Kigamicins are natural antitumor antibiotics that selectively kill pancreatic cancer PANC-1 cells only under nutrient-starved conditions. They also show antimicrobial activity against Gram-positive bacteria, including methicillin-resistant S. aureus. Kigamicin C inhibits PANC-1 cell survival in nutrient-deprived media at a 100-fold lower concentration than that required for cells maintained in nutrient-rich media. A related compound, kigamicin D, is active in vivo, suppressing the tumor growth of several pancreatic cancer cell lines in nude mice. It blocks the activation of Akt induced in PANC-1 cells placed in nutrient-deprived media. Kigamicin can also induce necrosis in human myeloma cells, but not normal lymphocytes, maintained in nutrient-rich media (CC50 = 100 nM).