SABCS 2024: Camizestrant Shows Promise in Combination with Ribociclib for Advanced Breast Cancer

In an interview with Pharmacy Times®, Richard Baird, MD, PhD, medical oncologist at the Cancer Research UK Cambridge Centre, shared encouraging data on camizestrant, a new class of anti-estrogen therapy that degrades the estrogen receptor rather than just blocking it. The combination of camizestrant and the CDK4/6 inhibitor ribociclib showed promising pharmacokinetic, safety, and efficacy results in a trial of patients with heavily pre-treated advanced ER+, HER2- breast cancer. Baird noted that the data supports further exploration of this combination in both metastatic and earlier settings.

Pharmacy Times

How does camizestrant differ from traditional hormone therapies in treating breast cancer?

Richard Baird, MD, PhD

Camizestrant is one of a new group of drugs that are anti-estrogen therapies, which rather than inhibiting the amount of estrogen in the circulation or antagonizing the receptor, actually aim to degrade plus or minus antagonism the receptor. What we're seeing is some encouraging data for this new class of drugs.

Pharmacy Times

What are the potential benefits of combining camizestrant with ribociclib in advanced breast cancer?

Baird

We presented here the latest results from the SERENA-1 trial, which is testing camizestrant, the oral SERD on its own, but also in combination with a number of different targeted therapies. We presented the latest data here in combination with ribociclib. The potential advantages are an improvement in clinical outcomes, and the potential to use this combination, both in the metastatic and possibly other settings.

Pharmacy Times

What are the key findings from the SERENA-1 Parts K/L trial regarding the safety, efficacy, and tolerability of camizestrant and ribociclib combination therapy?

Baird

In the results we presented here, about 60 patients with ER+, HER2- metastatic breast cancer was treated with camizestrant together with the CDK4/6 inhibitor ribociclib. Half of them, roughly, were treated with 75 mg of camizestrant and 400 mg of ribociclib, and the other half at a higher dose of ribociclib at 600 mg. The main findings really were from a pharmacokinetic standpoint, that actually the exposure we saw with ribociclib was that which we would expect from ribociclib monotherapy. The exposure, interestingly, to camizestrant, when you combine it with ribociclib, is a little bit higher. So the levels we saw would be typical of someone taking camizestrant on its own at 150 mg a day. The safety profile actually, it was a well-tolerated combination with the AEs, adverse events for the combination being what we would expect for either agent alone. We saw quite encouraging efficacy in this relatively small cohorts, with a clinical benefit rate at 24 weeks of just over 50% and an objective response rate of about 17% and that's in quite a heavily pretreated population. Over half of these patients have had prior fulvestrant, and nearly all of them had a prior CDK4/6 inhibitor.