# Precision Oncology Guided by Genomic Profiling in Breast Cancer: Real-World Data from a Molecular Tumor Board

## TL;DR

This study shows that genomic profiling and molecular tumor boards help provide personalized treatments for advanced breast cancer patients with limited options.

## Contribution

The study provides real-world evidence of the clinical utility of molecular tumor boards in advanced breast cancer treatment decisions.

## Key findings

- 72.3% of reviewed patients received at least one treatment recommendation from the molecular tumor board.
- 60.3% of patients with a treatment recommendation received targeted therapy matched to their genetic profile.
- Approximately 45.7% of patients receiving matched therapy experienced clinical benefit.

## Abstract

Precision oncology involves tailoring cancer treatment to a tumor’s molecular profile. In patients with advanced breast cancer, who have exhausted standard-of-care treatments, tumor samples are increasingly tested for traditional predictive biomarkers (e.g., hormone receptors and HER2 amplifications). In this study, we performed genetic profiling in 103 breast cancer patients using an NGS assay covering 324 cancer-relevant genes. The results were discussed in our multidisciplinary molecular tumor board. More than two-thirds of patients were provided with a systemic anti-cancer treatment recommendation. Approximately 60% of patients with a treatment recommendation received a targeted therapy matched to the genetic profile, of whom around 45% benefitted clinically. This study contributes to the real-world evidence supporting the role of molecular tumor boards in providing personalized treatment to breast cancer patients with otherwise limited treatment options.

Background/Objectives: Next-generation-sequencing-based genomic profiling (GP) of advanced breast cancer (BC) has been increasingly integrated into clinical practice. The growing number of biomarker-based therapies in BC increasingly complicates treatment decisions. As a result, molecular tumor boards (MTBs) have become pivotal. However, real-world data on the utility of MTBs in advanced BC remain limited. This study evaluates the translation of molecular findings in BC patients into MTB recommendations and examines their implementation and outcomes in real-world clinical practice. Methods: This retrospective, single-center study included 103 BC patients who received GP between January 2018 and December 2023. Patients were discussed at the weekly multidisciplinary MTB of our institution. Data retrieved included patient characteristics, GP results, and MTB recommendations, which were consecutively matched with treatment outcomes, namely the proportion of patients receiving an MTB treatment recommendation, proportion of patients receiving molecularly matched targeted therapy (MTT), and best treatment response. Results: The MTB reviewed 94 patients and provided 155 recommendations to 68 patients (72.3%), including systemic anti-cancer treatment (n = 123), clinical study participation (n = 4), genetic counseling (n = 12), and additional molecular testing (n = 16) recommendations. Treatment recommendations were provided to 63 patients (67%), of whom 38 (60.3%) received MTT. Of the 35 patients eligible for response assessment, 16 (45.7%) demonstrated clinical benefit: three achieved a complete response, six a partial response, and ten a stable disease > 6 months. Conclusions: GP and MTBs expand biomarker-matched treatment options to BC patients beyond the standard of care. Around half of the patients who receive MTT experience a clinical benefit. The standardization of procedures, the development of multi-biomarker-based prediction, and the enhancement in MTT delivery to patients are key challenges, which should be addressed in future initiatives.