Oncology / Solid Tumor (in CDK2 inhibitor context)

**What it means:** Oncology is the branch of medicine that deals with cancer. "Solid tumors" are cancers that form actual lumps or masses (as opposed to blood cancers like leukemia). Breast, ovarian, gastric, and other organ-based cancers are "solid tumors." **Why CDK2 inhibitors are tested for solid tumors:** Cancer cells divide uncontrollably. CDK2 is a key driver of cell division, so inhibiting it can slow or stop cancer growth. The Phase 1a/b trials for AL-605 and AVZO-021 are testing CDK2 inhibitors in solid tumor patients because that's where CDK2 is most overactive in cancer. The MHS connection is that the **same protein (CDK2)** that's overactive in cancer microglia is also overactive in brain microglia in MHS — so a drug that works for one might work for the other.