important conditions.

Unexpected: The event is not consistent with the known safety profile of the IP, as outlined in the Investigator’s Brochure (IB) or product label (SmPC/PI).

Suspected: There is a reasonable possibility that the IP caused the event, determined by causality assessment from the investigator or sponsor.

For example, if a participant in an oncology trial experiences a myocardial infarction that is not described in the IB and is assessed as possibly related to the study drug, the case qualifies as a SUSAR.

When to Report a SUSAR: Regulatory Requirements

Authorities enforce expedited reporting timelines for SUSARs:

• Fatal or life-threatening SUSARs: Must be reported within 7 calendar days of awareness, with follow-up information within 8 days.
• Other SUSARs: Must be reported within 15 calendar days of awareness.

For instance, under ICH E2A, sponsors are required to ensure expedited communication of SUSARs across all participating sites and regulatory authorities. The EU Clinical Trial Regulation (EU-CTR) enforces similar requirements via EudraVigilance, while the FDA requires IND safety reports containing SUSARs to be submitted electronically.

The rationale behind expedited timelines is to ensure rapid communication of emerging risks, enabling ethics committees and regulators to evaluate whether trial continuation remains safe for participants.

Case Study: Identifying a SUSAR in Practice

Consider a Phase II cardiovascular trial where a participant developed acute pancreatitis. The event was serious due to hospitalization. It was unexpected, as pancreatitis was not listed in the IB. Investigators suspected a causal relationship because the event occurred soon after drug administration and no alternative explanation was evident. The sponsor classified the event as a SUSAR and reported it to regulators within 7 days. This ensured compliance and demonstrated vigilance in patient safety monitoring.

Distinguishing SUSARs from SAEs and AESIs

One of the common challenges investigators face is differentiating SUSARs from other categories:

• SAE (Serious Adverse Event): Serious but not necessarily unexpected or related to the IP.
• AESI (Adverse Event of Special Interest): May not meet seriousness criteria but is of special concern for the IP class (e.g., QT prolongation for antiarrhythmic drugs).
• SUSAR: Must be serious, unexpected, and suspected to be related to the IP.

Understanding these distinctions ensures appropriate prioritization and timely regulatory reporting.

Global Regulatory Framework for SUSAR Reporting

Different regions maintain harmonized but distinct frameworks:

• FDA (US): Requires IND safety reports including SUSARs, submitted via the electronic gateway.
• EMA (EU): Mandates submission through EudraVigilance.
• MHRA (UK): Requires SUSARs to be reported through its MHRA safety portal.
• DCGI/CTRI (India): Mandates submission of SUSARs to the regulator and registration in CTRI systems.
• PMDA (Japan): Requires adherence to ICH guidelines with country-specific forms.

Despite broad harmonization under ICH, country-specific nuances mean sponsors must establish region-specific SOPs to remain compliant.

Challenges in Identifying and Reporting SUSARs

Practical challenges include:

• Unclear causality: Investigators may hesitate to classify an event as related without strong evidence, risking delays.
• Complex multi-country trials: Reconciling timelines across regions increases administrative burden.
• Incomplete data: Early reports may lack laboratory or imaging confirmation, requiring follow-up updates.
• System limitations: Inadequate eCRF design may fail to flag potential SUSARs promptly.

For example, in a large oncology program, multiple SAEs were initially misclassified as expected due to inadequate cross-checks with the IB. A sponsor audit revealed the gaps, leading to a corrective action plan with retraining and improved eCRF prompts.

Best Practices for SUSAR Identification and Reporting

Sponsors and investigators can adopt several strategies to strengthen SUSAR reporting:

• Provide training modules for investigators on distinguishing SUSARs from SAEs and AESIs.
• Embed real-time edit checks in eCRFs to flag potential SUSARs for sponsor review.
• Develop SOPs specifying timelines, responsibilities, and escalation pathways.
• Maintain a centralized pharmacovigilance team to review and confirm SUSAR classification.
• Reconcile SUSAR data across pharmacovigilance systems and regulatory submissions regularly.

For example, in a Phase III immunology trial, implementation of a centralized safety review committee reduced SUSAR misclassification by 35% and improved regulatory compliance.

Regulatory Implications of Poor SUSAR Reporting

Failure to identify and report SUSARs accurately can have significant consequences:

• Inspection findings: Regulators may cite major or critical deficiencies during inspections.
• Delayed submissions: Late SUSAR reporting can delay trial continuation or approvals.
• Patient safety risks: Failure to detect emerging risks undermines ethical oversight.
• Reputation damage: Sponsors with repeated SUSAR deficiencies may face stricter regulatory scrutiny.

Ensuring timely and accurate SUSAR reporting is therefore both a compliance obligation and a patient safety imperative.

Key Takeaways

SUSARs represent one of the most critical categories of safety reporting in clinical trials. To ensure compliance and patient safety, sponsors and investigators should:

• Understand the criteria that define a SUSAR (serious, unexpected, suspected).
• Report SUSARs within regulatory timelines (7 or 15 days).
• Document causality rationale and reconcile data across systems.
• Adopt SOPs, training, and centralized reviews to minimize misclassification.

By applying these practices, trial teams can improve regulatory compliance, enhance pharmacovigilance, and most importantly, protect participants enrolled in clinical research.