For in vitro diagnostic use. Others VENTANA HER2 4B5 Rabbit Monoclonal Primary Antibody RxDx CE IVD VENTANA® HER2 (4B5) Rabbit Monoclonal Primary Antibody RxDx PID00000679 CE-IVD 09 670 564 001 9 670 564 001 09670564001 9670564001 09670564001 VEN HER2 (4B5) RM PAB RxDx-US EXPORT2 VEN HER2 (4B5) RM PAB RxDx-US EXPORT2 07613336208021 Reagents, kits 790-7167 Not Available Not Available undefined VENTANA HER2 (4B5) Rabbit Monoclonal Primary Antibody RxDx is intended for the semi-quantitative detection of HER2 antigen by immuno- histochemistry (IHC) in sections of formalin-fixed, paraffin-embedded breast and gastric tissue stained on a BenchMark IHC/ISH instrument. This IHC device is indicated as a companion diagnostic for identifying breast cancer patients who are eligible for treatment with trastuzumab (IHC 3+ or IHC 2+/ISH amplified), pertuzumab (IHC 3+ or IHC 2+/ISH amplified), trastuzumab emtansine (IHC 3+ or IHC 2+/ISH amplified), or trastuzumab deruxtecan (IHC 1+ or IHC 2+/ISH non-amplified). Additionally, this IHC device is indicated as a companion diagnostic for identifying gastric cancer patients for whom trastuzumab treatment is being considered (IHC 3+ or IHC 2+/ISH amplified). This product should be interpreted by a qualified pathologist in conjunction with histological examination, relevant clinical information, and proper controls. This antibody is intended for in vitro diagnostic (IVD) use. en VENTANA HER2 (4B5) Assay contains a rabbit monoclonal antibody, which binds to HER2 in FFPE tissue sections. The specific antibody can be localized using a secondary antibody-HRP conjugate (ultraView Universal DAB Detection Kit). The specific antibody-enzyme complex is then visualized with a precipitating enzyme reaction product. Each step is incubated for a precise time and temperature. At the end of each incubation step, the instrument washes the sections to stop the reaction and to remove unbound material that would hinder the desired reaction in subsequent steps. The instrument also applies Liquid Coverslip, which minimizes evaporation of the aqueous reagents from the specimen slide.Clinical cases should be evaluated within the context of the performance of appropriate controls. The inclusion of a positive tissue control fixed and processed in the same manner as the patient specimen is recommended (for example, a weakly positive breast carcinoma). In addition to staining with VENTANA HER2 (4B5) Assay, a second slide should be stained with CONFIRM Negative Control Rabbit Ig. For the test to be considered valid, the positive control tissue should exhibit membrane staining of the tumor cells. These components should be negative when stained with CONFIRM Negative Control Rabbit Ig. In addition, it is recommended that a negative tissue control (for example, a HER2 negative breast or gastric carcinoma) be included for every batch of samples processed and run on a BenchMark IHC/ISH instrument. This negative tissue control should be stained with VENTANA HER2 (4B5) RxDx to ensure that the antigen enhancement and other pretreatment procedures did not create false positive staining. en

VENTANA^® HER2 (4B5) Rabbit Monoclonal Primary Antibody RxDx

CE-IVD

IVD

Leading the way in HER2 testing

The use of pre-diluted VENTANA HER2 (4B5) Rabbit Monoclonal Antibody RxDx¹, in combination with the fully automated BenchMark IHC/ISH slide staining instrument, standardizes all primary IHC processes from baking through staining, and reduces the possibility of human error. It also minimizes inherent variability resulting from individual reagent dilution and other processes found in manual and semi-automated IHC methods.

The Roche HER2 (4B5) clone* empowers you to:

Achieve consistently high proficiency assessment scores compared to other clones²
Employ the most widely adopted and reliable HER2-IHC primary antibody²
Demonstrate high concordance with HER2 FISH^3,4

Elevating hope for lower expression

Building on the same proven technology trusted for consistently achieving higher overall proficiency scores compared to other clones², Roche’s widely adopted assay is now approved to identify HER2-low and HER2-ultralow breast cancer patients*, helping to match even more women with highly effective, personalised therapies. It is the first and only test approved to identify breast cancer patients with the lowest levels of HER2 expression who may be eligible for targeted treatment with ENHERTU®.¹

* PATHWAY® anti-HER2/neu (4B5) Rabbit Monoclonal Primary Antibody and VENTANA HER2 (4B5) Rabbit Monoclonal Primary Antibody RxDx

Consistent performance and superior quality

The Roche HER2 (4B5) clone* has shown the most consistent performance and superior quality when compared to other on-market HER2 clones.²

* Based on data for PATHWAY anti-HER2/neu (4B5) Rabbit Monoclonal Primary Antibody and VENTANA anti-HER2/neu (4B5) Rabbit Monoclonal Primary Antibody products.

Intended use¹

This IHC device is indicated for identifying patients who are eligible for treatment with the following therapies in accordance with the approved therapeutic labeling

Breast carcinoma: HERCEPTIN® (IHC 3+ or IHC 2+/ISH amplified), KADCYLA® (IHC 3+ or IHC 2+/ISH amplified) or ENHERTU® (IHC 0 with membrane staining, IHC 1+ or IHC 2+/ISH non-amplified)

Biliary tract carcinoma (BTC): ZIIHERA® (IHC 3+)

Scoring conventions for the interpretation of VENTANA HER2 (4B5) Rabbit Monoclonal Primary Antibody RxDx

Below is a quick reference chart for staining criteria. Refer to Interpretation Guide for VENTANA HER2 (4B5) Rabbit Monoclonal Primary Antibody RxDx for a more detailed description with photographs of staining.

Criteria for intensity and pattern of cell membrane staining with VENTANA HER2 (4B5) Rabbit Monoclonal Primary Antibody RxDx

View full table

For breast carcinoma specimens when using the staining procedure for all HER2 assessment including potential HER2-low and HER2-ultralow assessment

Staining pattern	HER2 (4B5) score (report to treating physician)	HER2 status	Therapy
No membrane or staining is observed*	IHC 0 absent membrane staining	HER2-null	None
Any staining of the membrane in greater than 0 and less than or equal to 10% or less of the cancer cells,,**	IHC 0 with membrane staining	HER2-ultralow expression	ENHERTU (trastuzumab deruxtecan)
Faint, partial staining of the membrane in greater than 10% of the cancer cells*	IHC 1+	HER2-low expression	ENHERTU
Weak to moderate complete staining of the membrane in greater than 10% of the cancer cells	IHC 2+**** Reflex test: HER2 non-amplified	HER2-low expression	ENHERTU
	IHC 2+**** Reflex test: HER2 amplified	HER2-positive/overexpression	HERCEPTIN (trastuzumab) PERJETA (pertuzumab) KADCYLA (trastuzumab emtansine)
Intense complete staining of the membrane in greater than 10% of the cancer cells	IHC 3+	HER2-positive/overexpression

*Review at 40x is recommended to discern the presence or absence of any staining, such as faint, partial staining.
**Recommend re-reading by a second pathologist for cases classified as HER2-null or as HER2-ultralow expression with %tumor cells (%TC) ≤ 5%.
***In the HER2-ultralow “IHC 0 with membrane staining” category, partial membranous staining is usually faint but may exhibit stronger intensities, and such rare cases are scored as HER2-ultralow if they do not otherwise qualify for a higher score. Refer to the Interpretation Guide for case examples.
****Recommend reflex test to assess gene amplification per ASCO/CAP guidance.

View full table

For breast carcinoma specimens when using the alternative staining procedure intended for use in assessing HER2-positivity and not in assessing HER2-low or HER2-ultralow expression

Staining pattern	HER2 (4B5) score (report to treating physician)	HER2 status	Therapy
No membrane staining is observed or, Faint, partial staining of the membrane in 10% or less of the cancer cells	IHC 0	HER2-negative	None
Faint, partial staining of the membrane in greater than 10% of the cancer cells	IHC 1+	HER2-negative
Weak to moderate complete staining of the membrane in greater than 10% of the cancer cells	IHC 2+* Reflex test: HER2 non-amplified	HER2-negative
	IHC 2+* Reflex test: HER2 amplified	HER2 positive/overexpression	HERCEPTIN (trastuzumab) PERJETA (pertuzumab) KADCYLA (trastuzumab emtansine)
Intense complete staining of the membrane in greater than 10% of the cancer cells	IHC 3+	HER2 positive/overexpression

* Recommend reflex test to assess gene amplification per ASCO/CAP guidance

View full table

For gastric carcinoma specimens

Staining pattern - resection specimen	Staining pattern - biopsy specimen	Score (report to treating physician)	HER2 staining assessment	Therapy
No reactivity or membranous reactivity in < 10% of tumor cells	No reactivity or membranous reactivity in any tumor cell	IHC 0	HER2-negative	None
Faint/barely perceptible membranous reactivity in ≥ 10% of tumor cells; cells are reactive only in part of their membrane	Tumor cell cluster* with a faint/barely perceptible membranous reactivity irrespective of percentage of tumor cells stained	IHC 1+
Weak to moderate complete, basolateral or lateral membranous reactivity in ≥ 10% of tumor cells	Tumor cell cluster* with a weak to moderate complete, basolateral or lateral membranous reactivity irrespective of percentage of tumor cells stained	IHC 2+** Reflex test: HER2 non-amplified
		IHC 2+** Reflex test: HER2 amplified	HER2-positive	HERCEPTIN (trastuzumab)
Strong complete, basolateral or lateral membranous reactivity in ≥ 10% of tumor cells	Tumor cell cluster* with a strong complete, basolateral or lateral membranous reactivity irrespective of percentage of tumor cells stained	IHC 3+	HER2-positive	HERCEPTIN (trastuzumab)

* ≥ 5 cohesive cells
** Recommend reflex to ISH

View full table

For biliary tract carcinoma specimens

Staining pattern - resection specimen	Staining pattern - biopsy specimen*	Score (report to treating physician)	HER2 staining assessment	Therapy
No reactivity or membranous reactivity in < 10% of tumor cells	No reactivity or membranous reactivity in any tumor cell	IHC 0	HER2-negative	None
Faint/barely perceptible membranous reactivity in ≥ 10% of tumor cells; cells are reactive only in part of their membrane	Tumor cell cluster** with a faint/barely perceptible membranous reactivity irrespective of percentage of tumor cells stained	IHC 1+
Weak to moderate complete, basolateral or lateral membranous reactivity in ≥ 10% of tumor cells	Tumor cell cluster** with a weak to moderate complete, basolateral or lateral membranous reactivity irrespective of percentage of tumor cells stained	IHC 2+
Strong complete, basolateral or lateral membranous reactivity in ≥ 10% of tumor cells	Tumor cell cluster** with a strong complete, basolateral or lateral membranous reactivity irrespective of percentage of tumor cells stained	IHC 3+	HER2-positive	ZIIHERA (zanidatamab)

*Biopsy specimens include endoscopic, pinch (forceps), and needle core

** ≥ 5 cohesive cells

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References

VENTANA HER2 (4B5) Rabbit Monoclonal Primary Antibody RxDx Package Insert, CE IVD (1021867EN Rev D), 2025.
NordiQC Assessments. https://www.nordiqc.org/epitope.php; accessed July 2025.
Mayr D, et al. Comprehensive immunohistochemical analysis of Her-2/neu oncoprotein overexpression in breast cancer: HercepTest™ (Dako) for manual testing and Her-2/neuTest 4B5 (VENTANA) for VENTANA BenchMark automatic staining system with correlation to results of BenchMark automatic staining system with correlation to results of fluorescence in situ hybridization (FISH). Virchows Archiv. 2009; 454(3):241–248.
Brügmann A, Lelkaitis G, Nielsen S, et al. Testing HER2 in breast cancer: a comparative study on BRISH, FISH, and IHC. Appl Immunohistochem Mol Morphol. 2011;19(3):203-211.

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