In a patient with metastatic HR+ breast cancer progressing on single agent AI, would you use a different AI with CDK4/6 inhibitor?

I doubt that changing the AI would make a difference - in the EFECT trial, patients progressing or recurring on a nonsteroidal AI had a 3.7 month median TTP on exemestane (JCO 2007) (meaning that many patients had progressed by their first reassessment. The more intriguing question is the potential value of adding the cdk 4/6 inhibitor while continuing the same AI, as opposed to switching to an alternate endocrine agent such as fulvestrant. The TREnd trial, presented at ASCO 2017 (abstract 1002,...

CDK4/6 inhibitors with their manageable toxicity and oral dosage constitute a very important treatment option for breast cancer patients and will continue to gain traction in the treatment of ER –positive breast cancer (currently being evaluated in early stage). However, I do not believe we should be using a different second line AI with CDK4/6 inhibitor in a patient with HR +ve breast cancer who progressed on 1st line single agent AI until more data is available to show the safety and efficac...