Anais dos Simpósios de Oncobiologia
XIV Oncobiology Symposium

INTRODUCTION AND OBJECTIVE: Acral melanoma (AM) is a subtype of cutaneous melanoma that occurs on glabrous skin of the hands and feet (palms, soles and nail apparatus) and which is relatively more common in non-European descent populations such as those in Latin America. Compared to other subtypes, it is poorly studied and experimental models that faithfully reproduce human AM features are urgently needed. Here, we report the generation and preliminary characterization of a collection of patient-derived xenografts of acral melanomas (AM-PDX) from Latin-American patients. MATERIAL AND METHODS: Between March 2019 and February 2020, primary and metastatic samples of AM were collected from Brazilian and Mexican patients at the Instituto Nacional de Câncer (INCA) and the Instituto Nacional de Cancerologia (INCan), respectively. Samples were mechanically fragmented and subcutaneously implanted in NSG mice. Tumor growth was monitored weekly by calipering (length x width x height / 2). Patients’ clinical and histopathological data were collected from medical records. This study was approved by the Human and Animal Research Ethics Committees (CEP/CONEP and CEUA). RESULTS AND CONCLUSION: A total of 40 patients were included in the study, from whom 48 samples were collected. The mean age of the patients was 70.0 ± 2.09 years, 44% were female, and the majority were diagnosed with stage III disease. To date, twenty-six samples reached the experimental endpoint of either successful engraftment (n=15) or no tumor growth in six months (n=11), indicating a 58% success rate. The majority of the samples were acral lentiginous melanomas, ulcerated, with > 4mm Breslow depth and > 2 mitoses/mm2. There was no association between clinical and histopathological parameters and tumor growth in mice. Most lymph node metastases were successfully engrafted, but no differences were observed in the AM-PDX growth rate between the primary and metastatic samples. The implantation of the remaining samples of our collection and their molecular characterization are ongoing. This may reveal factors involved in successful establishment of AM-PDXs and also enable the investigation of the drivers and therapeutically targetable vulnerabilities of acral melanoma.