Proton pump inhibitors decrease efficacy of palbociclib in patients with metastatic breast.

OBJECTIVES: The objective of this investigation was to assess the impact of concurrent proton pump inhibitors (PPIs) on progression-free survival (PFS) in patients with hormone receptor-positive and HER2-negative metastatic breast cancer (mBC) who received palbociclib as first-line or successives therapy. MATERIALS AND METHODS: A retrospective observational study was conducted, enrolling patients diagnosed with estrogen receptor-positive, human epidermal growth factor receptor 2-negative mBC, and eligible for palbociclib treatment. Patients were categorized as "concurrent PPIs" if they received PPIs for at least two-thirds of the palbociclib therapy duration, and as "no concurrent PPIs" if they did not receive PPIs during the course of palbociclib treatment. RESULTS: A total of 165 patients were included in the study. Among first-line patients treated with palbociclib, those using concurrent PPIs exhibited a PFS of 8.88 months, while patients using palbociclib without concurrent PPIs had a PFS of 67.81 months (p < 0.0001). In second-line or subsequent treatments, patients on palbociclib with concurrent PPIs had a PFS of 7.46 months, whereas those using palbociclib without concurrent PPIs had a PFS of 17.29 months (p = 0.122). CONCLUSION: This study demonstrates that the concurrent use of PPIs in mBC patients receiving palbociclib negatively affects PFS, particularly in the first-line setting. Nevertheless, further investigation is warranted to explore the impact of PPIs on cycle-dependent kinase 4/6 inhibitors.

Subacute cutaneous lupus erythematosus following ribociclib therapy for metastatic breast cancer.

INTRODUCTION: Drug-induced subacute cutaneous lupus erythematosus (DI-SCLE) has been associated with drugs with different mechanisms of action, including anti-hypertensives, tumour necrosis factor-α inhibitors and even some chemotherapy medicines. In the last years, a few reports have been described in patients treated with cyclin-dependent kinase (CDK) 4/6 inhibitors, palbociclib and abemaciclib. CASE REPORT: Here, we describe a case of DI-SCLE in association with ribociclib and exemestane in a woman diagnosed with metastatic breast cancer. MANAGEMENT AND OUTCOME: Topical mometasone was prescribed for two weeks with complete resolution of lesions, also abemaciclib was substituted for ribociclib, and the patient had stable disease with no relapse of DI-SCLE. DISCUSSION: To our knowledge, this is the first report of ribociclib-induced SCLE but based on the DI-SCLE reported cases associated others CDK4/6 inhibitors, the role of this family of drugs in dermatopathology must be further investigated.