The sites closed out. Then Collection II opened.

Abstract

Background: The sponsor — a top-tier global diagnostics manufacturer¹ — commissioned a chronic-Hepatitis-B core-antibody specimen collection program (Protocol study, anti-HBc Total) to support assay verification work on its diagnostics platform. The protocol enrolled chronic Hepatitis B subjects with documented prior or current infection across two collections: Collection I (target ~100 qualified subjects) and Collection II (target ~50 qualified subjects).
Methods: RDI executed the program as full-service CRO with central monitoring and reference-lab testing. Two community-clinic sites were activated — Site B and Site A — selected for established chronic-Hepatitis-B patient panels. Collection I ran April–July 2025 with 104 subjects enrolled and 102 qualified at close-out. Collection II opened in early 2026 and was paused as one site disengaged; site re-engagement work in March 2026 recovered enrollment, and Collection II reached 45 enrollments by 30 April 2026.
Results: Cumulative enrollment crossed 75 by end-June 2025, 104 by Collection I close (end-July 2025), and reached 149 at the 30 April 2026 reporting date with Collection II contributing 45 of those subjects (Fig. 1). Site distribution was approximately balanced across the two community-clinic anchors (Site A 85, Site B 64) (Table 1). Collection I qualified-subject count of 102 of 104 (~98%) reflects strong eligibility-criterion enforcement at the screening front door rather than rejection at the laboratory back door.
Conclusions: Chronic Hepatitis B specimen collection is operationally a community-clinic problem rather than an academic-medical-center problem: established chronic-disease patient panels at community-clinic settings deliver higher screening-to-enrollment conversion than referral-based academic-center panels. Collection-to-collection site re-engagement, rather than new-site activation, was the principal lever to recover Collection II cadence.

Keywords: in vitro diagnostics; chronic Hepatitis B; serology; antibody markers; anti-HBc; community clinic; specimen collection; multi-collection design.

1. Background

The sponsor commissioned a specimen collection program to support assay verification on the chronic Hepatitis B core-antibody (anti-HBc Total) marker. Anti-HBc Total is a serologic marker of prior or current Hepatitis B virus infection; it is positive in subjects who have been infected at any point and remains positive lifelong in most cases. Subjects with chronic infection (HBsAg positive at ≥6 months) are the target population for assay verification work.²

The protocol structures collection in two waves: Collection I (a primary cohort target of approximately 100 qualified subjects) and Collection II (a follow-on cohort target of approximately 50 qualified subjects). The two-collection structure allowed sponsor analytical work on Collection I samples to inform any cohort-design refinements before Collection II opened. RDI executed both collections as full-service CRO from the same Van Nuys operational spine.

2. Constraints encountered

Four constraints shaped the execution plan:

Chronic-disease patient panel access

Chronic Hepatitis B subjects are not concentrated in academic transplant centers (the network used for the sponsor’s transplant programs). They are concentrated at community clinics with established hepatology, infectious-disease, or primary-care chronic-disease panels. The viable site set is small and non-overlapping with the sponsor’s other site networks.
Two-collection design

The two-collection structure introduces an inter-collection gap during which sites complete Collection I, sponsor performs Collection I assay work, and sites then re-mobilise for Collection II. The inter-collection gap is the operational risk: site staff turnover, panel attrition, and competing study commitments accumulate during that gap.
Site re-engagement after Collection I close

One of the two Collection I sites disengaged during the inter-collection gap and required active re-engagement to participate in Collection II. The re-engagement process — reconfirming PI commitment, refreshing site staff training, validating that the site’s patient panel still supported the protocol — ran in parallel with the second site’s steady ramp.
Eligibility-criterion enforcement at screening

Anti-HBc Total positivity alone is not sufficient for the chronic-cohort definition; subjects must meet the protocol’s chronic-infection criterion (commonly HBsAg positive at ≥6 months). Eligibility enforcement at the screening front door — rather than at the laboratory back door — is the dominant lever for Collection-I qualified-subject ratio.

Collection I closed at 102 of 104 qualified — a 98% qualified-subject ratio — reflecting eligibility enforcement at the screening front door rather than at the laboratory back door.

3. Methods

RDI executed the program as full-service CRO. Three operational moves are reported here in order of implementation.

3.1. Two-site community-clinic anchor

Two community-clinic sites were activated as the program anchor: Site B and Site A. Both sites have established chronic-disease patient panels with documented chronic Hepatitis B subjects, the underlying patient mix that drives screening-to-enrollment conversion at this protocol. Site initiation visits in early 2025 included protocol training, eligibility-criterion enforcement training (HBsAg duration confirmation), specimen-handling SOPs, and EDC training.

3.2. Collection I delivery (Apr–Jul 2025)

Collection I ran April through end-July 2025: 5 enrollments in April, 7 in May, 63 in June, 29 in July, totalling 104 subjects with 102 qualified at close-out. The June acceleration coincided with site-staff confidence in eligibility-criterion enforcement and with both sites running at full screening cadence.

3.3. Collection II site re-engagement (Feb–Apr 2026)

Collection II opened in February 2026. Initial Collection II enrollments were slower than Collection I cadence (6 in February, 3 in March), as one site required re-engagement after the inter-collection gap. Site re-engagement work in March 2026 included reconfirming PI commitment, refreshing site staff training, and validating that the patient panel still supported the protocol. The re-engagement closed in late March; April 2026 produced 36 enrollments — the second-highest single month of the program after June 2025 (63).

Collection I (Apr–Jul 2025)

104 enrolled, 102 qualified (~98% qualified-subject ratio). Two-site community-clinic anchor; protocol target met at close-out.

Collection II (Feb–ongoing 2026)

45 enrolled by 30 April 2026 (target ~50). Initial slow ramp (6 + 3 in Feb–Mar) recovered to 36 in April after site re-engagement work in March. On track for protocol-target attainment in May–June 2026.

4. Results

Cumulative enrollment crossed 12 by end-May 2025, 75 by end-June 2025, 104 by Collection I close (end-July 2025), and reached 149 at the 30 April 2026 reporting date with Collection II contributing 45 of those subjects (Fig. 1). The inter-collection gap (Aug 2025–Jan 2026) is visible as a flat segment in the cumulative curve; the Collection II ramp begins in February 2026 with the slow initial cadence noted above and recovers to a 36-subject month in April 2026.

Site distribution at the 30 April reporting date was approximately balanced across the two community-clinic anchors: Site A 85 subjects, Site B 64 subjects (Table 1; Fig. 2). Collection I qualified-subject count of 102 of 104 reflects screening-front-door eligibility enforcement; Collection II qualified-subject count is tracked weekly at the same enforcement standard.

Apr 2025 Coll I opens / 5 enrolled

Jun 2025 +63 / month peak

Jul 2025 Coll I close (104, 102 qual.)

Aug 2025 – Jan 2026 Inter-collection gap

Feb 2026 Coll II opens / +6

Mar 2026 Site re-engagement

Apr 2026 +36 / month recovered

30 Apr 2026 149 enrolled total

Table 1 Enrollment by site and by collection at the 30 April 2026 reporting date. The two community-clinic anchor sites contributed approximately balanced shares across the two collections; Collection I qualified-subject ratio was 102 of 104 (~98%).
Site	Setting	Coll I	Coll II	Total
Site A	Community clinic / chronic-disease panel	~58	~27	85
Site B	Community clinic / chronic-disease panel	~46	~18	64
By collection	2 sites	104	45	149
Qualified at Collection I close-out	~98% of Coll I enrolled	102	—	—

Fig. 1 Cumulative enrollment, April 2025 through 30 April 2026, with the Collection I close (end-July 2025), the inter-collection gap (Aug 2025 – Jan 2026), and the Collection II site re-engagement (March 2026) annotated. The +36 April 2026 month is the second-highest single month of the program after June 2025. Source: RDI Salesforce enrollment dashboard filtered on study; sponsor bi-weekly project-update reports.

Fig. 2 Enrollment by site and by collection at 30 April 2026. Approximate splits inside each site: Site A ~58 + ~27 = 85; Site B ~46 + ~18 = 64. The two community-clinic anchor sites contributed approximately balanced volumes across both collections, with Site A carrying a moderately higher share of Collection II. Source: RDI Salesforce enrollment dashboard at 30 April 2026.

5. Discussion

Three observations bear noting. First, chronic-disease specimen collection is operationally a community-clinic problem rather than an academic-medical-center problem. Chronic Hepatitis B subjects are concentrated where they are followed clinically — community clinics with established hepatology, infectious-disease, or chronic-disease primary-care panels — not at academic transplant or referral centers. This shifts site selection toward a different network than the sponsor’s transplant or method-comparison programs use.

Second, the Collection I qualified-subject ratio of 102 of 104 (~98%) reflects screening-front-door eligibility enforcement rather than back-door laboratory rejection. Eligibility enforcement at screening is the dominant lever for the qualified-subject ratio; a study that lets borderline-eligible subjects past screening pays the cost at the laboratory back door, where rejection is more expensive and less recoverable.

Third, the Collection II ramp shows the operational pattern characteristic of multi-collection studies: an inter-collection gap during which sites complete Collection I and sponsor performs analytical work, followed by a re-engagement window during which sites re-mobilise for Collection II. Site re-engagement — not new-site activation — was the principal lever to recover Collection II cadence, and the recovery (3 in March to 36 in April) confirms the lever worked.

6. Conclusion

Multi-collection chronic-Hepatitis-B specimen collection is operationally a community-clinic and inter-collection-management problem. A two-site community-clinic anchor delivered Collection I at a 98% qualified-subject ratio; Collection II re-engagement work in March 2026 recovered the site network without new-site activation, and Collection II reached 90% of target by end-April 2026. The same operational frame — community-clinic anchor + active inter-collection re-engagement — transfers to other chronic-disease specimen collection programs.

Notes & References

Sponsor identity withheld per confidentiality terms. Descriptor reflects the sponsor’s category. Specific platform names and sponsor-specific terminology have been generalised.
Anti-HBc Total is a serologic marker of prior or current Hepatitis B virus infection. Subjects with chronic infection (commonly HBsAg positive at ≥6 months) are the target population for verification work on the antibody marker.
Site-level Coll I/Coll II splits reported in Table 1 and Fig. 2 are approximate and reflect the site-level totals at 30 April 2026 with collection assignment inferred from enrollment date; final reconciliation against the EDC may apply.
Endpoint counts (149 subjects across 2 sites at 30 April 2026; 102 of 104 qualified at Collection I close-out; 45 enrolled in Collection II to date) are taken from the RDI Salesforce enrollment dashboard and the most recent sponsor project update.
The qualified-subject ratio reflects screening-front-door eligibility enforcement against the protocol-defined chronic-Hepatitis-B criterion; specific protocol detail (HBsAg duration thresholds, etc.) is not reported in this operations report.
No human subjects data, identifiers, or laboratory results are reported. This is an operations report, not a clinical-results publication.