ASS1 and metastatic melanoma: In conclusion, our findings support the theory that ASS1-deficient cancer cells have many biological advantages to promote cell survival and mediate resistance to chemotherapy that may be reversed by arginine depletion.11,24,25 Our preliminary clinical findings demonstrate that further evaluation of treatment with ADI-PEG20 plus cisplatin and the use of an anti-ADI-PEG20 antibody as a potential marker for antitumour efficacy is warranted in patients with metastatic melanoma and many other ASS1-deficient malignancies.