Palbociclib Induced Neutropenia; Risk Factors and Treatment Outcome in Metastatic Breast Cancer Patients

Palbociclib Induced Neutropenia; Risk Factors and Treatment Outcome in Metastatic Breast Cancer Patients

Aim of the study to assess the neutropenia induced by Palbociclib in patient receiving Palbociclib in combination with hormonal treatment as first-line therapy in metastatic hormone receptor- positive HER2 negative breast cancer. To evaluate the risk factors for occurrence of neutropenia and treatment outcome as 2 years PFS and OS.

Palbociclib is an orally active cyclin-dependent kinase (CDK) and is considered the standard treatment for hormone receptor (HR)-positive, (HER) negative metastatic breast cancer.

The PALOMA studies' showed improvement in progression-free survival (PFS) compared to endocrine therapy alone but a non-significant trend towards improved overall survival (OS).

MONALEESA and MONARCH suggest significantly improved OS with the addition of CDK inhibition.

Neutropenia is considered the dose-limiting and most frequent adverse effect of CDK inhibitors resulting in frequent dose reductions and treatment interruptions that are potentially associated with a lack of efficiency. Grade III/IV neutropenia rates were 62-66% in the PALOMA studies.

Some studies investigated the risk factors for the development of palbociclib-induced neutropenia. One concluded that no concomitant use of statins and high BMI were identified as significant predictors for the development of palbociclib-induced neutropenia. and another study also concluded that low baseline ANC, WBC, PLT, and BSA were associated with early grade III/IV neutropenia.

Regarding treatment outcome, two Phase Two clinical trials concluded that the treatment-related neutropenia in the first two cycles was significantly and independently associated with prolonged PFS, suggesting that neutropenia may be a useful pharmacodynamic marker to guide individualised palbociclib dosing.

However, another study concluded that limited dose modification may lead to longer PFS, without increasing toxicity, than the conventional dose scheme.

A study of variable risk factors and treatment outcomes for palbociclib-induced neutropenia will be useful for careful monitoring leading to adapted therapy.

Inclusion Criteria:

• Histological pathological confirmation of primary breast cancer or metastatic disease.
• Hormonal receptor-positive, HER2 negative.
• Metastatic breast cancer at presentation (Den novo) or recurrent.
• Patients did not receive any previous systemic therapy for metastatic disease.
• Performance status (ECOG) 0-2.

Exclusion Criteria:

• Patient with co-morbidity
• Pregnant and breast lactating women