Regulatory Guidance

On August 3, 2026, FDA announced the availability of a draft guidance for industry titled “Biosimilar and Interchangeable Biosimilar Products: Considerations for Container Closure Systems and Device Constituent Parts” (Docket FDA-2026-D-4272, 91 FR 48880-48882). The document matters because it is the first time FDA has proposed a dedicated, standalone framework for how sponsors of biosimilar and interchangeable biosimilar combination products — prefilled syringes, autoinjectable pens, and similar delivery devices — should build the chemistry, manufacturing, and controls (CMC) package for the container closure system and device constituent part, rather than relying on a single Q&A entry buried in a broader biosimilar policy document.

What FDA Is Actually Proposing — The Key Provisions That Will Change CMC Programs

Until now, FDA’s expectations on this topic lived in exactly two places: Q.I.4 of the 2021 “Questions and Answers on Biosimilar Development and the BPCI Act” guidance (86 FR 52154) and Section VIII of the 2019 “Considerations in Demonstrating Interchangeability With a Reference Product” guidance (84 FR 21342) — both treating container closure and device presentation as a secondary topic within a broader framework. This draft elevates it to its own document, and FDA states plainly that once finalized, it will update Section VIII of the Interchangeability guidance and remove Q.I.4 of the Biosimilar Q&As outright — meaning practitioners should read this draft as the forthcoming authoritative source, not a supplement to the existing text.

The operative CMC requirement is stated directly in the draft: “a general description of the entire presentation should be provided in the chemistry, manufacturing, and controls (CMC) section of the application,” and “there should be complete CMC information for the proposed container closure system and any device constituent parts,” including extractable/leachable studies, performance testing, and stability studies. None of that is new in principle — extractables/leachables and performance testing are established expectations for any parenteral container closure system — but codifying it for the 351(k) biosimilar pathway specifically closes a real gap: sponsors previously had to infer these expectations from general drug product CMC guidance rather than from biosimilar-specific text.

The more consequential new element is the three-part comparative analysis framework for evaluating user-interface differences between the proposed biosimilar combination product and its reference product: a physical comparison of the device constituent part itself, a comparative task analysis of how a patient or caregiver actually operates the device relative to the reference product, and a labeling comparison conducted side by side, line by line. FDA frames this as the mechanism for deciding whether presentation differences require additional data — and, critically, the draft confirms that a sponsor can seek licensure in a materially different presentation than the reference product (for example, an autoinjector where the reference product is supplied in a vial), provided the biosimilarity standard is met and the difference does not introduce a condition of use, dosage form, strength, or route of administration the reference product does not already have. Human factors data may be required to support that determination.

What the Industry Must Push Back On — The Provision That Creates Implementation Problems

The comparative task analysis is the provision that most needs a comment. FDA has published the requirement to conduct one, and it has published the outer boundary of acceptability — a design difference cannot produce a “clinically meaningful difference in safety, purity, or potency” relative to the reference product — but nothing in the Federal Register notice or the underlying guidance text, as reported, specifies what quantitative or qualitative evidence satisfies that standard for a device comparison. This is a Category 1 (Specification Standard)-adjacent gap: it does not set a numeric specification, but it sets the basis on which a sponsor’s human-factors and comparative-use data package will be judged, and every combination-product biosimilar program filed after this guidance is finalized will need to build its comparative task analysis against that undefined bar.

The practical risk is inconsistent internal FDA review. Without illustrative examples — even non-binding ones, of the kind FDA has provided in other human factors guidances — two review divisions could reach different conclusions about whether a difference in actuation force, injection time, or dose-confirmation feedback between a proposed autoinjector and a reference prefilled syringe is “clinically meaningful.” A sponsor building a formal comparative task analysis plus a summative human factors study — commonly a $2-4 million program for a self-administered biologic combination product — needs enough specificity at the protocol-design stage to avoid re-running studies after a mid-review deficiency letter. FDA got the underlying policy right — a sponsor should be free to differentiate on device design without replicating the reference product’s exact hardware — but the guidance as summarized does not yet give sponsors the tools to build a comparative task analysis with confidence FDA will accept the result.

The Comment Window Strategy — How to Structure a Submission That Changes the Final Guidance

The comment period closes October 2, 2026 — a standard 60-day window from the August 3 publication date, which is itself a signal FDA does not consider this a high-controversy topic requiring the longer 90-day period reserved for complex or high-impact guidances. That is exactly why a well-constructed comment has outsized influence here: comment volume on this docket will likely be modest, dominated by a handful of large biosimilar sponsors and device-focused law firms, which means a comment built on the four-element framework — specificity, scientific evidence, implementation impact, and an alternative proposal — has a real chance of shaping the final text rather than being one voice among hundreds.

The strongest comment opportunity is requesting FDA publish illustrative acceptance-criteria examples for the comparative task analysis, addressing what magnitude of difference in device-operation steps, actuation force, or user error rate would and would not be considered clinically meaningful. A second, narrower comment should ask FDA to clarify how the extractable/leachable and performance-testing expectations here interact with the Agency’s separate International Council for Harmonisation (ICH) Q3E extractables and leachables draft guidance (Docket FDA-2025-D-4678, comment period closed January 30, 2026), so sponsors are not required to run duplicative studies under two independently evolving frameworks. A third comment, addressed to the “different presentation” pathway, should request a worked example illustrating when a change from vial to prefilled syringe or autoinjector is and is not viable under the guidance’s stated limits — right now sponsors are inferring that boundary from a single illustrative sentence in the Federal Register summary.

The XGene Combination Product Draft Guidance Comment Architecture

1. Impact Assessment: Map every active or planned 351(k) biosimilar combination-product program against the three-part comparative analysis framework (physical comparison, comparative task analysis, labeling comparison) to identify which programs will need new comparative-use data before their next FDA interaction.

2. Comment Letter Architecture: Build each comment around FDA’s own four-element standard — cite the exact provision (Section VIII cross-reference or the specific paragraph of the new draft), support the request with human factors literature or prior FDA-accepted comparative-use precedent, quantify the cost and timeline impact of proceeding without clarity, and propose specific alternative language FDA can adopt.

3. CMC Gap Analysis: Cross-check extractable/leachable and performance-testing commitments already made in an open Investigational New Drug Application (IND) or Biologics License Application (BLA) CMC section against this draft’s stated expectations, flagging any program where the existing container closure data package would need supplementation before a 351(k) submission.

4. FDA Pre-Comment Engagement: For sponsors with a program directly affected by the “different presentation” pathway, request an early Type C or biosimilar initial advisory meeting before the guidance is finalized, using the draft’s own encouragement of “discussions with the Agency early during the development of such products” as the basis for the meeting request.

Under XGene’s tier framework: the comparative task analysis provision is comment-worthy, the extractables/leachables cross-reference is clarification-worthy, and the general product-quality consolidation effort is support-worthy — FDA consolidating scattered CMC expectations into one document is a genuine improvement worth endorsing even while pushing for more specificity elsewhere.

XGene Consulting works with biosimilar and interchangeable biosimilar sponsors on CMC regulatory strategy for combination products, including draft guidance impact assessment and FDA comment letter architecture. If your program includes a device constituent part that differs from its reference product’s presentation, this is the window to shape how FDA will evaluate that difference — reach out to discuss your program’s specific exposure before October 2, 2026.