Orthotopic Human Metastatic Uveal Melanoma Xenograft Mouse Models: Applications for Understanding the Pathophysiology and Therapeutic Management of Metastatic Uveal Melanoma

A rat-based preclinical platform facilitating transcatheter hepatic arterial infusion in immunodeficient rats with liver xenografts of patient-derived pancreatic ductal adenocarcinoma

Liver metastases from pancreatic ductal adenocarcinoma (PDAC) are highly fatal. A rat-based patient-derived tumor xenograft (PDX) model is available for transcatheter therapy. This study aimed to create an immunodeficient rat model with liver xenografts of patient-derived primary PDAC and evaluate efficacy of hepatic arterial infusion chemotherapy with cisplatin in this model. Three patient-derived PDACs were transplanted into the livers of 21 rats each (totally, 63 rats), randomly assigned into hepatic arterial infusion, systemic venous infusion, and control groups (n = 7 each) four weeks post-implantation. Computed tomography evaluated tumor volumes before and four weeks after treatment. Post-euthanasia, resected tumor specimens underwent histopathological examination. A liver-implanted PDAC PDX rat model was established in all 63 rats, with first CT identifying all tumors. Four weeks post-treatment, arterial infusion groups exhibited significantly smaller tumor volumes than controls for all three tumors on second CT. Xenograft tumors histologically maintained adenocarcinoma features compared to original patient tumors. Ki67 expression was significantly lower in arterial infusion groups than in the other two for the three tumors, indicating reduced tumor growth in PDX rats. A liver-implanted PDAC PDX rat model was established as a rat-based preclinical platform. Arterial cisplatin infusion chemotherapy represents a potential therapy for PDAC liver metastasis.

IGF1R Inhibition Enhances the Therapeutic Effects of Gq/11 Inhibition in Metastatic Uveal Melanoma Progression

Uveal melanoma (UM) is the most common intraocular tumor in adults, and up to 50% of patients develop metastatic disease, which remains uncurable. Because patients with metastatic UM have an average survival of less than 1 year after diagnosis, there is an urgent need to develop new treatment strategies. Although activating mutations in Gαq or Gα11 proteins are major drivers of pathogenesis, the therapeutic intervention of downstream Gαq/11 targets has been unsuccessful in treating UM, possibly due to alternative signaling pathways and/or resistance mechanisms. Activation of the insulin-like growth factor 1 (IGF1) signaling pathway promotes cell growth, metastasis, and drug resistance in many types of cancers, including UM, where expression of the IGF1 receptor (IGF1R) correlates with a poor prognosis. In this article, we show that direct inhibition of Gαq/11 by the cyclic depsipeptide YM-254890 in combination with inhibition of IGF1R by linsitinib cooperatively inhibits downstream signaling and proliferation of UM cells. We further demonstrate that a 2-week combination treatment of 0.3 to 0.4 mg/kg of YM-254890 administered by intraperitoneal injection and 25 to 40 mg/kg linsitinib administered by oral gavage effectively inhibits the growth of metastatic UM tumors in immunodeficient NOD scid gamma (NSG) mice and identifies the IGF1 pathway as a potential resistance mechanism in response to Gαq/11 inhibition in UM. These data suggest that the combination of Gαq/11 and IGF1R inhibition provides a promising therapeutic strategy to treat metastatic UM.

Evaluation of the Therapeutic Potential of Histone Deacetylase 6 Inhibitors for Primary and Metastatic Uveal Melanoma

Patients diagnosed with metastatic uveal melanoma (MUM) have a poor survival prognosis. Unfortunately for this rare disease, there is no known cure and suitable therapeutic options are limited. HDAC6 inhibitors (HDAC6i) are currently in clinical trials for other cancers and show potential beneficial effects against tumor cell survival in vitro and in vivo. In MUM cells, HDAC6i show an anti-proliferative effect in vitro and in preclinical xenograft models. The use of HDAC6 inhibitors as a treatment option for MUM should be explored further. Therefore, this review discusses (1) what is known about HDAC6i in MUM and (2) whether HDAC6 inhibitors offer a potential therapeutic option for MUM.