A Protein Engine May Flag Which Breast Cancers Resist a Common Targeted Therapy
Researchers in Australia studied a protein called CDK1 [1]. They found its activity may show which breast cancers resist a common drug [1].
The study looked at a common breast cancer type [1]. That type is fuelled by the hormone estrogen [1].
Key facts
Many patients with this cancer get drugs called CDK4/6 inhibitors [1]. They take those drugs with hormone therapy [1]. The drugs stop cancer cells from growing [1].
The drugs do not work for all patients [2]. In advanced cancer, they stop working for most patients in time [2].
CDK1 is in the same protein family as CDK4 and CDK6 [1]. Those proteins control when cells divide [1]. CDK1 is needed for the last step, when a cell splits in two [1].
How the signal was found
Liz Caldon led part of the work at Garvan [2]. She said doctors need a clear signal in the tumour itself [2]. That signal should show who will gain most from the drugs [2].
Caldon likened CDK1 to an engine [1]. The engine must start for a cell to divide [1]. Some cancer cells bypass the drugs, but they still need CDK1 to divide [1].
The team made a new lab model to track CDK1 [2]. It used a sensor that lights up when CDK1 is active [2]. With that model, they saw CDK1 rise as tumours grew more invasive [2].
The team also studied more than 400 patient biopsy samples [1]. In those samples, CDK1 rose as cancer grew more aggressive [1]. Higher CDK1 was linked to worse outcomes [1].
What resistance looks like
The team then used past trial data [2]. In tumours that did not respond, CDK1 genes stayed switched on [2]. The genes for its partner proteins stayed on too [2].
Lab cells grown with a CDK4/6 drug for around 10 months became resistant [1]. Those cells had also restarted their CDK1 engine [1].
In the lab model, tumours that kept growing had higher CDK1 activity [2]. Sarah Alexandrou was the first author of the study [1]. She said CDK1 kept showing up as a red flag [1]. It showed up in early cancer, in advanced cancer, and in cancer that beat treatment [1].
What happens next
The team said more tests are needed first [2]. Those tests should use larger groups of treated patients [2]. If those tests pass, doctors may one day use CDK1 to plan care [2].
The work could also lead to new drugs that target CDK1 [2]. Paul Timpson was a co-senior author [1]. He said no CDK1 drug exists yet [1]. He said that does not mean one will never exist [1].
For now, the goal is simple [2]. Doctors want to match each patient with the drug most likely to help them [2].
Sources
Verified: 2026-11-01
Disclosure: This article was drafted with AI assistance and reviewed by a human editor. Facts reflect sources available on the verified date; developing stories may have new details — check the cited sources for updates.