@timmyjuly I'm a little confused... the current CLBP trial is a...

@timmyjuly

I'm a little confused... the current CLBP trial is a phase 3 trial.

The only trial that may be up for accelerated approval are RMAT designated programs, of which there is currently only one in MSB's portfolio i.e. LVAD CHF trial.

Is that what you are referring to?

If so, here are some links that explain how a product can be approved using surrogate data (instead of a phase 3 trial). In summary surrogate data can be obtained from a phase 2 trial, but will at some stage need to be confirmed using a phase 4 confirmatory trial.

FDA on what RMAT designation means:
RMAT designation

Extract
"The meetings with sponsors of RMAT-designated products may include discussions of whether accelerated approval would be appropriate based on surrogate or intermediate endpoints reasonably likely to predict long-term clinical benefit, or reliance upon data obtained from a meaningful number of sites."

FDA on accelerated approval:
FDA Accelerated approval

Extract
"A surrogate endpoint used for accelerated approval is a marker - a laboratory measurement, radiographic image, physical sign or other measure that is thought to predict clinical benefit, but is not itself a measure of clinical benefit. Likewise, an intermediate clinical endpoint is a measure of a therapeutic effect that is considered reasonably likely to predict the clinical benefit of a drug, such as an effect on irreversible morbidity and mortality (IMM).

Using surrogate or intermediate clinical endpoints can save valuable time in the drug approval process. For example, instead of having to wait to learn if a drug actually extends survival for cancer patients, the FDA may approve a drug based on evidence that the drug shrinks tumors, because tumor shrinkage is considered reasonably likely to predict a real clinical benefit. In this example, an approval based upon tumor shrinkage can occur far sooner than waiting to learn whether patients actually lived longer. The drug company will still need to conduct studies to confirm that tumor shrinkage actually predicts that patients will live longer. These studies are known as phase 4 confirmatory trials."

FDA summary of designations
PDF of designations

Extract
"Approval based on an effect on a surrogate endpoint or an intermediate clinical endpoint that is reasonably likely to predict a drug’s clinical benefit "

NCBI published article
NCBI article

Extract
"Cancer drug approval has evolved as the understanding of cancer biology, and the ability to select patients for trials of targeted agents, has matured. The longstanding reliance on Phase III trials to prove drug efficacy and positive impact on patient survival may no longer be necessary, as early trials, particularly the expansion phase of a Phase I trial, may provide convincing evidence of a high response rate to a targeted drug in a patient population who has been poorly responsive to conventional therapy. If the new drug produces no safety signals of great concern, and if a validated biomarker for patient selection has been established and is readily available, accelerated approval may be achievable prior to completion of a randomized trial. The advantages, and potential downside, of rapid approval scenarios will be discussed in this article."

Does that answer your question?