183P - Final analysis of phase II clinical study evaluating the safety and effectiveness of neoadjuvant S-1 + oxaliplatin combination therapy for older patients with locally advanced gastric cancer

Background

In Asia, the standard treatment for locally advanced gastric cancer (LAGC) involves gastrectomy with D2 dissection and adjuvant chemotherapy. However, achieving adequate chemotherapy intensity after gastrectomy presents challenges. Previous trials have shown the effectiveness of neoadjuvant chemotherapy (NAC). Nevertheless, limited research has been conducted to explore the feasibility of NAC-SOX for older patients with LAGC. This phase II study (KSCC1801) aimed to assess the safety and efficacy of NAC-SOX in LAGC patients aged ≥ 70 years. Herein, we present the conclusive data analysis of KSCC1801, shedding light on its outcomes.

Methods

Patients received NAC consisting of three cycles of SOX130 (oxaliplatin 130 mg/m2 on day 1, oral S-1 40-60 mg twice daily for two weeks every three weeks), followed by gastrectomy with lymph node dissection. The primary endpoint was the dose intensity (DI) of the treatment. Secondary endpoints included safety, R0 resection rate, pathological response rate (pRR), overall survival, and relapse-free survival.

Results

The study enrolled 26 patients with a median age of 74.5 years. The median DI in the NAC-SOX130 treatment was 97.2% for S-1 and 98.3% for oxaliplatin. NAC was successfully administered to 25 patients (96.2%), among whom 24 (92.3%) underwent gastrectomy with lymphadenectomy. The R0 resection rate was 92.3%, and the pRR (≥ grade 1b) was 62.5%. Major adverse events (≥ grade 3) included neutropenia (20.0%), thrombocytopenia (11.5%), anorexia (11.5%), nausea (7.7%), and hyponatremia (7.7%). Postoperative complications such as abdominal infection, elevated blood amylase, and bacteremia occurred in one patient each. The 1- and 2-year OS rates were 93.3% and 89.7%, respectively. The 1- and 2-year RFS rates were 68.7% and 58.6%, respectively.

Conclusions

NAC-SOX130 proves to be a feasible therapy for older patients aged ≥ 70 years.

Clinical trial identification

jRCTs071180001.

Editorial acknowledgement

Legal entity responsible for the study

KSCC (Kyushu Study group of Clinical Cancer).

Funding

Yakult Honsha.

Disclosure

E. Oki: Financial Interests, Personal, Invited Speaker: Taiho Pharmaceutical Co. Ltd., Ono Pharmaceutical Co. Ltd., Chugai Pharmaceutical Co. Ltd., Bayer, Eli Lilly, Bristol-myers Squibbb, MSD; Financial Interests, Personal and Institutional, Research Grant: Guardant Health. All other authors have declared no conflicts of interest.