Malignant melanoma is a serious disease in both humans and dogs, and the high metastatic potential results in poor prognosis for many patients. Its similarities with human melanoma make spontaneous canine melanoma an excellent model for comparative studies of novel therapies and tumor biology. We report a pilot study of local adenovector CD40L (AdCD40L) immunogene treatment in 19 cases of canine melanoma (14 oral, 4 cutaneous, and 1 conjunctival). Three patients were World Health Organization stage I, 2 were stage II, 10 stage III, and 4 stage IV. One to 6 intratumoral injections of AdCD40L were given every 7 days, followed by cytoreductive surgery in 9 cases and only immunotherapy in 10 cases. Tumor tissue was infiltrated with T and B lymphocytes after treatment, suggesting immune stimulation. The best overall response included 5 complete responses, 8 partial responses, and 4 stable and 2 progressive disease statuses according to the World Health Organization response criteria. Median survival was 160 days (range, 20-1141 d), with 3 dogs still alive at submission. Our results suggest that local AdCD40L therapy is safe and could have beneficial effects in dogs, supporting further treatment development. Clinical translation to human patients is in progress.

Cutaneous canine melanomas are usually benign in contrast to human malignant melanoma. However, the canine oropharyngeal, uveal, and mucocutaneous neoplasms are aggressive and have metastatic potential. Surgery and to a lesser extent radiotherapy and chemotherapy are widely adopted treatments but are seldom curative in advanced stages. The similarities between human and canine melanoma make spontaneous canine melanoma an excellent disease model for exploring novel therapies. Herein, we report the first 2 adenovector CD40L immunogene (AdCD40L) treatments of aggressive canine malignant melanoma. Case no. 1 was an advanced stage III oral melanoma that was cured from malignant melanoma with 2 intratumor AdCD40L injections before cytoreductive surgery. After treatment, the tumor tissue was infiltrated with T lymphocytes and B lymphocytes suggesting immune activation. This dog survived 401 days after the first round of gene therapy and was free of melanoma at autopsy. Case no. 2 had a conjunctival malignant melanoma with a rapid progression. This case was treated with 6 AdCD40L injections over 60 days. One hundred and twenty days after start of gene therapy and 60 days after the last injection, the tumor had regressed dramatically, and the dog had a minimal tumor mass and no signs of progression or metastasis. Our results indicate that AdCD40L immunogene therapy is beneficial in canine malignant melanoma and could be considered for human malignant melanoma as well.

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Adoptive cell therapy with tumor-infiltrating lymphocytes (TIL) can mediate objective responses in up to 50% of malignant melanoma patients with a good performance status refractory to standard treatments. Current protocols for generation of TILs rely on open surgery for access to tumor tissue. We obtained tumor material by ultrasound-guided core needle biopsy or surgery from melanoma patients with progressive disease and were able to isolate >5 × 10(6) TILs from 23 of 24 patients who were subsequently treated with these cells. One-third of the individual TIL-positive cultures displayed interferon gamma activity after stimulation with relevant melanoma cell lines. When expanded TILs were used for treatment in combination with daily low dose s.c. IL-2 after prior lymphodepleting chemotherapy, we observed objective clinical responses in one patient treated with TILs obtained from surgery and 4 patients treated with TILs from core biopsies. The results of this study demonstrate for the first time the potential of core biopsies for generation of relevant numbers of TILs that can mediate objective responses in patients with metastatic malignant melanoma. Ultrasound-guided core needle biopsy is a robust, safe and inexpensive approach to obtain tumor tissue for TIL generation, and is especially valuable in instances where surgery is contraindicated.

Cryopreservation of lymphocytes during the rapid expansion protocol did not affect cell viability. Lymphocytes that underwent mass expansion or culture in high dose IL-2 were unable to respond to PHA stimulation by intracellular ATP production immediately after thawing (ATP = 16 ± 11 ng/ml). However, their reactivity to PHA was regained within 48 hours of recovery (ATP = 356 ± 61 ng/ml). Analysis of mRNA levels revealed downregulation of TGF-β and IL-10 at all time points. Culture in high dose IL-2 led to upregulation of p73 and BCL-2 mRNA levels while FoxP3 expression was elevated after culture in IL-2 and artificial TCR stimuli. FoxP3 levels decreased after short-term recovery without IL-2 or stimulation. Antigen specificity, as determined by IFNγ secretion, was unaffected by cryopreservation but was completely lost after addition of high dose IL-2 and artificial TCR stimuli. In conclusion, allowing short-time recovery of mass expanded and cryopreserved cells before reinfusion could enhance the outcome of adoptive cell therapy as the cells regain immune competence and specificity.