Successful Desensitization Treatment with Osimertinib after the Development of Osimertinib-induced Urticaria in a Patient Undergoing Treatment for Non-small Cell Lung Cancer Harboring the EGFR T790M Mutation

A case of successful desensitization treatment with tepotinib after tepotinib-induced rash

Tepotinib is one of the key drugs for MET exon 14-skipping mutation-positive non-small cell lung cancer (NSCLC). The main adverse event of tepotinib treatment is edema. Rash is a rare adverse event, affecting only 0.7% of patients. We report a case of successful desensitization after skin rash caused by tepotinib. A 61-year-old male was treated with tepotinib 500 mg as second-line therapy for NSCLC with MET exon 14-skipping mutation. Treatment was discontinued on day 12 due to grade 3 erythema throughout the body. After improvement of the skin rash, he was started on 250 mg tepotinib with an oral antihistamine and topical steroid. Treatment was discontinued on day 11 due to skin rash exacerbation. One month of treatment-free follow-up showed skin rash improvement but lung carcinoma growth. Tepotinib desensitization therapy was started at a dose of 12.5 mg and gradually increased to 250 mg/day. The patient has since continued tepotinib treatment without skin rashes. Desensitization therapy may be effective for managing skin rash due to tepotinib.

Successful desensitization under antihistamine suppression in a case with urticaria due to osimertinib

Introduction

Osimertinib is an approved therapy for patients with a Thr790met (T790M) mutation diagnosed with non-small cell lung cancer (NSCLC) that progresses during epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) therapy. However, in 7–13% of patients, drug-related side effects lead to discontinuation of osimertinib treatment. In such cases, osimertinib desensitization is a treatment option that can be considered.

Case report

A 59-year-old female patient, who was followed up with the diagnosis of stage 4 NSCLC, was consulted to the allergy clinic because of urticaria. The patient developed urticaria plaques 20 h after the third dose of osimertinib tablet.

Management & outcome

With the diagnosis of osimertinib-induced urticaria, desensitization was planned for the patient. Treatment was started with a dose of 0.1 mg/day osimertinib. The procedure was completed in approximately 50 days, and a dose of 80 mg/day was reached with antihistamine suppression.

Discussion

Here, a successful osimertinib desensitization in a patient with a history of osimertinib-related type 1 allergic reaction is reported. Osimertinib desensitization is a treatment option that should be considered in cases where treatment has to be ceased due to drug-related side effects.