Autophagy is the principal catabolic response to nutrient starvation. However, excessive autophagy can be cytotoxic or cytostatic, and contribute to cell death, but its mechanism of induction remains elusive. Here, it was demonstrated that prolonged arginine starvation by ADI-PEG20 induced an autophagy-dependent death of argininosuccinate synthetase 1 (ASS1)-deficient breast cancer cells. Consequently, arginine depleting agents such as ADI-PEG20 may be used in methods for killing one or more argininosuccinate synthetase 1 (ASS1)-deficient breast cancer cells. Further, abundance of ASS1 was either low or absent in more than 60% of 149 random breast cancer biosamples, which could be exploited as candidates for arginine starvation therapy.