MAUDE Adverse Event Report: VENTANA MEDICAL SYSTEMS INC. CONFIRM ANTI-ESTROGEN RECEPTOR (ER) (SP1) RABBIT MONOCLONAL PRIMARY ANTIBODY; ESTROGEN (OESTROGEN)/PROGESTERONE RECEPTOR IVD, ANTIBODY

Catalog Number	05278406001
Medical Device Problem Codes	Product Quality Problem (1506); Incorrect, Inadequate or Imprecise Result or Readings (1535)
Health Effect - Clinical Code	Insufficient Information (4580)
Date of Event	06/18/2025
Type of Reportable Event	Serious Injury
Additional Manufacturer Narrative
The serial number of the analyzer is (b)(6).The investigation is ongoing.
Event or Problem Description
There was an allegation of discrepant results with the confirm anti-estrogen receptor (er) (sp1) rabbit monoclonal primary antibody results for patient samples tested on a benchmark ultra stainer module.It was reported that restaining of low-expressing tumors with a new lot of er sp1 antibody has led to notable clinical differences in scoring.Initially, 6 cases were tested, which resulted in 3 patients being scored as 2/3 due to the low expression of er sp1 antibody; however, on retesting showed a score of 4/5.Further restaining of 33 cases originally scored 0-5 identified, 5 cases were found to be eligible for treatment.One patient reportedly received unnecessary chemotherapy.There is no information about any significant deleterious effects associated with the receipt of chemotherapy.Further information related to the patient, including current condition, any deleterious effects, and diagnostic decisions based on the assay results, has been requested.
Additional Manufacturer Narrative
The correct serial number of the analyzer is (b)(6).Regarding the alleged patient who reportedly received unnecessary chemotherapy, the initial run occurred on 18-jun-2025 and the repeat run was on 23-oct-2025.The final score for this patient was 5, not 6.Medwatch fields b3 date of event and d4 lot no were updated.The investigation is ongoing.
Additional Manufacturer Narrative
The following information was provided regarding the patient who reportedly received unnecessary chemotherapy: left axillary node biopsy: metastatic adenocarcinoma (from previous breast ca).Initially reported as er 2, pr 2, and her2 negative.Therefore, the patient was treated as triple negative and given systemic chemo.The new staining result was er 5/6.It was reported that oncology discussed starting hormonal therapy and a cdk 4/6 inhibitor for the patient.However, the outcome of this consultation was not provided.No further information was provided.
Additional Manufacturer Narrative
The provided case images and corresponding data were reviewed by the roche pathology office.All 5 cases provided represent challenging, borderline cases which are known to have higher inter-observer variability even in optimal staining conditions.As noted in the method sheet, "specific staining of stroma and lymphocytes may be observed" with confirm anti-er (sp1) antibody.The positive on slide controls for case images provided showed acceptable staining.Regarding the patient who reportedly received unnecessary chemotherapy, the initial er-stained slide shows scattered weakly staining tumor nuclei.There is no h&e to correlate er staining with tumor morphology, or to aid in distinguishing tumor nuclear staining from staining of lymphocytes and stroma.This is a borderline and challenging case, which is difficult to interpret.Based upon this, the ihc image alone it is favored 1-10% of tumor cells positive, status: er low positive.The repeat er-stained slide shows weak to moderate to strong staining in about 20% of tumor nuclei, consistent with an er-positive tumor.The pathologist mentioned that there is a known "bounce" in antibody stain intensity, and it may occur from run to run.Usually, a 0.5 point difference in stain intensity is acceptable.The pathologist also reviewed the er factory acceptance testing slides to meet acceptability criteria in the areas of definitive invasive carcinoma.A preliminary internal investigation of the issue revealed a reduction in tumor stain intensity and percent tumor cell staining in weak-staining breast carcinoma cases when testing specific batches of raw material.Current raw material batches utilized in the production of finished goods show no evidence of light staining.Roche has advised customers to discontinue the use of and discard any remaining inventory of the affected 11 reagent lots.The issue would not cause adverse health consequences when the external positive control tissues and staining procedures are used, as recommended in the product method sheet, which states that a positive tissue control must be run with each run and cap/clia guidelines are followed.The results are interpreted by a qualified pathologist in conjunction with histological examination and relevant clinical information to detect inappropriate cell staining on known control tissues and internal control cells, per the product method sheet.

• Brand Name: CONFIRM ANTI-ESTROGEN RECEPTOR (ER) (SP1) RABBIT MONOCLONAL PRIMARY ANTIBODY
• Common Device Name: ESTROGEN (OESTROGEN)/PROGESTERONE RECEPTOR IVD, ANTIBODY
• Manufacturer (Section D): VENTANA MEDICAL SYSTEMS INC.; 1910 e innovation park dr; tucson AZ 85755
• Manufacturer (Section G): VENTANA MEDICAL SYSTEMS INC.; 1910 e innovation park dr; tucson AZ 85755
• Manufacturer Contact: natalie catton ; 9115 hague road; indianapolis, IN 46250 ; 9253534412
• MDR Report Key: 24038601
• Report Number: 2028492-2026-00138
• Device Sequence Number: 13026078
• Product Code: MYA
• UDI-Device Identifier: 04015630972241
• UDI-Public: 04015630972241
• Combination Product (Y/N): N
• Initial Reporter Country: UK
• PMA/510(K) Number: K110215
• Number of Events Summarized: 1
• Summary Report (Y/N): N
• Serviced by Third Party (Y/N): Unknown
• Reporter Type: Manufacturer
• Report Source: Foreign,Health Professional,User Facility
• Initial Reporter Occupation: Other Health Care Professional
• Type of Report: Initial,Followup,Followup,Followup
• Report Date (Section B): 04/09/2026

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: Yes
• Operator of Device: Health Professional
• Device Catalogue Number: 05278406001
• Device Lot Number: M24839, M08022
• Was Device Available for Evaluation?: Yes
• Is the Reporter a Health Professional?: Yes
• Type of Report(Section G): Follow-Up
• Initial Date Received by Manufacturer: 12/17/2025
• Supplement Date Received by Manufacturer: 01/26/2026; 02/09/2026; 03/16/2026
• Initial Report FDA Received Date: 01/12/2026
• Supplement Report FDA Received Date: 02/16/2026; 03/04/2026; 04/09/2026
• Was Device Evaluated by Manufacturer? (Y/N): Yes
• Is the Device Labeled for Single Use? (Y/N): No
• Is This a Single-Use Device that was Reprocessed and Reused on a Patient? (Y/N): No
• Patient Sequence Number: 1
• Outcome Attributed to Adverse Event: Other
• Patient Sex: Unknown