hepatocellular carcinoma (HCC), 3rd line PD-L1+ gastric (GA)/gastroesophageal junction (GEJ) adenocarcinoma), at Vanderbilt Ingram Cancer Center, Winship Cancer Institute and Stanford Cancer Institute. Our primary aim was to compare progression-free survival (PFS) and overall survival (OS) between pts who did and did not experience IRAEs. Secondary aims were comparison of these outcomes within pts who experienced IRAEs, by initial IRAE severity (Grade (G)3/G4 vs G1/G2) (CTCAE v5.0), time-to-onset (TTO) (≤ 6 weeks (w) vs > 6 w) and management (steroids vs drug cessation vs observation). PFS and OS were determined by Kaplan-Meier (KM) analysis; KM comparisons were done by the logrank test. Results: Between 1/2015-12/2018 61 GI cancer pts with HCC (28), colorectal cancer (27) and GA/GEJ cancer (6) were treated with ICIs; median age was 63 years. The majority (59) received single-agent nivolumab or pembrolizumab while minority (2) received nivolumab and ipilimumab; median time on ICIs was 5.9 months (mos). Twenty-four pts experienced initial IRAEs (6 G3/G4, 18 G1/G2); median TTO was 3.8 mos. Pts who experienced any IRAE had improvements in PFS and OS compared to those who did not (PFS: 32.4 mos (95% confidence interval (CI), 32.4-not reached (NR)) vs 4.8 mos (95% CI, 2.9-8.7), p = 0.0001; OS: 32.4 mos (95% CI, 32.4-NR) vs 8.5 mos (95% CI, 6-NR), p = 0.0036). Among pts who experienced IRAEs, PFS and OS differences between above-specified subgroups did not meet statistical significance. Conclusions: GI cancer pts who experienced IRAEs while on ICIs had marked improvements in PFS and OS compared to those who did not, suggesting the predictive potential for IRAEs as a clinical biomarker in this population.

This trial was designed to assess efficacy and safety of erlotinib with sorafenib in the treatment of patients with advanced pancreatic adenocarcinoma. An exploratory correlative study analyzing pretreatment serum samples using a multivariate protein mass spectrometry-based test (VeriStrat®), previously shown to correlate with outcomes in lung cancer patients treated with erlotinib, was performed. Patients received sorafenib 400 mg daily along with erlotinib 150 mg daily with a primary endpoint of 8-week progression free survival (PFS) rate. Pretreatment serum sample analysis by VeriStrat was done blinded to clinical and outcome data; the endpoints were PFS and overall survival (OS). Difference between groups (by VeriStrat classification) was assessed using log-rank P values; hazard ratios (HR) were obtained from Cox proportional hazards model. Thirty-six patients received study drug and were included in the survival analysis. Eight-week PFS rate of 46% (95% confidence interval (CI): 0.32–0.67) did not meet the primary endpoint of a rate ≥70%. Thirty-two patients were included in the correlative analysis, and VeriStrat “Good” patients had superior PFS (HR = 0.18, 95% CI: 0.06–0.57; P = 0.001) and OS (HR = 0.31 95% CI: 0.13–0.77, P = 0.008) compared to VeriStrat “Poor” patients. Grade 3 toxicities of this regimen included fever, anemia, diarrhea, dehydration, rash, and altered liver function. This study did not meet the primary endpoint, and this combination will not be further pursued. In this small retrospective analysis, the proteomic classification was significantly associated with clinical outcomes and is being further evaluated in ongoing studies.

Background Targeting angiogenesis in advanced colorectal cancer (CRC) has been one of the many factors prolonging survival. Bevacizumab was the first agent to demonstrate this, but even after progression on bevacizumab, continued VEGF-inhibition continues to improve survival. Combining epidermal growth factor receptor monoclonal antibodies with standard frontline therapies have also improved clinical outcomes, yet the improved benefit is not observed in patients with mutant KRAS. Thus, an unmet medical need exists to develop additional therapeutic options for patients with KRAS mutant CRC. Methods Patients received the anti-angiogenic agent linifanib at the recommended phase II dose of 17.5 mg. Primary endpoint was objective response rate (ORR), with a goal of 10%. Secondary endpoints were progression-free survival (PFS), overall survival (OS), and safety. Simon’s optimal two-stage design was used to assess futility. Linifanib was considered inactive if two or fewer patients among the first 30 achieved an objective response. Results Thirty patients were enrolled on study. Grade 3 treatment-related toxicities occurring in at least two patients were fatigue, hypertension, proteinuria, diarrhea, nausea, oral pain, vomiting, thrombocytopenia, and arthralgia. Although no responses were observed, 63.5% of patients achieved stable disease. The median PFS and OS were 4.7 months and 9.5 months, respectively. Stopping rules for lack of clinical efficacy led to study closure. Conclusion Despite observing zero responses, a majority of patients had stable disease and eight patients had stable disease lasting longer than 5 months. These results suggest that linifanib has some anti-tumor activity in KRAS mutant metastatic and refractory CRC.

Background and purpose This single institution phase I trial determined the maximum tolerated dose (MTD) of concurrent vorinostat and capecitabine with radiation in non-metastatic pancreatic cancer. Material and methods Twenty-one patients received escalating doses of vorinostat (100–400mg daily) during radiation. Capecitabine was given 1000mg q12 on the days of radiation. Radiation consisted of 30Gy in 10 fractions. Vorinostat dose escalation followed the standard 3+3 design. No dose escalation beyond 400mg vorinostat was planned. Diffusion-weighted (DW)-MRI pre- and post-treatment was used to evaluate in vivo tumor cellularity. Results The MTD of vorinostat was 400mg. Dose limiting toxicities occurred in one patient each at dose levels 100mg, 300mg, and 400mg: 2 gastrointestinal toxicities and one thrombocytopenia. The most common adverse events were lymphopenia (76%) and nausea (14%). The apparent diffusion coefficient (ADC) increased in most tumors. Nineteen (90%) patients had stable disease, and two (10%) had progressive disease at time of surgery. Eleven patients underwent surgical exploration with four R0 resections and one R1 resection. Median overall survival was 1.1years (95% confidence interval 0.78–1.35). Conclusions The combination of vorinostat 400mg daily M–F and capecitabine 1000mg q12 M–F with radiation (30Gy in 10 fractions) was well tolerated with encouraging median overall survival.

Colorectal cancer (CRC) is the second leading cause of cancer death in the United States, and research advances over the past 20 years have allowed us to better understand the molecular mechanisms underlying both tumorigenesis and resistance to therapy. As a result, there are a wide range of novel agents currently under development that we anticipate will enter the clinical arena within the coming years. This review seeks to discuss a spectrum of key pathways and agents that may be particularly relevant to the treatment of CRC in the near future, as well as briefly discuss some of the challenges we face in this new era of drug discovery.

Pancreas cancer is a significant cause of cancer mortality; therefore, the development of early diagnostic strategies and effective treatment is essential. Improvements in imaging technology, as well as use of biomarkers such as CA 19-9, are changing the way that pancreas cancer is diagnosed and staged. Although progress in treatment for pancreas cancer has been incremental, development of combination therapies involving both chemotherapeutic and biologic agents is ongoing. This article reviews current strategies in the diagnosis and treatment of resectable and advanced pancreas cancer.

369 Background: The first-in-class recombinant fusion protein IPA blocks WNT signaling by binding WNT ligands, and in combination with Nab-P/G caused tumor regression in pt-derived PC xenografts. This open-label Phase 1b dose escalation study evaluated the combination of IPA with Nab-P/G in untreated mPC pts using a standard 3+3 design. Methods: Dose escalation in cohort 1 started with Nab-P 125 mg/m2 and G 1000 mg/m2 given on days 1, 8 ,15, with IV IPA (3.5 mg/kg) on days 1 and 15, in 28-day cycles. Due to fragility fractures seen in other studies with similar targeted agents, cohorts 2-4 were 6-pt cohorts treated with weekly Nab-P/G + IPA 3 mg/kg (cohort 2) or 5 mg/kg (cohorts 3 and 4) on day 1. These cohorts included strict bone marker monitoring and use of bisphosphonates as indicated. Based on pre-clinical data suggesting improved efficacy with sequential dosing, pts in Cohort 4 received IPA on day 1 followed by weekly chemotherapy starting on day 3 of 28-day cycles. Objectives included safety, maximum tolerated dose, recommended phase 2 dose, pharmacokinetics, immunogenicity, pharmacodynamics, and preliminary efficacy. Results: Twenty-six pts in four dose escalation cohorts were enrolled, five in the cohort one and seven each in cohorts 2-4. Median age was 61.7 years and a majority were male (73%). Reported IPA-related AEs of any grade occurring in ≥ 20% of pts included fatigue, nausea, vomiting, anorexia and pyrexia. IPA-related AEs grade ≥ 3 included 2 events of AST elevation, and 1 each of nausea, maculopapular rash, vomiting and WBC decrease. No dose limiting toxicities or fragility fractures were observed. Of 26 evaluable pts, 9 (34.6%) had a partial response and 12 (46.2%) stable disease, with clinical benefit rate of 80.8%. The study was closed due to termination of the program by the sponsor. At time of data cut off, median progression free survival was 5.9 months (95% CI 3.4-18.4), median overall survival was 9.7 months (95% CI: 7.0-14). One pt remains on therapy under compassionate use with ongoing response. Conclusions: IPA can be safely administered with Nab-P and G in pts with mPC. Additional studies targeting the WNT pathway in pancreatic cancer are warranted. Clinical trial information: NCT02050178.

249 Background: Vantictumab is a fully human monoclonal antibody that inhibits Wnt pathway signaling through binding FZD1, 2, 5, 7, and 8 receptors. A phase Ib study of VAN in combination with Nab-P and G was performed in patients with untreated stage IV pancreatic adenocarcinoma. Methods: Patients received VAN at escalating doses (3-7 mg/kg) in combination with standard dosing of Nab-P and G according to a 3+3 design. Due to fragility fractures occurring in this and other related clinical trials, dosing on an every 2 week schedule in cohorts 1 and 2 was transitioned to every 4 week dosing for cohorts 3 through 5. In these later cohorts, a minimum of six patients were treated at each dose level and additional criteria for maximum tolerated dose (MTD) integrating bone safety parameters were added. The bone safety plan was also revised for these cohorts. Sequential dosing of VAN followed by Nab-P and G was explored in cohort 5. Results: Thirty-one patients (52% male, 48% female) were enrolled and treated in 5 dosing cohorts. Median age was 66. Most common study-treatment related adverse events were nausea (68%) and fatigue (52%). One dose limiting toxicity (DLT) event occurred in the study population—grade 3 dehydration in 1 of 9 patients in cohort 4 (5 mg/kg q4w). Fragility fractures attributed to VAN occurred in two patients in cohort 2 (7 mg/kg q2w). Once the dosing schedule was revised to every 4 weeks, the maximum administered VAN dose was 5 mg/kg. No fragility fractures attributed to VAN occurred in these cohorts; pathologic fracture not attributed to VAN was documented in 2 patients. The study was terminated due to lack of an acceptable therapeutic index. Partial response was documented in 13 patients (42%) and stable disease in 11 (36%). Conclusions: The MTD of VAN plus Nab-P and G was not determined, but the maximum administered dose (MAD) of VAN, 7 mg/kg every 2 weeks, was considered unsafe related to bone toxicity, a known effect of WNT inhibition. After the study was revised, the MAD was 5 mg/kg every 4 weeks, with no protocol-specified bone toxicity observed (n = 16). Clinical trial information: NCT02005315.

574 Background: Epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) are approved in RAS WT mCRC; however, patients (pts) will develop resistance to these agents. Alterations in glutamine (Gln) metabolism play a critical role in cancer cell growth. In cancers such as CRC, EGFR and Gln cooperate to provide signals and fuel for mitogen activated protein kinase-dependent cell growth. Our in vitro data show that Gln abrogates EGFR inhibition, and blockade of Gln transport restores sensitivity. We also observed a greater antitumor response in vivo with EGFR mAb plus CB-839, an inhibitor of a rate-limiting enzyme of Gln metabolism, than either agent alone. We designed a phase I/II study (NCT03263429) to evaluate CB-839 + panitumumab + irinotecan in anti-EGFR refractory RAS WT mCRC. Methods: Dose escalation used a Bayesian continual reassessment method targeting a 25% toxicity probability. CB-839 (600 mg or 800 mg twice daily [BID]) were evaluated with panitumumab (6 mg/kg) and irinotecan (180 mg/m2). Irinotecan was included in phase I to establish a future phase II dose of the triplet. Prior EGFR mAb treatment (tx) was not required for phase I. Dose-limiting toxicity (DLT) was any tx-related non-hematologic ≥Gr 3 toxicity (except fatigue, rash, or elevated liver enzymes) or ≥Gr 4 hematologic toxicity during the first 28 days. Results: Nine pts have been enrolled; 2 were not evaluable for DLT and replaced. Zero DLTs were observed at dose level 1 (n = 3) or 2 (n = 4); 2 more pts are needed to confirm the maximum tolerated dose (MTD). Most frequent toxicities were anemia and hypomagnesemia (88%) and elevated alkaline phosphatase, nausea, and rash (75%), most ≤Gr 2. One of 7 evaluable pts (14%) has an ongoing partial response, and 5 pts had stable disease (SD; 71%). Three pts have been on tx > 6 months, and 3 pts with prior EGFR mAb tx achieved SD. Conclusions: Triplet combination was tolerable at full doses of each drug, and preliminary antitumor activity was observed in a majority of pts. Phase II will begin after phase I completion and will evaluate efficacy of CB-839 (800 mg BID) and panitumumab (6 mg/kg). Imaging studies using investigational PET tracers to evaluate Gln metabolism as a function of tumor response are planned. Clinical trial information: NCT03263429.