Modified Quality Range Method for Analytical Similarity Evaluation

In September 2017, the United States Food and Drug Administration (FDA) circulated draft guidance on analytical similarity assessment for comments. In the draft guidance, FDA recommended that an equivalence test can be used for analytical similarity assessment between a proposed biosimilar (test) product and a reference product for critical quality attributes with high-risk ranking relevant to clinical outcomes. Recently, FDA circulated new draft guidance for comparative analytical assessment. In the draft guidance, FDA suggested the use of the QR method for comparative analytical assessment. Accordingly, the FDA requires totality-of-the-evidence be provided to support biosimilarity between the proposed biosimilar and the US licensed counterpart. The QR method is designed for quality control/assurance, which is not designed for analytical similarity evaluation. For analytical similarity assessment, the QR method is valid only under the assumption that the proposed biosimilar product and the reference product have similar population mean and population standard deviation.