Abstract OT2-01-07: A phase 2 study of abemaciclib plus pembrolizumab for patients with hormone receptor positive (HR+), HER2 negative (HER2-) metastatic breast cancer (MBC)

Targeting DNA Damage Repair for Immune Checkpoint Inhibition: Mechanisms and Potential Clinical Applications

DNA damage repair (DDR) pathways play an essential role in maintaining genomic integrity. DDR dysfunction leads to accumulated DNA damage, predisposition to cancer, and high sensitivity to chemotherapy and radiotherapy. Recent studies have demonstrated that DDR status is associated with response to immune checkpoint inhibitors (ICIs). Among the DDR pathways, mismatch repair is one of the most recognized predictive biomarkers for ICIs. Furthermore, preclinical and early clinical studies suggest the rationale of combining agents targeting the DDR pathways, such as poly (ADP-ribose) polymerase (PARP) inhibitors, cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, and ataxia telangiectasia and rad3-related (ATR) kinase inhibitors, with ICIs. In the present review, we describe the predictive role of DDR pathways in ICIs and summarize the advances in potential combination strategies of novel agents targeting DDR with ICIs for cancer treatment.

Emerging data and future directions for CDK4/6 inhibitor treatment of patients with hormone receptor positive HER2-non-amplified metastatic breast cancer

Cyclin-dependent kinase (CDK4/6) inhibitors in combination with endocrine therapy are currently the optimal first line treatment for hormone receptor (HR) positive, human epidermal growth factor receptor 2 (HER2) non-amplified metastatic breast cancer (MBC). However, not all patients benefit from this treatment and all patients will inevitably progress. Identifying therapeutic strategies in this setting is therefore of immediate clinical importance. We present an overview of the mechanisms of resistance to CDK4/6 inhibitors and review potential biomarkers that may guide therapy selection. We also discuss the use of CDK4/6 inhibitors in the context of non-HR-positive/HER2-non-amplified breast cancer and in combination with therapies other than endocrine therapy.