A Phase I Trial of Oxaliplatin, Irinotecan, and S-1 Combination Therapy (OX-IRIS) as Chemotherapy for Unresectable Pancreatic Cancer (HGCSG 1403)

A phase-I study of second-line S-IROX for unresectable pancreatic cancer after gemcitabine plus nab-paclitaxel failure

Gemcitabine plus nab-paclitaxel (GnP) and FOLFIRINOX are widely used as first-line regimens for unresectable pancreatic cancer (PC). When GnP therapy is selected, considering patient age or condition, second-line FOLFIRINOX is sometimes difficult to administer owing to its toxicity. This study aimed to determine the recommended dose (RD) of S-IROX (S-1, oxaliplatin, and irinotecan combination) regimens in patients with unresectable PC after first-line GnP failure. This phase-I study used the "3 + 3" dose-escalation design with two dose levels. Patients who failed first-line GnP therapy for unresectable PC were enrolled. Oxaliplatin and irinotecan were administered on day 1, and S-1 was administered orally twice daily on days 1-7, followed by 7 days of rest. The primary endpoints were dose-limiting toxicities (DLTs) and determination of RD. The secondary endpoint was the evaluation of potential antitumor activity. Nine patients received the second-line S-IROX regimen. In level-0 (S-1, 80 mg/m2; oxaliplatin, 85 mg/m2; and irinotecan, 120 mg/m2), no patient experienced DLT; however, one patient experienced grade 3 neutropenia. At level-1 (irinotecan increased to 150 mg/m2), one of six patients experienced DLTs, including G3 diarrhea. The RD was confirmed at the level-1 dose. The response rate, disease control rate, median progression-free survival, and median overall survival were 33.3%, 77.8%, 172 (range:77-422) days, and 414 (101-685) days, respectively. One patient underwent surgery after the second-line S-IROX therapy. Second-line S-IROX treatment was deemed acceptable. The RD was set at level-1 dose (S-1, 80 mg/m2; oxaliplatin, 85 mg/m2; and irinotecan, 150 mg/m2).

Efficacy and safety of SOXIRI versus mFOLFIRINOX in advanced pancreatic cancer

Background

Modified fluorouracil/leucovorin/irinotecan/oxaliplatin (FOLFIRINOX) regimen (mFOLFIRINOX), comprised of fluorouracil, leucovorin, irinotecan and oxaliplatin, is the first-line standard chemotherapy in patients with advanced pancreatic cancer. The S-1/oxaliplatin/irinotecan (SOXIRI) regimen has also been studied recently under similar conditions. This study compared its efficacy and safety.

Methods

All cases of locally advanced or metastatic pancreatic cancer treated with the SOXIRI or mFOLFIRINOX regimen in Sun Yat-sen University Cancer Centre from July 2012 to June 2021 were reviewed retrospectively. The data of patients who satisfied the inclusion criteria were compared between two cohorts, including overall survival (OS), progression-free survival (PFS), objective response rate, disease control rate and safety.

Results

A total of 198 patients were enrolled in the study, including 102 patients treated with SOXIRI and 96 patients treated with mFOLFIRINOX. There was no significant difference in OS [12.1 months versus 11.2 months, hazard ratio (HR) = 1.04, p = 0.81] or PFS (6.5 months versus 6.8 months, HR = 0.99, p = 0.96) between patients treated with SOXIRI and mFOLFIRINOX. In the subgroup analysis, patients with slightly elevated baseline total bilirubin (TBIL) or underweight patients before chemotherapy were more likely to have a longer OS or PFS from SOXIRI than from mFOLFIRINOX. In addition, the carbohydrate antigen (CA)19-9 decline was a good predictor for the efficacy and prognosis of both chemotherapy regimens. All grade adverse events were parallel in all kinds of toxicities except that anaemia was more common in the SOXIRI group than in the mFOLFIRINOX group (41.4% versus 24%, p = 0.03). The occurrence of any grade 3 to 4 toxicity was similar in the two groups.

Conclusions

For locally advanced or metastatic pancreatic cancer patients, the SOXIRI regimen had similar efficacy and controllable safety compared with the mFOLFIRINOX regimen.

Safety and efficacy of S-IROX (S-1, irinotecan and oxaliplatin combination therapy) in patients with advanced pancreatic cancer: A multicenter phase 1b dose-escalation and dose-expansion clinical trial

BACKGROUND

This phase 1b trial evaluated the toxicity and efficacy of S-1, irinotecan, and oxaliplatin combination therapy (S-IROX) as first-line chemotherapy in patients with advanced pancreatic cancer (APC).

METHODS

Patients aged 20-75 years with APC and an Eastern Cooperative Oncology Group performance status of 0 or 1 were eligible to receive escalating doses of S-1 (60 or 80 mg m²·day) on days 1-7, fixed doses of oxaliplatin (85 mg/m²) biweekly, and escalating doses of irinotecan (150, 165, or 180 mg/m²) once every 2 weeks. In the dose-escalation cohort, a 3 + 3 design was used to determine the maximum-tolerated dose (MTD) and explore the recommended dose (RD). A dose-expansion cohort was added to further evaluate the safety and efficacy of the combination. This trial was registered at UMIN-CTR (UMIN000012054).

RESULTS

Approximately 47 patients were enrolled, of whom 45 were eligible for the analysis. The MTD was not determined, but the RD was determined to be dose level 1 based on a review of data from each level. Among the 45 patients, the ORR was 51.1% [95% confidence interval (CI), 35.8-66.3%]. The median progression-free survival and median overall survival was 6.9 months (95% CI, 5.1-8.8 months) and 15.8 months (95% CI, 9.8-20.8 months), respectively. Common adverse events included neutropenia, elevated liver enzyme levels, diarrhoea, and nausea.

CONCLUSIONS

The S-IROX regimen showed promising efficacy with manageable toxicities in Japanese patients with APC. A randomised phase 2/3 trial comparing S-IROX, mFOLFIRINOX, and gemcitabine plus nab-paclitaxel is currently ongoing (jRCTs031190009).

Study protocol of the HGCSG1803: a phase II multicentre, non-randomised, single-arm, prospective trial of combination chemotherapy with oxaliplatin, irinotecan and S-1 (OX-IRIS) as first-line treatment for metastatic or relapsed pancreatic cancer

INTRODUCTION

Combination chemotherapy with oxaliplatin, irinotecan, fluorouracil and leucovorin (FOLFIRINOX) has become one of the standard treatments for metastatic pancreatic cancer. However, the use of FOLFIRINOX requires prolonged infusion. Therefore, we planned to develop a new combination chemotherapy regimen with oxaliplatin, irinotecan and S-1 (OX-IRIS) for advanced pancreatic cancer. In the phase Ⅰ study that was conducted previously, the safety and recommended dose of OX-IRIS were assessed. In this study, we will evaluate the efficacy and safety of OX-IRIS.

METHODS AND ANALYSIS

The HGCSG1803 study started as a multicentre, non-randomised, single-arm, prospective, phase II study in December 2019. Eligible subjects were patients with untreated metastatic or relapsed pancreatic cancer. OX-IRIS is administered as follows: 30 min infusion of antiemetic; 2-hour infusion of oxaliplatin (65 mg/m2); 1.5-hour infusion of irinotecan (100 mg/m2) on day 1 and 15 of each 4-week cycle; and oral S-1 (40 mg/m2) twice daily from after dinner on day one to after breakfast on day 15, followed by a 14-day rest, to be repeated every 2 weeks until disease progression, unacceptable toxicity or patient refusal. The primary endpoint is response rate. The secondary endpoints are overall and progression-free survival, safety and dose for each drug. Using a binomial test, a sample size of 40 patients was set with a threshold value of 10% and expected value of 30%. Registration of 40 cases is planned from 18 institutions in Japan.

ETHICS AND DISSEMINATION

All the procedures will be conducted in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Declaration of Helsinki of 1964 and its later versions. All the patients will receive written information about the trial and will provide informed consent before enrolment. This trial was approved by the Hokkaido University Certified Review Board (approval No: 018-037).

TRIAL REGISTRATION NUMBER

jRCTs011190008.