The invention is related to a new method for treating liquid and solid cancers, in a mammal, including human, wherein methioninase is administered before asparaginase. The invention also encompasses the use of a dietary methionine deprivation, possibly combined with methioninase administration, in advance of asparaginase treatment. Methioninase and asparaginase may be used in particular under free form, pegylated form or encapsulated into erythrocytes.