What happened, in summary

A 34-year-old woman who had never smoked was diagnosed with invasive mucinous lung adenocarcinoma after right lower lobectomy in December 2016. The tumor was classified as pT4N2M0. It did not express PD-L1 and had a low tumor mutation burden. She completed 4 cycles of adjuvant cisplatin and pemetrexed.

Nine months after surgery, biopsy confirmed relapse in both lungs. Whole-transcriptome sequencing identified an SDC4-NRG1 fusion. Afatinib began at 40 mg daily in January 2018 and produced a partial response within 6 weeks. Progression appeared after 5 months when the drug level was low. Increasing the dose to 50 mg produced another partial response that lasted until December 2018.

She later entered a phase I trial and had stable disease for 6 months before slow progression. A short afatinib rechallenge did not help after rapid lung progression. Paclitaxel and bevacizumab started in November 2019 and were ongoing at the February 2020 follow-up.