CBER’s Learnings on Regenerative Medicine Development Reflected in Guidance Updates

By James E. Valentine & Josephine M. Torrente & Jeffrey K. Shapiro & Sarah Wicks* —

With a little over a year under FDA’s belt implementing its Comprehensive Regenerative Medicine Policy Framework (which we blogged about here), CBER has updated its current thinking with the issuance of final versions of the two Regenerative Medicine Advanced Therapy (“RMAT”)-related guidance documents:

It is obvious from the nature of many of the changes found in these final guidances that they are based upon learnings by CBER’s Office of Tissues and Advanced Therapies (“OTAT”) as it gains more and more experience with reviewing both a range of RMAT designation requests and more advanced cell and gene therapy development programs. Those of us that work in this space appreciate CBER’s continued attempts to keep the industry updated on its evolving regulatory framework. For example, many of the changes in these 2019 RMAT guidance documents were forecasted by Commissioner Gottlieb and CBER Director Marks in their January 2019 statement on new policies to advance the development of cell and gene therapies, which we blogged about here. These guidances go further than that statement by clarifying the types of therapies which are eligible for the RMAT designation program and the preliminary clinical evidence required to warrant expedited development and review.

There were no substantive changes to the guidance on Devices Used with RMAT (previously discussed here), so we will focus the remainder of this post on updates made in the final Expedited Programs for RMAT guidance (“2019 RMAT guidance”).

Updates to the RMAT Program

Before we describe the changes to the RMAT program, we first note that there were no substantive changes in the final guidance’s discussion of the 4 other expedited programs (i.e. fast track designation, breakthrough therapy designation, accelerated approval, and priority review) which are programs not specific to cell and gene therapies.

Definition of RMAT: Narrowing & Expanding Its Scope

The 2019 RMAT guidance clarifies FDA’s interpretation of regenerative medicine therapies as defined in Section 506(g)(8) of the Federal Food, Drug and Cosmetic Act (“FDC Act”). Section 506(g)(8) defines regenerative advanced therapy as “including cell therapies, therapeutic tissue engineering products, human cell and tissue products, and combination products using any such therapies or products, except for those regulated solely under section 361 of the Public Health Service Act (“PHS Act”) (42 U.S.C. 264) and [21 C.F.R. Part 1271].” The first update to the interpretation of this provision is with regard to cell therapies. FDA clarifies that it interprets “cell therapies” to include both allogeneic and autologous cell therapies, as well as xenogeneic cell products. 2019 RMAT guidance at 2.

Then, while the draft guidance included FDA’s interpretation that gene therapies meet the definition of a regenerative advanced therapy even though not explicitly listed in the statute (see discussion of this evolution here), the 2019 RMAT guidance clarifies that this interpretation is limited to “human gene therapies” and explicitly excludes microorganisms (e.g., viruses, bacteria, fungi) that are not genetically modified. Id. The 2019 guidance also states that genetically modified cells includes those that lead to a “sustained effect on cells or tissues”, moving away from requiring “durable modification of cells or tissues”. Id.

Clarifying How to Qualify for RMAT Designation

FDA provides additional clarification to sponsors surrounding the preliminary clinical evidence required for an investigational product to be eligible for RMAT designation. FDA considers it essential for preliminary clinical evidence to be generated using the product that the sponsor intends to use for clinical development. Id. at 6. This is directly in line with Commissioner Gottlieb and CBER Director Marks’ January 2019 joint statement on the development and regulation of cell and gene therapies. This statement emphasized that efficient development of cell and gene therapies will focus on perfecting the manufacturing of the final product prior to the initiation of clinical studies. In the 2019 RMAT guidance, FDA acknowledged that manufacturing regenerative medicine therapies is complex and noted that manufacturing changes made to products during the development program will not necessarily preclude or rescind RMAT designation, but rather be considered on a case-by-case basis. Id.

FDA also made a slight modification to the factors CBER will consider when determining whether preliminary clinical evidence is sufficient to support RMAT designation. Rather than consider the “nature and meaningfulness” of the outcomes, the 2019 RMAT guidance clarifies that the “consistency and persuasiveness” of the outcomes will be considered, among other listed criteria that remain unchanged (e.g., the rigor of data collection, the number of patients or subjects, and the number of sites, contributing to the data; severity, rarity, or prevalence of the condition, and bias). Id.

It is also noteworthy to mention that the 2019 RMAT guidance requires sponsors to provide not only a rationale for the investigational new drug meeting RMAT designation, but also a description of the product. This implies that companies may not have been providing sufficient information to allow FDA to make this determination when considering RMAT designation applications. Id. at 7.

CBER’s Evolution in Thinking about Developing Cell and Gene Therapies

Considerations in Clinical Trial Design

Similar to the draft version of the guidance, the 2019 RMAT guidance articulates that CBER will consider clinical trials that incorporate adaptive designs, enrichment strategies, or novel endpoints in support of a BLA for regenerative medicine therapies. The most substantive change to this section of the guidance is the addition of historical controls as an acceptable innovative trial design for regenerative medicine therapies. FDA clarifies that natural history data may provide the basis of a historical control, but “only if the control and treatment populations are adequately matched, in terms of demographics, concurrent treatment, disease state, and other relevant factors.” Id. at 11-12. Adequate matching on key prognostic factors has been a staple of FDA’s consideration of strength of historical controls, so it is not surprising to see CBER endorse this approach.

The guidance also adds that trial designs in which multiple clinical sites participate in a trial investigating a regenerative medicine therapy that is manufactured at each site using a common manufacturing protocol with the intent of sharing the combined trial data to support separate BLAs from each of the individual centers/institutions could be considered the “same drug” for purposes of orphan-drug designation and exclusivity. Id. at 12. This was also forecasted by the Commissioner and CBER Director Marks’ January 2019 statement, as noted above.

Relatedly, FDA clarifies that in these situations where a trial is conducted at a specified number of clinical sites, each site would be required to meet the BLA requirements, including current good manufacturing practice (“cGMP”) requirements. Flagging an important regulatory consideration for sponsors in this scenario, FDA recommends that sponsors address any concerns regarding orphan-drug exclusivity prior to agreeing to pool their data, which would prevent the approval of multiple BLAs. Id.

An Earlier Opportunity for Interactions Between Sponsors and CBER Review Staff

The last section of the 2019 RMAT guidance encourages sponsors of regenerative medicine therapies to engage with CBER OTAT review staff early in the product development process. The final guidance recommends that sponsors obtain early nonbinding, regulatory advice from OTAT through an “INitial Targeted Engagement for Regulatory Advice on CBER producTs” (“INTERACT”) meeting. Id. at 13. This appears to be the formalization of a “Pre-Pre-IND meeting” where sponsors can discuss early pre-clinical, pharmacology/toxicology, CMC, and clinical development issues that need to be addressed prior to moving forward with the submission of a pre-IND meeting request. More information on INTERACT meetings can be found here and here.

*Law Clerk