March 10, 2025 — (Docket No. FDA-2024-D-3334)
The National Center for Health Research (NCHR) [and the Cancer Prevention and Treatment Fund] appreciate[s] the opportunity to comment on the FDA’s draft guidance on Accelerated Approval and Considerations for Determining Whether a Confirmatory Trial is Underway. We strongly support the FDA’s efforts to ensure timely completion of confirmatory trials; however, we have concerns regarding the vagueness of key criteria to be used to determine when a trial is considered “underway.” FDA’s clearly defined and specified regulatory expectations are needed to improve corporate achievements and public trust in the Accelerated Approval process.
Concerns About Imprecise Language & Lack of Specificity
As currently written, the guidance relies heavily on important terms such as “diligent and timely,” which are very vague and leave room for inconsistent interpretation by sponsors. Unfortunately, some companies’ definitions of diligent and timely will not be considered timely or diligent by regulators or public health experts and will not reduce the frequent delays in the completion of confirmatory trials. The lack of specific enrollment and timeline benchmarks will result in delays that expose patients to drugs without verified clinical benefit for many years.This is exactly the situation that the guidance is intended to correct. For that reason, we strongly recommend that the FDA replace ambiguous terms with clear, measurable criteria, including concrete benchmarks and milestones and clearly defined interim analyses to avoid delays.
Timeline for confirmatory trials. The draft guidance states that a confirmatory trial’s target completion date should be “consistent with diligent and timely conduct.” This language is too broad and subjective, resulting in a wide range of timelines for target completion dates, many of which will be lengthier than necessary. Since these are just the target completion dates, the actual completion dates are likely to be even later, and there are no specific warnings or penalties in the guidance of how the FDA plans to strengthen accountability. Instead of this vague wording, the FDA should specify that confirmatory trials should be completed within 1-3 years of accelerated approval, depending on how rare the disease is and how large and longitudinal the study is.That is consistent with a review of oncology drugs granted accelerated approval from December 11, 1992, to May 31, 2017.[1] Although 40% of the 93 indications had not yet completed confirmatory trials or verified benefit when the study was published in 2018, those with confirmatory trials underway at the time of approval were verified after a median of 3.1 years. For the 9 indications without ongoing trials at the time of approval, those that were verified later were verified after a median of 5.5 years, ranging from 0.5 to 12.6 years. Additionally, 8 indications had remained on the market for more than 5 years without verifying their benefit, and 5 indications (5%) were withdrawn from the market. These findings confirm that a substantial percentage of confirmatory studies experience delays or remain incomplete for extended periods, highlighting the need for stronger regulatory oversight to ensure timely completion and protect patient safety.
Patient Enrollment Prior to Approval. The current guidance states that “enrollment of the confirmatory trial has been initiated.” This needs to be clarified. Does “enrollment has been initiated” mean that:
- one or more patients were enrolled
- or some number or percentage of patients have been identified as suitable but have not yet agreed to participate
- or some number or percentage have started providing baseline data
- or some number or percentage of patients have started treatment
- or some number or percentage of patients have almost completed treatment?
A 2015 study found that 19% of clinical trials failed to meet accrual goals or were terminated early due to insufficient enrollment, with recruitment challenges cited as a major barrier to trial completion.[2] That is why it is essential that “enrollment has been initiated” be defined as a substantial number of patients (such as 25 patients or 25% of patients, whichever is larger) already have been in treatment long enough to determine if adverse events or other missing data are likely to be a problem.That would better ensure that the trial is feasible as designed.
We agree with the guidance that completion of a confirmatory trial will be compromised when a drug granted accelerated approval becomes available on the market. This is especially a concern when the trial is a randomized, blinded trial, but it is also important to ensure an appropriate comparison sample for any confirmatory study. For that reason, it is essential that all patients be enrolled for most of the planned length of the trial prior to granting accelerated approval or at least prior to making the newly approved drug available on the market. FDA should not permit researchers to break the blinding of an ongoing study or switch to open label as soon as a product has been approved, because it undermines the integrity of the study and makes any results inconclusive or potentially inaccurate. That is unfair to all the patients who enrolled in the study, whether in the experimental or control group, because the study becomes useless in terms of determining the safety and efficacy of the treatment compared to a control group.
We agree with the guidance that “to ensure the confirmatory trial enrolls and retains sufficient U.S. participants, the sponsor’s enrollment strategy should prioritize early U.S. recruitment.” Because of demographic differences, differences in health habits, and differences in medical care and medical systems, U.S. study participants should be considered the most important study population for confirmatory trials submitted to the FDA. However, we disagree with the guidance that implies it is sufficient for the U.S. recruitment “be closer to completion at the time of accelerated approval.” Instead, recruitment in the U.S. should be completed and the treatment of those U.S. study participants should be near completion.
Progress Reports. The 180-day progress reports need to be improved by requiring them to include recruitment rates, patient retention, adverse events and other safety concerns, and additional metrics that will help identify barriers to the timely completion of the study. FDA guidance should clarify what is acceptable and not acceptable if enrollment targets are not met or drop out rates or missing data undermine the integrity of the study.These reporting requirements will improve transparency and accountability and help ensure a level playing field among companies conducting confirmatory trials.
Concerns Regarding Rare Disease Trials. The FDA acknowledges the unique challenges of conducting randomized post-marketing confirmatory trials for certain rare diseases, particularly those with very small populations and high unmet need. As a result, the proposed guidance permits non-randomized post-marketing studies and, in some cases, does not require that a confirmatory trial be underway before granting accelerated approval—provided there is appropriate justification.
While we recognize the difficulties in patient recruitment and trial feasibility in rare disease settings, this plan is overly flexible and will inevitably result in patients, CMS, and other healthcare entities spending millions of dollars on treatments that have not been proven to provide meaningful clinical benefits. An example of this is the case with Sarepta accelerated approval drugs for Duchenne Muscular Dystrophy.[3] Without a clear requirement that studies be underway, patients will not have the information they need to make informed treatment decisions for many years, and meanwhile other companies will have less incentive to develop new treatments and conduct their studies in a timely manner. Furthermore, the FDA guidance allowing confirmatory trials to be a continuation of the accelerated approval’s trial evaluating the same surrogate endpoint should not be considered to be a confirmatory trial, since many surrogates do not accurately predict a clinically meaningful outcome. However, continuing the initial study for a confirmatory trial that follows the study participants for a longer period of time to evaluate a meaningful clinical endpoint should be encouraged. We previously raised our objection to confirmatory trials that use unproven biomarkers and surrogate endpoints that are not clinically meaningful in our comment for the guidance entitled “Expedited Program for Serious Conditions—Accelerated Approval of Drugs and Biologics” [Docket No. FDA-2024-D-2033], which highlighted the need for stronger evidence.[4]
Patients with rare diseases are desperate for treatments, but deserve better efficacy evidence than has often been provided by the many expensive treatments approved by the FDA. Patients will not get the evidence they need unless the FDA requires specific enrollment milestones pre-approval and a clearly defined timeline for confirmatory trials, with FDA providing incentives to comply and penalties or disincentives for non-compliance. If studies take longer than promised, the FDA should require companies to allow patients to have free access to the drugs under the FDA’s expanded access program until the confirmatory trial is completed. This would balance the need for patient access with scientific rigor and patient safety.
Conclusions
We support the FDA’s efforts to improve the accelerated approval process, but the vague wording of this guidance is very unlikely to achieve that goal. The FDA needs to be more specific and less “flexible” to ensure that confirmatory trials are completed within a few years of accelerated approval and that the trials provide the clinically meaningful information that patients need to make informed decisions.
References
[1] Beaver, J. A., Howie, L. J., Pelosof, L., Kim, T., Liu, J., Goldberg, K. B., Sridhara, R., Blumenthal, G. M., Farrell, A. T., Keegan, P., Pazdur, R., & Kluetz, P. G. (2018). A 25-year experience of US Food and Drug Administration accelerated approval of malignant hematology and oncology drugs and biologics: A review. JAMA Oncology, 4(6), 849–856. https://doi.org/10.1001/jamaoncol.2017.5618
[2] Bull, J., Uhlenbrauck, G., Mahon, E., Furlong, P., & Roberts, J. (2015, September 3). Barriers to clinical trial recruitment and possible solutions: A stakeholder survey. Applied Clinical Trials. https://www.appliedclinicaltrialsonline.com/view/barriers-clinical-trial-recruitment-and-possible-solutions-stakeholder-survey
[3] Bendicksen, L., Zuckerman, D. M., Avorn, J., Phillips, S., & Kesselheim, A. S. (2023). The Regulatory Repercussions of Approving Muscular Dystrophy Medications on the Basis of Limited Evidence. Annals of internal medicine, 176(9), 1251–1256. https://doi.org/10.7326/M23-1073
[4] National Center for Health Research. (2025, February 4). Public comment on FDA draft guidance: Expedited program for serious conditions—Accelerated approval of drugs and biologics (Docket No. FDA-2024-D-2033). National Center for Health Research. https://www.center4research.org/nchr-comment-accelerated-approval-draft-guidance