Meyer, Tim

4100 Background: Checkpoint inhibition with anti-PD1 is able to elicit objective response rates (ORR) of ̃ 20% in patients with advanced hepatocellular carcinoma (aHCC) but molecular biomarkers predicting response remain unknown. Here, we define biomarkers of response and primary resistance to anti-PD1 in aHCC by analyzing molecular features prior to systemic therapy. Methods: Through an international consortium of 13 referral centers, we gathered 111 fresh and archived tumor samples from patients with advanced HCC treated with single agent anti- PD1 therapy. Genomic analysis was performed with whole genome expression arrays, CTNNB1 exon 3 mutation assessment and histological evaluation. Results: Overall, we performed transcriptomic analysis in 83 patients, 28 of which were treated in first-line (ORR: 42.9%) while the remaining 55 patients were treated either in 2nd (41 patients, ORR 29.3%) or 3rd line (14 patients, ORR 7.1%) after prior therapy with tyrosine- kinase inhibitors (TKI) sorafenib or lenvatinib. In patients treated in frontline, response was associated with a significant upregulation in Interferon-γ signaling (IFNγ) and genesets relatedto the antigen presentation machinery (FDR < 0.05). Through differential expression analysis we defined an 11-gene signature that was significantly associated with both major pathways (FDR < 0.01) and was capable of predicting OR as well as progression-free- (PFS) and overall survival (OS) in patients with aHCC. The signature was validated in three independent cohorts of melanoma, lung cancer, and head and neck squamous cell cancer patients were high expression was associated with a significant increase in ORR and longer PFS. In HCC, high expression of the signature was associated with a distinct profile in the immune infiltrate, where an increase in M1 macrophages (p = 0.003), CD4 memory T cell (p < 0.01) and CD4 naïve T cell-infiltration (p = 0.026) was observed. Conversely, low expression of the signature was associated with a marked upregulation of regulatory T cells (p < 0.001). No association was found, however, between either the overall immune infiltrate or CTNNB1 mutations and response. In patients that were treated with TKIs in frontline before receiving subsequent anti-PD1 therapy, the signature was no longer able to predict either OR or PFS/OS, suggesting that TKIs may reshape the microenvironment in a way that renders previously inflamed tumors no longer amenable to anti-PD1. Conclusions: Here, we define an 11-gene signature of response to anti-PD1 in first line aHCC. The signature was validated in patients with other solid cancer types, where it retained its predictive ability. Of note, the signature was not able to identify responders among HCC patients that were treated with TKIs prior to anti-PD1 therapy. The molecular changes induced by different treatment lines would, thus, require fresh biopsies prior to anti-PD1to enable biomarker-driven treatment.

8522 Background: CC-223 is an ATP-competitive inhibitor of the mTOR kinase, including both TORC1 and TORC2 complexes. CC-223 was selected to address resistance of rapamycin analogues mediated by TORC2 activation. Methods: Following establishment of the MTD (reported at ASCO 2012), subjects with advanced DLBCL, MM and select solid tumors were enrolled in parallel expansion cohorts of up to 20 evaluable subjects. CC-223 was dosed at 45 mg once daily in 28 day cycles until disease progression. Results: As of 09 January, 2013, 35 subjects were enrolled including DLBCL (21) and MM (14). Results in solid tumor cohorts are reported separately. The most common (> 20%) related adverse events (all grades) were fatigue, hyperglycemia, rash, anorexia, nausea, vomiting and diarrhea. In addition, related serious adverse events included infection (2), pneumonitis (1), renal insufficiency (2), pancreatitis (1) and thrombocytopenia (1). CC-223 dose reduction was required in 9 subjects (27%), usually during cycle 1 or 2, and 4 additional subjects with DLBCL dropped out during cycle 1 due to toxicity. Systemic exposure was similar between the two tumor cohorts and was associated with inhibition of TORC1 (p4EBP1) and TORC2 (pAKT) biomarkers in blood cells. Reduction in glucose uptake (32 – 98% decrease) on PET imaging at day 15 was observed in 7/7 DLBCL subjects with results currently available. Three of 17 evaluable subjects with DLBCL had partial responses (PR) after 2 cycles; two with rapid and near complete regression (> 90%) of target lesions by CT and PET with PR confirmed and treatment ongoing at 6 and 8 cycles. Both had failed multiple prior treatment regimens (5 and 3, respectively), including autologous stem cell transplant (ASCT). No responses were observed in 10/14 evaluable subjects with MM although 2 subjects have prolonged stable disease (SD) with treatment ongoing at 12 and 14 cycles. Conclusions: Encouraging signals of biomarker and clinical activity were observed in DLBCL, including two near complete responses, which are ongoing. Due to dose reductions and interruptions, a starting dose of 30 mg QD is recommended for future studies. Clinical trial information: NCT01177397.