549P - Analyses of risk factors for adverse events with palbociclib and the association between adverse events occurrence and survival

Background

Palbociclib is used for treating hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced or metastatic breast cancer. However, the treatment is associated with severe neutropenia and diarrhea, which sometimes causes treatment postponement or discontinuation. Considering that a few published studies reported on the risk factors for these AE and the effect of AE on survival, we investigated them in this multicenter study.

Methods

This study included patients treated with palbociclib at four hospitals in Japan from December 2017 to November 2020. Baseline patient demographic information (including age, body mass index [BMI], and concomitant medications) and laboratory data (including absolute neutrophil count [ANC], hemoglobin [Hb], platelet [PLT], and alanine transaminase [ALT]), neutropenia and diarrhea grades in accordance with CTCAE ver 5.0, PFS, and OS were retrospectively investigated from electronic medical records. Multivariate logistic regression and Cox proportional hazards regression analyses were used to analyze the risk factors for AE and the association between AE occurrence and survival.

Results

This study analyzed 261 patients, and the incidence of grade ≥3 neutropenia was 68.6% and the incidence of grade ≥1 diarrhea was 7.3%. Multivariate logistic regression analysis revealed that BMI of ≤23.2 kg/m² (odds ratio [OR]: 2.29, 95% confidence interval [CI]: 1.14–4.59, P = 0.02), ANC of ≤3,546/mm³ (OR: 9.44, 95% CI: 4.48–19.90, P < 0.001), PLT of ≤25.1 × 10⁴ /mm³ (OR: 2.37, 95% CI: 1.19–4 .69, P = 0.01), and ALT of ≤25 U/L (OR: 3.10, 95% CI: 1.42–6.77, P = 0.005) were independent significant risk factors for severe neutropenia with palbociclib treatment. Moreover, as the number of risk factors increases alongside the incidence of severe neutropenia. The occurrence of neutropenia was not associated with either PFS or OS. Additionally, the study revealed no risk factors associated with the occurrence of grade ≥1 diarrhea. The study revealed that the onset of diarrhea did not affect survival.

Conclusions

It may be preferable to use palbociclib in patients who manifested fewer than the four identified risk factors that affected the occurrence of grade ≥3 neutropenia.

Clinical trial identification

Retrospective observational study.

Editorial acknowledgement

Legal entity responsible for the study

The author.

Funding

Has not received any funding.

Disclosure

H. Ishikawa: Financial Interests, Personal and Institutional, Non remunerated activity, No: Department of Pharmacy, Shizuoka Cancer Center.