Amblyomin-X, a recombinant protein from A. cajennense salivary glands, triggers apoptosis in murine renal adenocarcinoma cells (Renca) by inhibiting the proteasome and endoplasmic reticulum stress. Our results provide evidences that Amblyomin-X induces tumor cell death in a selective form on an orthotopic kidney tumor model, reducing drastically incidence of lung metastases by the same mechanisms previously demonstrated for its in vitro effect. In addition, image assays using fluorescence-labelled Amblyomin-X, showed that this molecule was indeed detected in the tumor stroma, whereas in healthy animals it was rapidly metabolized and excreted. Taken these findings together, Amblyomin-X can be considered as a potentially anti-RCC drug candidate. Pre-clinical assays are currently under development to determine its toxicity in two animal species (rodent and non-rodent). In the next steps, the involvement of immune response upon Amblyomin-X activity will be investigated and the drug will undergo clinical trials for safety evaluation.