Panitumumab in combination with irinotecan plus S-1 (IRIS) as second-line therapy for metastatic colorectal cancer

Background Irinotecan plus S-1 (IRIS) is the only oral fluoropyrimidine-based regimen reported to be non-inferior to FOLFIRI and widely used in clinical practice for metastatic colorectal cancer (mCRC) patients. However, the combination of IRIS plus an anti-EGFR agent has not been evaluated previously. This study aimed to investigate the feasibility and efficacy of IRIS with panitumumab as second-line therapy for wild-type KRAS mCRC.
Methods Main inclusion criteria were patients with wild-type KRAS mCRC refractory to one prior chemotherapy regimen for mCRC, ECOG PS 0-2, and age ≥ 20 years. Patients received panitumumab (6mg/kg) and irinotecan (100mg/m2) on days 1 and 15 and S-1 (40-60 mg according to body surface area) twice daily for 2 weeks, repeated every 4 weeks. The primary endpoint was the feasibility of the therapy. The secondary endpoints were response rate (RR), progression-free survival (PFS), and overall survival (OS).
Results A total of 36 patients received protocol treatment in eight centers. Of these, 23 patients (63.9%) completed protocol treatment, demonstrating achievement of the primary endpoint. The most frequent grade 3/4 toxicities were diarrhea (16.7%), acne-like rash (13.9%), and neutropenia (11.1%). The overall RR was 33.3% (12/36). Of these 4 five underwent conversion surgery. Median PFS and OS were 9.5 months (95% CI 3.5-15.4 months) and 20.1 months (95% CI 16.7-23.2 months), respectively.
Conclusion IRIS plus panitumumab has an acceptable toxicity profile and a promising efficacy in patients with previously treated wild-type KRAS mCRC. Accordingly, this regimen can be an additional treatment option for second-line chemotherapy in wild-type KRAS mCRC.

内容要旨・審査要旨・論文本文の公開:
内容要旨・審査要旨 : LID201701051002.pdf
論文本文 : k2997_fulltext.pdf
著者の申請により要約(2017-01-05公開)に替えて論文全文を公開(2019-04-23)
本論文は, 著者Toshi Takaokaの学位論文として提出され, 学位審査・授与の対象となっている。

The final publication is available at link.springer.com.