In my previous post, I explained the definitions FDA used to determine that CFS is a serious or life-threatening condition. But the true significance of FDA’s decision is that it makes CFS treatments eligible for programs that speed up the process of getting those treatments to patients. To understand these programs, you first have to understand the drug approval process.
The Pipeline: A Hypothetical
Let’s say that XYZ drug company has created a drug called PemX to treat CFS, and has tested that drug in animals to show that it is not toxic. XYZ then files an Investigative New Drug (IND) application with FDA and includes information on the drug and the plans for clinical trials in humans. XYZ conducts a Phase 1 clinical trial in 75 patients to test the safety of PemX. The results show PemX is safe, so XYZ conducts a Phase 2 clinical trial in 300 patients. The Phase 2 trial is designed to test whether PemX is effective in treating CFS, so half of the patients get PemX and half receive placebo. Since Phase 2 was a success, XYZ and the FDA discuss the design of Phase 3 trials. Phase 3 trials typically involve thousands of patients, and are designed to test appropriate dosages, side effects and drug interactions.
XYZ believes that the Phase 3 trials are a success, and files a New Drug Application (NDA). This is a request to FDA to approve PemX for sale in the United States, and the application includes all the data from all the studies. FDA has 60 days to decide whether to file the NDA for review. If the NDA is filed for review, then an FDA review team is appointed to examine all the data, the proposed labeling, and the manufacturing facility. FDA may also ask an advisory committee to examine the data. After all the reviews, FDA decides whether to approve PemX, including what dosages should be available.
Fast Track is an expedited process for drugs that treat serious diseases and fill an unmet medical need. Serious diseases include cancer, heart disease, AIDS, and now includes CFS as well. An unmet medical need is a condition for which there are no approved treatments (like CFS) or when the proposed drug is potentially superior to existing drugs.
Fast Track designation must be requested by the drug company, and the request can be made at any point in the drug review process. In our hypothetical, XYZ requests Fast Track status after the Phase 2 trials, and FDA has 60 days to make that determination. FDA approves Fast Track for PemX, and so now XYZ will have more meetings and more correspondence with FDA about the clinical trials. PemX is now eligible for rolling review, meaning that XYZ can submit portions of the NDA as they are completed rather than waiting to the end and submitting all at once. PemX is also now eligible for Accelerated Approval.
There are many potential treatments that can take years to show true effectiveness. For example, a chemotherapy drug may be intended to extend the lives of cancer patients but it could take a decade or more to prove that the drug does in fact do so. To address these situations, FDA uses Accelerated Approval to base review on a surrogate endpoint. For cancer, that endpoint might be tumor shrinkage. The chemotherapy drug could be approved because it successfully shrinks tumors, and FDA would require post-approval studies to verify that the drug does in fact extend the lives of the cancer patients.
In my example, PemX is intended to treat CFS, but it could take years to be certain that patients experience long-lasting benefits that make it possible to return to work or normal life. In the Accelerated Approval process, XYZ proposes that exercise testing be used as a surrogate endpoint. Patients are put through two-day exercise challenges before treatment and then at six and twelve months post-treatment. Improvement in exercise capacity and reduction in recovery time are used as surrogate endpoints, and longer term studies would be needed to prove that PemX really did enable patients to return to work. If PemX is approved in the accelerated process, then FDA can require post-approval studies and restrictions on use of the drug.
Normally, FDA has a goal of ten months to review an NDA for approval. But a drug company can request Priority Review for a treatment that offers a major advance over existing therapies or where no treatment exists. If FDA assigns Priority Review for a drug, the goal timeline for review is six months. Priority Review does not change the requirements for clinical trials or drug safety and effectiveness. In our hypothetical, XYZ requests Priority Review for PemX because there are no existing therapies for CFS. FDA grants the request and the review process for the PemX NDA is now six months.
Because FDA has determined that CFS is a serious or life-threatening condition, my hypothetical drug PemX gets to market faster. First, XYZ requests Fast Track status and this means that FDA has more contact with XYZ during the trials process, and XYZ can submit sections of its final NDA as they are completed. PemX also becomes eligible for Accelerated Approval, meaning that exercise testing is used as a surrogate endpoint for treatment success. As a result, clinical trial data can be collected for 12 months instead of many years. XYZ also requests and is granted Priority Review for PemX, and the final NDA review process takes only six months instead of ten. These three programs shorten the time it takes for PemX to move from “bench to bedside,” and it all happens because FDA determined CFS is a serious or life-threatening condition.
Note: PemX is a drug invented in my imagination, and all the examples in this post are purely hypothetical. The FDA website has an incredible amount of information on the drug approval process, and I relied heavily on the FDA’s descriptions of these programs in writing this post.