Study

Whole exome sequencing of longitudinal samples from a melanoma patient receiving MEK plus CDK4/6 inhibitor therapy.

Study ID Alternative Stable ID Type
EGAS00001002846 Other

Study Description

Combined MEK and CDK4/6 inhibition (MEKi+CDK4i) has shown promising clinical outcomes in NRAS mutant melanoma patients. Here, we interrogated longitudinal biopsies from a patient who initially responded to MEKi+CDK4i therapy but subsequently developed resistance. Whole exome sequencing and functional validation identified an acquired PIK3CAE545K mutation as conferring drug resistance. We demonstrate that PIK3CAE545K pre-existed in a rare subpopulation that was missed by both clinical and research testing, but was revealed upon multi-region sampling due to PIK3CAE545K being non-uniformly distributed. This resistant population rapidly expanded after the initiation of MEKi+CDK4i therapy and persisted in all successive samples even after immune checkpoint therapy and distant metastasis. Functional studies identified activated S6K1 as both a key marker and specific therapeutic vulnerability downstream of PIK3CAE545K-induced resistance. These results demonstrate that comprehensive analysis of pre-treatment samples can reveal rare pre-existing resistant subpopulations and also posit S6K1 ... (Show More)

Study Datasets 1 dataset.

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Dataset ID Description Technology Samples
EGAD00001003989
Longitudinal biopsies from a melanoma patient who initially responded to MEK plus CDK4/6 inhibitor therapy were whole exome sequenced to identify potential resistance mutations. The biopsies included normal tissue, pre-treatment, on-treatment, and several post-resistance timepoints.
Illumina HiSeq 2500 6

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