Therapy Resistance Mechanisms for Cancer

Division Of Basic Sciences - Nci

Investigators

Linked publications, trials & patents

Abstract

We use a variety of next-generation sequencing methods including exome, bulk RNAseq, and single cell RNAseq as well as epigenetic analysis to identify mechanisms of resistance to small molecules inhibitors and adoptive cell therapies. Currently, the gold standard treatment for these patients is thyroidectomy. The efficacy of surgery as a standalone treatment option is limited by the fact that many patients have been found to have metastatic disease upon initial presentation. Just under half of patients initially present with stage III or IV disease and are associated with 10-year survival rates of 71% and 21% respectively. Despite the availability of RET inhibitors, 10% of patients develop metastases . Several tyrosine kinase inhibitors (TKIs) that target RET tyrosine kinase signaling have been evaluated for treatment of advanced MTC in recent years. Of the TKIs that reached phase III clinical trials (axitinib, cabozantinib, gefitinib, imatinib, motesanib, sorafenib, sunitinib, and vandetanib), vandetanib and cabozantinib have been approved by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for treatment of advanced MTC. Along with targeting RET kinases, vandetanib also targets EGFR and VEGFR kinases. Meanwhile, cabozantinib targets RET, c-MET, and VEGFR kinases. However, despite the promising results of vandetanib and cabozantinib in patients with advanced disease, there are a subset of patients who develop drug resistance accompanied by adverse side effects and poor tolerability. This project aims to identify the genetic and epigenetic changes in MTC cells which results in development of resistance to different RET inhibitors. We will develop new therapies that may be synergistic and prevent or treat therapy resistance to small molecule inhibitors of RET. For mechanisms of resistance to adoptive cell therapies, we focus on Chimeric antigen receptor (CAR) T cell therapies targeting single antigens. These have performed poorly in clinical trials for solid tumors due to heterogenous expression of tumor-associated antigens (TAAs), limited T cell persistence, and T cell exhaustion. We aim to identify optimal CARs against glypican 2 (GPC2) or CD276 (B7-H3), which were highly but heterogeneously expressed in neuroblastoma (NB). We use pooled competitive optimization of CAR by cellular indexing of transcriptomes and epitopes by sequencing (CITE-Seq), termed P-COCC, to simultaneously analyze protein and transcriptome expression of CAR T cells to identify high-activity CARs. We perform cytotoxicity assays to identify the most effective CAR against each target and combined the CARs into a bicistronic "OR" CAR (BiCisCAR). We test if the BiCisCAR T cells demonstrate prolonged persistence and resistance to exhaustion when compared with CARs targeting a single antigen. This study aims to show that targeting multiple TAAs with BiCisCAR may overcome resistance to therapy due to heterogenous expression of target antigens in solid tumors to identify potent, clinically relevant CARs against NB.