The effect of a drug is related to the interaction of the numerous gene products that participate in a drug pathway. The clinical importance of genetic variability on the overall outcome of most drug ...pathways remains to be determined. As a result, there is a need to efficiently identify the genes that not only participate in the pathway but also play a significant role in regulating the effects of a drug. The emerging technique of specific gene silencing through RNA interference initiated by small inhibitory RNA may prove to be a useful and powerful tool in the credentialing of candidate genes in drug pathways.
Activating mutations in tyrosine kinase (TK) genes (eg, FLT3 and KIT) are found in more than 30% of patients with de novo acute myeloid leukemia (AML); many groups have speculated that mutations in ...other TK genes may be present in the remaining 70%. We performed high-throughput resequencing of the kinase domains of 26 TK genes (11 receptor TK; 15 cytoplasmic TK) expressed in most AML patients using genomic DNA from the bone marrow (tumor) and matched skin biopsy samples (“germline”) from 94 patients with de novo AML; sequence variants were validated in an additional 94 AML tumor samples (14.3 million base pairs of sequence were obtained and analyzed). We identified known somatic mutations in FLT3, KIT, and JAK2 TK genes at the expected frequencies and found 4 novel somatic mutations, JAK1V623A, JAK1T478S, DDR1A803V, and NTRK1S677N, once each in 4 respective patients of 188 tested. We also identified novel germline sequence changes encoding amino acid substitutions (ie, nonsynonymous changes) in 14 TK genes, including TYK2, which had the largest number of nonsynonymous sequence variants (11 total detected). Additional studies will be required to define the roles that these somatic and germline TK gene variants play in AML pathogenesis.
Abstract
Background: MET ex14 skipping, present in ~3% of lung cancer, is a strong oncogenic driver which is further evidenced by case reports of patients response to MET TKI treatment. ~15% of ...tumors in patients that harbor MET ex14 skipping also have MET amplification (amp). Merestinib is a type II MET kinase inhibitor1. Emibetuzumab, a bivalent MET Ab, internalizes MET receptor. Each single agent and the combination were evaluated in the Hs746t gastric cancer line bearing MET ex14 skipping and MET amp. Methods: Each agent was evaluated in vitro for inhibition of Hs746t cell proliferation and pMET levels. In vivo study in Hs746t-derived xenograft mouse model (n=7 mice/ arm, 28 day dosing) initiated when tumors were 150-350mm3: merestinib at 6 mg/kg (suboptimal dose - insufficient target coverage for 24 hrs) or 12 mg/kg (optimal dose) qd orally, emibetuzumab at 10 mg/kg qw by IP. Results: Merestinib inhibited Hs746t cell proliferation with IC50=34 nM and totally eliminated pMET at 65-100 nM. Emibetuzumab slightly inhibited Hs746t cell proliferation (IC50>100 nM), reduced 10-20% cell surface MET, and no effect on pMET expression (at 130-650 nM). In the Hs746t xenograft model, merestinib (12 mg/kg) treatment resulted in 91.8% tumor regression after 21 day dosing, while 6 mg/kg merestinib provided transient tumor regression followed by re-growth while on treatment with T/C=18.3% after 21 day dosing. No tumor re-growth was observed in 6/7 mice in the 12 mg/kg merestinib cohort during the 5 weeks post-treatment. Emibetuzumab treatment provided transient tumor regression (37.7%) after 3 doses, but tumors re-grew while on treatment. Combination of 6 mg/kg merestinib and 10 mg/kg emibetuzumab resulted in 85% tumor regression for the duration of the 28 day dosing period and the treatment was well tolerated. Tumors in animals re-grew upon termination of this combination treatment. Conclusion: Merestinib (12 mg/kg) treatment resulted in durable and complete response in 6/7 mice bearing Hs746t tumors with MET ex14 skipping and MET amp. When used singly, merestinib (6 mg/kg) or emibetuzumab (10 mg/kg) resulted in only transient tumor regression in this model, while the combination resulted in substantial tumor regression while on treatment. This combination treatment was however, not as durable as was observed with single agent 12 mg/kg merestinib. Single agents and the combinations were well tolerated. As a type II MET inhibitor, merestinib may provide a therapeutic option to treatment naïve patients or those who have progressed on type I MET inhibitor treatment, whose tumors have MET exon 14 skipping and/or MET amplification 2,3. Data in this study support a clinical evaluation of merestinib in patients with MET exon 14 skipping (NCT02920996). 1 - Yan et al. Invest New Drugs 2013;31:833-844 2 - Ou et al. J Thorac Oncol. 2016; PMID:27666659 3 - Heist et al. J Thorac Oncol. 2016;11:1242-1245
Citation Format: Sau-Chi Betty Yan, Suzane L. Um, Victoria L. Peek, Jennifer R. Stephens, Wei Zeng, Bruce W. Konicek, Ling Liu, Volker Wacheck, Richard A. Walgren. Evaluation of single agent merestinib (LY2801653) or emibetuzumab (LY2875358) and the combination in a xenograft tumor model bearing MET exon 14 skipping abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 528. doi:10.1158/1538-7445.AM2017-528
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Background: Treatment approaches combining anti-angiogenic therapy with chemotherapy have shown promising clinical results in metastatic bladder cancer (BC). In order to interrogate ...the potential clinico-pathologic and molecular basis of these findings, we evaluated VEGFR2, vascular density and molecular subtyping in a series of BC patients. Methods: A custom-TMA with primary BC tissues from 117 patients (mean age 71 yrs; range 38-99 yrs; M:F = 83:34) treated at a single institution, was stained and scored (0-3) for CD34 (vascular density) and for VEGFR2 on tumor vessels and cells. CK5/6 and GATA3 IHC was scored by a pathologist to identify main molecular classes of BC. The association between clinico-pathologic variables, VEGFR2, CD34 and molecular subtypes was analyzed by Fisher’s exact test and ANOVA. Univariate and multivariate Cox proportional models were used for survival analysis. Results: Of 112 analyzable BC tissues, 41% were muscle-invasive (MIBC) vs. 56% non-muscle invasive (NMIBC) and 3% undetermined. Compared to NMIBC patients those with MIBC had shorter overall survival (p < 0.001). The main molecular subtypes included basal (11%), mixed baso-luminal (28%) and luminal (61%). Compared to luminal and baso-luminal subtypes, the majority of basal BCs were muscle invasive (p = 0.036). VEGFR2 expression was higher in tumor vessels but variable in tumor cells. 74% of BCs showed high-medium levels of VEGFR2 (scores 3-2) in tumor vessels and 88% had high-medium levels of tumor vascular density. Within basal, luminal and baso-luminal subtypes, 58%, 78% and 71% had high-medium levels of vascular VEGFR2 (p = 0.52), while 83%, 91% and 82% had high-medium levels of tumor vascular density (p = 0.08). Survival analyses showed increasing patient age, higher stage and lower VEGFR2 levels as independent predictors of shorter survival. Conclusions: Given the observed complexity of BC regarding VEGFR2 expression and vascular density across molecular subtypes, further investigation is warranted to understand how the frequent expression of VEGFR2 on tumor vasculature and variable expression in tumor cells relates to the efficacy of anti-angiogenic agents across these subtypes in bladder cancer.
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