Studies on the Safety and Efficacy of Pyrotinib in the Treatment of HER2-Positive Advanced Solid Tumors Excluding Breast Cancer

Background: Human epidermal growth factor receptor 2 (HER2) is a member of the ErbB family and is a key proto-oncogene in solid tumors. This pilot study investigated the safety and efficacy of pyrotinib in HER2-positive non-breast advanced solid tumors. Patients and Methods: Twenty-five patients with HER2-positive advanced solid tumors excluding breast cancer were enrolled to receive pyrotinib-based therapy. The primary end point was progression-free survival (PFS). Results: The median PFS and overall survival (OS) were 3.5 months (95% CI: 2.2-5.0 months) and 9.6 months (95% CI: 4.4-9.9 months), respectively. Ten patients with lung cancer and 9 patients with gastric cancer had a median PFS of 2.5 months (95% CI: 0.97-6.53 months) and 2.9 months (95% CI: 1.50-7.17 months), respectively. The median OS was 9.9 months (95% CI: 4.4-9.9 months) in patients with lung cancer and 5.9 months (95% CI: 4.0-9.6 months) in patients with gastric cancer. No statistical significance of a median OS was observed, nonetheless, patients receiving > 3 lines had a numerically lower median OS than those receiving <= 3 lines of treatment (9.9 vs 5.1 months, P = 0.706). All 23 patients were available for efficacy evaluation. The objective response rate (ORR) was 52.17% and disease control rate (DCR) was 91.3%. The ORR for lung cancer was 44.4% and for gastric cancer was 50%. In addition, the DCR for lung cancer was 77.8% and for stomach cancer was 100%. Moreover, patients receiving <= 3 lines of treatment had a numerically higher DCR than those receiving >3 lines of treatment (94.1% vs 83.3%, P = 0.462). The most common treatment-related adverse events (TRAEs) were diarrhea (92%), but only 5 (20%) patients reported grade 3 diarrhea which could be well controlled. Conclusion: Pyrotinib-based therapy demonstrates promising efficacy for HER2-positive advanced solid tumors excluding breast cancer and toxicities could be well controlled. The study is a pilot study motivating larger studies to elucidate the safety and efficacy of pyrotinib in non-breast solid tumors.