Gilles Tapolsky

Targeting 6-Phosphofructo-2-Kinase (PFKFB3) as a Therapeutic Strategy against Cancer

In human cancers, loss of PTEN, stabilization of hypoxia inducible factor-1α, and activation of Ras and AKT converge to increase the activity of a key regulator of glycolysis, 6-phosphofructo-2-kinase (PFKFB3). This enzyme synthesizes fructose 2,6-bisphosphate (F26BP), which is an activator of 6-phosphofructo-1-kinase, a key step of glycolysis. Previously, a weak competitive inhibitor of PFKFB3, 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO), was found to reduce the glucose metabolism and proliferation of cancer cells. We have synthesized 73 derivatives of 3PO and screened each compound for activity against recombinant PFKFB3. One small molecule, 1-(4-pyridinyl)-3-(2-quinolinyl)-2-propen-1-one (PFK15), was selected for further preclinical evaluation of its pharmacokinetic, antimetabolic, and antineoplastic properties in vitro and in vivo. We found that PFK15 causes a rapid induction of apoptosis in transformed cells, has adequate pharmacokinetic properties, suppresses the glucose uptake and growth of Lewis lung carcinomas in syngeneic mice, and yields antitumor effects in three human xenograft models of cancer in athymic mice that are comparable to U.S. Food and Drug Administration–approved chemotherapeutic agents. As a result of this study, a synthetic derivative and formulation of PFK15 has undergone investigational new drug (IND)-enabling toxicology and safety studies. A phase I clinical trial of its efficacy in advanced cancer patients will initiate in 2013 and we anticipate that this new class of antimetabolic agents will yield acceptable therapeutic indices and prove to be synergistic with agents that disrupt neoplastic signaling. Mol Cancer Ther; 12(8); 1461–70. ©2013 AACR.

Discovery of a PFKFB3 inhibitor for phase I trial testing that synergizes with the B-Raf inhibitor vemurafenib

Background In human cancers, loss of PTEN, stabilization of hypoxia inducible factor-1a, and activation of Ras and AKT converge to increase the activity of a regulator of glycolysis, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3). This enzyme synthesizes fructose-2,6-bisphosphate (F2,6BP), which is an activator of 6-phosphofructo1-kinase, a key step of glycolysis that is tightly controlled by multiple metabolic feedback mechanisms. We recently identified the first competitive small molecule inhibitor of PFKFB3, 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO), and have now sought to develop a more potent PFKFB3 inhibitor with improved PK properties for testing in clinical trials. Materials and methods Methods included recombinant PFKFB3 assays, PK studies using mass spectrometry, pre-clinical toxicity and efficacy studies, Western blot analyses for HIF-1a and PFKFB3 in A375 melanoma cells, F2,6BP assessments and flow cytometry for apoptosis. Results

Abstract 557: Taking the sweet out of Th17 cells to potentiate immuno-oncology drugs

The major subsets of T cells that produce IL-17 include adaptive CD4+ Th17 cells and innate γδ T17 cells. IL-17 and both cellular sources are elevated in multiple human cancers and have been found to correlate with decreased patient survival. IL-17 produced by these cells promotes tumor growth by increasing the tumor infiltration and function of myeloid-derived suppressor cells (MDSCs), which in turn stimulate angiogenesis and suppress CD4+ and CD8+ T cell tumor homing and activation. Recently, two independent groups discovered that Th17 cell differentiation requires the transcription factor, hypoxia inducible factor 1α (HIF-1α), which promotes glycolytic enzymes and increases glucose metabolism. An established transcriptional target of HIF-1α and stimulator of glucose metabolism is 6-phosphofructo-2-kinase (PFKFB3) which synthesizes fructose 2,6-bisphosphate (F2,6BP), a potent allosteric activator of the rate-limiting enzyme 6-phosphofructo-1-kinase (PFK-1). In unpublished studies, we have found that human Th17 cells generated ex vivo produce increased PFKFB3 and F2,6BP relative to total T cells. We postulate that Th17 cells may selectively require the activity of PFKFB3 for their differentiation and tumor-promoting functions. We examined the immunomodulatory effects of a first-in-class PFKFB3 inhibitor, (E)-1-(pyridyn-4-yl)-3-(7-(trifluoromethyl)quinolin-2-yl)-prop-2-en-1-one (PFK-158) on Th17 cells in vitro, in B16 melanoma-bearing mice and in cancer patients participating in a phase 1 multi-center clinical trial (clinicaltrials.gov # NCT02044861) and found that PFK-158: (i) suppresses human Th17 cell differentiation in vitro (200 nM); (ii) decreases splenic and tumor-infiltrating Th17 cells, γδ T17 cells and MDSCs, and increases CD4+ and CD8+ T cells in the tumors of B16-F10 melanoma-bearing mice (0.06 mg/gm QD x 3 days); and (iii) decreases peripheral blood Th17 cells, γδ T cells and MDSCs and increases activated effector CD4+ and CD8+ T cells in cancer patients. Furthermore, we observed that homozygous genomic deletion of Pfkfb3 in C57Bl/6 mice (but not in implanted B16 melanoma cells) reduces B16 tumor growth, decreases splenic and tumor-infiltrating Th17 cells, γδ T17 cells and MDSCs, and increases tumor-filtrating CD4+ and CD8+ T cells. Based on these immunological effects, we predicted that PFK-158 would improve the anti-tumor activity of an immune checkpoint inhibitor, anti-CTLA4, in the B16-F10 model - we observed a marked increase in tumor growth inhibition by anti-CTLA4 when combined with PFK-158 in vivo. Taken together, these studies provide the first pre-clinical and clinical rationale for the conduct of phase 1/2 trials to examine the anti-cancer efficacy of PFKFB3 inhibitors in combination with FDA-approved immune checkpoint inhibitors and other immunostimulatory agents such as the GM-CSF-producing oncolytic herpes virus talimogene laherparepvec. Citation Format: Sucheta Telang, Kavitha Yaddanadupi, Gilles Tapolsky, Rebecca Redman, Jason Chesney. Taking the sweet out of Th17 cells to potentiate immuno-oncology drugs. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 557.

Abstract B90: PFK-158 is a first-in-human inhibitor of PFKFB3 that selectively suppresses glucose metabolism of cancer cells and inhibits the immunosuppressive Th17 cells and MDSCs in advanced cancer patients

Background: 6-phosphofructo-2-kinase (PFKFB3) is an enzyme that controls the intracellular concentration of fructose-2,6-bisphosphate which is an allosteric activator of 6-phosphofructo-1-kinase (PFK-1), a key enzyme of glycolysis. PFK-1 is tightly controlled by multiple metabolic feedback mechanisms and dictates the overall rate of glycolytic flux to lactate and the TCA cycle. In human cancers, several oncogenic proteins (e.g. HIF-1α, PTEN, and AKT) converge to increase the expression and activity of PFKFB3, leading to the high glycolytic rates typically observed in cancer cells. In addition to being a promising cancer metabolism target, PFKFB3 is required for the differentiation and tumor-promoting functions of the immunomodulatory Th17 cells and myeloid derived suppressor cells (MDSCs), which are attractive cellular targets to induce tumor immunity and potentially mediate intrinsic resistance to immune checkpoint inhibitors. PFK-158 is a potent selective small molecule inhibitor of PFKFB3 that displays broad anti-tumor activity causing significant growth inhibition in human and syngeneic preclinical models. As resistance mechanisms frequently activate pathways that result in up-regulation of glycolysis and PFKFB3, combination treatments of PFK-158 with cytotoxic and targeted agents have resulted in increased efficacy and tumor regression. Results: PFK-158 is a potent selective small molecule inhibitor of PFKFB3 that displays broad anti-tumor activity and causes significant growth inhibition in multiple human and syngeneic preclinical models. The tolerability and potential clinical benefit of PFK-158 are being investigated in advanced cancer patients with solid malignancies in a Phase 1 dose-escalation, multi-center clinical trial (clinicaltrials.gov # NCT02044861). The final cohort (650 mg/m2) has been open for enrollment and PFK-158 has been well tolerated to date. Secondary end-points have been incorporated to assess peripheral F2,6BP levels and immunosuppressive and effector cells populations. Of the 15 patients evaluable for response assessment at the end of two months of treatment, 6 patients have experienced a clinical benefit associated with PFK-158 administration, including a late stage pancreatic cancer patient that had a 75% reduction in her CA19-9 levels after 1 month, a renal cell carcinoma patient currently in month 9 and an adenocystic carcinoma patient in month 12. In addition, we examined the immunomodulatory effects of PFK-158 on Th17 cells and MDSCs in vitro, in B16 melanoma-bearing mice and in advanced cancer patients and found that PFK-158: (i) suppresses human Th17 cell and MDSC differentiation in vitro; (ii) decreases splenic and tumor-infiltrating Th17 cells, γδ T17 cells and MDSCs, and increases CD4+ and CD8+ T cells in the tumors of B16-F10 melanoma-bearing mice; and (iii) decreases peripheral blood Th17 cells, γδ T17 cells and MDSCs and increases activated effector CD4+ and CD8+ T cells in advanced cancer patients. Interestingly, we are discerning a correlation between the initial level of circulating Th17 cells and clinical responses to PFK-158. Conclusion: PFK-158 is the first-in-human and first-in-class PFKFB3 inhibitor that is currently under clinical development. To date, PFK-158 has been well tolerated and shows signs of clinical activity. In addition to controlling glycolysis, over expression of PFKFB3 in key immunesuppressive cells also leads to an immunomodulatory mechanism of action, suggesting that additional clinical benefit could result from combining PFK-158 with targeted agents as well as with immunotherapeutic agents. Note: This abstract was not presented at the conference. Citation Format: Sucheta Telang, Kavitha Yaddanapudi, Jaspreet Grewal, Rebecca Redman, Siqing Fu, Paula Pohlmann, Devalingam Mahalingam, Michael Kurman, Gilles Tapolsky, Jason Chesney.{Authors}. PFK-158 is a first-in-human inhibitor of PFKFB3 that selectively suppresses glucose metabolism of cancer cells and inhibits the immunosuppressive Th17 cells and MDSCs in advanced cancer patients. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B90.

Therapeutic targeting of PFKFB3 with a novel glycolytic inhibitor PFK158 promotes lipophagy and chemosensitivity in gynecologic cancers: Therapeutic targeting of PFKFB3 with a novel glycolytic inhibitor PFK158 promotes lipophagy and chemosensitivity in gynecologic cancers

Metabolic alterations are increasingly recognized as important novel anti‐cancer targets. Among several regulators of metabolic alterations, fructose 2,6 bisphosphate (F2,6BP) is a critical glycolytic regulator. Inhibition of the active form of PFKFB3ser461 using a novel inhibitor, PFK158 resulted in reduced glucose uptake, ATP production, lactate release as well as induction of apoptosis in gynecologic cancer cells. Moreover, we found that PFK158 synergizes with carboplatin (CBPt) and paclitaxel (PTX) in the chemoresistant cell lines, C13 and HeyA8MDR but not in their chemosensitive counterparts, OV2008 and HeyA8, respectively. We determined that PFK158‐induced autophagic flux leads to lipophagy resulting in the downregulation of cPLA2, a lipid droplet (LD) associated protein. Immunofluorescence and co‐immunoprecipitation revealed colocalization of p62/SQSTM1 with cPLA2 in HeyA8MDR cells uncovering a novel pathway for the breakdown of LDs promoted by PFK158. Interestingly, treating the cells with the autophagic inhibitor bafilomycin A reversed the PFK158‐mediated synergy and lipophagy in chemoresistant cells. Finally, in a highly metastatic PTX‐resistant in vivo ovarian mouse model, a combination of PFK158 with CBPt significantly reduced tumor weight and ascites and reduced LDs in tumor tissue as seen by immunofluorescence and transmission electron microscopy compared to untreated mice. Since the majority of cancer patients will eventually recur and develop chemoresistance, our results suggest that PFK158 in combination with standard chemotherapy may have a direct clinical role in the treatment of recurrent cancer.

Abstract A84: Regulation of 6-phosphofructo-2-kinase (PFKFB3) by estradiol and implications for the treatment of ER+ metastatic breast cancer

Estradiol (E2) administered to estrogen receptor positive (ER+) breast cancer patients stimulates glucose uptake by tumors. This E2-induced metabolic flare is predictive of the clinical effectiveness of anti-estrogens and downstream metabolic regulators of E2 are expected to have utility as targets for the development of anti-breast cancer agents. While the stimulation of glucose metabolism by E2 has been demonstrated, relatively little is known about the precise downstream effectors required for E2 to stimulate glucose metabolism in breast cancer. The family of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatases (PFKFB1-4) control glycolytic flux via their product, fructose-2,6-bisphosphate (F26BP), which activates 6-phosphofructo-1-kinase (PFK-1). We recently demonstrated that PFKFB3 expression is elevated in breast cancer lymph node metastases and that exposure of human MCF-7 and T-47D breast cancer cells to E2 causes a rapid increase in 14 C-glucose uptake and glycolysis that is coincident with an induction of PFKFB3 mRNA (via ER binding to its promoter), protein expression and the intracellular concentration of its product, F26BP. Importantly, we also found that selective inhibition of PFKFB3 expression and activity using siRNA or a PFKFB3 inhibitor, PFK158, markedly reduces the E2-mediated increase in F26BP, 14 C-glucose uptake and glycolysis. In the current study, we sought to determine if co-administration of PFK158, with ICI 182,780 (fulvestrant), would offer a greater anti-tumor effect. In unpublished results, we demonstrated that the combination of the anti-estrogen, fulvestrant, with PFK158 results in greater regressions of MCF-7 xenografts than either drug alone in athymic BALB/C mice. In addition to regulating glucose metabolism, PFKFB3 has been found to be a regulator of the cell cycle via cyclin dependent kinases. We postulated that the combination of PFK158 with the newly FDA-approved CDK4/6 inhibitor palbociclib may result in a synergistic increase in apoptosis. We found that PFK158 markedly increased apoptosis caused by palbociclib in MCF-7 breast cancer cells but not in normal human mammary epithelial cells. Taken together, these data indicate that PFKFB3 inhibitors such as PFK158 may have clinical utility for the treatment of ER+ breast cancers when combined with anti-estrogen agents and/or CDK4/6 inhibitors. Citation Format: Yoannis Imbert-Fernandez, Brian Clem, Gilles Tapolsky, Jason Chesney. Regulation of 6-phosphofructo-2-kinase (PFKFB3) by estradiol and implications for the treatment of ER+ metastatic breast cancer. [abstract]. In: Proceedings of the AACR Special Conference: Metabolism and Cancer; Jun 7-10, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(1_Suppl):Abstract nr A84.

Abstract 56: Suppression of 6-Phosphofructo-2-Kinase (PFKFB3) for the treatment of breast cancer

Glucose uptake by tumors is stimulated by estradiol (E2) administration in estrogen receptor positive (ER+) breast cancer patients. Notably, this E2-induced metabolic flare is predictive of the clinical effectiveness of anti-estrogens and, therefore, downstream metabolic regulators of E2 are expected to have utility as anti-breast cancer agents. Although the stimulation of glucose metabolism by E2 has been demonstrated, relatively little is known about the precise downstream effectors required for E2 to stimulate glucose metabolism in breast cancer. We have demonstrated that the expression of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), a key regulator of the glycolytic flux, is elevated in breast cancer lymph node metastases and that exposure of ER+ human MCF-7 and T-47D breast cancer cells to E2 causes a rapid increase in 14C-glucose uptake and glycolysis that is coincident with an induction of PFKFB3 mRNA (via ER binding to its promoter), protein expression and the intracellular concentration of its product, fructose-2,6-bisphosphate (F26BP). Importantly, we also found that selective inhibition of PFKFB3 expression and activity using siRNA or a PFKFB3 inhibitor, PFK158, markedly reduces the E2-mediated increase in F26BP, 14C-glucose uptake and glycolysis. In the current study, we sought to determine if co-administration of PFK158, with ICI 182,780 (fulvestrant), would offer a greater anti-tumor effect. In unpublished results, we demonstrated that the combination of the anti-estrogen, fulvestrant, with PFK158 results in greater regressions of MCF-7 xenografts than either drug alone in athymic BALB/c mice. In addition to regulating glucose metabolism, PFKFB3 has been found to be a regulator of the cell cycle via cyclin dependent kinases. We postulated that the combination of PFK158 with the newly FDA-approved CDK4/6 inhibitor palbociclib may result in a synergistic decrease in tumor cell growth. We found that exposure of breast cancer cells to palbociclib and PFK158 causes a synergistic increase in cell cycle arrest and apoptotic cell death. In addition, we observed a synergistic decrease in phospho-retinoblastoma protein (Rb), a key downstream target of CDK4/6. Importantly, we found that the combination of PFK158 and palbociclib did not cause an increase in cell cycle arrest or apoptosis in normal human mammary epithelial cells. Taken together, these data indicate that PFKFB3 inhibitors such as PFK158 may have clinical utility for the treatment of ER+ breast cancers when combined with anti-estrogen agents and/or CDK4/6 inhibitors. Citation Format: Yoannis Imbert-Fernandez, Amy Clem, Brian Clem, Gilles Tapolsky, Sucheta Telang, Jason Chesney. Suppression of 6-Phosphofructo-2-Kinase (PFKFB3) for the treatment of breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 56.

Abstract 4478: 6-Phosphofructo-2-Kinase (PFKFB3): At the crossroads of resistance to targeted cancer therapies

Targeted cancer therapies that block the growth and spread of cancer by interfering with specific onco-proteins are limited by signaling mechanisms that drive intrinsic and acquired resistance. In particular, the MAPK and the PI3K/AKT pathways have been found to both reduce response rates to these agents and to mediate the acquisition of resistance via mutations that activate both pathways. For example, two recently approved BRAFV600E inhibitors, vemurafenib and dabrafenib, cause dramatic clinical responses in ∼50% of BRAFV600E + melanoma patients but universally become ineffective within 5-6 months as a result of genetic alterations that activate the MAPK and PI3K-AKT pathways, including amplifications in BRAFV600E, loss of PTEN, and activating mutations in NRAS and KRAS, MEK, AKT1/3, PIK3CA and PIK3CG. Several of these mutated signaling proteins stimulate glucose metabolism, required for survival and proliferation, in part by increasing the expression and activity of 6-phosphofructo-2-kinase (PFKFB3). For example, PFKFB3 transcription is induced by HIF-1α (which is increased by BRAFV600E, RAS and MEK), loss of PTEN, and PFKFB3 activity is stimulated by AKT via phosphorylation of serine 461. We postulated that PFKFB3 is an essential downstream target of targeted cancer therapies and that the multitude of mutations and amplifications in signaling pathways that cause resistance to these agents activate PFKFB3. In new studies, we demonstrate that BRAFV600E, estradiol and epidermal growth factor each regulate PFKFB3 expression in melanoma cells, breast cancer cells and NSCLC cells, respectively. Moreover, we find that simultaneous inhibition of these oncoproteins or their co-ligands (i.e. the estrogen and EGF receptors) and PFKFB3 using a novel PFKFB3 inhibitor currently in a phase 1 trial, PFK-158, causes a synergistic increase in apoptosis and cytotoxicity in vitro, suggesting that PFK-158 can overcome the intrinsic resistance to these agents. We then decided to determine if these significant synergies would translate in vivo by investigating them in the A375 and A2058 melanoma preclinical models, and in the MCF-7 ER-dependent breast model. For instance, we compared the anti-tumor effects in A375 melanoma xenograft-bearing mice of: (i) the BRAFV600E inhibitor vemurafenib; (ii) PFK-158; or (iii) the combination of vemurafenib and PFK-158. Although we observed significant tumor growth inhibition with both monotherapies (>80%), we only observed tumor regression with the combination therapy (>50%). Results in these different models will be presented. Taken together, these data demonstrate that the PFKFB3 inhibitor PFK-158 may be able to universally overcome resistance to targeted cancer therapies. Furthermore, we predict that phase 1/2 trials of PFK-158 in combination with targeted cancer agents will yield improvements in objective response rates as well as improvements in progression-free survival. Citation Format: Sucheta Telang, Julie O9Neal, Yoannis Imbert-Fernandez, Brian Clem, Nadiia Lypova, Gilles H. Tapolsky, John Trent, Jason Chesney. 6-Phosphofructo-2-Kinase (PFKFB3): At the crossroads of resistance to targeted cancer therapies. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4478. doi:10.1158/1538-7445.AM2015-4478

Abstract CT206: PFK-158, first-in-man and first-in-class inhibitor of PFKFB3/ glycolysis: A phase I, dose escalation, multi-center study in patients with advanced solid malignancies

Metabolic alterations in cancer have been recognized as important novel targets, especially glycolysis. Over-expression of HIF-1α, activation of Ras, AKT or PI3K, loss of p53 or PTEN are associated with the development of human cancers and converge on glycolysis by activating PFKFB3, a bifunctional enzyme. This enzyme interconverts fructose-6-phosphate (F6P) to fructose-2,6-bisphosphate (F2,6BP) and F2,6BP is an allosteric activator of 6-phosphofructo-1-kinase (PFK-1), a rate-limiting enzyme and control point in the glycolytic pathway. PFKFB3 is of particular interest since it controls the intracellular concentration of F2,6BP, is required for tumorigenic growth and it has been found to be activated in human cancer cell lines and tumors, to be increased by hypoxic exposure via HIF-1α and by several oncogenes and mutations. PFK-158 is a potent and selective inhibitor of PFKFB3 that is currently being investigated in a phase I study in patients with advanced solid malignancies. PFK-158 is: (i) is a nanomolar inhibitor of recombinant PFKFB3; (ii) inhibits PFKFB3 activity and glycolysis in cancer cells; (ii) is well tolerated in vivo; and (iv) is very effective in multiple preclinical mouse models of human-derived tumors and syngeneic murine models. IND-enabling safety and toxicity studies demonstrated that PFK158 is well tolerated in rats and dogs and supported the initiation of a phase I trial that is now underway. The primary objective of the study is to describe the dose limiting toxicity and to determine either the maximum tolerated dose or biological effective dose of PFK-158 in a “3+3” cohort-based dose escalation design that follows a modified Fibonacci scheme. The pharmacokinetic profile of PFK-158 will also be determined. Multiple secondary endpoints have been incorporated to assess the effects of PFK-158 on peripheral blood mononuclear cell (F6P; F2,6BP; 14C-2-dexoyglucose uptake) and on glucose uptake using FDG-PET imaging. This trial, opened at two US sites, is currently enrolling Cohort 3 (96 mg/m2). Prior cohorts (24 and 48 mg/m2) have been completed without dose-limiting toxicities or drug-related significant adverse events. Of the patients enrolled to date, a patient of Cohort 1 was on study for 6 cycles during which his overall hepatic metastatic tumor burden decreased. In addition, numerous publications demonstrated that over-expression of HIF-1α, activation of Ras, AKT or PI3K, loss of p53 or PTEN converge on glycolysis by activating PFKFB3. Results of preclinical studies show that combination of PFK-158 with targeted agents, which indirectly activate glycolysis, leads to clear therapeutic benefits. In conclusion, PFK158 is the first-in-man and first-in-class PFKFB3 inhibitor to be examined in a phase I trial and may have significant clinical utility either as a monotherapy or when combined with targeted agents. Citation Format: Rebecca Redman, Paula Pohlmann, Michael Kurman, Gilles H. Tapolsky, Jason Chesney. PFK-158, first-in-man and first-in-class inhibitor of PFKFB3/ glycolysis: A phase I, dose escalation, multi-center study in patients with advanced solid malignancies. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT206. doi:10.1158/1538-7445.AM2015-CT206

Abstract 2706: Inhibition of PFKFB3/glycolysis overcomes chemoresistance in ovarian cancers

Metabolic alterations in cancer are increasingly being recognized as important novel targets. Among different regulators of altered metabolism, 6-PhosphoFructo-2-Kinase/Fructose-2,6-Bisphosphatases 3 (PFKFB3) a glycolytic enzyme required for tumorigenic growth, and produces fructose-2,6-bisphosphate (F2,6BP), is recognized as important regulator of glycolysis. We determined that the active form of PFKFB3ser471 was overexpressed in chemo-resistant ovarian cancer (OVCA) cell lines and resistant patient derived xenograft (PDX) models compared to their isogenic chemo-sensitive cell lines and sensitive PDX models. These results suggest that targeting PFKFB3 will have beneficial effects in patients with OVCA. PFK-158 is a potent and selective inhibitor of PFKFB3 that is currently being investigated in a Phase 1 study in patients with advanced solid malignancies. Here we report for the first time, PFK-158 dose-dependently inhibits cell proliferation and colony formation ability in both carboplatin and paclitaxel (PTX) resistant cell lines. PFK-158 markedly suppresses glycolysis by reducing glucose uptake, ATP production, lactate dehydrogenase activity and lactate secretion. Interestingly, both Chou-Talalay synergy analysis and apoptosis assay by annexin V-PI staining showed PFK-158 strongly synergies with both PTX and carboplatin in PTX and cisplatin resistant cell lines respectively. PFK-158 induced apoptosis through a significant increase in caspase-3/7 activation and PARP cleavage. Moreover, in a highly metastatic PTX-resistant in vivo model, combination of PFK-158 with carboplatin and PTX significantly reduced tumor weight, ascites and metastasis compared to untreated and PFK-158, carboplatin or PTX alone treated mice. Since the majority of OVCA patients recur with chemo-resistant disease, our results suggest that PFK-158 in combination with standard chemotherapy may have clinical utility in late stage ovarian cancer patients. Citation Format: Susmita Mondal, Debarshi Roy, Eleftheria Kalogera, Ashwani Khurana, Gilles H. Tapolsky, Sucheta Telang, Jason Chesney, Viji Shridhar. Inhibition of PFKFB3/glycolysis overcomes chemoresistance in ovarian cancers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2706. doi:10.1158/1538-7445.AM2015-2706