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A Phase II study of S-1 plus oral leucovorin in heavily treated metastatic colorectal cancer patients

Authors Hsu HC, Chou WC, Kuan FC, Lee KD, Rau KM, Huang JS, Yang TS

Received 7 July 2018

Accepted for publication 24 October 2018

Published 21 November 2018 Volume 2018:10 Pages 6061—6070


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 3

Editor who approved publication: Dr Rituraj Purohit

Hung-Chih Hsu,1,2 Wen-Chi Chou,1,2 Feng-Che Kuan,2,3 Kuan-Der Lee,4 Kun-Ming Rau,2,5 Jen-Seng Huang,2,6 Tsai-Sheng Yang1,2

1Division of Hematology and Oncology, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Guishan, Taoyuan, Taiwan, Republic of China; 2College of Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China; 3Division of Hematology and Oncology, Chang Gung Memorial Hospital, Chiayi, Puzi City, Taiwan, Republic of China; 4Division of Hematology and Oncology, Department of Medicine, Taipei Medical University Hospital and Taipei Medical University, Taipei, Taiwan, Republic of China; 5Division of Hematology and Oncology, Chang Gung Memorial Hospital, Kaohsiung, Taiwan, Republic of China; 6Division of Hematology and Oncology, Chang Gung Memorial Hospital, Keelung, Taiwan, Republic of China

Purpose: Fewer treatment options are available for refractory metastatic colorectal cancer (mCRC). In early trials, S-1 monotherapy was effective for mCRC patients after chemotherapy failure and its combination with oral leucovorin therapy offers promising results in untreated mCRC. Hence, we conduct a Phase II trial to assess the efficacy of S-1 plus oral leucovorin (SL) in refractory mCRC that progressed after multiple prior standard therapies.
Methods: In this open-label, single-arm study, we enrolled the refractory mCRC patients who received fluoropyrimidine, oxaliplatin, and irinotecan treatment and at least one targeted therapy previously. The doses of SL were 40–60 and 30 mg twice daily separately. They were administered for 7 days in a 2-week cycle. Treatment was continued until disease progression.
Results: Of the 41 enrolled patients, 36 patients were evaluable with 61.1% disease control rate. The median progression-free survival and overall survival were 2.55 and 7.63 months, respectively. Regression change in tumor size stayed 10%–20% in five patients (13.9%) through 18 weeks after treatment, and two patients continued free from tumor progression at 30 and 42 weeks. Compared with moderate heavily pretreated mCRC patient subgroup (≤4 prior regimens), the severe heavily pretreated subgroup (≥5 prior regimens) showed similar disease control rate and survival benefit. Grade 3 or higher toxicities were documented only in 11 patients (26.8%).
Conclusion: SL shows potential as a salvage regimen in refractory mCRC patients especially in the severe heavily pretreated setting and is well tolerated in these patients.

Keywords: refractory metastatic colorectal cancer, S-1, oral leucovorin, Phase II, survival and safety

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