6 inhibitor with docetaxel in lung cancer cell lines harboring KRAS mutations

Poster Session – Molecular targeted agents I, Wednesday 29 November 2016 84 Poster (Board P055) Synergistic effect of combined CDK4/6 inhibitor with docetaxel in lung cancer cell lines harboring KRAS mutations S. Kyoung Hwa1 , S. Jung Young1 , K. Jeong Oh1 , K. Min Young1 , K. Jin Hyoung1 . 1 The Catholic University, Seoul, Korea, Oncology lab, Seoul, Korea Background: LY2835219 (LY), a novel CDK4/6 inhibitor, arrests the G1 phase and inhibits the cell proliferation. Docetaxel (DTX) is a cytotoxic anticancer drug which induces G2/M arrest and apoptosis. In present study, we evaluated the activities of CDK4/6 inhibitor alone or combined with docetaxel on the anti-proliferation, cell cycle and apoptosis in lung cancer cell lines harboring KRAS mutations. Material and Methods: We measured the anti-proliferative activities of LY or DTX single and their combinations (DTX+LY 72 h and DTX 24 h → LY 48 h) on cell proliferation in Calu-3(WT), A549(G12S) and H727(G12V) cells using CCK-8 assay. We evaluated the expression of CDK2, CDK4, cPARP and caspase-3 by Western blot. The cell cycle distribution and apoptosis detection were analyzed by flow cytometry. Results: The IC50 values of the LY and DTX alone were 0.73±0.6 uM and 3.03±1.4 nM in Calu-3 cells, 0.4±0.2 uM and 0.9±0.2 nM in A549 cells and 2.0±0.7 uM and 3.1±0.3 nM in H727 cells, respectively. Both LY and DTX alone inhibited cell proliferation in a dose-dependent manner in 3 NSCLC cell lines. The CI (Combination index) of the DTX→LY sequential and the DTX+LY simultaneous treatments were 0.1 and 0.4 (CI < 1; synergism) in Calu-3 cells, 0.8 and 0.9 in A549 cells and 0.6 and 0.8 in H727 cells, respectively. In three cells, a synergistic activity of LY and DTX was observed in the DTX→LY in Calu-3, A549 cells and LY→DTX in H727 cells. In A549 cells, after DTX alone for 72 h, the cell population in G2/M phase increased by 54.5% relative to control (24.6%). With LY alone, the fraction of A549 cells in G0/G1 phase increased compared to control (78.4% vs. 49.5%). In case of DTX+LY, the G2/M fraction of A549 cells significantly increased by 33% vs 24.6% in a dose-dependent manner. Meanwhile, in DTX→LY, cell fractions in G2/M were increased (44.5% vs 24.6%), especially those in G0/G1 phases were remarkably reduced (14.7% vs 49.5%). In addition, In case of DTX alone, the subG1 fractions of both A549 and H727 cells increased in a dose-dependent manner (0.7% vs. 17.4% and 2.5% vs. 28.1%, respectively). In DTX→LY, the subG1 fraction increased in a dosedependent manner by relative to control (23.3% vs 10.9%). The DTX→LY induced significant apoptotic cell death in A549 cells relative to control and DTX alone (38.2%, 21.5% and 2.6%, respectively). The expression of apoptosis-related proteins, c-PARP and caspase-3 was increased by the DTX alone and two different combination schedule and CDK2 and CDK4 expressions were decreased by LY alone and DTX→LY. MEK1/2, pERK expressions were decreased by DTX→LY in A549 cells and KRAS, pERK expressions were decreased by LY→DTX in H727 cells. Conclusions: Taken together, our results suggest that DTX→LY sequential treatment has enhanced antitumor efficacy with synergistic interaction in lung cancer cell lines carrying KRAS mutation. No conflict of interest. 85 Poster (Board P056) RXDX-105 demonstrates anti-tumor efficacy in multiple preclinical cancer models driven by molecular alterations in RET or BRAF oncogenes L. Martin1 , C. Walsh1 , S. Uryu1 , J. Joseph1 , A. Franovic1 , A. Schairer1 , R. Patel1 , R. Shoemaker2 , A. Diliberto3 , D. Murphy3 , J. Christiansen3 , J. Oliver4 , E. Kowack5 , P. Multani4 , G.G. Li1 . 1 Ignyta, Translational Research, San Diego, USA; 2 Ignyta, Computational Biology, San Diego, USA; 3 Ignyta, Diagnostics, San Diego, USA; 4 Ignyta, Clinical Development, San Diego, USA; 5 Ignyta, Program Management, San Diego, USA Molecular alterations in RET, including rearrangements and activating point mutations, have been identified as oncogenic drivers. Point mutations in RET are typically detected in multiple endocrine neoplasia (types A and B), as well as familial medullary thyroid carcinoma. RET gene rearrangements have been identified in a significant portion of papillary thyroid cancer (PTC), up to 2% of non-small cell lung cancers (NSCLC) and at lower frequencies in multiple other malignancies. Although small molecule RET inhibitors have shown preclinical and clinical activity, there remains a need for better tolerated, more effective RET inhibitors for the treatment of patients with relevant molecular alterations. Molecular alterations in BRAF are commonly identified in 10% to 15% of colorectal cancers, and 1% to 2% of NSCLC. Although notable clinical activity has been achieved with single-agent vemurafenib and dabrafenib in treating melanoma harboring the BRAF V600E mutation, their clinical efficacy in colorectal cancer (CRC) and NSCLC has not been satisfactory. RXDX-105 is a clinical stage multikinase inhibitor (MKI) that has demonstrated potent inhibition of RET and BRAF. In biochemical assays,

Poster abstracts

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RXDX-105 potently antagonized constitutively active, rearranged and pointmutated RET proteins. In cell based assays, RXDX-105 demonstrated a dose-dependent inhibition of RET and downstream signaling events, resulting in inhibition of cellular proliferation. In vivo, RXDX-105 achieved dose-dependent anti-tumor activity, including tumor regression at clinically achievable exposures in several patient derived xenograft (PDX) models harboring RET rearrangements. Similarly, RXDX-105 demonstrated significant antitumor activity in a panel of CRC PDX models harboring BRAF mutations, including V600E and non-V600E variants. In addition to RET and BRAF, RXDX-105 is believed to potentially drive additional anti-tumor activity, durability and/or therapeutic potential from its MKI properties, such as anti-angiogenesis and immune-modulatory activities. In conclusion, the potent anti-RET and BRAF activity of RXDX-105 in molecularly defined preclinical models, supplemented with its MKI activities, provides a strong rationale for clinical development of RXDX-105, as a single agent or in combination with standard of care agents in a variety of tumor types. Conflict of interest: Ownership: All authors are employees of Ignyta, and own Ignyta stocks. 86 Poster (Board P057) A first-in-man phase 1a study of the bispecific anti-DLL4/anti-VEGF antibody OMP-305B83 in patients with previously treated solid tumors A. Jimeno1 , K. Moore2 , M. Gordon3 , R. Chugh4 , J. Diamond1 , R. Aljumaily2 , R. Stagg5 , J. Dupont5 , D. Smith4 . 1 University of Colorado Medical Center, Medical Oncology, Aurora, USA; 2 Stephenson Oklahoma Cancer Center at the University of Oklahoma, Medical Oncology, Oklahoma City, USA; 3 Pinnacle Oncology, Medical Oncology, Scottsdale, USA; 4 University of Michigan Cancer Center, Medical Oncology, Ann Arbor, USA; 5 OncoMed Pharmaceuticals, Medical Oncololgy, Redwood City, USA Background: OMP-305B83 is a bispecific antibody that inhibits both the Notch ligand delta-like ligand 4 (DLL4) and VEGF. Inhibition of DLL4 has been shown to decrease CSC frequency in minimally passaged human xenograft models and to have a potential immunomodulatory effect by decreasing myeloid derived suppressor cells in preclinical studies. In addition, inhibition of both DLL4 and VEGF have been shown to result in an antiangiogenic effect. OMP-305B83 has demonstrated significant antitumor activity against several tumor types in human xenograft models. Material and Methods: A 3+3 dose escalation design was used. Objectives were determination of maximum tolerated dose (MTD), safety, pharmacokinetics (PK), pharmacodynamics (PD), and efficacy. A doselimiting toxicity (DLT) was defined as any  grade 3 adverse event in the first 21 days (except grade 3 hypertension or proteinuria resolving before the next scheduled dose). Results: Forty-six patients received escalating doses of OMP-305B83 ranging from 0.5−10 mg/kg once every 3 weeks. Additional dose cohorts are planned at 12.5 and 15 mg/kg if tolerated. The median age was 58.5 years and the most common tumor types were ovarian cancer (8), endometrial cancer (4), breast cancer (3) and pancreatic cancer (3). One DLT of diverticulitis requiring surgical resection occurred and the MTD has not been reached. Adverse events related to study drug in at least 10% of patients included: systemic hypertension (54%), fatigue (20%), headache (24%), anemia (13%), dyspnea (11%), and pulmonary hypertension (11%). Systemic hypertension was successfully managed with anti-hypertensives. One of the 39 evaluable patients (a patient with uterine carcinosarcoma) had a partial response (PR) and 14 patients had stable disease. Twelve patients had a reduction in their RECIST target lesion size. Five of the 7 evaluable ovarian cancer patients had reduction in their target lesion size that did not meet PR criteria and these 5 patients were on treatment for 64+, 129, 177+, 185 and 309 days. Conclusion: OMP-305B83 was generally well tolerated with hypertension and fatigue being the most common drug related toxicities. Encouraging early clinical activity has been observed especially in platinum-resistant ovarian cancer. Phase 1b studies are being initiated in ovarian cancer and colorectal cancer. Enrollment is ongoing and updated results will be presented. No conflict of interest. 87 Poster (Board P058) Preclinical characterization and antitumor efficacy of DS-6051b, a novel, orally available small molecule tyrosine kinase inhibitor of ROS1 and NTRKs M. Kiga1 , S. Iwasaki1 , N. Togashi1 , Y. Takeda1 , Y. Kagoshima1 , K. Kanai1 , Y. Kamai1 , Y. Tominaga1 , T. Isoyama1 . 1 Daiichi Sankyo Co. Ltd., R&D Division, Tokyo, Japan Background: Gene rearrangements of ROS1 or NTRKs (NTRK1, NTRK2, NTRK3) have been reported in various cancers including non-small cell lung cancer. These cancers express activated fusion kinases that drive