Optimal Treatment of Hormone Receptor-positive Advanced Breast Cancer Patients With Palbociclib.

BACKGROUND/AIM: Palbociclib was the first cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor approved worldwide. Currently, CDK4/6 inhibitors are strongly recommended for endocrine therapy in the first or second line with hormone receptor-positive advanced breast cancer. It is expected the use of CDK4/6 inhibitor will further increase. Therefore, the aim was to investigate and better understand the use of palbociclib. PATIENTS AND METHODS: We retrospectively analyzed the data of patients with advanced breast cancer who were treated with palbociclib in three hospitals between 2018 and 2022. Clinical data were obtained from the patients' medical electronic records. RESULTS: A total of 143 patients were enrolled. The median age was 66 years (range=33-89), and the majority (90.9%) were postmenopausal patients. In total, median time-to-treatment discontinuation (TTD) (95% confidence interval, CI) was 7 (6-10) months. Median TTD (95% CI) was 13 (7-20) months for the first or second line, and significantly prolonged compared to TTD for the third or later lines with palbociclib (p<0.0001). The importance of front-line use was indicated. Multivariate analyses showed that no visceral metastasis or first or second line therapy influenced the longer TTD. Between patients above or below 70 years of age, older age did not negatively affect TTD, though there were significantly more cases of dose reduction or withdrawal in patients over 70 years old. The variation of adverse events (AEs) among hospitals was very large (9.0%, 31.3%, 4.5%). We found that understanding of AE management was important. CONCLUSION: This study showed that dose reduction or withdrawal of palbociclib had no harmful effects in Japanese patients. Efficacy was also high in older patients. It is important to manage palbociclib administration more safely and appropriately. A combination of dose reduction and withdrawal is key to this therapeutic strategy.

[A Case of Aortitis Caused by Pegfilgrastim Use during Neoadjuvant Chemotherapy for Treating Breast Cancer].

Granulocyte colony-stimulating factor(G-CSF)is useful for preventing febrile neutropenia induced by chemotherapy. Recently, some cases of aortitis have been reported following administration of G-CSF. Here, we present a case of aortitis induced by pegfilgrastim(peg-G)use during neoadjuvant chemotherapy for treating breast cancer. A 61-year-old woman with breast cancer(cT2N1M0, stage ⅡB, triple negative)started neoadjuvant chemotherapy FEC(100). Eleven days after the third course of peg-G administration, the patient developed a fever and general malaise. Blood test results showed an increase in inflammatory markers and severe anemia. The symptoms were not controlled with antibiotics. Blood and urine culture test results were negative. Computed tomography revealed remarkable wall thickening of the aorta. Therefore, we suspected aortitis induced by peg-G. The symptoms rapidly improved with prednisolone therapy. The possibility of aortitis should be considered for those with fever or raised inflammatory markers following the use of G-CSF. Steroids can be used for the treatment of G-CSF-induced aortitis.