Anemia, usually the most common among haematologic AEs, might be related to PARP2 inhibition that affects the differentiation of erythroid progenitors, reducing erythrocytes’ life expectancy in mice, even if erythropoietin plasma concentrations are increased, thus suggesting that supplementation might not be the best therapeutic option to manage anemia in these patients. The gene discussed is PARP2; the disease is anemia (phenotype).