Should we optimize cytotoxic therapy by dosing to neutropenia? Lessons from TAS-102

Prognostic impact of severe neutropenia in colorectal cancer patients treated with TAS-102 and bevacizumab, addressing immortal-time bias

BACKGROUND

Several studies have reported an association between severe neutropenia and long-term survival in patients treated with trifluridine-tipiracil (TAS-102). Because some of these studies failed to address immortality time bias, however, their findings should be interpreted with caution. Additionally, the association between severe neutropenia and survival in patients receiving TAS-102 in combination with bevacizumab (Bmab) remains unclear.

PATIENTS AND METHODS

We conducted a single-center retrospective cohort study in patients with colorectal cancer who received Bmab + TAS-102. We compared overall survival (OS) between patients who developed grade ≥ 3 neutropenia during the treatment period and those who did not. To account for immortal time bias, we used two approaches, time-varying Cox regression and landmark analysis.

RESULTS

Median OS was 15.3 months [95% CI: 14.1-NA] in patients with grade ≥ 3 neutropenia and 10.0 months [95% CI: 8.1-NA] in those without. In time-varying Cox regression, onset grade ≥ 3 neutropenia was significantly related to longer survival after adjustment for age and modified Glasgow Prognostic Score. Additionally, 30-, 60-, 90-, and 120-day landmark analysis showed that grade ≥ 3 neutropenia was associated with longer survival after adjustment for age and modified Glasgow Prognostic Score, with respective HRs of 0.30 [0.10-0.90], 0.65 [0.30-1.42], 0.39 [0.17-0.90], and 0.41 [0.18-0.95].

CONCLUSION

We identified an association between long-term survival and the development of severe neutropenia during the early cycle of Bmab + TAS-102 using an approach that addressed immortality time bias.

Efficacy and safety of trifluridine/tipiracil plus bevacizumab and trifluridine/tipiracil or regorafenib monotherapy for chemorefractory metastatic colorectal cancer: a retrospective study

Background:

The C-TASK-FORCE phase I/II and Danish randomized phase II trials reported the promising efficacy of trifluridine/tipiracil (TAS102) plus bevacizumab (BEV) in patients with chemorefractory metastatic colorectal cancer (mCRC). However, there had been no direct comparative phase III trial to compare the efficacy between TAS102 plus BEV and standard therapy with either TAS102 or regorafenib monotherapy.

Methods:

We retrospectively reviewed the medical records of patients with mCRC who received TAS102 plus BEV, TAS102 monotherapy, or regorafenib monotherapy after standard chemotherapies during 2013–2019.

Results:

Patients received TAS102 plus BEV (n = 139), TAS102 monotherapy (n = 153), or regorafenib monotherapy (n = 133). With a median follow-up of 25.3 months, median overall survival (OS) was 11.5 months [95% confidence interval (CI), 9.9–13.9] for TAS102 plus BEV, 8.1 months (95% CI, 6.8–9.2) for TAS102 monotherapy, and 6.8 months (95% CI, 5.7–8.5) for regorafenib monotherapy. The hazard ratios were 0.67 (95% CI, 0.51–0.88) for TAS102 plus BEV versus TAS102 monotherapy and 0.71 (95% CI, 0.54–0.94) for TAS102 plus BEV versus regorafenib monotherapy. Median progression-free survival (PFS) was 4.4 months (95% CI, 3.7–5.4) for TAS102 plus BEV, 2.5 months (95% CI, 1.6–2.3) for TAS102 monotherapy, and 2.1 months (95% CI, 1.6–2.3) for regorafenib monotherapy. The hazard ratios were 0.57 (95% CI, 0.45–0.73) for TAS102 plus BEV versus TAS102 monotherapy and 0.44 (95% CI, 0.34–0.58) for TAS102 plus BEV versus regorafenib monotherapy. On multivariate analysis, TAS102 plus BEV was independently correlated with better OS and PFS. No unexpected adverse events were observed in any group.

Conclusion:

Our study shows that OS and PFS are longer in patients treated with TAS102 plus BEV than in those treated with TAS102 or regorafenib monotherapy.