The Reality of Early-Phase Clinical Trial Timelines in 2026
Despite advances in clinical trial regulation, infrastructure, and technology, early-phase clinical trials continue to miss timelines with striking consistency. These delays are rarely the result of a single issue. Instead, they arise from a combination of interdependent challenges spanning protocol design, site capacity, start-up execution/regulatory approval process, IMP readiness and finalisation, contracting timelines, and internal sponsor operations.
Several themes consistently define early-phase delivery in 2026. Timelines are systematically overestimated. Site capacity, not site interest, is the true constraint. And critically, misalignment across Investigational Medicinal Product (IMP) readiness, site contracting timelines, and delivery models continue to drive avoidable delays in clinical research.
This paper explores these challenges in depth and provides a practical perspective on how sponsors can improve predictability in early-phase development.
Why Clinical Trial Timelines Slip: The Four Core Bottlenecks
1. Structural Misalignment: Planning vs. Execution
Early-phase trials are still frequently planned using assumptions that reflect ideal conditions in medical research rather than operational reality and clinical studies designed with the participants in mind. Sponsors often rely on best-case scenarios when forecasting timelines, assuming efficient site activation, rapid recruitment, and minimal disruption while gathering safety and efficacy data for their drug or device.
In reality, variability is the defining characteristic of early-phase delivery. Each stage introduces uncertainty, and these uncertainties usually accumulate. Small delays in start-up lead to downstream recruitment challenges, while overly optimistic feasibility assumptions create structural gaps that are difficult to recover from.
The result is not a single point of failure, but a gradual erosion of timeline integrity from the outset.
A key issue is that designing a study is often disconnected from execution. Decisions are made based on theoretical capability rather than current conditions. This disconnect is particularly visible in site selection and feasibility, where interest is frequently mistaken for time and availability.
2. Start-Up: The Most Underestimated Phase
Start-up remains one of the most critical and underestimated phases of early-phase trials. While timelines of the regulatory approval process have improved, operational timelines have not kept pace.
The period between approval and activation is often assumed to be predictable, yet it is influenced by multiple variables including contract negotiation, drug readiness, site readiness, and institutional processes. Delays during this phase are rarely recovered later in the study.
Treating start-up as an administrative step rather than a strategic phase is one of the most common and costly mistakes in early-phase clinical research.
Effective start-up requires active management, clear prioritisation, and close alignment between sponsor, CRO, and site teams. Without this, delays accumulate quickly and set the tone for the remainder of the trial.
Clinical trial timelines
| Phase | Typical Timeline (Industry Assumption) | Realistic / Observed Timeline | Optimised Timeline (Best Practice) |
|---|---|---|---|
| Protocol Finalisation | 2-4 weeks | 4-8 weeks (internal alignments and multiple review cycles, feasibility feedback) | 3-5 weeks (early site & CRO input) |
| IMPD Readiness | Aligned with study regulatory submission | Frequently delayed / iterative | Locked prior to study planning |
| Site Contracting | 4-6 weeks | 8-16 weeks (negotiation variability) | 6-10 weeks (parallel negotiation strategy) |
| Site Activation | Immediate post-approval | 4-8 weeks delay (contracting, readiness, availability of site staff) | 2-4 weeks (pre-activation alignment) |
| First Patient In (FPI) | 1-2 weeks post-approval | 12-20+ weeks | 2-6 weeks |
| Recruitment (Early Phase) | Linear projection | Highly variable; capacity constrained and often stop-and-go due to study design (e.g. for dose groups) | Capacity-driven planning according to the study design |
| Total Study Start-Up to FPI | ~3 months | 5-9 months | 5-6 months |
Table 1. Comparison of typical, observed, and optimised early-phase clinical trial timelines. Based on industry experience and common operational bottlenecks including IMP readiness, site contracting, and site capacity constraints.
3. IMP and IMPD Readiness: The Hidden Critical Path
While operational and site-related challenges are widely recognised, delays related to drug/ investigational medicinal product (IMP) availability and IMPD readiness remain some of the most significant, and frequently underestimated, drivers of early-phase timeline slippage.
In many studies, IMP manufacturing sits firmly on the critical path. However, timelines are often built on optimistic assumptions, particularly where manufacturing processes are still being developed, transferred, or scaled. This is especially relevant in early-phase programmes where processes are not yet fully stabilised.
Delays can arise from process development challenges, batch failures, release testing timelines, and dependencies on external manufacturing partners. In addition, placebo manufacturing is often underestimated in both complexity and lead time, particularly where matching requirements are stringent. Alongside this, the timing and completeness of the IMPD (Investigational Medicinal Product Dossier) plays a critical role. In early-phase settings, IMPDs are frequently still evolving during CRO selection and early planning stages. Where there is limited transparency, or where timelines are presented optimistically, the effect can be misaligned assumptions across the study team.
CROs may plan based on expected readiness dates that are subsequently delayed, leading to knock-on impacts across regulatory approval process, site activation, and overall study timelines. In some cases, incomplete visibility of CMC readiness results in premature study planning and inefficient sequencing of start-up activities.
The consequence is straightforward but significant. Drug Studies are unable to proceed with regulatory applications due to lack of available IMP or incomplete documentation. A study cannot start without regulatory approvals and drug supply, yet IMP and IMPD readiness are often not fully integrated into early planning assumptions.
4. Site Contracting: The Persistent European Bottleneck
While improvements have been made in certain regions, including Germany and the UK, site contracting usually remains one of the most consistent and time-consuming drivers of delay in early-phase trials.
Unlike regulatory timelines, which have seen increasing standardisation, contracting remains highly variable. Budget negotiations, legal terms, and institutional requirements differ across sites and countries, introducing a level of unpredictability in clinical research that is difficult to fully control. Even where standard templates are used, local adaptations and internal review processes can extend timelines significantly. In practice, contracting timelines are often underestimated during planning, with assumptions based on best-case scenarios rather than real-world experience.
This variability has a direct impact on site activation. Delays in contract execution prevent sites from initiating, regardless of regulatory status or investigator readiness. As a result, drug or device trials that appear operationally ready are effectively paused at the final step before activation.
In many early-phase trials, contracting, not regulatory approval, becomes the true pacing factor for site activation.
This is particularly relevant in multi-country European trials, where differences in institutional processes and negotiation approaches can create uneven activation timelines across regions.
Strategic Solutions to Improve Clinical Trial Timeline Predictability
From Site Interest to Real Site Capacity
Site capacity has become another defining constraint in early-phase trials. While there is no shortage of interested investigators, there is a limited pool of sites with the resources and availability to include patients and deliver consistently. High-performing sites are often engaged in multiple studies with many patients simultaneously. This limits their ability to prioritise new drug and device trials, regardless of scientific interest. As a result, recruitment projections based on feasibility responses frequently fail to materialise.
Sponsors often attempt to mitigate this risk by increasing the number of sites, even for a low number of patients. However, this introduces additional complexity without addressing the underlying constraint. More sites mean more variability, more contracts, and greater coordination challenges.
The focus should shift from identifying interested sites to identifying available capacity. This requires a more rigorous and realistic approach to feasibility, patient recruitment strategy and site selection.
Designing Protocols for Clinical Trial Execution
Protocol complexity continues to increase, driven by scientific ambition and regulatory expectations. However, this complexity often creates operational challenges that are not fully considered during design.
More complex protocols increase burden on both sites and patients. This can reduce recruitment rates, increase screen failures, and slow overall trial progression. In some cases, protocols are not aligned with standard clinical workflows or patients’ personal lives, creating additional friction.
Balancing scientific objectives with operational feasibility is essential. Protocols that are not designed with execution in mind will inevitably face delivery challenges and slow the clinical trial timeline.
Aligning IMP Readiness with Clinical Trial Planning
Clinical trial supply chains are complex and subject to uncertainty in patient recruitment, making it essential to incorporate drug/ IMP Readiness directly into the study startup plan to ensure continuous drug availability throughout patient treatment.
For example, a key strategy is early and dynamic drug demand forecasting, supported by scenario-based planning to address variable enrollment rates. This enables more flexible supply approaches, such as optimized safety stock or just-in-time manufacturing. Regulatory requirements, particularly under frameworks like the EU Clinical Trials Regulation (CTR), further require parallel planning to ensure compliant labeling and timely batch release.
In addition, risk mitigation strategies-such as overage planning, flexible distribution models, and robust logistics oversight are essential to handle uncertainties like shipment delays or changing dosing needs.
CRO Model Mismatch and Its Impact on Clinical Trial Timelines
The assumption that larger CROs reduce risk is deeply embedded in the industry. A key differentiator in early-phase delivery is the ability to identify and address risks early, particularly around IMP readiness and contracting timelines, which are often underestimated at study outset. However, early-phase studies require a different approach to delivery.
Large CROs are typically optimised for scale, efficiency, and standardisation. These strengths are valuable in late-phase programmes but can be less effective in early-phase settings where agility and responsiveness are critical.
Sponsors may experience reduced senior oversight, slower decision-making, and less flexibility. These factors can contribute to delays, particularly when rapid adjustments are required.
The key issue is not capability, but alignment. The most effective CRO model for early-phase trials is one that prioritises focus, senior involvement, and close operational alignment.
Improving Predictability
Improving clinical trial timeline predictability requires a shift in approach. Sponsors must move away from optimistic planning and towards realistic execution strategies.
This includes designing protocols with feasibility in mind, selecting sites based on capacity, and actively managing start-up. It also requires maintaining internal momentum and ensuring rapid, informed decision-making.
Selecting the right CRO partner is a critical component of this strategy. The focus should be on alignment, responsiveness, and ability to execute, not just scale.
Looking for a resilient partner for your next clinical program?
Operational Perspective: Improving Clinical Trial Timelines with FGK Clinical Research / Clinicology
FGK Clinical Research (Clinicology UK) operates with a delivery model designed specifically for early-phase and mid-sized biotech sponsors. Our approach emphasises senior-led delivery, realistic planning, and close alignment across site capacity, IMP readiness, and contracting timelines, ensuring studies are set up for execution, not just approval.
We prioritise proactive communication, rapid issue resolution, and maintaining momentum throughout the study lifecycle. By focusing on execution and alignment, we aim to deliver more predictable outcomes for our clients.
Conclusion
Early-phase trial delays are not inevitable, but they are predictable. They arise from structural misalignment between planning and execution, and from assumptions that do not reflect operational reality.
Sponsors who address these challenges early can significantly improve delivery outcomes. In early-phase research and development, success is determined by alignment, focus, and execution, not scale.
About the Author:
Mark Thomas
Managing Director FGK UK
Mark is the founder and Managing Director of Clinicology Ltd, a specialized Contract Research Organization (CRO) based in Guildford, UK, which was acquired by FGK Clinical Research in 2024. Before founding Clinicology, he was founding director and board member of a medium sized global CRO. Mark has over 30 years of experience in managing pharmaceutical and medical device studies.
FAQs about Clinical Trial Timelines
How does IMPD readiness affect study start?
Delays in IMP availability and IMPD readiness can arise from manufacturing challenges, batch failures, and dependencies on external CMC partners as well as the fact that the IMPD is often still evolving in significant parts until being submitted in early phases. Site Initiation may have been planned based on expected readiness dates that are subsequently delayed, leading to delays across regulatory approval, study site activation, and overall study timelines.
Why does CRO staff continuity matter for biotech startups?
A low staff turnover ensures project continuity when a study transitions from planning to execution. Also, the difference for successful versus static study site management partly lies in relationships that go beyond what is written on paper: Sites perform better with CRAs and CRO contacts who support them on eye-level on a continuous basis.
How do timeline delays impact the overall budget of a drug or device trial?
Operational delays can cost anywhere from thousand to tens of thousands of euros per day, depending on the trial and even more it later stages in development. Especially for start-ups, delays can result in the end of clinical development if no financial buffer is available and investors may loose confidence.
Download our full whitepaper “Clinical Trial Timelines: Why Early-Phase Studies Slip and How To Improve Predictability”