Complete pathological response of hormone receptor positive invasive breast cancer in a patient with multiple myeloma treated with ixazomib.

Multiple myeloma is a hematological cancer characterized by relapse after treatment and poor prognosis. Ixazomib, a second-generation protease inhibitor, is one of the most recently available treatments for relapsed or refractory multiple myeloma, while it has also shown good potential as antitumoral agent in preclinical solid tumor models such as breast cancer cell lines. Here we report the case of a 68-year-old female with multiple myeloma and an incidental cT1b (9 mm) hormone receptor positive breast cancer lesion that showed a complete pathological response to a three-month combination therapy with Ixazomib, bendamustine and dexamethasone and no signs of disease relapse during the later follow-up.