Abstract IA23: Overcoming drug resistance and tumor heterogeneity in gastrointestinal cancers

Personalized cancer medicine approaches, inhibiting kinases in tumors driven by defined genomic alterations, have demonstrated striking efficacy in many cancer types. However, the development of drug resistance is a major limitation to the efficacy of targeted therapies in oncology. Identifying and understanding the molecular mechanisms driving resistance may foster opportunities to develop therapeutic strategies to overcome resistance. For example, in the ~10% of colorectal cancer patients whose tumors harbor BRAF V600 mutations, we have found that feedback reactivation of MAPK signaling, often mediated by EGFR, underlies the relative insensitivity of these cancers to RAF inhibitors. The development of targeted therapy combination strategies to block feedback reactivation of MAPK signaling has led to marked improvements in response rates for these patients from ~5% to >30% over the past few years. However, in patients who respond to these targeted combinations, the rapid development of acquired resistance still limits clinical benefit. Acquired resistance in BRAF mutant colorectal cancer and in other molecularly-defined tumor types can be marked by the development of extensive molecular heterogeneity due to the selection of sub-clonal tumor cell populations, capable of growing under drug pressures, which poses significant diagnostic and therapeutic challenges. We will present data demonstrating how a single-lesion biopsy at disease progression to diagnose the mechanism of...
Source: Molecular Cancer Therapeutics - Category: Cancer & Oncology Authors: Tags: Resistance against Drug Combinations: Oral Presentations - Invited Abstracts Source Type: research