Continuous dosing of AUM001 with cyclical gemcitabine/nab-paclitaxel to maintain the tumor growth kinetics in KPC xenograft model.

Abstract

e15112 Background: PDAC is a highly desmoplastic and aggressive disease with limited therapeutic options and poor 5-year survival outcome. Gemcitabine (GEM) plus nab-paclitaxel (nPTX) is widely used as a first line treatment for PDAC but advancement for greater improvement on efficacy is still warranted. Dysregulated mRNA translation of pro-tumorigenic genes has contributed to the proliferative and metastatic nature of PDAC. Targeting oncogenic mRNA translation via MNK-coupled phosphorylation of eIF4E could serve as a target for inhibition to synergize chemotherapy. AUM001 is a novel MNK1/MNK2 inhibitor undergoing clinical trials in various solid tumors. We hypothesize that combination of AUM001 with GEM-nPTX would have synergistic effect in modulating the tumor growth kinetics and maintaining the tumor in a stable state. Methods: PDAC KPC cells were subcutaneously implanted into BL6 mice and randomized into five treatment groups once tumor volumes of 60-80mm3 were reached. Saline (control), GEM-nPTX were administered intraperitoneally on days 1, 4 and 8 while AUM001 was given orally on a daily basis for 8 days. The combination of GEM-nPTX and AUM001 were administered at similar doses and frequency. AUM001 was given for another 3 weeks in the continuous dosing group. Body weight and tumor volume were measured thrice weekly. Immunohistochemistry staining was performed on FFPE sections for Ki67, angiogenesis and stromal markers. Apoptosis was analyzed by Annexin V-propidium iodide flow cytometric assay. P < 0.05 was considered as statistically significant. Results: GEM-nPTX and AUM001 (GPA) or GEM-nPTX (GP) alone resulted in approximately 30% reduction in relative tumor volume. The continuous dosing of AUM001 (GPAc) after the cessation of chemotherapy showed a marked 55% decline in relative tumor volume ( P= 0.0079) compared to GPA. The phosphorylation of EIF4E (target of MNK1/2) and Myc expression were significantly inhibited in GPAc vs GPA groups at end of observation (EOO) (P < 0.05). VEGFA expression at EOO was found to be suppressed in GPAc compared to GPA group ( P= 0.0159) with no difference in MVD ( P> 0.05). Greater fraction of apoptotic cells was detected in GPAc at EOO ( P= 0.055) than GPA ( P> 0.999) when referenced to GP group. Conclusions: This study demonstrated that continuous dosing of AUM001 with cyclical GEM-nPTX is well-tolerated and confers good anti-tumor effect. Pharmacodynamic analysis also suggests that AUM001 may potentiate the reduction in pro-tumorigenic protein expression. This is the first study depicting the continuous dosing of AUM001 after cessation of chemotherapy could help to maintain the tumor state, facilitating its possible use in clinics as maintenance therapy in PDAC.