Dichloroacetate / PUMA Cancer Research Results

Dichloroacetate — Dichloroacetate, usually administered as sodium dichloroacetate, is a small-molecule metabolic modulator that inhibits pyruvate dehydrogenase kinases and thereby activates the mitochondrial pyruvate dehydrogenase complex. It is formally classified as an investigational metabolic drug and pyruvate dehydrogenase kinase inhibitor. DCA is a synthetic chlorinated acetate historically investigated for congenital mitochondrial and lactic-acidosis disorders; it is not an approved anticancer therapy. Its principal translational limitation is the narrow separation between concentrations that alter tumor metabolism and chronic exposures associated with peripheral neuropathy.

Primary mechanisms (ranked):

1. Inhibition of PDK isoenzymes, especially PDK2, causing ↓ inhibitory PDH phosphorylation and ↑ pyruvate entry into mitochondrial oxidation.
2. Partial reversal of the Warburg phenotype through ↓ lactate-producing glycolytic flux and ↑ mitochondrial oxidative phosphorylation.
3. Remodeling of cancer-cell mitochondrial membrane potential and restoration of intrinsic apoptotic susceptibility.
4. ↑ mitochondrial ROS and oxidative stress in susceptible cancer cells, particularly under hypoxic or treatment-stressed conditions.
5. Attenuation of the HIF-1α–PDK metabolic adaptation to hypoxia, with context-dependent effects on tumor oxygenation and treatment resistance.
6. Radiosensitization and chemosensitization through metabolic reprogramming, increased oxidative stress, altered autophagy and reduced hypoxia-associated resistance.
7. Context-dependent modulation of Kv1.5, intracellular K⁺, NFAT and Ca²⁺-linked apoptotic signaling.

Bioavailability / PK relevance: Oral DCA is systemically bioavailable, but its pharmacokinetics are nonlinear and time-dependent. DCA is metabolized primarily by GSTZ1, while DCA also irreversibly inhibits GSTZ1, producing reduced clearance and progressive drug accumulation during repeated exposure. GSTZ1 genotype, age and treatment duration can substantially alter plasma exposure. Chronic exposure is limited principally by reversible or incompletely reversible peripheral sensory and motor neuropathy; gastrointestinal, hepatic and hematologic adverse effects have also been reported.

In-vitro vs systemic exposure relevance: Many anticancer studies use approximately 1–20 mM DCA, frequently 5–20 mM. Sustained human plasma concentrations at the upper end of this range are generally not achievable without substantial toxicity. Clinical PK data indicate that tolerated concentrations may inhibit constitutive PDK2 but may be inadequate for less-sensitive or highly induced PDK isoforms. Consequently, strong cytotoxicity observed at high millimolar concentrations should not be assumed to translate directly to patients.

Clinical evidence status: Extensive preclinical evidence; several small phase I and phase II human studies; one randomized placebo-controlled phase II adjunct study with cisplatin chemoradiotherapy; no phase III validation and no regulatory approval for cancer. Early trials demonstrate measurable metabolic effects and generally manageable short-term administration, but objective anticancer efficacy remains inconsistent and unproven. A randomized head-and-neck cancer study did not establish a clear survival advantage, while reporting increased low-grade fever and thrombocytopenia. DCA remains an investigational adjunct rather than a standard anticancer treatment.

Dichloroacetate Mechanistic Profile

P: 0–30 min    R: 30 min–3 hr    G: >3 hr