ASS1 and neoplasm: Representative tumors that exhibit this biology are T-lymphoblastic leukemia, melanoma and small cell lung cancer.18, 23, 42 ADI-PEG20 treatment of prostate cancer is unique in that arginine starvation in these tumor cells causes chromatophagy, a form of autophagy in which cells start incorporating chromatin into autophagosomes, followed by cell death.42, 43 In contrast, sarcoma cells are able to use sustained autophagy until they reprogram and re-express ASS1, a change that renders single-agent ADI-PEG20 treatment ineffective.