# Dynamic changes in tumor profiling reveal intra- and inter-tumoral heterogeneity focused on an uncharacterized HER2 mutation: a case report of a young breast cancer patient

## TL;DR

A young breast cancer patient's tumor changes over time, showing how detailed profiling can help find better treatments when standard options fail.

## Contribution

The case highlights how dynamic tumor profiling can reveal evolving heterogeneity and guide novel therapeutic strategies.

## Key findings

- Comprehensive profiling showed ongoing tumor evolution in a metastatic breast cancer patient.
- Dynamic changes in tumor profiling identified potential new therapeutic strategies.
- The case demonstrates the value of profiling beyond standard clinical guidelines.

## Abstract

Despite multiple recent advances in systemic therapy for metastatic breast cancer, cases which display suboptimal response to guideline-driven treatment are frequently seen in the clinic. Effective options for such patients are limited, particularly in later line of therapy, and selection of optimal treatment options is essentially empirical and based largely on considerations of previous regimens received. Comprehensive cancer profiling includes detection of genetic alterations in tissue and circulating tumor DNA (ctDNA), immunohistochemistry (IHC) from re-biopsied metastatic disease, circulating tumor cells (CTCs), gene expression analysis and pharmacogenomics. The advent of this methodology and application to metastatic breast cancer, facilitates a more scientifically informed approach to identification of optimal systemic therapy approaches independent of the restrictions implied by clinical guidelines. Here we describe a case of metastatic breast cancer where consecutive comprehensive tumor profiling reveals ongoing tumor evolution, guiding the identification of novel effective therapeutic strategies.