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Adjuvant S-1 therapy superior to observation in resected biliary tract cancer

Presented by
Dr Masafumi Ikeda, Japan Clinical Oncology Group, Japan
ASCO GI 2022
Phase 3, JCOG1202, ASCOT
Adjuvant S-1 therapy improved the overall survival (OS) of patients with biliary tract cancer (BTC) who underwent resection via surgery. Also, S-1 therapy was well tolerated in this patient population. Therefore, adjuvant S-1 therapy may be considered as standard-of-care in patients with resected BTC in Japan [1].

“In Japan, capecitabine is currently accepted as the standard adjuvant therapy for patients with curatively resected BTC, despite the fact that no significant OS benefit has been demonstrated of this agent in this population,” Dr Masafumi Ikeda (Japan Clinical Oncology Group, Japan) explained. “In addition, a phase 2 trial demonstrated that S-1, an oral fluoropyrimidine derivative, may provide benefits for patients with advanced BTC [2].”

The current phase 3 JCOG1202 ASCOT trial (UMIN000011688) investigated the safety and efficacy of adjuvant S-1 therapy in 440 adult patients with curatively resected BTC. The patients were randomised 1:1 to surgery alone or surgery plus adjuvant S-1 therapy, 40 mg/m2 twice daily, 4 weeks on, 2 weeks off, for 4 cycles. The primary endpoint was OS.

Adjuvant S-1 therapy outperformed observation regarding the 3-year OS rates (77.1% vs 67.6%; HR 0.69; P=0.008). Moreover, subgroup analyses revealed that this effect was consistent across most subgroups. Although the 3-year relapse-free survival rate was higher in patients receiving adjuvant S-1 therapy compared with patients receiving surgery alone (62.4% vs 50.9%), this effect was not significant at the time of the analysis. Dr Ikeda argued that a longer follow-up is needed to see whether a significant result can be reached for this secondary outcome measure.

Adjuvant S-1 therapy was well tolerated. The most common adverse events were related to myelosuppression, gastrointestinal toxicity, or skin toxicity. All grade 3 events occurred in less than 5% of the participants, except for decreased neutrophils, which occurred in 14% of the patients receiving adjuvant S-1 therapy.

“This trial showed that adjuvant S-1 therapy is well tolerated and leads to significantly longer OS times in patients with resected BTC. Therefore, this therapy should be considered as standard therapy in the investigated patient population,” concluded Dr Ikeda.

  1. Ikeda M, et al. Adjuvant S-1 vs. observation in curatively resected biliary tract cancer: a phase 3 trial (JCOG1202:ASCOT). Rapid Abstract Session B, ASCO GI 2022, 20–22 January.
  2. Furuse J, et al. Cancer Chemother Pharmacol. 2008;62:849–855.


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