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TPS195 Background: Outcomes with first-line (1L) chemotherapy for GC/GEJC are limited and new strategies to increase efficacy without added toxicity are needed. Avelumab, a human anti-PD-L1 IgG1 monoclonal antibody, is approved for metastatic Merkel cell carcinoma (US and EU) and advanced urothelial carcinoma after progression on platinum therapy (US). In phase 1 studies in advanced GC/GEJC, avelumab showed antitumor activity and a manageable safety profile, including in a subgroup of patients (pts) without progression on 1L chemotherapy who received avelumab as maintenance therapy. JAVELIN Gastric 100 (NCT02625610) is a global, randomized, open-label, phase 3 trial comparing maintenance therapy with avelumab vs continuation of 1L chemotherapy in pts with advanced GC/GEJC who have not progressed after 12 weeks of 1L oxaliplatin/fluoropyrimidine chemotherapy. Methods: Eligible pts have histologically confirmed, unresectable, measurable, locally advanced or metastatic GC/GEJC adenocarcinoma, no prior chemotherapy for advanced disease, no prior therapy targeting T-cell coregulatory proteins, and ECOG PS of 0–1. Pts are not preselected based on PD-L1 expression and pts with HER2+ tumors are excluded. Approximately 466 pts who achieve at least stable disease following 12 weeks of 1L oxaliplatin/fluoropyrimidine chemotherapy will be randomized 1:1 to receive maintenance therapy with either avelumab 10 mg/kg by IV infusion Q2W or continuation of 1L chemotherapy. Maintenance therapy is given until disease progression, unacceptable toxicity, or withdrawal. Primary endpoints are overall survival and progression-free survival. Secondary endpoints include best overall response, quality of life measures, safety (NCI-CTCAE v4.03), and tumor biomarkers. Responses are evaluated per RECIST 1.1 and adjudicated by independent review committee. Enrollment is ongoing at sites in North/South America, Asia-Pacific, and Europe. Clinical trial information: NCT02625610.

2507 Background: LY3009120, a pan-Raf and dimer inhibitor, demonstrates inhibition of phospho-Mek/Erk and tumor growth inhibition in several non-clinical cancer models with BRAF, NRAS, or KRAS mutations. This is the first-in-human phase 1 study of LY3009120 in patients (pts) with advanced cancer. Methods: The safety and tolerability of LY3009120 was evaluated in pts with cancer aged 18 years or older who had an ECOG performance status ≤1, at least 1 unidimensionally measurable lesion (RECIST 1.1), and adequate organ function (NCT02014116; I6X-MC-JBDA; Eli Lilly & Co.). The study sought to determine a recommended phase 2 dose using the toxicity band method and the safety, pharmacokinetic, and preliminary efficacy of LY3009120. Pharmacodynamic (PD) biomarkers, including pERK, p27 and Ki67, were evaluated in tumor tissue. The dose escalation phase evaluated dosages from 50 mg to 500 mg by mouth twice daily in pts with advanced cancers. Results: 34 pts (3 at 50 mg, 4 at 100 mg, 3 at 200 mg, 15 at 300 mg, 7 at 400 mg, and 2 at 500 mg) in dose escalation and 1 pt in dose expansion (1 at 300 mg) received at least one dose of LY3009120 by January 2, 2016 (median age = 47.4 yrs, range: 26-82 ). Most pts had a gene mutation (BRAF, n = 7; N/KRAS, n = 18); the most common cancer types included colon (n = 9), non–small cell lung cancer (n = 8), and pancreatic (n = 5). There were 6 dose-limiting toxicities in the dose escalation phase: 2 pts at 300 mg (G3 dermatitis acneiform [n = 1] and G2 blurred vision [n = 1]); 2 pts at 400 mg (G2 increased ALT with G3 hyperbilirubinemia [n = 1] and G3 increased ALT [n = 1]); 2 pts at 500 mg: (G3 arthralgia/myalgia [n = 1] and G3 stomatitis/pain [n = 1]). Based on these data, the maximum tolerated dose for LY3009120 was determined to be 300 mg twice daily. Treatment-emergent adverse events related to LY3009120 occurring in ≥10% of pts included fatigue (34%), nausea (31%), decreased appetite (20%), and dermatitis acneiform (20%) (Grade 1,2). A dose proportional increase in exposure was observed, but not at the 400 mg dose. The best response was stable disease in 5 pts. PD effect by rtPCR was not observed in tested paired tumor samples. Conclusions: LY3009120 is well tolerated at doses of 300 mg twice daily. Updated data from dose expansion will be presented in the meeting. Clinical trial information: NCT02014116.

10501 Background: Options for patients (pts) with unresectable/metastatic STS are limited. While Dox is standard of care, Dox combinations have yet to improve overall survival (OS) over Dox alone. Olaratumab (IMC-3G3), a fully human monoclonal antibody, selectively binds PDGFRα (a signaling pathway implicated in STS), blocks ligand binding, and enhances Dox activity in preclinical sarcoma models. Methods: We conducted a phase Ib, open-label, randomized phase II study of Dox ± olaratumab in unresectable/metastatic STS (NCT01185964). Pts received Dox (75 mg/m2 Day 1) with (Arm A) or without (Arm B) olaratumab (15 mg/kg Days 1 and 8, every 21 days), a dose and schedule confirmed safe in phase Ib, for up to 8 cycles. In Arm A, olaratumab monotherapy continued after Dox until disease progression; in Arm B, pts could cross over to olaratumab at progression. The primary endpoint was progression-free survival (PFS; target hazard ratio [HR] = 0.67, 80% power, α = 0.2) with OS as a secondary endpoint. Results: Of 1...