Regulatory approval is regarded as the defining milestone of drug development. In competitive therapeutic areas, earlier approval can make a therapy available to eligible patients sooner.
In 2019, the FDA approved Trikafta™, a triple-combination therapy for patients with cystic fibrosis. This program benefited from multiple expedited development and review mechanisms including Priority Review, Fast Track, Breakthrough Therapy and orphan drug designation.
While the approval was welcomed by patients, it also highlights an important regulatory question: do expedited pathways change the evidentiary requirements for approval? In my experience, they do not. Rather, these mechanisms enable earlier engagement with regulators, prioritised review and more innovative development approaches, while maintaining expectations for robust evidence, mature Chemistry, Manufacturing, and Controls (CMC) data, manufacturing control or quality assurance.
In my view, acceleration depends less on regulatory compression and more on early reduction of scientific, quality and manufacturing uncertainty. Regulatory readiness is therefore not a submission activity; it is a development discipline.
As Regulatory Science director at Cytiva, I’ve supported developers across a range of therapeutic modalities. In my experience, promising drug candidates can lose time late in development when analytical methods aren’t sufficiently mature, supplier documentation is incomplete, or manufacturing changes haven’t been assessed early enough for comparability impact. I’ve also seen programs that addressed these issues earlier become better positioned to respond to regulatory questions and maintain momentum.
These experiences have reinforced a simple belief: regulatory readiness isn’t achieved through a last-minute push. It should be built in from the start.
In my work, four practical principles repeatedly emerge:
1. Engage regulators early and make the questions decision-ready
Early interactions with regulators help test assumptions, clarify evidential expectations and identify gaps while the program can still be adjusted. This can be particularly important for novel modalities, where precedents for manufacturing approaches and analytical methods may be limited.
Recent FDA guidance highlights the importance of having structured discussions throughout drug development, using meeting types such as pre-IND, Type B (including pre-IND), Type C, Type D and INTERACT meetings based on the stage of development and the questions being addressed. Type D meetings are particularly relevant where you need input on a narrow set of critical issues or follow-up questions that could affect development progress.
In my experience, the most effective engagement focuses on questions that could change development decisions, such as the acceptability of an endpoint, control strategy, comparability plan or manufacturing change.
In one program I supported, a developer preparing for first-in-human studies using an early regulatory interaction to discuss evidence expected for a novel analytical method and manufacturing control strategy. The discussion didn’t remove work from the program. It helped the team prioritize relevant studies earlier and reduce the likelihood of redesigning the CMC package later.
I’d advise developers to map the likely pathway before pivotal decisions are fixed, identify relevant authorities, assess whether expedited or innovation programs may apply and anticipate regional differences. A global strategy should preserve a common evidence base while identifying questions that require region-specific engagement.
Keep your briefing packages concise, evidence-based and decision-oriented. They should define the question, explain why feedback is needed now, present the scientific rationale, and describe how identified risks will be controlled. Regulatory advice should then be translated into accountable development actions.
2. Put CMC and manufacturing readiness on the critical path
Clinical efficacy alone doesn’t create an approvable or commercially viable therapy. Developers also need to show that the product is well-characterized, the process is understood, relevant variability is controlled and supply can be maintained consistently.
A program may be clinically advanced, yet you may still face approval questions if methods are immature, critical materials are poorly controlled, process knowledge is incomplete, or commercial-scale manufacturing hasn’t been planned. Manufacturing development, analytical maturity, stability data and process understanding take time to build and can’t simply be reconstructed shortly before filling.
Published reviews of a set of released FDA Complete Response Letters (CRLs) reported that facility and quality-related issues were more common than both clinical safety and efficacy issues combined (1).
In my view, CMC readiness should start during process development. An integrated clinical, regulatory and manufacturing roadmap should define the evidence required at each milestone, including material controls, analytical development, impurity characterization, stability, comparability, process validation, facility readiness and commercial supply planning.
While this may feel a lot of premature work when teams are balancing evolving data and competing milestones, I’ve seen the benefits play out. In one program I supported, early review of supplier documentation identified gaps in material traceability and change notification commitments before pivotal development. The team addressed those gaps while it still had more flexibility to strengthen its controls.
Finally, ensure your roadmap shows key interdependencies. Changes to materials, manufacturing steps, scale, sites or analytical methods may affect comparability, stability commitments, clinical supply and future submissions. Good CMC planning makes these risks visible before they become late-stage constraints.
3. Control quality risks at the source and use innovation deliberately
Quality should be designed into your process. Critical quality attributes and process risks should be defined early. End-product testing remains essential, but it can’t be a substitute for control of variability, contamination or impurities within the manufacturing process.
When a manufacturing approach is intended to reduce a defined risk, your regulatory rationale should explain the problem, mechanism, context of use, supporting evidence, controls and limitations. This creates a scientifically credible argument without relying on claims about a specific platform.
Impurity control should also be mechanism-based. Regulators will expect you to understand where impurities arise, how they are characterized, what risks they present and how your process controls or removes them across batches and scales.
Documentation should be generated as the evidence develops. Development reports, risk assessments, method history, deviations, change assessments and scientific decisions should form a maintained knowledge base. This makes it easier to explain your rationale shortly before submission.
Being proactive pays off. For example, a team I worked with were preparing an aseptic manufacturing line for audit identified environmental monitoring weaknesses several weeks ahead of inspection. By addressing quality, trend analysis and procedural clarity early, the team was better prepared to demonstrate control rather than reacting under inspection pressure.
Change management should support innovation without losing traceability. Changes to materials, equipment, sites, scale or analytical methods may trigger comparability, validation or filing requirements. The goal is to introduce change with sufficient evidence to protect the program.
Manufacturing innovation can improve your process control, consistency, reliability and supply resilience when it’s justified and controlled. Novelty alone isn’t evidence of regulatory readiness. You need to define intended use, demonstrate maturity and characterize both benefits and risks.
4. Design early decisions for commercial scale and lifecycle success
In my experience, scale-up risks are often identified later than teams would like. Decisions that are efficient at laboratory or early clinical scale may create constraints in validation, routine manufacturing, quality control or supply continuity.
I’ve seen processes rely on manual interventions, scarce materials, unsuitable analytics or equipment that can’t transfer to a commercial facility. Planning for commercial scale doesn’t require premature investment in full-scale capacity. It means considering whether early choices could make reliable supply difficult later.
You should plan early for future manufacturing needs by translating patient population, dosing and demand assumptions into batch size, facility capacity, testing and material requirements. It’s also useful to consider how process parameters and controls may change with scale.
Materials and equipment should be selected for lifecycle suitability, including quality, scalability, supplier documentation, change-notification commitments, availability and security of supply. A convenient research material may become a comparability risk if replaced late in development.
If you expect your manufacturing process to evolve, the transition point and the required comparability and regulatory evidence should be defined before pivotal studies or filing strategy are locked.
Technology transfer should be treated as transfer of process knowledge, not only a batch record. Transfer to a CDMO or commercial site requires clear documentation, qualified methods, reference materials, training and retained process understanding.
I’ve supported a program where early supplier engagement helped identify equipment and consumable limitations before a developer’s process was locked for later-stage development. The team could then adjust their scale-up strategy while they still had room to generate the necessary evidence, rather than introducing a major change close to filing.
Early supplier collaboration can help identify scale-up limitations, documentation gaps and change-control risks before they affect submission quality or commercial supply.
Make regulatory readiness part of your development
In my view, regulatory readiness helps teams resolve important uncertainties early, generating evidence that can withstand regulatory scrutiny and building processes capable of supplying patients consistently at scale.
The regulatory strategies I’ve seen work well connect clinical development, manufacturing, quality, supply and commercial objectives in a coherent plan.
Ultimately, regulatory readiness is not an administrative step on the way to commercial success. It is one of its scientific and operational foundations.
References
- Siciliano B. Anatomy of a Rejection: A Data-Driven Analysis of 202 FDA Complete Response Letters. Radyus R&D; July 22, 2025.
- U.S. Food and Drug Administration. FDA approves new breakthrough therapy for cystic fibrosis. 21 October 2019.
- U.S. Food and Drug Administration. Trikafta approval package, NDA 212273. Approval date: 18 October 2019.
- U.S. Food and Drug Administration. Chemistry, Manufacturing, and Controls Development and Readiness Pilot Program.
- Federal Register. FDA’s Strategy Document on Facilitating Chemistry, Manufacturing, and Controls Readiness for Products With Accelerated Clinical Development. 23 July 2026.
- U.S. Food and Drug Administration. Formal Meetings Between the FDA and Sponsors or Applicants of PDUFA Products: Guidance for Industry. August 2026.
- openFDA. Complete Response Letters database.
- U.S. Food and Drug Administration. FDA embraces radical transparency by publishing Complete Response Letters. 10 July 2025.
