| Question | Answer |
|---|
| Is there an FDA-approved CDx test? | The only FDA-approved CDx test for CLDN18.2 is the VENTANA CLDN18 (43-14A) RxDx Assay.1 |
| We have difficulty finding validation tissue. Do you know where we can procure this? | Tissue controls are commercially available through various providers. You can find a link to this information under the “Sample Preparation and Testing” section of this website. |
| We will develop an LDT for this biomarker. Can you provide any information on antibodies? | You can find some information on CLDN18 antibodies under the “Sample Preparation and Testing” section of this website. |
| Is there an approved therapy for this biomarker? | We cannot provide you with that information, but you can contact Astellas for more information. |
| Is CLDN18.2 testing applicable to any other disease areas or indications? | At this time, the only FDA-approved CLDN18.2 CDx test is for gastric/GEJ cancer. |
| What training is available for CLDN18.2 expression? | There are several resources available that educate on CLDN18.2 expression. This website provides whole-slide, consensus-scored images, quizzes, and additional resources for pathologist education. Additionally, Roche offers eLearning at cancerdiagnosticeducation.comcancerdiagnostic education.com |
| How long can unstained FFPE sections (ie, cut but unstained slides) be stored and still provide reliable CLDN18.2 staining? | If the FFPE block is cut and applied to an unstained slide, slides should be stained immediately, as antigenicity of cut tissue sections may diminish over time. If not stained immediately, slides should be desiccated and stored at room temperature (30±5 °C). Because environmental factors are known to affect antigen stability on cut slides, laboratories should validate cut-slide stability within their own environment when storing beyond 45 days.1 |
| Can archival tissue (ie, FFPE blocks) be used for CLDN18.2 staining? | Archival tissue was used for evaluation in a Phase 3 clinical trial evaluating CLDN18.2 expression.2 Laboratories should follow standard protocols for maintaining FFPE blocks. |
| Can cytology specimens be utilized for evaluation of CLDN18.2 expression? | Cytology samples were not included in recent Phase 3 trials evaluating CLDN18.2 expression.2,3 Using cytology specimens would be considered off-label when using the CDx test.1 |
| The CLDN18 test detects both 18.1 and 18.2, how do I know if the patient is 18.2-positive? | Claudins are present throughout the body, but each isoform is localized to certain tissues. CLDN18.1 is found in normal lung tissue and is negligible or absent in gastric/GEJ adenocarcinoma.4,5 CLDN18.2 presents in gastric cancers as well as pancreatic and esophageal cancers.4 This specificity allows the presence of CLDN18 staining in G/GEJ tumor tissue to be attributed to CLDN18.2.1,4 |
| Can I expect to see any overlap with other biomarkers? | Multiple studies looking at correlations between CLDN18.2 status and other biomarkers in patients with advanced G/GEJ cancer have been conducted. Across these studies, no clear differences have been observed in the global prevalence of established biomarkers between CLDN18.2-positive and CLDN18.2-negative patients.6-8 |
CDx, companion diagnostic; CLDN18, claudin 18; CLDN18.1, claudin 18 isoform 1; CLDN18.2, claudin 18 isoform 2; FDA, U.S. Food and Drug Administration; FFPE, formalin-fixed, paraffin-embedded; G/GEJ, gastric/gastroesophageal junction; LDT, laboratory-developed test.
