Mirvetuximab after anaphylaxis to Paclitaxel: A case report.

Introduction: Patients with platinum resistant epithelial ovarian cancer have limited treatment options which are further limited by hypersensitivity reactions to first line medications such as paclitaxel. Paclitaxel is a taxane that inhibits microtubules and has a high incidence of hypersensitivity reactions. Mirvetuximab soravtansine-gynx (MIRV) is a folate receptor alpha (FRα) directed antibody and microtubule inhibitor that is approved for patients with FRα positive platinum resistant recurrent epithelial ovarian cancer. Both medications are microtubule-targeting agents with similar binding sites, therefore a theoretical risk of cross reactivity between paclitaxel and MIRV may exist. Additionally, phase II clinical trial, SORAYA, did not include data on patients with prior hypersensitivity to paclitaxel. Case: This is the case of a 33-year-old female with recurrent stage IIIC epithelial ovarian cancer with a history of severe anaphylaxis to paclitaxel. She was deemed eligible for MIRV after progression on multiple regimens, but MIRV was given with caution given her severe reaction history. With proper pre-treatment and monitoring, she was treated with MIRV without a reaction. Discussion: It is suspected that most paclitaxel reactions are due to the cremophor solvent rather than paclitaxel itself; however, cross reactivity with docetaxel which is suspended in a polysorbate solution can also occur. Therefore, there is no clear way to determine the risk of cross reactivity between paclitaxel and similar medications. MIRV is also suspended in polysorbate and has a similar mechanism to taxanes, therefore it was unknown if a patient with a prior grade 5 reaction to paclitaxel would also have a reaction to MIRV. Though this is one case, patients with a history of severe hypersensitivity to paclitaxel and meet the criteria for MIRV could be treated with MIRV with careful monitoring.