S-1 Plus Leucovorin and Oxaliplatin in Combination with Lentinan as First-line Therapy in Patients with Metastatic Gastric Cancer

Background: Metastatic gastric cancer has a poor prognosis, despite recent therapeutic improvements. The phase 3 SOLAR study confirmed better efficacy of S-1, oxaliplatin, and leucovorin (SOL) than S-1 plus cisplatin in advanced gastric cancer. Lentinan, (1, 3)-glucan purified from Shiitake mushrooms, has been reported to improve the overall survival of cancer patients receiving chemotherapy. We conducted a preliminary study of SOL combined with lentinan during these 4 years. Methods: The clinical study was approved by the ethics committee of Nagoya Memorial Hospital in 2016. After explaining the protocol of this study, patients with recurrent or unresectable gastric cancer were enrolled, if they had the intention to participate. Medical records were retrospectively reviewed to determine the objective response rate (ORR), disease control rate, overall survival, and adverse effects. Results: Twelve patients (age: 59-81 years; sex: 9 men, 3 women) with metastatic gastric cancer (liver: 3, lung: 2, peritoneal: 12, ascites: 9) were treated with SOL in combination with lentinan as the first-line regimen. The cycles ranged from 4 to 15. The ORR and disease control rates were 58.3% (complete response [CR], 1; partial response, 6) and 91.7%, respectively. One patient with CR survived for > 23 months after the initiation of chemotherapy. Concerning adverse events, peripheral neuropathy was the most common event observed in all patients. However, there were no severe side effects, such as febrile neutropenia and diarrhea. Conclusions: SOL combined with lentinan can be a promising option for the treatment of far advanced metastatic gastric cancer.