PO-416 A novel multifunctional polypeptide-based platform as an immunotherapeutic approach for melanoma

• Published in: ESMO open Vol. 3; no. Suppl 2; p. A393
• Main Authors: Moura, L, Duro-Castano, A, Peres, C, Gallon, E, Matos, A, Vicent, MJ, Florindo, H
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2018
• ISSN: 2059-7029; 2059-7029
• DOI: 10.1136/esmoopen-2018-EACR25.927

IntroductionMelanoma is the most dangerous type of skin cancer and novel treatments are needed. Alternative therapeutics should be devised isolated or in combination with targeted immunotherapies, to efficiently stimulate specific anti-tumour responses. Branched polypeptides exhibit advanced engineered complexity and unique structural properties inaccessible to linear polymers that make them ideal drug delivery systems with enhanced biological performance. Branched nanosystems have the ability to activate immune cells, as dendritic cells (DC) and natural killer (NK) cells, constituting potential platforms to modulate the release profile of loaded molecules, including tumour associated antigens (TAA), adjuvants and drugs. This work aims to evaluate the in vivo anti-tumour efficacy of peptide-1 -conjugated polypeptide (pept-1-BP), with special emphasis on their impact on the modulation of the immune cell function.Material and methodsBP were synthesised and conjugated with the peptide-1 (pept-1-BP) via reductive-sensitive disulfide linker. To address in vitro and in vivo studies, Cy5.5 was conjugated to platform. To evaluate the effect of the conjugate on melanoma tumour growth, B16.F10 cells were implanted subcutaneously into C57BL/6 mice. At day 7, animals were injected with two doses (1 week apart) of 100 µL of PBS, Toll-like receptor ligands CpG (20 µg/dose) and Poly I:C (40 µg/dose) in solution, BP backbone (575 µg/dose) and pept-1-BP (575 µg/dose) mixed with adjuvants. Every 2 days, weight of the mice and tumour growth was followed. At day 21, mice were sacrificed and tumour and lymph nodes were collected. A cell suspension from tumour cells and lymph nodes of each animal was prepared and analysed for infiltrated lymphocytes (CD45.1, CD3e, CD8α, CD4, CD107, PD-1, CTLA-4) by flow cytometry.Results and discussionsThe BP presented a size of 81.86±1.63 nm and a zeta potential of −45.10±1.72 mV, while pept-1-BP showed a mean average diameter of 104.1±2.21 nm and a zeta potential of −24.8±0.64 mV, with a pept-1 loading efficiency of 8.7% (w/w).In vivo results showed a significant reduction of tumour size in conjugate treated mice compared with the other groups. In addition, the FACS analysis of infiltrating lymphocytes within tumour site evidenced an increased expression for CD4, CD8α and NK cells.ConclusionOverall, our results support the promising use of this novel conjugate for the delivery of TAA, as an effective anti-tumour immune therapeutic strategy able to decrease and control of tumour growth.