Leukocyte migration and immunomonitoring in patients with cutaneous melanoma treated with immunotherapeutic vaccine

PAMPENA, MARÍA BETINA; ROCCA, YAMILA SOL; JULIÁ, ESTEFANÍA PAULA; BLANCO, PAULA; BARRIO, MARÍA MARCELA; MORDOH, JOSÉ; LEVY, ESTRELLA MARIEL

Congreso; IV LASID Meeting LXIII Argentinean Immunology Society Meeting II French-Argentinean Immunology Meeting; 2015

BACKGROUND In a Phase II/III randomized clinical trial (CASVAC-0401, NCT01729663), cutaneous melanoma (CM) patients (pts) stages II/III received CSF-470 vaccine (N=21) or IFN-alpha (N=11). CSF-470 is a mini-allograft of four lethally-irradiated allogeneic CM cell lines, with BCG and rhGM-CSF. As higher distant-metastases-free-survival was observed in vaccinated pts; here we analyzed leukocytes migration promoted by the vaccine components to understand first steps of vaccination; and we performed immunomonitoring to evaluate changes induced by treatment.METHODS For cell migration, we performed transwell assays with healthy donors? leukocytes or mononuclear cells (MN) towards vaccine components. For immunomonitoring, PRE and POST treatment pts? MN cells were characterized. All assays were analyzed by flow cytometry. RESULTS In transwell assays, CSF-470 vaccine induced higher attraction of polymorphonuclear cells and lymphocytes compared to medium (*p=0.0165 and **p=0.0022, respectively, unpaired-T-test). Although GM-CSF and BCG did not exert any attraction, they contributed to the migration triggered by irradiated cells (vaccine vs irradiated cells; *p=0.0298 unpaired-T-test). When using MN, CSF-470 highly attracted monocytes, representing 10% to 60% of the migrating CD45+ population (*p=0.0243 paired-T-test). Among lymphocytes, natural killer (NK) cells were the most attracted towards the vaccine, in detriment of TCD8+cells (**p=0.0061 paired-T-test). Moreover, immunomonitoring revealed that NK cells, but not T cells, increased their frequency in vaccinated pts (PRE vs POST1 **p=0.0046, paired-T-test). CONCLUSIONS CSF-470 vaccine recruits leukocytes from innate and adaptive immune system favoring crosstalk, and contributing to antigen processing and presentation. Peripheral blood increase in NK cells after treatment would favor elimination of circulating tumor cells.