Stage IV ERBB2-Mutated Lung Cancer With Extensive Bone Metastases

What happened, in summary

A 61-year-old woman with a 10-pack-year smoking history was diagnosed with Stage IV lung carcinoma after presenting with extensive bone disease, including a destructive lesion in the right femur, together with a mass in the left lower lung. The femur required urgent surgical stabilization, and pathology confirmed metastatic carcinoma from a lung primary. Molecular testing identified an ERBB2 exon 20 insertion. She received carboplatin, paclitaxel, bevacizumab and an investigational anti-MET treatment. The lung lesions initially decreased slightly, followed by slow progression over the next 14 months. She then received vinorelbine plus trastuzumab for 7 months. A later combination of docetaxel plus trastuzumab, together with focal palliative radiation for bone metastases, produced stable disease for about 5 more months. After another progression, she was treated with pemetrexed. The cancer continued to progress, and she transitioned to hospice care. Additional molecular testing at progression identified a PIK3CA R425L alteration that was considered a possible mechanism of resistance to prior HER2-directed treatment.