Thoracic Oncology

Hello Thoracic Pharmacists,

We have had two EGFR-mutant NSCLC patients in the past month develop FGFR3-TACC3 fusions as possible mechanisms of resistance to osimertinib. Thanks to the update in the NCCN Guidelines which lists erdafitinib as a category 2A recommendation for the treatment of patients with metastatic NSCLC and FGFR alterations, we were able to get erdafitinib approved by insurance (one on PA and the second on appeal). One patient is going to start next Tues and the other patient following her baseline eye exam tomorrow. We will be continuing osimertinib 80 mg in both patients and adding erdafitinib 8 mg/d. We will be following phos levels and have partnered with an ophthalmologist for routine eye exams. I have reached out to my institutional colleague in GU oncology and she advised that the hyperphos is real and dose limiting and that nail changes and diarrhea are usually manageable--I am wondering how this will be compounded by the concurrent osimertinib. Does anyone have experience with the combination of osi + erdafitinib that will help me prepare my two patients?

Thanks!

Stefanie Houseknecht, PharmD, BCOP

Clinical Pharmacy Specialist, Thoracic Malignancies

Johns Hopkins Hospital and Bayview Medical Center