532P - G-CSF secondary prophylaxis in patients (pts) with metastatic colorectal cancer (mCRC) treated with trifluridine/tipiracil (FTD/TPI): The GERCOR LONGBOARD study

Background

FTD/TPI has demonstrated its effectiveness in pts with mCRC resistant to standard treatments, alone or in combination with bevacizumab. Hematological toxicity is the main adverse effect of FTD/TPI, with a rate of grade ≥3 neutropenia in approximately 40% of pts, including 4% with febrile neutropenia. LONGBOARD is a non-randomized multicenter prospective cohort designed to evaluate the effectiveness of secondary prophylaxis with G-CSF (SP-G-CSF) in cases of grade ≥3 neutropenia.

Methods

Pts received FTD/TPI monotherapy (35 mg/m² twice daily for 5 days a week for 2 consecutive weeks, a 28-day cycle) with primary prophylaxis with G-CSF. The inclusion and exclusion criteria were those of the pivotal study. If grade ≥3 neutropenia was observed, pts were included in the interventional study with SP-G-CSF (given daily from the 14^th through the 18^th day), without FTD/TPI dose reduction. The primary endpoint was the rate of pts free from dose reduction or cycles postponement >7 days at 6 months (RFRP-6m). 53 pts had to be included in the interventional study in order to rule out, with a one-stage Fleming design, a RFRP-6m of 50% if a RFRP-6m occurred in 70% (one sided type-I error rate of 0.025 and power of 85%). 234 pts were expected in the prospective cohort.

Results

From May 2020 to March 2023, 176 pts were included in the cohort, with 74 in the interventional study. The RFRP-6m was of 91.9% (95% CI 83.2-97); 5 pts experienced delayed cycles >7 days, and 1 had dose reduction. LONGBOARD achieved its primary objective. RFRP-6m rates were 92.5% for pts <70 years and 91.2% for those ≥70 years. Among the interventional study pts, 88% experienced grade ≥3 neutropenia within the first two cycles. The median follow-up was 23.7 months (95% CI 20-25.5). Median overall survival, progression-free survival and ECOG PS deterioration-free survival were 12.3, 3.6, and 10.2 months, respectively, for those with grade ≥3 neutropenia, compared to 5.6, 1.7, and 4.0 months for those without.

Conclusions

SP-G-CSF prophylaxis proves effective in maintaining FTD/TPI dose intensity. The occurrence of grade ≥3 neutropenia seems to be associated with FTD/TPI efficacy.

Clinical trial identification

NCT04166604.

Editorial acknowledgement

Editorial assistance was provided by Magdalena Benetkiewicz, with funding from Gercor.

Legal entity responsible for the study

Gercor.

Funding

Gercor, Servier.

Disclosure

All authors have declared no conflicts of interest.