Impact of circulating biomarkers in patients with metastatic colorectal cancer treated with first-line FOLFOX-aflibercept therapy. Results of the GERCOR VELVET Phase II study

Poster Session – Molecular targeted agents II, Thursday 1 December 2016 sought. Sigma receptors (SR1 and SR2) are members of a class of unique receptors integrated in plasma, mitochondrial and endoplasmatic reticulum membranes of mammalian cells. They have received much attention in the drug-discovery field other than their role in several neurological disorders, also for their probable involvement in cancer cell proliferation and aggressiveness. Therefore, inhibitors or modulators are of great interest as novel therapeutic anti-cancer drugs. In the present work, 3-D primary cultures of GBM endowed with stemness features, were used to evaluate the antitumor activity of a novel sigma receptor modulator RC-106. Materials and Methods: Primary cultures of hGBM have been isolated starting from surgical tumor samples and grown as monolayer or 3Dcell cultures. Growth and morphology of the 3D tumor colonies were monitored by open-source AnaSP and ReViSP software tools. The molecular analyses were performed by flow cytometry and qRT-PCR. Cell viability was measured using CellTiter-Glo® 3D Cell Viability and MTS Assays. The apoptosis and cell cycle were analyzed by flow cytometry. Results: We established a number of cell lines with different growth properties and different stemness gene expression profile. In particular, we evaluated the expression levels of the target genes S1R and S2R, and of tumor propagating cells surface markers as EphA2, CD44 and CD133 by flow cytometric and qRT-PCR analysis. Notwithstanding the inter-tumor heterogeneity observed, the treatment with RC-106 significantly inhibited cell viability and caused a strong apoptosis induction in all cell cultures tested. Conversely, the exposure to different concentrations of temozolomide did not induce significant cytotoxic effet. In particular, RC106 (25mM) induced an impairment of in vitro clonogenic ability of GBM cells, and such effect persist until 42 days, the longest time tested. Conclusions: The high level of expression of S1R and S2R gene detected in patient’s tissues and in their derivative cell lines support the interest for these receptors as potentially druggable targets also in GBM. Notably, RC106 compound showed to be able to induce a strong cytotoxic effect in all the cell lines tested both actively proliferating and in low proliferation rate in response to serum deprivation. No conflict of interest. 449 Poster (Board P128) Impact of circulating biomarkers in patients with metastatic colorectal cancer treated with first-line FOLFOX-aflibercept therapy. Results of the GERCOR VELVET Phase II study A. Tijeras-Raballand1 , A. De Gramont1 , M. Chiron2 , J.B. Bachet3 , T. Andre´ 4 , D. Auby5 , J. Desrame´ 6 , N. Baba-Ahmed7 , C. Lecaille8 , V. Lebrun9 , C. Louvet10 , C. Tournigand11 , S. Benner12 , M. Attia13 , A. De Gramont14 , F. Bonnetain15 , B. Chibaudel14 . 1 AFR Oncology, Preclinical and Translational Department, Paris, France; 2 Sanofi, Translational Medicine, Oncology Department, Vitry sur Seine, France; 3 ˆ ´ ´ ere, ` Hopital Pitie-Salp etri Gastroenterology Department, Paris, France; 4 ˆ Hopital Saint-Antoine, Medical Oncology Department, Paris, France; 5 Centre Hospitalier Mont de Marsan, Gastroenterology Department, Mont ˆ Prive´ Jean Mermoz, Gastroenterology and de Marsan, France; 6 Hopital ˆ Hepatology Department, Lyon, France; 7 Hopital Saint-Joseph, Medical Oncology Department, Paris, France; 8 Polyclinique Bordeaux Nord Aquitaine, Gastroenterology Department, Bordeaux, France; 9 Centre Hospitalo-Universitaire de Limoges, Medical Oncology, Limoges, France; 10 Institut Mutualiste Montsouris, Medical Oncology, Paris, France; 11 Centre ´ Hospitalo-Universitaire Henri Mondor, Medical Oncology, Creteil, France; 12 AFR Oncology, Translational and Clinical Department, Paris, France; 13 GERCOR, Medical Oncology, Paris, France; 14 Institut Hospitalier Franco-britannique, Medical Oncology Department, Levallois-Perret, France; 15 Centre Hopistalo-Universitaire de Besan¸con, Quality of Life in Oncology and Methodology Department, Besan¸con, France Background: The combination of aflibercept to OPTIMOX (VELVET study) was evaluated in patients with previously untreated advanced colorectal cancer (Chibaudel B et al, J Clin Oncol 33, 2015 (suppl; abstr 3567). A biomarker program was set-up to explore the expression of several biomarkers upon treatment cycles to identify the best monitoring biomarkers of the treatment strategy. Methods: VELVET was a prospective, single arm phase II trial. Patient’s plasma samples were collected at baseline, and during induction therapy at day 1 of the first 6 cycles. Circulating biomarkers were analyzed using multiplexing immunoassays (31 biomarkers, 3 panels). All assays were conducted on a Biorad Bioplex platform. Results: Among 49 patients included in the VELVET study from May 2013 to May 2014, 44 (90%) patients were evaluable for circulating biomarkers expression. The proportion of patients with tumor response (CR or PR) was higher in patients with high baseline levels of sVEGFR2, sEGFR, G-CSF, Prolactin and low baseline levels of VEGFA and MIF. Progressionfree survival (PFS) was higher in patients with low baseline levels of sIL6Ra (HR: 0.52; P = 0.045) and Osteopontin (HR: 0.53; P = 0.045) and in

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patients with high baseline levels of VEGF-C (HR: 0.45; P = 0.014) and sVEGFR3 (HR: 0.50; P = 0.045). Overall survival was higher in patients with high sVEGFR3 (HR: 0.36; P = 0.030) and IL-8 (HR: 0.32; P = 0.014) levels. In both responders and non-responders, sVEGFR-1 dramatically increased upon exposure to aflibercept and remained overexpressed for the all course of induction therapy. Induction therapy also comes with increased expression of VCAM (+42%), SDF-1 (+62%) and SP-D along with decreased expression of sVEGFR-3, VEGF-C, Ang1, Ang2, PDGF and IL-8 Tumor expression of some of these markers will be presented at the meeting. Conclusions: Exposure to aflibercept is associated with an increase of sVEGFR-1 at cycle 1. Elevated baseline expression levels of on-target sVEGFR3 predict favorable outcome in patients treated with aflibercept. Conflict of interest: Advisory Board: Pr C. Tournigand (Sanofi); Pr C. Louvet (Sanofi, Roche, Celgene); Dr JB Bachet (Amgen, Lilly, Celgene, Roche); Pr A. Thierry (Roche, Boeringher); Dr B. Chibaudel (Sanofi); Pr A. de Gramont (Sanofi). Other Substantive Relationships: Marielle Chiron is an employee of Sanofi. 450 Poster (Board P129) Development of AVID100, a novel antibody–drug conjugate for the treatment of EGFR expressing solid tumors M. O’Connor-McCourt1 , J. Koropatnick2 , S. Maleki2 , R. Figueredo2 , I. Tikhomirov3 , M. Jaramillo4 . 1 Formation Biologics, R&D, Montreal, Canada; 2 Lawson Health Research Institute, Cancer Research Program, London, Canada; 3 Formation Biologics, R&D, Houston, USA; 4 National Research Council Of Canada, Human Health Therapeutics, Montreal, Canada Background: AVID100 is a novel epidermal growth factor receptor (EGFR)targeting antibody–drug conjugate (ADC). EGFR is an important oncogene overexpressed by many types of solid tumors, including lung, breast, head and neck, and others. Unlike currently marketed anti-EGFR therapeutics that depend on EGFR blockade for anti-cancer activity, AVID100 has an additional mechanism of action of direct cytotoxicity via conjugated payload. This is expected to result in significantly enhanced anti-cancer activity of AVID100 compared to currently marketed anti-EGFR agents. We conducted in vitro and in vivo studies to evaluate the anticancer activity of AVID100. Methods: Effects of AVID100 were tested against EGFR+ cancer cell lines, including those resistant to marketed anti-EGFR agents. Activity of AVID100 against non-transformed EGFR+ keratinocytes was also evaluated. Pharmacology studies investigating the anti-cancer activity of AVID100 were performed in mice bearing human tumor xenograft models, including breast and head and neck cancers. Results: AVID100 demonstrated potent and broad activity against multiple cell lines with IC50 values in the pM to nM range. The ADC was also active against cell lines resistant to marketed to anti-EGFR therapeutics. In vivo, AVID100 demonstrated significant anti-cancer activity in multiple cancer models including complete remissions in breast and head and neck cancer xenografts. Importantly, AVID100 was demonstrated to be minimally toxic against normal EGFR+ keratinocytes. Skin toxicity is a class effect of anti-EGFR therapeutics and this result suggests AVID100 skin toxicity will be comparable to other agents in the class, despite significantly higher potency of AVID100 on tumors. Tolerability of AVID100 was subsequently confirmed in non-human primate studies. Conclusion: AVID100 is a promising anti-cancer therapeutic for the treatment of EGFR expressing tumors, including tumor types resistant to currently marketed anti-EGFR agents. AVID100 is currently undergoing IND-enabling development with clinical trials planned for 2016. Conflict of interest: Ownership: Formation Biologics. Advisory Board: Formation Biologics. Board of Directors: Formation Biologics. Corporatesponsored Research: Formation Biologics. 451 Poster (Board P130) Development of a novel chromogenic RNA in situ hybridization method for detection of somatic mutations X.M.M. Wang1 , X. Wu1 , L. Pan1 , N. Su1 , E. Park1 , R. Monroe1 , Y. Luo1 , X.J. Ma1 . 1 Advanced Cell Diagnostics, R&D, Newark, USA Background: The identification of somatic mutations in tumors is becoming increasingly important for patient selection for targeted therapies. While high throughput sequencing technologies allow for comprehensive mutation-profiling, sequencing does not permit assessment of intratumoral heterogeneity or the association of genetic alterations with cellular morphology. In addition, DNA mutational status does not predict expression of the mutant allele which may provide information connecting genotype to phenotype. Therefore, a technology for mutation detection directly in the tumor context is desirable. We present a chromogenic in situ hybridization