The Enrollment Cliff in a Two-Arm Device Trial
You are the PM for a 220-subject, two-arm randomized trial of a wound-care device at 9 sites. Month 9 of an 18-month enrollment window. Target was 12 subjects/site/month; actual is 4.2. Two sites (both high-enrolling on paper) have enrolled 0 in 11 weeks after their sub-investigator left; a third site has screened 31 but randomized only 6, with 19 screen failures concentrated on one exclusion criterion. The sponsor's contract has a milestone payment tied to 50% enrollment by Month 10, and the CRO's site payments are per-randomized-subject, so the zero-enrolling sites have no financial incentive to fix their pipeline. The protocol is under a FDA-cleared IDE; a protocol amendment to relax the exclusion criterion would take an estimated 10-14 weeks including IRB review at all sites.
1. What is the highest-leverage first action, and how do you sequence the options against the Month 10 milestone?
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Separate the problem into three distinct failure modes, because they have different fixes and different timelines:
Zero-enrolling sites (capacity problem). 11 weeks with no sub-investigator is a staffing failure, not a protocol problem. Immediate action: escalate to the site PI and institution in writing, request a named replacement investigator with a dated start, and confirm the delegation of authority will be updated. In parallel, assess whether their IRB-approved staff can pre-screen from existing clinic lists so the pipeline is warm when the investigator starts. If no replacement is committed within ~3 weeks, activate a pre-qualified backup site - but note a new site needs IRB approval and a contract, so this is a Month 13+ lever, not a Month 10 lever.
High-screen-failure site (eligibility problem). 19 of 31 failing on one criterion is a signal, not noise. Pull the screening log and characterize the failures: are they genuinely ineligible, or is the criterion being misapplied? If misapplied, a targeted retraining and a screening checklist can recover subjects within weeks - no amendment needed. If genuinely ineligible, that site's population doesn't match the protocol and its forecast should be revised down, not propped up.
Systemic underperformance (structural problem). 4.2 vs 12 across all sites means the 12/site/month assumption was wrong. An amendment is the right long-term fix but at 10-14 weeks it lands around Month 22-24 - after the enrollment window closes. Do not let the amendment become the plan for the milestone.
Sequencing for Month 10: (a) this week - screening-log review at the high-screen-failure site and a written escalation to the two dark sites; (b) weeks 1-3 - retraining where misapplication is found, investigator replacement confirmed or backup site initiated; (c) week 2 - a revised enrollment forecast by site with documented assumptions, taken to the sponsor before the milestone date rather than after. The forecast is the deliverable that protects the relationship: it converts "we missed" into "here is the recovery plan and the decision you need to make." Initiate the amendment in parallel for the long-term fix, but explicitly decouple it from the milestone conversation.
Contract angle: flag to the sponsor that per-randomized-subject CRO payments remove any incentive for the dark sites to work their pipeline. Proposing a modest per-screened-subject or per-activated-site component is a structural fix that costs little and addresses the root cause.
2. The sponsor asks you to "just relax the exclusion criterion now and paper the amendment later." How do you respond?
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Decline, clearly and without hedging, and explain the mechanism rather than just citing a rule.
The device is under an FDA-cleared IDE. The protocol as approved by the IRB defines the population in which the investigational device has been determined to be safe and effective enough to study. Enrolling a subject who does not meet the current criterion means enrolling them outside the approved protocol and outside the IRB-approved consent document's description of the study. That is a protocol deviation at minimum; if done deliberately and systematically at your direction, it is a serious noncompliance finding that can trigger:
- IRB suspension of enrollment at affected sites,
- a reportable event to FDA and possibly a clinical hold on the IDE,
- invalidation or exclusion of those subjects from the analysis, which is the opposite of the enrollment goal,
- personal and institutional liability for you and the investigators.
The "paper it later" framing is the tell: a retroactive amendment cannot make an already-enrolled ineligible subject eligible, because the subject was consented under the old criteria and the IRB never reviewed the change.
What to offer instead - give the sponsor a real path so the refusal isn't a dead end:
- Fast-track the amendment with a compressed but complete package: a written rationale with the screening-log data showing how many subjects the change would recover, a safety analysis of what relaxing the criterion means for the risk profile, and a request for expedited IRB review where the change qualifies as minor.
- Ask sites to pre-identify and hold potentially eligible subjects so they can be screened the day the amendment is approved.
- If the criterion can be clarified without changing its substance (e.g., the site is misreading a lab threshold), a clarification memo and retraining is legitimate and immediate.
Document the request and your response in the project file. If the sponsor persists, escalate through your organization's regulatory/QA function and the sponsor's clinical/regulatory lead - not just the commercial contact who asked.