Concomitant EGFR Mutations and ALK Rearrangements in Lung Adenocarcinoma Treated With Osimertinib.

Lung cancer is the third most common cancer in addition to being the cancer responsible for the most annual deaths in the United States, comprising 15% of all diagnosed cancers, and 28% of all cancer deaths in 2020. Major advances in survival are because of gene sequencing and the advent of targeted biological therapy. The prevalence of epidermal growth factor receptor (EGFR) mutations coexisting with anaplastic lymphoma kinase (ALK) rearrangements is quite low. However, the clinical relevance and effective treatment of these cancers require further investigation. This case series describes two patients diagnosed with stage IV adenocarcinoma with coexisting EGFR and ALK rearrangements. In Case 1, a 73-year-old male presented with worsening ataxia and headaches. In Case 2, a 64-year-old female presented with worsening dyspnea. Molecular studies revealed ALK gene fusion and the L861Q EGFR mutation in Case 1 and L858R EGFR mutation and ALK gene fusion in Case 2. Both patients received a gamma knife and an EGFR-tyrosine kinase inhibitor (TKI), osimertinib. In one of the cases, following the discovery of new brain metastases, the dose of osimertinib was increased from 80 to 160 mg. The patient passed away nine months after beginning EGFR-TKI treatment, one month after increasing the dose. The second patient experienced a significant interval reduction in the size of enhancing metastasis in both the right frontal and left parietal lobe after four months of EGFR-TKI treatment. The cases of coexisting EGFR mutations and ALK rearrangements are quite rare, and treatment can be challenging. Here, EGFR-TKI had a mixed response among our patients.