CDK11 inhibition encounters a toxicity barrier in mouse cancer models
A peer-reviewed preclinical study found that blocking the cancer dependency CDK11 also harms normal tissues. Genetically engineered mice helped attribute much of the toxicity to inhibition of the intended target. At tolerated doses, tested inhibitors had limited antitumour activity. The result exposes a therapeutic-window problem in these experiments rather than establishing clinical effectiveness or ruling out every future strategy.
Science··Midday
A cancer dependency also supports normal tissues
Linda Julian and colleagues investigated CDK11, an enzyme involved in processing RNA, the molecules that carry genetic instructions. Their peer-reviewed preclinical study combined cancer cells, breast-cancer organoids and mouse models. Inhibition interfered with RNA splicing and genes involved in DNA repair. Cells with the loss of one copy of chromosome region 1p36 were particularly sensitive, a candidate vulnerability that has yet to become a validated patient-selection test.[1]
Resistant mice separated target effects from other toxicity
The experimental inhibitor MEL-495R can be given orally. To study its effects, the researchers engineered a drug-resistant form of CDK11 in mice. Comparing these animals with ordinary mice attributed substantial widespread toxicity to inhibition of CDK11 itself. Dosing at the tolerated maximum left inadequate target engagement in tumours and normal tissues. A chemically different inhibitor also showed limited tumour-growth control at a safe dose.[1]
Two genes complicate genetic screening
In humans, CDK11A and CDK11B can each supply enough enzyme function for cell survival. Disrupting only one gene can therefore miss the dependency. The researchers used binding measurements, RNA sequencing and genetic rescue to examine target selectivity. Tumour-specific delivery or activation remains a research direction; the study supplies no human efficacy trial and does not settle whether all future CDK11 strategies will share this dose limitation.[1]
