Erythropoiesis-stimulating agents and pure red-cell aplasia: you can't fool Mother Nature.

Subtle alterations in the properties of biopharmaceutical agents may increase their immunogenicity and lead to the production of autoantibodies. Biosimilar agents may not undergo the same quality control in their production, packaging, storage, and distribution as their patented competitors. The extensive use of biosimilar erythropoiesis-stimulating agents led to an epidemic of pure red-cell aplasia in Thailand. The response of Thai regulators may be a model for other countries as the use of biosimilar agents expands.