Association of PI3K Pathway Mutations with Early Positron-Emission Tomography/CT Imaging Response after Radioembolization for Breast Cancer Liver Metastases: Results of a Single-Center Retrospective Pilot Study
Metastatic breast cancer remains a leading cause of cancer death in women and predictors of response to hepatic metastases treated by radioembolization have not been well established.
The authors of this retrospective review sought to describe the response and survival after radioembolization with a focus on pathways affecting radiation sensitivity. They performed a retrospective review of 31 patients who had undergone radioembolization for metastatic invasive ductal carcinoma to the liver. No patient underwent external radiation to the liver or previous transarterial therapy and all but 2 patients had multifocal liver disease. In addition, all patients had received at least 3 lines of systemic therapy prior to radioembolization. Twenty-four patients underwent genetic profiling before radioembolization, with tumor tissue specimens obtained from various sites. Twenty-two patients were treated with resin spheres and 9 were treated with glass spheres with 14 patients undergoing treatment of both hepatic lobes and the remaining patients receiving unilobar or segmental treatments. Imaging response was assessed on PET/CT imaging with the changes in SUVmax evaluated. Among the 26 patients with PET/CT imaging before and after radioembolization, 18 had complete or partial imaging response and 8 did not respond. Genetic profiling was available in 24 patients with 21 patients having both genetic profiling and imaging available. Of these 21 patients, 15 had a response (complete or partial) and 6 did not respond. Radiographic response was found to be significantly associated with PI3K mutations but not MAPK/ERK or TP53 mutations or HER2 receptor status; only 5 of 11 of PI3K wild-type patients (45%) had an imaging response, but all 10 with PI3K mutations showed a response. Furthermore, complete or partial response by PET/CT at 2– 4 months was associated with significantly longer median survival (967 d) compared with patients without imaging response (291 d).
Figure 2. Kaplan–Meier survival analysis of all patients in the cohort demonstrates a median survival of 10.9 months after radioembolization.
The researchers found that P13K pathway mutations are associated with early imaging response after radioembolization of metastatic breast cancer to the liver and that imaging response is associated with prolonged survival. While a relatively small sample size was studied, this study adds to our knowledge of genomic profiling as it relates to radioembolization outcomes. The ultimate goal is to optimize patient selection for our therapies and this work represents important progress in that direction.
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Deipolyi, Amy R. et al. Association of PI3K Pathway Mutations with Early Positron-Emission Tomography/CT Imaging Response after Radioembolization for Breast Cancer Liver Metastases: Results of a Single-Center Retrospective Pilot Study. Journal of Vascular and Interventional Radiology, Volume 29, Issue 9, 1226–1235.
Zagum Bhatti, MD
Department of Radiology, Interventional Radiology Division
University of Texas Health Science Center at Houston, Houston, TX