Just to clarify this term "appears sufficient" once and for all, which is standard FDA terminology from everyone from their inspectors who write reports to other forms of feedback, such as -pre-BLA meetings.
Yes, the literal definition of sufficient is "to meet the need". FDA means it in this sense. They never say "exceeds the need" or "knocks it out of the park". You only need to meet a need or requirement, never exceed it or be measured on how much you exceeded it by. Others, like insurers might care but the FDA does not.
So why then qualify with appears? In the case of, say an standard operating procedure, which has changed to address some non-compliance to regulations (cGMP/QSR) or it causing faulty product to be produced, they might review a change to procedure and state it appears sufficient to address XYZ. They can never state it will eliminate the production of a non-compliant product forever but it appears to address their concern based on available information eg root cause analysis based on statistics available of non-compliance. When it comes to MSB's feedback on clinical data; new assay, change in FDA policy, new FDA management or whatever the outstanding issues were which did not allow GVHD001 to be considered an adequate and well controlled trial, then all they can state prior to submission for final and formal evaluation, is it appears sufficient. If they state it is sufficient then they have accepted the data prior to formal review, which is not possible due to legal and process requirements. Another alternative would have been "it does not appear sufficient" which I think has been their base case since CRL No.1 (and prior).
So, this is why the market jumped on the announcement on March 26 whilst those less in the know here debated the language in ignorance of FDA terminology/protocols. It's a green light. Does not mean FDA can't knock it back after submission but they would need to find new evidence/data which they have not seen to date. I do not believe this would be likely since they have been working closely with the FDA and its review team for 4 years since the CRL. Whatever triggered their change in stance was significant because Mesoblast had already committed to the Adult trial pathway. Its not like the office lady checked out the new data and though it appeared sufficient. It was the reviewers/team who had been dealing with GVHD001 for 4 years and more.
Here are a couple of examples I found where FDA has used the language "appears sufficient" in their feedback to firms. Not a lot around as it generally does not get published, as you can see from MSB's case. And links to their subsequent approvals (search for "appears sufficient" in the docs). You can't infer anything from those examples, except that the language in question is not incompatible with approval.
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