Search

Canine malignant melanoma provides a clinically relevant, large animal parallel patient population to study the GD2-reactive hu14.18-IL-2 immunocytokine as it is similar to human melanoma and expresses GD2. The objectives of this study were to evaluate safety, radiation fractionation, and identify informative biomarkers of an in-situ tumor vaccine involving local radiation therapy plus intratumoral–immunocytokine in melanoma tumor-bearing dogs. Twelve dogs (six dogs/arm) with locally advanced or metastatic melanoma were randomized to receive a single 8 Gy fraction (arm A) or three 8 Gy fractions over 1 week (arm B) to the primary site and regional lymph nodes (when clinically involved) with the single or last fraction 5 days before intratumoral–immunocytokine at 12 mg/m2on 3 consecutive days. Serial tumor biopsies were obtained. All 12 dogs completed protocol treatment, and none experienced significant or unexpected adverse events. Evidence of antitumor activity includes one dog with a complete response at day 60, one dog with a partial response at day 60, and four dogs with mixed responses. Histology of serial biopsies shows a variably timed increase in intratumoral lymphocytic inflammation in some dogs. Canine NanoString analyses of serial biopsies identified changes in gene signatures of innate and adaptive cell types versus baseline. There were no significant differences in NanoString results between arm A and arm B. We conclude that intratumoral–immunocytokine in combination with local radiation therapy in canine melanoma is well tolerated and has antitumor activity with the potential to inform clinical development in melanoma patients.

Supplemental Digital Content is available in the text.This study examines whether 6-thioguanine resistant T cells (mutant) from metastatic melanoma patients are enriched for melanoma-associated T cells compared to T cells obtained analogously without thioguanine selection (wild-type). Melanoma-associated antigen pentamer staining was performed on 5 tumour and 9 peripheral blood samples from metastatic melanoma patients. T cell receptor beta chain repertoire was examined via Sanger sequencing of mutant and wild-type in blood and tumour from metastatic melanoma patients at times of tumour progression (n = 8) and via Illumina sequencing in tumour derived T cells and in uncultured T cells (uncultured), wild-type and mutant from blood before and after immune checkpoint blockade (n = 1). Mutant from tumour (3 of 5; P< 0.001), but not blood (0 of 9), were enriched compared to wild-type for binding melanoma-associated antigen pentamers. T cell receptor beta analysis in patients with tumour progression (n = 8) detected increased melanoma associated T cells in mutant compared to wild-type from blood (Monte Carlo P= 10−7). Comparison of blood samples before and after immune checkpoint blockade with prior tumor from one metastatic melanoma patient detected increased T cell receptor beta sharing between tumour and mutant compared to tumour and wild-type or tumour and uncultured: 11.0% (72/656), 1.5% (206/13 639) and 1.3% (381/29 807), respectively (Monte Carlo P= 10−7for mutant versus wild-type and mutant versus uncultured). These data demonstrate that mutant in metastatic melanoma patients are enriched for melanoma-associated T cells and are candidate probes to study in vivo melanoma-reactive T cells.

We report an in situ vaccination, adaptable to nearly any type of cancer, combining radiotherapy targeting one tumor and intratumoral injection of this site with tumor-specific antibody and IL2 (3xTx). In a Phase I clinical trial, administration of 3xTx (with an immunocytokine fusion of tumor-specific antibody and IL2, hu14.18-IL2) to subjects with metastatic melanoma increases peripheral CD8+T cell effector polyfunctionality. This suggests the potential for 3xTx to promote antitumor immunity against metastatic tumors. In poorly immunogenic syngeneic murine melanoma or head and neck carcinoma models, 3xTx stimulates CD8+T-cell-mediated antitumor responses at targeted and non-targeted tumors. During 3xTx, NK cells promote CTLA4+regulatory-T-cell (Treg) apoptosis in non-targeted tumors. This is dependent on NK cell expression of CD86, which is upregulated downstream of KLRK1. NK cell depletion increases Treginfiltration, diminishing CD8+T-cell-dependent antitumor response. These findings demonstrate that NK cells sustain and propagate CD8+T cell immunity following 3xTx.

Atopic disorders are associated with an imbalanced THcell response biased toward a strong TH2 type, resulting in excessive production of IgE antibodies, eosinophil recruitment and activation, and mast cell degranulation. Restoring the TH1-TH2 balance by increasing the antigen-specific TH1 response has been pursued for specific allergy immunotherapy. Synthetic oligodeoxynucleotides containing unmethylated CG dinucleotides (CpG) are strong TH1 adjuvants and are being investigated for allergy immunotherapy.