Effect of Timing, Dose and Interstitial Versus Nanoparticle Delivery of Tumor Necrosis Factor Alpha in Combinatorial Adjuvant Cryosurgery Treatment of ELT-3 Uterine Fibroid Tumor

Cryosurgery has shown potential as a minimally invasive technology for tumor treatment. However, incomplete destruction followed by tumor recurrence after cryosurgery is a common drawback. This study characterizes several variables in the cryoadjuvant TNF-α enhancement of conservative cryosurgery (i.e. freezing to the visible edge) of ELT-3 (uterine leiomyoma) tumor in a female nude mouse model. The variables include pretreatment time, mode of TNF-α delivery (native vs. CYT-6091, a PEGylated 33 nm colloidal gold core nanoparticle) and dose of TNF-α. Survival and tumor growth delay were measured up to 30 days and showed: 1) pretreatment with TNF-α required 4 hours incubation prior to cryosurgery to produce a tumor growth delay over cryosurgery alone, and 2) CYT-6091 reduced the toxicity of TNF-α administration over intratumoral or peritumoral injection of native TNF-α. Taken together, 5 g TNF-α delivered by the nanodrug CYT-6091 4 hours prior to cryosurgery yielded a dramatic reduction in tumor growth over cryosurgery alone and in some cases even total remission of the tumor. However, some toxicity at higher doses (i.e. 5 g) with CYT-6091 was noted compared to previous work in prostate (LNCaP) cancer grown in a male nude mouse. Potential reasons for this, including sex and weight of the animals are discussed. Further opportunities to optimize the TNF-α enhanced cryosurgical response of this tumor include dosing between 2 - 5 g at 4 hours prior to cryosurgery, and freezing beyond the visible edge of the tumor.