CDK4/6 inhibition as maintenance and combination therapy for high grade serous ovarian cancer

Area of Science:

• Oncology
• Cell Biology
• Pharmacology

Background:

• High-grade serous ovarian cancer (HGSOC) has a high relapse rate and poor survival, necessitating novel therapeutic strategies.
• Targeted CDK4/6 inhibitors are emerging as a promising maintenance therapy for various cancers.
• The CDK4/6 pathway is frequently altered in ovarian cancer, suggesting potential therapeutic vulnerability.

Purpose of the Study:

• To evaluate the efficacy of Ribociclib, a CDK4/6 inhibitor, in preclinical models of HGSOC.
• To assess Ribociclib's activity as a monotherapy, in combination with chemotherapy, and as maintenance therapy.
• To investigate the underlying mechanisms of Ribociclib's action in HGSOC.

Main Methods:

• Treatment of multiple HGSOC cell lines and *in vivo* tumor models with Ribociclib.
• Assessment of cellular proliferation, senescence markers, and cell cycle regulation.
• Combination therapy studies with cisplatin, followed by maintenance therapy evaluation.
• Analysis of key cell cycle checkpoints, including ATR and CHK1 phosphorylation.

Main Results:

• Ribociclib significantly restricted proliferation in HGSOC cell lines, inducing a pseudo-senescent phenotype.
• Concurrent Ribociclib and cisplatin therapy followed by Ribociclib maintenance demonstrated synergistic effects.
• Ribociclib exhibited activity against both platinum-sensitive and platinum-resistant HGSOC models.
• Evidence suggests Ribociclib may impact the G2/M checkpoint by dephosphorylating ATR and CHK1.

Conclusions:

• Ribociclib demonstrates significant preclinical efficacy in HGSOC models.
• The combination of Ribociclib with cisplatin and its use as maintenance therapy warrants further investigation.
• Ribociclib's potential to overcome platinum resistance in ovarian cancer is supported by these findings.
• This study provides a strong rationale for clinical trials evaluating Ribociclib in ovarian cancer treatment.