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This report describes the case of a 71-year-old woman with nodular melanoma who experienced rapid clinical deterioration 3 weeks after receiving immunotherapy treatment. Given this presentation, there was high suspicion for tumor hyperprogression, which has been observed as a paradoxical response to the use of immunotherapy in the treatment of melanoma. Histopathologic and genomic changes of primary tumor are documented at several different timepoints relative to immunotherapy treatment that may depict important alterations associated with hyperprogressive disease. To our knowledge, this case is the first to document the evolution of histopathologic features of melanoma associated with hyperprogressive disease.

TAS-102 is approved for treatment of refractory metastatic gastroesophageal carcinoma (mGEC). This study sought to determine whether the combination of TAS-102 with irinotecan (TASIRI) was safe and effective in previously treated mGEC. This was a single-arm phase 1b study for patients (pts) with mGEC previously treated with at least one line of fluoropyrimidine and platinum-containing regimen. TAS-102 was given at 25mg/m2 twice daily on days 1 to 5 with irinotecan 180mg/m2 on day 1 of a 14-day cycle. The primary endpoint was progression-free survival at 6months ≥ 35% (PFS-6). 20 Pts were enrolled. The study met its primary endpoint. PFS-6 is 40% (95% CI 19.3-60.0). Median PFS and overall survival are 5.3months and not reached, respectively. 17 of 20 pts had measurable disease by RECIST criteria. Of the 17, 13 had stable disease and 4 had progressive disease as best response (8 pts had tumor shrinkage 5% of pts were anemia (20%) and neutropenia (10%). 2 serious TRAE were reported: G4 febrile neutropenia (n = 1) and G3 hypotension (n = 1). There was no G5 TRAE. The combination of TASIRI showed encouraging clinical activity with a meaningful improvement in PFS-6 compared to historic controls.

Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine skin cancer with steadily increasing incidence and poor prognosis. Despite recent success with immunotherapy, 50% of patients still succumb to their diseases. To date, there is no Food and Drug Administration-approved targeted therapy for advanced MCC. Aberrant activation of phosphatidylinositide-3-kinase (PI3K)/AKT/mTOR pathway is frequently detected in MCC, making it an attractive therapeutic target. We previously found PI3K pathway activation in human MCC cell lines and tumors and demonstrated complete clinical response in a Stage IV MCC patient treated with PI3K inhibitor idelalisib. Here, we found that both PI3K-α and -δ isoforms are abundantly expressed in our MCC cell lines and clinical samples; we therefore examined antitumor efficacy across a panel of five PI3K inhibitors with distinctive isoform-specificities, including idelalisib (PI3K-δ), copanlisib (PI3K-α/δ), duvelisib (PI3K-γ/δ), alpelisib (PI3K-α), and AZD8186 (PI3K-β/δ). Of these, copanlisib exerts the most potent antitumor effects, markedly inhibiting cell proliferation, survival, and tumor growth by suppressing PI3K/mTOR/Akt activities in mouse models generated from MCC cell xenografts and patient-derived tumor xenografts. These results provide compelling preclinical evidence for application of copanlisib in advanced MCC with aberrant PI3K activation for which immunotherapy is insufficient, or patients who are unsuitable for immunotherapy.

Background: Patients with castration-resistant prostate cancer derive only modest clinical benefit from available therapies. Blockade of the inhibitory programmed death 1 (PD-1) receptor by monoclonal antibodies has been effective in several malignancies. Results from the prostate adenocarcinoma cohort of the nonrandomized phase Ib KEYNOTE-028 trial of pembrolizumab in advanced solid tumors are presented. Materials and methods: Key eligibility criteria included advanced prostate adenocarcinoma, unsuccessful standard therapy, measurable disease per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST v1.1), and PD-1 ligand (PD-L1) expression in >= 1% of tumor or stromal cells. Patients received pembrolizumab 10 mg/kg every 2 weeks until disease progression or intolerable toxicity for up to 24 months. Primary end point was objective response rate (ORR) per RECIST v1.1 by investigator review. Results: Median patient age in this cohort (n = 23) was 65 years; 73.9% of patients received at least two prior therapies for metastatic disease. There were four confirmed partial responses, for an ORR of 17.4% [95% confidence interval (CI) 5.0%-38.8%]; 8 of 23 (34.8%) patients had stable disease. Median duration of response was 13.5 months. Median progression-free survival (PFS) and overall survival (OS) were 3.5 and 7.9 months, respectively; 6-month PFS and OS rates were 34.8% and 73.4%, respectively. One patient remained on treatment at data cutoff. After a median follow-up of 7.9 months, 14 (60.9%) patients experienced treatment-related adverse events (TRAEs), most commonly nausea (n = 3, 13.0%). Four (17.3%) experienced grade 3/4 TRAEs: grade 3 peripheral neuropathy, grade 3 asthenia, grade 3 fatigue, and grade 4 lipase increase. No pembrolizumab-related deaths or discontinuations occurred. Conclusion: Pembrolizumab resulted in durable objective response in a subset of patients with heavily pretreated, advanced PD-L1-positive prostate cancer, and its side effect profile was favorable.

Purpose To establish the safety profile and antitumor activity of the anti–programmed death 1 receptor monoclonal antibody, pembrolizumab, in patients with recurrent or metastatic nasopharyngeal carcinoma (RM-NPC) that expressed programmed death-ligand 1 (PD-L1). Patients and Methods KEYNOTE-028 (NCT02054806) is a nonrandomized, multicohort, phase Ib trial of pembrolizumab in patients with PD-L1–positive advanced solid tumors. Key eligibility criteria for the NPC cohort included unresectable or metastatic disease, failure on prior standard therapy, and PD-L1 expression in 1% or more of tumor cells or tumor-infiltrating lymphocytes. Patients received pembrolizumab 10 mg/kg every 2 weeks up to 2 years or until disease progression or unacceptable toxicity. Primary end point was objective response rate (ORR) per investigator review. Tumor response was assessed according to Response Evaluation Criteria in Solid Tumors (RECIST; version 1.1) every 8 weeks for the first 6 months and every 12 weeks thereafter. Results Twenty-seven patients received pembrolizumab. Median age was 52.0 years (range, 18 to 68 years); 92.6% received prior therapies for RM-NPC; 70.4% had received three or more therapies. Partial response and stable disease were observed in seven and 14 patients, respectively, for an ORR of 25.9% (95% CI, 11.1 to 46.3) over a median follow-up of 20 months. ORR by central review was similar (26.3%). Drug-related adverse events that occurred in 15% or more of patients included rash (25.9%), pruritus (25.9%), pain (22.2%), hypothyroidism (18.5%), and fatigue (18.5%). Grade ≥ 3 drug-related adverse events occurred in eight patients (29.6%), and there was one drug-related death (sepsis). As of the data cutoff (June 20, 2016), two patients remained on pembrolizumab treatment. Conclusion Pembrolizumab demonstrated antitumor activity and a manageable safety profile in patients with RM-NPC.

Introduction The incidence of neuropathy with checkpoint inhibitors is 0.3–1%, typically occurring 2–12 weeks after treatment initiation. Common neuropathy phenotypes include inflammatory myopathies, myasthenia gravis, acute and chronic demyelinating polyradiculopathies, vasculitic neuropathies, isolated cranial neuropathies, aseptic meningitis, autoimmune encephalitis, multiple sclerosis and hypophysitis. Carpal tunnel syndrome is the most common entrapment neuropathy in the general population; however, the association of carpal tunnel syndrome with checkpoint inhibitors is exceedingly rare. Case Report We report two cases of patients with no prior history of carpal tunnel syndrome treated with checkpoint inhibitors that developed de novo bilateral carpal tunnel syndrome. Management & Outcome: For both patients, the neurologic symptoms improved with cessation of the checkpoint inhibitor and initiation of corticosteroids. Discussion Given the prevalence of carpal tunnel syndrome in the general population, a high index of suspicion for carpal tunnel in patients receiving checkpoint inhibitors and prompt treatment with corticosteroids is essential.

e16006 Background: FTD/TPI, an antimetabolite, is approved for treatment of refractory mGEC. This study sought to determine whether the combination of FTD/TPI with IRI (“TASIRI”) was safe and effective in mGEC previously treated with FP. Methods: This investigator‐initiated, multicenter, open‐label, single-dose level, single‐arm phase 1b study enrolled pts with mGEC previously treated with at least one line of FP containing regimen. FTD/TPI was given at 25 mg/m2 twice daily on days 1 to 5 with 180 mg/m2 IRI on day 1 of a 14‐day cycle. The primary endpoint was progression-free survival at six months (mo) (PFS-6). The aim was to show an improvement of PFS-6 from 15% to at least 30% based on historical controls. Results: At the time of data-cutoff (03Feb2021), 23 pts were screened and ultimately 20 pts were treated. The study met its primary endpoint. With a median follow-up of 9.8 mo (range 0.7 – 17), 8 pts are still on treatment and 4 pts have died. PFS-6 is 53.9% (lower limit of 95% CI: 28%). Median PFS and overall survival are 6.9 mo and not reached, respectively. At the time of data-cutoff, data were available for 13 pts with measurable disease by RECIST criteria and at least 1 on-treatment scan. Of those, 11 had stable disease and 2 had progressive disease as best response (5 pts had tumor shrinkage < 30%), therefore the disease control rate was 84.6%. The most common any grade (G) treatment related adverse events (TRAE) were nausea (n = 14, 70%), diarrhea (n = 9, 45%), and fatigue (n = 8, 40%). G3-4 TRAE in > 5% of pts were anemia (17%) and neutropenia (9%). 2 serious TRAE were reported: G4 febrile neutropenia (n = 1) and G3 hypotension (n = 1). There was no G5 TRAE. Conclusions: The combination of TASIRI showed encouraging clinical activity with a meaningful improvement in PFS-6 compared to historic controls. TASIRI was well tolerated and no new safety signals were seen. TASIRI warrants further investigation for patients with refractory mGEC and limited treatment options. Updated results with longer follow-up will be presented at the meeting. Clinical trial information: NCT04074343.

Background Safety and efficacy of pembrolizumab, a humanized programmed death 1 monoclonal antibody, was assessed in KEYNOTE-028, a multicohort, phase Ib trial for patients with programmed death ligand 1 (PD-L1)-positive advanced solid tumors. We report results for the cohort of patients with advanced anal carcinoma. Patients and methods Patients with PD-L1-positive tumors (≥1%) received intravenous pembrolizumab 10 mg/kg once every 2 weeks for up to 2 years or until confirmed progression or unacceptable toxicity. Response was assessed every 8 weeks for the first 6 months and every 12 weeks thereafter per Response Evaluation Criteria In Solid Tumors, version 1.1. Primary endpoints were safety and overall response rate per investigator review. Secondary endpoints included progression-free survival, overall survival, and response duration. Data cutoff date was 1 July 2015. Results Of the 43 patients with advanced anal carcinoma evaluable for PD-L1 expression, 32 (74%) had PD-L1-positive tumors as assessed with the 22C3 prototype assay, of whom 25 were enrolled between April and September 2014. Sixteen patients (64%) experienced treatment-related adverse events; the most common ones were diarrhea and fatigue in four patients (16%) each and nausea in three patients (12%). There were no treatment-related deaths or discontinuations as of the data cutoff date. Among the 24 patients with squamous cell carcinoma histology, four had confirmed partial response, for an overall response rate of 17% [95% confidence interval (CI), 5%–37%) and 10 (42%) had confirmed stable disease, for a disease control rate of 58%. One additional patient with non-squamous histology had confirmed stable disease. Conclusion In this population of patients with PD-L1-positive advanced squamous cell anal carcinoma, pembrolizumab demonstrated a manageable safety profile and encouraging antitumor activity. These data support further study of pembrolizumab for this patient population. ClinicalTrials.gov NCT02054806.

This phase I study evaluated the safety, tolerability, and pharmacokinetics of copanlisib, an intravenously administered pan-phosphatidylinositol 3-kinase inhibitor in patients with advanced solid tumors or non-Hodgkin's lymphoma. Copanlisib was well tolerated with a manageable safety profile, with anti-tumor activity in both advanced solid tumors and hematological malignancies., Background To evaluate the safety, tolerability, pharmacokinetics, and maximum tolerated dose (MTD) of copanlisib, a phosphatidylinositol 3-kinase inhibitor, in patients with advanced solid tumors or non-Hodgkin's lymphoma (NHL). Patients and methods Phase I dose-escalation study including patients with advanced solid tumors or NHL, and a cohort of patients with type 2 diabetes mellitus. Patients received three weekly intravenous infusions of copanlisib per 28-day cycle over the dose range 0.1–1.2 mg/kg. Plasma copanlisib levels were analyzed for pharmacokinetics. Biomarker analysis included PIK3CA, KRAS, BRAF, and PTEN mutational status and PTEN immunohistochemistry. Whole-body [18F]-fluorodeoxyglucose positron emission tomography (18FDG-PET) was carried out at baseline and following the first dose to assess early pharmacodynamic effects. Plasma glucose and insulin levels were evaluated serially. Results Fifty-seven patients received treatment. The MTD was 0.8 mg/kg copanlisib. The most frequent treatment-related adverse events were nausea and transient hyperglycemia. Copanlisib exposure was dose-proportional with no accumulation; peak exposure positively correlated with transient hyperglycemia post-infusion. Sixteen of 20 patients treated at the MTD had reduced 18FDG-PET uptake; 7 (33%) had a reduction >25%. One patient achieved a complete response (CR; endometrial carcinoma exhibiting both PIK3CA and PTEN mutations and complete PTEN loss) and two had a partial response (PR; both metastatic breast cancer). Among the nine NHL patients, all six with follicular lymphoma (FL) responded (one CR and five PRs) and one patient with diffuse large B-cell lymphoma had a PR by investigator assessment; two patients with FL who achieved CR (per post hoc independent radiologic review) were on treatment >3 years. Conclusion Copanlisib, dosed intermittently on days 1, 8, and 15 of a 28-day cycle, was well tolerated and the MTD was determined to be 0.8 mg/kg. Copanlisib exhibited dose-proportional pharmacokinetics and promising anti-tumor activity, particularly in patients with NHL. ClinicalTrials.gov NCT00962611; https://clinicaltrials.gov/ct2/show/NCT00962611.

TPS251 Background: In 2L+ aGEC, taxanes +/- ramucirumab or IRI are recommended treatment options. IRI has been tested in multiple single arm and randomized trials in second line (2L)+ aGEC, with reported objective response rates (ORR) in the 15-29% range and median progression-free survival (PFS) of

Introduction: Neoepitopes (neoE) derived from private tumor-exclusive mutations represent compelling targets for personalized TCR-T cell therapy. An ultra-sensitive and high-throughput process was developed to capture tumor mutation-targeted CD8 T cells from patient blood. NeoTCRs cloned from the captured CD8 T cells, when engineered into fresh CD8 and CD4 T cells, effected killing of patients' autologous tumor cells in vitro. These observations have been leveraged for the development of a fully personalized adoptive T cell therapy (NeoTCR-P1). A Phase 1 clinical trial testing NeoTCR-P1 in subjects with solid tumors is ongoing (NCT03970382). Study Design: During the initial trial phase, escalating doses of NeoTCR-P1 T cells administered without and with IL-2 in the regimen, and following conditioning chemotherapy, will be evaluated in subjects with advanced or metastatic solid tumors (melanoma, urothelial cancer, colorectal cancer, ovarian cancer, HR+ breast cancer, and prostate cancer). The objective of the Phase 1a study is to establish a recommended Phase 2 dose. Primary endpoints include the incidence and nature of DLTs and overall process feasibility. The proliferation, persistence, and trafficking of NeoTCR-T cells will be characterized. In the expansion trial phase, preliminary anti-tumor activity of NeoTCR-P1 will be assessed in selected tumors. The combination of NeoTCR-P1 dosing plus nivolumab will be tested in a Phase 1b study. Conclusion: This is the first clinical study of an autologous, fully personalized adoptive T cell therapy directed against private tumor-exclusive mutations, generated without using recombinant viral vectors. Citation Format: Mihaela Cristea, Bartosz Chmielowski, Roel Funke, Todd Stallings-Schmitt, Mitch Denker, Mark Frohlich, Alex Franzusoff, Mehrdad Abedi, Samuel Ejadi. A Phase 1a/1b, open-label first-in-human study of the safety, tolerability, and feasibility of gene-edited autologous NeoTCR-T cells (NeoTCR-P1) administered to patients with locally advanced or metastatic solid tumors [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 CT250.

e22001 Background: Optimal duration of anti-PD-1 antibody therapy remains undefined. Currently, treatment is given up to two years in metastatic melanoma based on clinical trials. However, recent observations suggest that anti-PD-1 antibodies may work as well if given for shorter time periods. To better understand duration of anti-PD-1 antibody treatment, we reviewed outcomes for patients who discontinued immunotherapy earlier than 2 years in our Cancer Center. Methods: This is a retrospective, single-institution review of metastatic melanoma patients who received anti-PD-1 antibodies from January 2010 to December 2019. We further identified the patients discontinuing treatment before completion of 2 years for reasons other than disease progression. Duration was categorized into three groups: < 6 months (A), 6-12 months (B) and > 12 months (C) and outcomes were analyzed. Progression free survival (PFS) was defined as the time from the initiation of anti-PD1-therapy to the date of progression as determined by treating physician based on radiological, biochemical and/or clinical criteria. Results: 25 patients with mean age 69 years (49-91; N = 19 > 60yo) were identified. Number of patients who received anti-PD-1 antibodies were N = 8, N = 9 and N = 8 in in groups A, B and C respectively. 44% of patients discontinued treatment after achieving either partial or near complete remission, whereas the remaining 66% of patients discontinued treatment due to adverse events. Majority of patients who stopped treatment due to adverse events were older than 60 (71.4%). In 29 months of median follow up (range 11-54), none of patients who received treatment in group B progressed, whereas in groups A and C, 25% percentage progressed in each group with 80% PFS at 12.8 months and 88% PFS at 26 months respectively. 12.5% of patients in group A had progression at 12 months follow up, where no progression was noticed in groups B and C during the same time period. Conclusions: Retrospective analysis of our experience supports other retrospective findings that treatment with anti-PD-1 antibodies more than 12 months might not add further benefit in responding or non-progressing older patients though further study with longer follow up is required.

TPS3151 Background: Neoepitopes (neoE) derived from private tumor-exclusive mutations represent compelling targets for personalized TCR-T cell therapy. An ultra-sensitive and high-throughput process was developed to capture tumor mutation-targeted CD8 T cells from patient blood. NeoTCRs cloned from the captured CD8 T cells, when engineered into fresh CD8 and CD4 T cells, effected killing of patients’ autologous tumor cells in vitro. These observations have been leveraged for the development of a fully personalized adoptive T cell therapy (NeoTCR-P1). A Phase 1 clinical trial testing NeoTCR-P1 in subjects with solid tumors is ongoing (NCT03970382). Methods: During the initial trial phase, escalating doses of NeoTCR-P1 T cells administered without and with IL-2 in the regimen, and following conditioning chemotherapy, will be evaluated in subjects with advanced or metastatic solid tumors (melanoma, urothelial cancer, colorectal cancer, ovarian cancer, HR+ breast cancer, and prostate cancer). The objective of the Phase 1a study is to establish a recommended Phase 2 dose. Primary endpoints include the incidence and nature of DLTs and overall process feasibility. The proliferation, persistence, and trafficking of NeoTCR-T cells will be characterized. In the expansion trial phase, preliminary anti-tumor activity of NeoTCR-P1 will be assessed in selected tumors. The combination of NeoTCR-P1 dosing plus nivolumab will be tested in a Phase 1b study. Conclusion: This is the first clinical study of an autologous, fully personalized adoptive T cell therapy directed against private tumor-exclusive mutations, generated without using recombinant viral vectors. Clinical trial information: NCT03970382 .

Background In this first-in-human, Phase 1 study of a microRNA-based cancer therapy, the recommended Phase 2 dose (RP2D) of MRX34, a liposomal mimic of microRNA-34a (miR-34a), was determined and evaluated in patients with advanced solid tumours. Methods Adults with various solid tumours refractory to standard treatments were enrolled in 3 + 3 dose-escalation cohorts and, following RP2D determination, expansion cohorts. MRX34, with oral dexamethasone premedication, was given intravenously daily for 5 days in 3-week cycles. Results Common all-cause adverse events observed in 85 patients enrolled included fever (% all grade/G3: 72/4), chills (53/14), fatigue (51/9), back/neck pain (36/5), nausea (36/1) and dyspnoea (25/4). The RP2D was 70 mg/m2 for hepatocellular carcinoma (HCC) and 93 mg/m2 for non-HCC cancers. Pharmacodynamic results showed delivery of miR-34a to tumours, and dose-dependent modulation of target gene expression in white blood cells. Three patients had PRs and 16 had SD lasting ≥4 cycles (median, 19 weeks, range, 11–55). Conclusion MRX34 treatment with dexamethasone premedication demonstrated a manageable toxicity profile in most patients and some clinical activity. Although the trial was closed early due to serious immune-mediated AEs that resulted in four patient deaths, dose-dependent modulation of relevant target genes provides proof-of-concept for miRNA-based cancer therapy. Clinical trial registration NCT01829971.

Purpose Current first-line chemotherapy for patients with metastatic adrenocortical cancer (ACC) includes doxorubicin, etoposide, cisplatin, and mitotane with a reported response rate of only 23.2%. New therapeutic leads for patients with refractory tumors are needed; there is no standard second-line treatment. Methods Samples from 135 ACC tumors were analyzed by immunohistochemistry, in situ hybridization (FISH or CISH), and/or gene sequencing at a single commercial reference laboratory (Caris Life Sciences) to identify markers associated with drug sensitivity and resistance. Results Overexpression of proteins related to demonstrated chemotherapy sensitivity or resistance included topoisomerase 1, progesterone receptor, and topoisomerase 2-alpha in 46%, 63%, and 42% of cases, respectively. Loss of excision repair cross-complementary group 1 (ERCC1), phosophatase and tensin homolog, O(6)-methylguanine-methyltransferase, and ribonucleotide reductase M1 (RRM1) was identified in 56%, 59%, 71%, and 58% of cases, respectively. Other aberrations included overexpression of programmed death-ligand 1 or programmed cell death protein 1 tumor-infiltrating lymphocytes in >40% of cases. In all, 35% of cases had a mutation in the canonical Wnt signaling pathway (either CTNNB1 or APC) and 48% had a mutation in TP53. No other genomic alterations were identified. Conclusion Biomarker alterations in ACC may be used to direct therapies, including recommendations for and potential resistance of some patients to traditional chemotherapies, which may explain the low response rate in the unselected population. Limited outcomes data support the use of mitotane and platinum therapies for patients with low levels of the proteins RRM1 and ERCC1.

Idasanutlin, a selective small-molecule MDM2 antagonist in phase 3 testing for refractory/relapsed AML, is a non-genotoxic oral p53 activator. To optimize its dosing conditions, a number of clinical pharmacology characteristics were examined in this multi-center trial in patients with advanced solid tumors. This was an open-label, single-dose, crossover clinical pharmacology study investigating the effects of strong CYP3A4 inhibition with posaconazole (Part 1), two new oral formulations (Part 2), as well as high-energy/high-fat and low-energy/low-fat meals (Part 3) on the relative bioavailability of idasanutlin. After completing Part 1, 2, or 3, patients could have participated in an optional treatment with idasanutlin. Clinical endpoints were pharmacokinetics (PK), pharmacodynamics (PD) of MIC-1 elevation (Part 1 only), and safety/tolerability. The administration of posaconazole 400 mg BID × 7 days with idasanutlin 800 mg resulted in a slight decrease (7%) in Cmax and a modest increase (31%) in AUC for idasanutlin, a marked reduction in Cmax (~ 60%) and AUC0 (~ 50%) for M4 metabolite, and a minimal increase (~ 24%) in serum MIC-1 levels. Cmax and AUC were both 45% higher for the SDP formulation. While the low-fat meal caused a less than 20% increase in all PK exposure parameters with the 90% CI values just outside the upper end of the equivalence criteria (80–125%), the high-fat meal reached bioequivalence with dosing under fasting. In patients with solid tumors, multiple doses of posaconazole, a strong CYP3A4 inhibitor, minimally affected idasanutlin PK and PD without clinical significance. The SDP formulation improved rBA/exposures by ~ 50% without major food effect.

Background Colorectal cancers (CRCs) expressing programmed death ligand 1 (PD-L1) have poor prognosis. In the multicohort KEYNOTE-028 trial, the anti-PD-1 antibody pembrolizumab was evaluated in 20 PD-L1-positive advanced solid tumors. Herein, we report results for the advanced CRC cohort. Methods Patients with advanced, treatment-resistant PD-L1-positive carcinoma of the colon or rectum were enrolled, regardless of microsatellite instability (MSI) status. Pembrolizumab 10 mg/kg was administered every 2 weeks for up to 2 years or until disease progression/unacceptable toxicity. Response was assessed every 8 weeks for the first 6 months and every 12 weeks thereafter. Primary end points were safety and overall response rate by investigator review per Response Evaluation Criteria in Solid Tumors version 1.1. Data cutoff was June 20, 2016. Results Of 137 patients with CRC and samples evaluable for PD-L1 expression, 33 (24%) had PD-L1-positive tumors, of which 23 were enrolled. Median follow-up was 5.3 months, and 8 patients (35%) reported treatment-related adverse events (AEs), most commonly fatigue (n = 3, 13%), stomatitis (n = 2, 9%), and asthenia (n = 2, 9%). One patient (4%) experienced grade 4 treatment-related increased blood bilirubin. No grade 3 AEs, discontinuations, or deaths were attributed to treatment. Most patients (n = 15, 65%) experienced progressive disease. One partial response occurred in a patient (4%) with MSI-high CRC. Conclusion Pembrolizumab demonstrated a favorable safety profile in advanced PD-L1-positive CRC. Antitumor activity was observed in a single patient with MSI-high CRC, warranting further evaluation in this patient population. (Clinicaltrials.gov registration: NCT02054806).

9011 Background: Repotrectinib is a next-generation ROS1/TRK/ALK TKI inhibiting ROS1 with > 90-fold greater potency than crizotinib. Preclinical studies showed robust kinase inhibitory activity of repotrectinib against all known ROS1 fusion positive resistance mutations, including the most common ROS1 solvent-front mutation (SFM) G2032R. Methods: In this ongoing phase 1 study (NCT03093116), TKI-naïve and TKI-refractory (≥1 TKI) patients (pts) with advanced ROS1/TRK/ALK+ solid tumors received repotrectinib treatment. Endpoints include safety, PK, and confirmed overall response (cORR). Safety analysis for all pts (n = 75) and efficacy analysis for ROS1+ NSCLC pts (n = 28) enrolled on the study was conducted. Results: As of 31-Oct-2018, 75 pts were treated with repotrectinib at dose levels from 40 mg QD to 200 mg BID. Most AEs were manageable and grade (Gr) 1-2. Common ( > 20%) treatment-related AEs were dizziness (49%), dysgeusia (48%), paresthesia (28%), and constipation (20%). Four DLTs (Gr3 dyspnea/hypoxia (n = 1); Gr2 (n = 1) and Gr3 (n = 1) dizziness at 160 mg BID, and Gr3 dizziness (n = 1) at 240 mg QD) occurred and were managed with dose modifications. The MTD has not been reached. Median number of prior TKI treatment was 1 (0-3) with all of TKI naïve and 83% of TKI pre-treated pts received prior chemotherapy. Among 10 evaluable TKI-naïve ROS1+ NSCLC pts, confirmed ORR by Blinded Central Review (BCR) was 90% (95% CI 56 - 100) with median duration of response (DOR) not reached ((range 5.5+ – 14.9+ months (mos)). Among 18 TKI-pretreated pts, confirmed ORR by BCR was 28% (95% CI 10 – 54) with DOR of 10.2 mos. Subgroup analysis showed cORR 44% (95% CI 14 - 79) in 9 prior TKI pts and treated at dose levels of 160 mg QD or above. In 7 pts with measurable target CNS lesions at baseline, the intracranial ORR was 3/3 (100%) with DOR (5.5+; 7.2+; 14.85+ mo) in TKI-naïve pts and 2/4 (50%) with DOR (5.5+;14.8+, mo) in TKI-pretreated pts, respectively. Conclusions: Repotrectinib was well tolerated and demonstrated encouraging overall and intracranial clinical activity in pts with ROS1 fusion-positive NSCLC. Enrollment in phase 1 continues until the RP2D is determined. A global phase 2 study is planned. Clinical trial information: NCT03093116.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) enhances immune responses by inducing proliferation, maturation, and migration of dendritic cells (DCs) as well as expansion and differentiation of B and T lymphocytes. The potency of DNA vaccines can be enhanced by the addition of DNA encoding cytokines, acting as molecular adjuvants. We conducted a phase I/II trial of human GM-CSF DNA in conjunction with a multipeptide vaccine (gp100 and tyrosinase) in stage III/IV melanoma patients. Nineteen human leukocyte antigen (HLA)-A*0201+ patients were treated. Three dose levels were studied: 100, 400, and 800 microg DNA/injection, administered subcutaneously every month with 500 microg of each peptide. In the dose-ranging study, three patients were treated at each dose level. The remaining patients were then treated at the highest dose. Most toxicities were grade 1 injection-site reactions. Eight patients (42%) developed CD8+ T-cell responses, defined by aor =3 SD increase in baseline reactivity to tyrosinase or gp100 peptide in tetramer or intracellular cytokine staining (ICS) assays. There was no relationship between dose and T-cell response. Responding T cells had an effector memory cell phenotype. Polyfunctional T cells were also demonstrated. At a median of 31 months follow-up, median survival has not been reached. Human GM-CSF DNA was found to be a safe adjuvant.

2508Background: Each miRNA modulates expression of hundreds of genes across distinct cellular pathways, giving miRNA-based therapy potential to simultaneously repress multiple oncogenic processes in the tumor microenvironment, including growth and proliferation, resistance, cancer stem cells, metastasis, and immune evasion. The tumor suppressor miR-34a down-regulates expression of >30 oncogenes (eg, MET, MEK1, PDGFR-α, CDK4/6, BCL2, WNT 1/3, NOTCH1, CD44), as well as genes involved in tumor immune evasion (eg, PD-L1, DGKζ). MRX34, a liposomal miR-34a mimic, is a potential first-in-class miRNA therapy for cancer. Methods: Pts with advanced solid tumors (N=99) were enrolled in a standard 3+3 dose escalation trial of MRX34 infused IV on a biweekly (BIW) or daily x 5 (QDx5) schedule. The primary objective was MTD and recommended phase II dose (RP2D); secondary objectives were safety, PK, and biological and clinical activity. Results: Pts with HCC (42), RCC (2), acral melanoma (2), and other tumor types (53) w...

2547Background: Polo-like kinase 1 (PLK1) regulates critical aspects of tumor progression. High expression levels correlate with poor survival in ACC. TKM-080301 is a lipid nanoparticle formulation of a siRNA against PLK1. Methods: TKM-080301 was evaluated in an open-label study with dose escalation and expansion phases in patients with refractory ACC. TKM-080301 was infused IV over 30 minutes on days 1, 8, and 15 of a 28-day cycle. Primary study objectives included assessment of safety and anti-tumor activity by RECIST 1.1 after every 2 cycles. Results: Sixteen patients were treated at 0.6 or 0.75 mg/kg/week for up to 18 cycles. Eight received at least 2 cycles of study treatment and were evaluable for tumor response. Four had a best response of stable disease including one with a 13% reduction of target tumor diameter. One 51 yo man with metastatic intraperitoneal non-functional ACC had a partial response (target tumor reduction of 19% after cycle 2 and 49% after cycle 14). Residual tumor was resected a...

Malignant melanoma presents a substantial clinical challenge. Current diagnostic methods are limited in their ability to diagnose early disease and accurately predict individual risk of disease progression and outcome. The lack of adequate approaches to properly define disease subgroups precludes rational treatment design and selection. Better tools are urgently needed to provide more accurate and personalized melanoma patient management. Recent progress in the understanding of the molecular aberrations that underlie melanoma oncogenesis will likely advance the diagnosis, prognosis, and treatment of melanoma. The emerging pattern of molecular complexity in melanoma tumors mirrors the clinical diversity of the disease and highlights the notion that melanoma, like other cancers, is not a single disease but a heterogeneous group of disorders that arise from complex molecular changes. Understanding of molecular aberrations involving important cellular processes, such as cellular signaling networks, cell cycle regulation, and cell death, will be essential for better diagnosis, accurate assessment of prognosis, and rational design of effective therapeutics. Defining an individual patient's unique tumor characteristics may lead to personalized prediction of outcomes and selection of therapy. We review the emerging molecular landscape of melanoma and its implications for better management of patients with melanoma.

Background: MRX34 is a liposomal nanoparticle formulation with an encapsulated mimic of the naturally occurring microRNA-34 (miR-34), which is lost or expressed at reduced levels in many tumors. miR-34 inhibits key oncogenic pathways by repressing multiple important oncogenes including BCL2, E2F3, HDAC1, MET, MEK1, CDK4/6, PDGFR-ɑ/β, SIRT1, WNT1/3, NOTCH-1, β-catenin, CD44, Nanog and AXL. miR-34 also represses the expression of PD-L1 and DGKζ, thereby possibly triggering an anti-tumor immune response and cancer cell death. A multicenter Phase 1 clinical trial of MRX34 is being conducted in patients with advanced malignancies. Methods: Eligible patients were enrolled in a standard 3 + 3 dose escalation study and were given a MRX34 starting dose of 10 mg/m2, administered intravenously (IV) twice weekly (BIW) for 3 weeks in 28-day cycles. Enrollment is ongoing into a second MRX34 dosing schedule, daily x 5 (QD x 5) in 21-day cycles. The primary objectives are to determine the maximum tolerated dose (MTD) and recommended Phase 2 dose (RP2D) for the two dosing schedules. Secondary objectives include assessments of safety, tolerability and the pharmacokinetic profile of MRX34 after intravenous dosing as well as to assess any biological and clinical activity. Results: As of July 2015, 75 patients with advanced solid tumors were enrolled and evaluable: 44 Caucasians, 47 males, a median age of 61 years and a median of 4 prior treatments. Histologies included 30 hepatocellular carcinoma (HCC), 7 pancreatic cancer, 4 cholangiocarcinoma, 3 each of bladder, breast, colorectal, cervix and lung. The remaining 19 patients represented various other malignancies Conclusions: MRX34 has a manageable safety profile with confirmed partial responses in two patients with advanced HCC and melanoma. Due to better tolerability, QD x 5 schedule has been chosen for further study. Following MTD determination, enrollment will soon begin into the QD x 5 expansion cohorts for selected tumors. Citation Format: Muhammad Shaalan Beg, Andrew Brenner, Jasgit Sachdev, Samuel Ejadi, Mitesh Borad, Yang-Kon Kang, Ho Lim, T-Y Kim, Andreas Bader, Jay Stoudemire, Susan Smith, Sinil Kim, David Hong. Safety, tolerability, and clinical activity of MRX34, the first-in-class liposomal miR-34 mimic, in patients with advanced solid tumors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C43.

5509 Background: The programmed death-1 receptor (PD-1) and its ligand (PD-L1) are key therapeutic targets in the reactivation of the immune response against multiple cancers. Avelumab (proposed IN...

469 Background: Appendiceal cancers are rare and there are no established guidelines for adjuvant treatment and metastatic disease. Methods: Samples were identified from > 60,000 global tumors analyzed at a referral molecular profiling CLIA certified laboratory (Caris Life Sciences) for biomarkers of drug sensitivity, under an approved protocol. 285 samples with primary tumor sites of appendix were identified (M/F ratio of 38%/62%; mean age of 55). Approximately 80% of samples were adenocarcinomas, 10% carcinoids, and 10% of indeterminate histology. IHC assays (n=273) were performed with up to 30 biomarkers; FISH (n=39) for c-Myc, cMET, EGFR, HER2 and/or TOPO2A gene copy amplifications; and sequencing done ( n= 223) for KRAS, EGFR, PIK3CA, and BRAF. Results: Targets on IHC: 97% high BCRP; 16% high KIT; 80% high COX-2; 50%high EGFR; 30% low MGMT, 81% high MRP1, 35% high PDGFR, 82% low PTEN, 27% high RRM1, 39% high SPARC; 67% high TLE3, 27% high TOPO2A ; 63% high TOPOI, and 99% negative TS. Targets on FISH: 5% amplified EGFR and 0% amplified Her2/Neu. Sequencing results: 53% mutated KRAS and 2% mutated BRAF. Conclusions: The high levels of drug resistance proteins (BCRP and MRP1) highlights the difficulty in treating these tumors. The incidence of KRAS mutations (53%) and low expression of TS (99%) is noteworthy, and points towards using 5FU/capecitabine as a backbone of therapy. Therapeutic options are varied and options include TOPO1 inhibitors (irinotecan/topotecan), EGFR inhibitors (erlotinib, cetuximab), PDGFR antagonists (regorafenib, axitinib), MGMT (temazolamide), BRAF inhibitors (vemurafenib, dabrafenib) and SPARC (nab-paclitaxel). These findings indicate the need to evaluate patient samples for patterns in marker expression and alteration, in order to better understand the molecular biology and formulate a personalized therapy approach in these difficult to treat cancers, and to pursue whole genomic sequencing. Supported by a grant from Caris Life Sciences.

9082 Background: Human tumors, including melanoma, are complex mixtures of individual, molecularly distinct subpopulations, or clones of cancer cells. Effective cancer therapy will likely require targeting of all tumor subsets within a given cancer. Understanding the tumor complexity and the ability to identify points of therapeutic vulnerability within the individual tumor subsets will be essential for development of effective personalized cancer therapies. Methods: We have developed an approach that combines identification of individual tumor subsets using a multiparameter nuclear flow cytometry coupled with a high-resolution genomic analysis using the array-based comparative genomic hybridization (aCGH). Melanoma nuclei were isolated from tumor tissues and subjected to flow cytomery using melanocyte-specific antibodies (to separate melanoma cells from stroma) and DNA content, to separate individual tumor subpopulations. DNA extracted from isolated nuclear subpopulations was extracted and analyzed by aCGH. This approach was adopted for both fresh-frozen and paraffin-embedded clinical specimens. Results: We initially demonstrate the feasibility of the outlined approach by successful separation of melanoma from stromal nuclei and separation of individual melanoma nuclear subpopulations by DNA content. aCGH analysis of the DNA derived from isolated tumor subpopulations allowed successful identification of potentially targetable molecular aberrations in individual subsets of tumor cells. Notably, such aberrations were often not detected in unsorted, bulk tumors analyzed by the same high-resolution aCGH approach. Conclusions: We demonstrate a feasible approach to in-depth molecular analysis of tumor subpopulations within a clinical cancer tissue. This approach allows identification of potentially targetable molecular aberrations within individual tumor subsets, thus opening a possibility for a broad tumor targeting through design of individually-tailored therapeutic approaches. No significant financial relationships to disclose.

8531 Background: To test the hypothesis that the ∼30% response rate we observed in metastatic melanoma (mel) patients (pts) treated with temozolomide (TMZ) using an extended dosing schedule with either thalidomide or interferon was largely due to TMZ alone, we conducted a phase II trial of TMZ alone. We also hypothesized that mel expression of methylguanine methyltransferase (MGMT) would correlate with drug resistance. Methods: Stage IV mel pts without brain metastases or prior chemotherapy were stratified into two cohorts based on whether or not they had stage M1c disease. Each cycle consisted of TMZ 75 mg/m2/day for 6 weeks followed by 2 weeks with no treatment. Treatment cycles were repeated as long as pts did not progress. The primary endpoint was the proportion of complete or partial responses by RECIST criteria. The trial was powered to exclude the null hypothesis that the response rate in each cohort was + lymphopenia (+ lymphopenia No significant financial relationships to disclose.

The mutagenic and carcinogenic chemical aflatoxin B1 (AFB1) reacts almost exclusively at the N(7)-position of guanine following activation to its reactive form, the 8,9-epoxide (AFB1 oxide). In general N(7)-guanine adducts yield DNA strand breaks when heated in base, a property that serves as the basis for the Maxam-Gilbert DNA sequencing reaction specific for guanine. Using DNA sequencing methods, other workers have shown that AFB1 oxide gives strand breaks at positions of guanines; however, the guanine bands varied in intensity. This phenomenon has been used to infer that AFB1 oxide prefers to react with guanines in some sequence contexts more than in others and has been referred to as "sequence specificity of binding". Herein, data on the reaction of AFB1 oxide with several synthetic DNA polymers with different sequences are presented, and (following hydrolysis) adduct levels are determined by high-pressure liquid chromatography. These results reveal that for AFB1 oxide (1) the N(7)-guanine adduct is the major adduct found in all of the DNA polymers, (2) adduct levels vary in different sequences, and, thus, sequence specificity is also observed by this more direct method, and (3) the intensity of bands in DNA sequencing gels is likely to reflect adduct levels formed at the N(7)-position of guanine. Knowing this, a reinvestigation of the reactivity of guanines in different DNA sequences using DNA sequencing methods was undertaken. The reactivities of 190 guanines were determined quantitatively and considered in a pentanucleotide context, 5'-WXGYZ-3', where the central, underlined G represents the reactive guanine and W, X, Y, and Z can be any of the nucleotide bases. Methods are developed to determine that the X (5'-side) base and the Y (3'-side) base are most influential in determining guanine reactivity. The influence of the bases in the 5'-position (X) is 5'-G (1.0) greater than C (0.8) greater than A (0.3) greater than T (0.2), while the influence of the bases in the 3'-position (Y) is 3'-G (1.0) greater than T (0.8) greater than C (0.4) greater than A (0.3). These rules in conjunction with molecular modeling studies (to be published elsewhere) were used to assess the binding sites that might be utilized by AFB1 oxide in its reaction with DNA.

Supplementation with increasing quantities of selenium (Se), as sodium selenite, to cultures of rat mammary epithelial cells resulted in a proportional depression in 7,12-dimethylbenz[a]anthracene (DMBA) binding to DNA. A depression in the two major anti bay-region dihydrodiol epoxide-deoxyribonucleoside adducts largely accounted for the reduced binding. DMBA-DNA binding in freshly isolated mammary cells from rats fed a diet containing 2.0 p.p.m. Se and incubated in culture with DMBA for 24 h was decreased 32% compared to binding in cells obtained from rats fed 0.1 p.p.m. Se. DMBA-DNA binding in mammary cells obtained from rats fed supplemental Se for 2 weeks or more was depressed compared to that occurring in cells from unsupplemented rats. The reduced ability of cells obtained from rats previously fed a 2.0 p.p.m. Se diet to activate DMBA to intermediates capable of binding to DNA became increasingly apparent with the duration of exposure to the carcinogen. Consistent with the in vitro supplementation study, cells isolated from rats previously fed a diet containing 2.0 p.p.m. Se had a reduced occurrence of the two major anti dihydrodiol epoxide adducts. The depression in DMBA binding following selenite supplementation, both in vitro and in vivo, supports the ability of Se to inhibit the initiation phase of carcinogenesis.