Abstract B080: PKM2 activation modulates metabolism and enhances immune response in solid tumor models

Abstract Pyruvate kinase functions as the key enzyme in the final step of glycolysis. Cancer cells largely utilize the M2 isoform of pyruvate kinase (PKM2) due to the ability of PKM2 to be allosterically regulated between fully active (tetramer) and less active (dimer) forms of the enzyme. This dynamic regulation is associated with metabolic reprogramming of cancer cells creating a balance between energy needs and anabolic cellular requirements to support cell growth and division. Furthermore, the allosteric regulation creates an opportunity to design a small molecule activator to reverse the metabolic reprogramming favoring cancer growth and immune evasion. TP-1454 is a novel PKM2 activator with low nanomolar PKM2 activation in biochemical assays (AC50 = 10 nM) and in A549 epithelial lung carcinoma cells (AC50 < 20 nM). TP-1454 potently suppresses A549 cell viability (IC50 = 19 nM) and inhibits the tumor growth (60%) under serine auxotrophy conditions both in vitro and in vivo. PKM2 also plays a critical role in the regulation of the adaptive metabolism required to mount an innate immune response. We hypothesized that PKM2 activation may reverse the immune-suppressive microenvironment often observed in many cancers in part by decreasing tumor lactate levels and favoring glucose utilization by immune cells over cancer cells. To test this hypothesis, we explored the combination of TP-1454 with immunotherapy in both immune-suppressive and immune-permissive mouse syngeneic tumors. TP-1454 combination with α-PD1 and α-CTLA4 resulted in tumor regression in the MC38 syngeneic mouse colorectal cancer model with no adverse toxicity or effects on body weights. TP-1454 combination with α-PD1, α-CTLA4 or triple combination with α-PD1 and α-CTLA4 resulted in tumor growth inhibition (TGI) of 76%, 96% and 99% respectively, in the MC38 model. We observed increased levels of glucose and decreased levels of glucose 6-phosphate, phosphoglycerate, phosphoenolpyruvate and lactate in TP-1454 treated compared to vehicle treated MC38 tumors. Kaplan Meier survival analysis revealed 90% and 100% survival for TP-1454 combination with α-CTLA-4 or triple combination with α-PD1 and α-CTLA4 respectively, a vast improvement over the 10% survival of the vehicle group. TP-1454 or α-PD1 alone demonstrated <10% TGI in a CT26 colorectal syngeneic model but synergized in combination resulting in a 68% TGI. Potential downstream biomarkers, including metabolism, immune gene alterations and immune phenotyping are currently under evaluation using LC-MS/MS, NanoString and flow cytometry. These preclinical studies strongly suggest the potential novel therapeutic activity of TP-1454 in cancer models through metabolism and tumor microenvironment modulation. The immune-modulatory and metabolic alterations by TP-1454 offer a unique mechanism to potentially activate the immune response in cancer patients when combined with immunotherapy. Citation Format: Satya Pathi, Peter Peterson, Ryan Mangelson, Ethika Tyagi, Jason M. Foulks, Clifford J. Whatcott, David J. Bearss, Steven L. Warner. PKM2 activation modulates metabolism and enhances immune response in solid tumor models [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr B080. doi:10.1158/1535-7163.TARG-19-B080