Khanna, Chand

Abstract Despite remarkable therapeutic advances in malignant melanoma, an incomplete understanding of melanoma's extraordinary genetic diversity, complex disease course and ability to resist treatment continues to impede rational, curative clinical intervention. This is particularly true for the understudied “dark matter” of the melanoma genome, i.e. cases that lack mutations in the three most commonly-mutated melanoma genes (BRAF, NRAS, NF1) and that display extensive mutational heterogeneity. Clearly a pressing need exists for transformative approaches to melanoma medicine. We have therefore broadened our traditional focus on melanoma in human patients to include canine melanoma as a model of human disease. Given canine melanoma's clinicopathological resemblance to human non-cutaneous triple-negative subtypes, study of this disease in each species may inform the other. Further, the accelerated clinical course of canine melanoma and flexibility in veterinary clinical trial design may allow for evaluation of novel treatment designs that would not be possible in human cancer trials. Thus, we have undertaken a first-in-dog genomic characterization study of canine melanomas from a cohort of 37 dogs to further explore the landscape of this comparative model. This analysis combines comprehensive genomics (whole genome, whole genome long-insert, RNA sequencing, and array comparative genomic hybridization) in 7 matched canine melanoma/normal tissues with targeted analysis in an additional 27 tumors and 3 cell lines. These canine tumors display striking patterns of mutation and subtype heterogeneity resembling that of their non-cutaneous human counterparts with the majority being BRAF, NRAS, and NF1 wild type and lacking recurrent single nucleotide variants. Despite heterogeneity at the single nucleotide level, shared patterns of structural variation and gene expression exist and these patterns suggest core pathways that may define therapeutic vulnerabilities in these disease subtypes. These data provide the genomic framework for further clinical pursuit of melanoma in the canine model as a paradigm for drug development. Citation Format: William P. Hendricks, Victoria Zismann, Berry Button, Christophe Legendre, Waibhav Tembe, Holly Yin, Michael Bittner, Donald Berry, Matthew Huentelman, Chand Khanna, Patricia LoRusso, Matthew Breen, Aleksandar Sekulic, Jeffrey Trent. The genomic landscape of canine melanoma reveals broad mutational heterogeneity and recurrent patterns of structural variation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3417. doi:10.1158/1538-7445.AM2014-3417

Abstract Although interleukin 2 (IL-2) has been associated with modest anti-tumour responses in man, treatment-related toxicity has limited its widespread use. The local delivery of liposomal formulations of interleukin 2 to the lung as aerosols has been demonstrated to be non-toxic, biologically active, and associated with regression of spontaneous pulmonary metastases in dogs. This study was undertaken to evaluate the physical and biological characteristics of nebulized interleukin 2 liposomes. The aerosol droplet size distribution and the physical stability of interleukin 2 liposomes were examined in-vitro using an Andersen cascade impactor and studies of liposome entrapment of interleukin 2 before and after nebulization. The biological stability of interleukin 2 liposomes after nebulization was demonstrated using the CTLL-2 bioassay for interleukin 2. In-vivo studies of pulmonary biodistribution and clearance of inhaled technetium (99mTc)-labelled interleukin 2 liposomes were undertaken in a normal dog. Aerosols of free interleukin 2 and of interleukin 2 liposomes were compared in both in-vitro and in-vivo experiments. The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) of interleukin 2 liposomes were 1–98 μm and 202, respectively. Independent analysis of aerosol particle-size distribution using the constitutive components of the interleukin 2 liposomes (interleukin 2: lipid: HSA) demonstrated a close correlation of size distributions (r = 0.9445; P < 0.001). The entrapment of interleukin 2 in liposomes was 93 ± 4.3% before nebulization and 90 ± 8.9% after. After delivery to an anaesthetized dog, interleukin 2 liposome aerosols were deposited evenly throughout the lung (mean ± s.d. central lung-to-peripheral lung deposition was 1–12 ± 0.03). After approximately 24 h inhalation, interleukin 2 liposomes were retained within the lung and were taken up in part by the spleen. The results of this study are indicative of the stability of this interleukin 2 liposome formulation to nebulization. Such nebulization might be an attractive immunotherapeutic strategy for treatment of pulmonary metastases and primary lung cancers.