AIM: To evaluate the anti-tumour activity and toxicological effects of Orthosiphon stamineus extract formulation (ID: C5EOSEW5050ESA trademarked as Nuva-staticTM), and gemcitabine combination on pancreatic xenograft model.

METHODS: Mice were randomly divided into six groups of 6 mice each (n = 6) and given different treatments for 28 d. The study design consisted of a 2 x 3 factorial treatment structure, with gemcitabine (yes/no) by oral (at 1200 and 400 mg/kg per day). Human pancreatic cancer cells were injected subcutaneously into the flanks of athymic nude mice. C5EOSEW5050ESA (200 or 400 mg/kg per day) was administered orally, while gemcitabine (10 mg/kg per 3 d) was given intraperitoneally either alone or in combination treatment. Histopathological analyses of vital organs, tumour tissues, and incidence of lethality were analysed. Analyses of tumour necrosis and proliferation were determined by haematoxylin-eosin staining and immunohistochemistry for Ki-67, respectively.

RESULTS: No signs of toxicity or damage to vital organs were observed in all treatment groups compared to the untreated group. C5EOSEW5050ESA at 200 mg/kg and gemcitabine combination had no additive antitumor effects compared to a single treatment. Remarkably, a comparably greater response in a reduction in tumour growth, Ki-67 protein expression, and necrosis was demonstrated by 400 mg/kg of C5EOSEW5050ESA and gemcitabine combination than that of the individual agents.