566P - Impact of weekly irinotecan’s cycles during preoperative chemoradiotherpy in locally advanced rectal cancer: A post-hoc analysis of the CinClare study

Background

The CinClare phase III study (NCT02605265) demonstrated that the addition of irinotecan to capecitabine in combination with radiotherapy significantly increased the pathologic complete response(pCR) rate in locally advanced rectal cancer (LARC). However, it was not well tolerated among some patients, who failed to complete their planned weekly irinotecan chemotherapy. This study is a post-hoc analysis of the CinClare study designed to assess the impact of irinotecan chemotherapy completion in preoperative chemoradiotherapy on efficacy, toxicity, and long-term survival.

Methods

Patients were categorized into three groups based on the cycles of weekly irinotecan they actually received in the CinClare study. Group A received only capecitabine, while Group B and C actually received 1-3 or 4-5 cycles of weekly irinotecan during the course of chemoradiotherapy, respectively. Tumor response, toxicity, and long-term survival were compared among the three groups.

Results

A total of 356 patients were included in the analysis. The pCR rates were 17.4%, 20.8%, and 38.4% in Groups A, B, and C, respectively (P < 0.001). Grade 3-4 adverse events were 6.2%,52.8%,32.0% respectively. The 5-year DFS and OS rates in Groups A, B, and C were 70.6% vs. 76.9% vs. 78.1% and 76.1% vs. 80.0% vs. 84.2%, respectively.

Conclusions

The administration of 4-5 cycles of weekly irinotecan in preoperative chemoradiotherapy was significantly associated with better tumor response and showed a trend toward beneficial DFS and OS in patients with LARC.

Clinical trial identification

NCT02605265.

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.