Locoregional Interaction of Ixabepilone (ixempra) After Breast Cancer Radiation

Background: Radiation recall is an acute inflammatory reaction within a previously irradiated field triggered by chemotherapy administration. We observed a series of patients with unexpectedly severe reactions that included radiation recall and delayed healing when patients received the microtubule stabilizer ixabepilone (Ixempra; Bristol-Myers Squibb, Princeton, NJ) after radiation. We therefore decided to evaluate our experience in patients receiving ixabepilone following radiotherapy.

Methods: We performed a retrospective chart review of all patients treated with curative intent in the Department of Radiation Oncology at the MD Anderson Cancer Center from 2008-2011 who received any ixabepilone after completion of external-beam radiation therapy. These patients received adjuvant ixabepilone on one of two protocols, either for locally advanced breast cancer or for metastatic breast cancer. In total, 19 patients were identified and their charts were subsequently reviewed for evidence of ixabepilone-related toxicity.

Results: Of the 19 patients identified who received ixabepilone following radiation therapy, three (15.8%) had unexpectedly serious reactions in the months following radiation therapy. Complications included delayed wound closure and drain placement into the seroma, intense erythema, and delayed wound closure and grade 4 chest wall necrosis requiring latissimus flap and skin grafting. The average number of days between the end of radiation therapy and documentation of reaction was 99.

Conclusions: Ixabepilone chemotherapy may induce radiation recall and delayed wound healing when used shortly after the completion of external-beam radiotherapy. Significant clinical interactions have not been previously reported and merit further evaluation.