Prime, then activate.
A combination-ready mechanism: selective PHD1 inhibition primes latent p53; genotoxic standard-of-care chemotherapy activates it.
Mechanism
PHD1 (EGLN2)
An oxygen-dependent dioxygenase at the convergence of hypoxic signaling, p53, and NF-κB. Selective loss of PHD1 activity primes a p53-dependent death program.
Isoform selectivity
PHD2 is the dominant oxygen sensor governing erythropoiesis; sparing PHD2/PHD3 avoids the HIF-driven systemic toxicity of pan-PHD inhibitors.
Combination logic
EBP-4 primes a latent p53 pool; genotoxic chemotherapy activates it — chemo-potentiation in combination, not standalone cytotoxicity.
The EBP-4 mechanism
PHD1 lets cancer cells adapt to treatment — reprogramming metabolism, remodeling the cell cycle, and driving survival — leading to resistance, invasion, and metastasis. EBP-4 inhibits PHD1 to block that adaptation, so cells remain sensitive and chemotherapy drives apoptosis.
What we have shown
Structure-based design produced a proof-of-mechanism tool compound (EBP-4) with concordant wet-lab evidence of p53-axis engagement and anti-proliferative activity in the microsatellite-stable colorectal cancer line HCT-116.
p53-axis engagement
EBP-4 increased p53 protein (Western blot). By qPCR, EBP-4 increased p53, p21, p16, and p300, while the metabolic gene PDK1 was unchanged — consistent with engagement of the p53/cell-cycle/senescence axis.
Anti-proliferative activity
In HCT-116, EBP-4 suppressed proliferation to an extent comparable to cisplatin at 48 hours (MTT), consistent with on-target activity.
Early tolerability signal
In endothelial cells (HUVEC), EBP-4 suppressed LPS-induced IL-6 — an early tolerability readout consistent with a clean off-target profile.
Computational affinity and selectivity values are docking-derived predictions (AutoDock Vina), pending enzymatic confirmation.