Securing a "Group" claim is a significantly higher regulatory bar. The MFDS requires you to provide a robust scientific rationale and clinical boundary documentation. This involves demonstrating that the biomarker's clinical utility is uniform across the drug class and providing analytical performance data that covers the range of cut-offs used by all drugs in that group. If different drugs in the class have different clinical decision thresholds (e.g., 1% vs. 10% expression), your CDx must be validated at each specific threshold. Without this cross-validation, the MFDS will likely restrict your labeling to only the specific therapeutic products supported by your direct clinical evidence.

The MFDS has established a co-review framework to ensure synchronized market entry. You and your pharmaceutical partner should notify the MFDS early in the development phase. While the drug (NDA) and the device (IVD Approval) follow separate legal tracks, the reviewers coordinate to ensure the Companion Diagnostic's IFU and the Drug's Label are mutually consistent. In many cases, if the CDx is essential for safe use, the drug approval will be conditioned upon or timed with the issuance of the CDx certificate to prevent off-label use with unvalidated tests.

“后续”CDx 的注册确实可以采用等效性路径。您需要通过与已获批的“谓词”（Comparator）CDx 进行对比实验来证明等效性。MFDS 特别关注决策阈值（Decision Threshold）附近的检测一致性。对于不一致的结果，您不能简单地将其视为实验误差，必须进行深入的根本原因分析（Root Cause Analysis），并可能需要通过第三方参考方法（如 Sanger 测序或 IHC 评分复核）来验证哪个结果更符合临床实际。

MFDS 允许在商业化试剂盒与临床试验检测（CTA）不一致时进行桥接研究。然而，MFDS 非常强调样本的临床代表性。一致性评价应优先使用临床试验中的留存样本。对于极罕见的突变位点，虽然可以有条件地接受人工模拟样本（如细胞系稀释物），但您必须提供详尽的论证，说明模拟样本如何反映真实临床样本的复杂性（如基质效应和突变负荷分布），且核心临床有效性数据仍必须来源于患者样本。

根据 MFDS 的最新指导原则，IVD-CDx 的预期用途必须将检测与治疗紧密绑定。通常要求在预期用途中同时标明活性成分名称及其对应的商品名。如果相关药物在韩国尚未上市，您可以先标注活性成分，但必须在临床证据中证明该检测与该特定分子的安全性及有效性直接相关。一旦药物获批，您通常需要更新说明书（IFU）以包含特定的商品名，以确保医护人员在处方时的准确性。