Phase I clinical and pharmacokinetic study of S-1 plus oral leucovorin in patients with metastatic colorectal cancer

A multicenter, phase I/II trial of biweekly S-1, leucovorin, oxaliplatin and gemcitabine in metastatic pancreatic adenocarcinoma-TCOG T1211 study

BACKGROUND

This phase I/II study evaluated the feasibility and efficacy of S-1, leucovorin, oxaliplatin and gemcitabine (SLOG), a triplet regimen, for treating patients with metastatic pancreatic ductal adenocarcinoma (PDAC).

METHODS

Patients with chemo-naive, metastatic PDAC were eligible to receive fixed-rate infusion (10 mg/m²/min) of gemcitabine of 800 mg/m² followed by oxaliplatin of 85 mg/m² on day 1 plus oral S-1 and leucovorin (20 mg/m²) twice daily from days 1 to 7 in a 2-week cycle. The dose of S-1 would be escalated from 20, 30, 35 to 40 mg/m2 in a 3 + 3 designed phase I part to determine the maximum tolerated dose (MTD) for phase II study, in which the primary end-point was objective response rate (ORR). The recommended dose of S-1 was from phase I. This trial is registered at ClinicalTrials.gov: NCT01415713.

RESULTS

Seventy-three patients were enrolled. In the phase I study (n = 19), the MTD of S-1 was 35 mg/m² twice daily. Of 54 patients in phase II, the ORR was 40.7% (95% confidence interval [CI], 28%-55%). The median progression-free survival and overall survival were 7.6 (95% CI, 5.6-11.0) and 11.4 (95% CI, 8.1-16.3) months, respectively. The most common grade III/IV adverse event was neutropenia (40.7%). Twenty-four percent of patients had SLOG treatment for more than 1 year. The mean relative dose intensities of gemcitabine, oxaliplatin, and S-1 were 92%, 92% and 89%, respectively.

CONCLUSION

Biweekly SLOG is a feasible regimen with promising activity and safety profiles. A randomised study comparing SLOG versus modified folinic acid, fluorouracil, irinotecan, and oxaliplatin (FOLFIRINOX) in advanced PDAC is ongoing (ClinicalTrials.gov: NCT03443492).

TAS-118 (S-1 plus leucovorin) versus S-1 in patients with gemcitabine-refractory advanced pancreatic cancer: a randomised, open-label, phase 3 study (GRAPE trial)

BACKGROUND

In our previous randomised phase 2 study for patients with gemcitabine-refractory advanced pancreatic cancer, S-1 plus leucovorin improved progression-free survival compared with S-1 alone. Here, we evaluated the efficacy of TAS-118 (S-1 plus leucovorin) versus S-1 in overall survival (OS).

PATIENTS AND METHODS

This randomised, open-label, phase 3 study was conducted at 58 centres in Japan and Korea. Patients with metastatic pancreatic cancer that progressed during first-line gemcitabine-based chemotherapy or recurred during or after post-operative gemcitabine-based adjuvant treatment were randomly assigned (1:1) to receive either S-1 (40-60 mg, twice daily for 4 weeks in a 6-week cycle) or TAS-118 (S-1 40-60 mg plus leucovorin 25 mg, twice daily for 1 week in a 2-week cycle). The primary end-point was OS.

RESULTS

A total of 603 patients were randomised, and 300 and 301 patients received TAS-118 and S-1, respectively. There was no difference in OS between groups (median OS for TAS-118 versus S-1, 7.6 months versus 7.9 months; hazard ratio [HR], 0.98 [95% confidence interval (CI), 0.82-1.16]; P = 0.756). Progression-free survival was significantly longer with TAS-118 than S-1 (median, 3.9 months versus 2.8 months; HR, 0.80 [95% CI, 0.67-0.95]; P = 0.009). There were interactions between Japan and Korea (P = 0.004) and between unresectable and recurrent disease (P = 0.025) in OS. Incidence, profile and severity of adverse events were similar between groups.

CONCLUSION

TAS-118 did not improve OS in patients with gemcitabine-refractory advanced pancreatic cancer compared to S-1. Further studies are needed to find patients who have benefit from adding leucovorin to S-1.

Phase II study of S-1 plus leucovorin in patients with metastatic colorectal cancer: Regimen of 1 week on, 1 week off

A phase II study of S‐1 plus leucovorin (LV) given in a 4‐week schedule (2 weeks’ administration followed by 2 weeks’ rest) for patients with untreated metastatic colorectal cancer (mCRC) showed that the combination was effective, but grade 3 toxicities (diarrhea, stomatitis and anorexia) occurred at a relatively high rate. In this phase II study, we evaluated the efficacy and safety of a 2‐week schedule of S‐1 plus LV. Patients with mCRC received oral S‐1 (40–60 mg) and LV (25 mg) twice daily for 1 week, followed by 1 week's rest. Treatment was repeated until disease progression or unacceptable toxicity. The primary endpoint was response rate. The pharmacokinetics of S‐1 and LV in Chinese patients were evaluated on day 1 of the first cycle. Seventy‐three patients were enrolled in Japan and China. Of 71 eligible patients, the response rate was 53.5%, and the disease control rate was 83.1%. Median progression‐free survival and median overall survival were 6.5 and 24.3 months, respectively. The incidences of grade 3 toxicities were diarrhea 8.3%, stomatitis 8.3%, anorexia 2.8% and neutropenia 9.7%. There were no treatment‐related deaths. The pharmacokinetics profiles of S‐1 plus LV in Chinese patients were similar to those in Japanese patients. This 2‐week schedule of S‐1 plus LV showed good efficacy and better tolerability than the 4‐week schedule. This therapy will be the base regimen for mCRC to be added by other cytotoxic or molecular‐targeted drugs. The optimized treatment schedule for S‐1 plus LV was 1 week on and 1 week off.