Ireland-based Cosmo Pharmaceuticals has received a complete response letter from the US Food and Drug Administration (FDA) stating that it cannot approve the company's Methylene Blue MMX as a visualisation aid to increase detection of lesions in the colon, it was reported yesterday.

The complete response letter is consistent with the preliminary feedback the company announced on 9 May 2018, stating that the US FDA identified unspecified deficiencies that preclude the continuation of the discussion of labelling and post-marketing requirement/commitments. It states that the FDA has determined it cannot approve the NDA in its present form and offers recommendations needed for resubmission.

The FDA did not raise any safety or manufacturing concern. The complete response letter states instead that, although the result of the phase III trial has translated in a statistically significant result, the outcome is not sufficiently 'robust' and thus recommends the company provide confirmation of effectiveness with a second phase III trial.