In a patient with de novo stage IV breast carcinoma harboring an RB1 Q395* (nonsense) mutation, would treatment with a CDK4/6 inhibitor be appropriate, or should it be avoided due to likely resistance?

Thank you for bringing up this question. As I outlined below, it makes sense based on the evidence available that CDK4/6 inhibitors are less effective or ineffective in patients with tumors harboring Rb LOF mutations. There is, however, little guidance from clinical trials or guidelines to lead us t...

My understanding of RB mutations is that they are rare and occur with prior exposure to CDK4/6 inhibitors. Therefore, testing with biomarkers (i.e., liquid biopsy) is vital to identify these mutations. Thankfully, these mutations may not routinely influence our therapy as many of us switch therapy t...