A heavily pre-treated adenocarcinoma patient with EGFR exon 20 insertion mutation responded to pembrolizumab plus nab-paclitaxel/bevacizumab: a case report.

Non-small cell lung cancer (NSCLC) patients harboring epidermal growth factor receptor (EGFR) exon 20 insertions are often associated with poor clinical outcomes due to low response rate to EGFR tyrosine kinase inhibitors. Although recent studies have demonstrated that several novel small molecule compounds could selectively inhibit these mutations, there are still some patients who cannot benefit from them. Another potential therapeutic approach is the use of immune checkpoint inhibitors. Growing evidence suggests that patients harboring EGFR mutations show low efficacy with the use of immunotherapy. However, according to the different immunogenicity of different EGFR mutations, the role of immunotherapy in EGFRex20ins NSCLCs needs further confirmation. Herein we report a case of a 39-year-old woman with NSCLC harboring EGFRex20ins who was diagnosed as postoperative recurrence of lung cancer. She failed with oral poziotinib, then underwent four cycles of systemic chemotherapy with pemetrexed plus carboplatin and bevacizumab. CT scan after chemotherapy showed the metastatic tumors increased in size. The patient then received osimertinib plus cetuximab. CT evaluation performed one month after treatment revealed the enlargement of bilateral lung metastasis. Pembrolizumab plus nab-paclitaxel/bevacizumab was given every three weeks afterwards. Significant shrinkage in multiple metastatic tumors was observed through CT, resulting in a partial response and a progression-free survival of more than 5.0 months. This case highlighted that the use of pembrolizumab in combination with nab-paclitaxel/bevacizumab could help in the management of the uncommon EGFRex20ins in heavily pretreated patients.