Dual and Specific Inhibition of NAMPT and PAK4 By KPT-9274 Decreases Kidney Cancer Growth

Abstract

Kidney cancer (or renal cell carcinoma, RCC) is the sixth most common malignancy in the US and one of the relatively few whose incidence is increasing. Due to the near universal resistance which occurs with the use of current treatment regimens, reprogrammed metabolic pathways are being investigated as potential targets for novel therapies of this disease. Borrowing from studies on other malignancies, we have identified the PAK4 and NAD biosynthetic pathways as being essential for RCC growth. We now show, using the dual PAK4/NAMPT inhibitor KPT-9274, that interference with these signaling pathways results in reduction of G2/M transit as well as induction of apoptosis and decrease in cell invasion and migration in several human RCC cell lines. Mechanistic studies demonstrate that inhibition of the PAK4 pathway by KPT-9274 attenuates nuclear β-catenin as well as the Wnt/β-catenin targets cyclin D1 and c-Myc. Furthermore, NAPRT1 downregulation which we show occurs in all RCC cell lines tested makes this tumor highly dependent on NAMPT for its NAD requirements, such that inhibition of NAMPT by KPT-9274 leads to decreased survival of these rapidly proliferating cells. When KPT-9274 was administered in vivo to a 786-O (VHL-mut) human RCC xenograft model, there was dose-dependent inhibition of tumor growth with no apparent toxicity; KPT-9274 demonstrated the expected on-target effects in this mouse model. KPT-9274 is being evaluated in a phase 1 human clinical trial in solid tumors and lymphomas which will allow this data to be rapidly translated into the clinic for the treatment of RCC.

Anticystogenic activity of a small molecule PAK4 inhibitor may be a novel treatment for autosomal dominant polycystic kidney disease

“…When injected into rats, the compound and its acetylated metabolite were found by LC-MS analysis to be present in plasma and bile but undetectable in urine (unpublished observations). Specificity of inhibition of PAK4 by KPT-9274 was previously demonstrated using a CRISPR PAK4 knock out cell line 9,16 and is demonstrated here by a dose-dependent reduction in phosphorylated PAK4 (pPAK4) and total PAK4 in lysates of both postnatal Pkd1 -null (PN24) and Pkd1 -heterozygous (PH2; control) cells as well as Pkd1 -null versus wild-type (wt) control mouse embryonic kidney (MEK) cells, with a more substantial decrease in Pkd1 -null MEK null cells as compared MEK-wt (Fig. 1b).…”

“…1a) that shows dual inhibition of PAK4 and NAMPT 9,15,17,18 . When injected into rats, the compound and its acetylated metabolite were found by LC-MS analysis to be present in plasma and bile but undetectable in urine (unpublished observations).…”

“…In addition, administration of KPT-9274 reduces cystogenesis both ex vivo and in vivo with the expected on-target effects. Based on our data presented in this report, the minimal toxicity of oral administration of KPT-9274 given either for short or long periods in other animal models 9,16–18 and the fact that KPT-9274 has entered human Phase 1 clinical trials in advanced solid malignancies (NCT02702492), there is strong evidence that this small molecule could be directly evaluated in a clinical trial of ADPKD patients.…”

“…Building on studies in cancer 7–9 , we have identified the PAK/WNT/β-catenin signaling as a potential target for PKD. Overexpression of PAKs influence a broad range of cellular activities with involvement in several oncogenic signaling pathways, including cell proliferation and mitogenesis 9 , hence their evaluation as potential targets for dysregulated proliferative diseases including renal cystic disease.…”

“…Overexpression of PAKs influence a broad range of cellular activities with involvement in several oncogenic signaling pathways, including cell proliferation and mitogenesis 9 , hence their evaluation as potential targets for dysregulated proliferative diseases including renal cystic disease. PAK4, the first of the group II PAKs to be cloned and characterized, is involved with regulating such cyst-promoting events as actin-mediated cell morphology, embryonic development, and cell cycle regulation 10–12 .…”