Research Communications of the 27(th) ECVIM-CA Congress: Intercontinental, Saint Julian's, Malta, 14th to 16th September 2017

Disclosures: Disclosures to report. Several authors of this study belong to Laboklin GmbH & Co.KG -a diagnostic laboratory, which is offering the AMH measurement for clients. Gum arabic coated radioactive gold nanoparticles AuNP) are effectively retained and result in 80% tumor reduction in a mouse model of human prostatic carcinoma. Our objectives were to determine the toxicity and preliminary efficacy of AuNP administered intralesionally to dogs with spontaneously occurring carcinoma of the prostate. The hypothesis was that intralesional AuNP would cause short term swelling but cause no systemic toxicity and result in tumor stabilization or shrinkage. Following Institutional Animal Care and Use Committee approval, dogs with a diagnosis of prostate carcinoma without bladder involvement were eligible for enrollment with informed owner consent. Staging was performed and injection of AuNP was achieved with CT guidance (100-200 lL per site in multiple sites, total amount varied based on tumor size). A complete blood count, chemistry panel, and urinalysis were performed weekly for 4 weeks following treatment; a CT scan was performed 4 weeks after treatment. Nuclear scintigraphy was performed regularly (15 min, 1 h, 4 h, 1, 2, 4, and 5 days post-injection) to determine the degree of retention of AuNP in the prostate. Following the 4 week trial period, chemotherapy could be started at the discretion of the pet owner. Twenty-two dogs were enrolled; 3 dogs had metastasis to the lymph nodes in the sublumbar region and 19 dogs had no evidence of metastasis. Two dogs were treated to a biologically equivalent dose of 50 Gy and 20 dogs were treated to 105 Gy. One dog died 12 days post injection due to urethral obstruction from either tumor swelling or disease progression. Following this event, dogs with evidence of urethral obstruction had urethral stents placed (n = 15) prior to treatment. Fifteen dogs received chemotherapy. The median survival time of dogs receiving chemotherapy was 132 days (range 55-420 days) compared to 56 days (range 12-255 days) in dogs that did not. The average tumor retention of AuNP was 70% at 5 days post-injection; loss occurred into the urine through the bladder. No accumulation of dose was found in heart, lung, liver, spleen, and kidney as determined by whole body planar imaging up to 5 days posttreatment. The median reduction in tumor volume was 10% one month after AuNP therapy in 14 dogs. In conclusion, intratumoral administration of AuNP caused no acute systemic toxicities in any dog and may be effective in decreasing tumor size, however, local tumor swelling is possible and dogs must be closely monitored for evidence of urethral obstruction.