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Faulty Reagent Caused 'Marginal' Over-Reporting of Breast Cancer Recurrence With MammaPrint

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This article has been updated to include comments from Asuragen President Rollie Carlson.

By Turna Ray

A faulty third-party reagent used with Agendia's MammaPrint test has resulted in certain women's risk for breast cancer recurrence to be over-estimated, Pharmacogenomics Reporter has learned.

Hans Herklots, head of corporate communications at Agendia, confirmed this week that the error in test results was discovered late last year, when the company "detected a trend in the MammaPrint reporting, indicating a small increase in high-risk patient results."

The company did not say how many breast cancer patients' results were affected, but Herklots said that Agendia has notified all of the physicians who received these results "and provided new, corrected MammaPrint reports."

In addition, he said that the company has since implemented additional internal quality-control measures to guard against a similar issue in the future.

Herklots said that upon discovering the errors last year, Agendia "examined all quality control metrics, including methodologies, instrumentation and reagents."

The investigation revealed that a particular batch of reagents "caused a marginal shift in MammaPrint reporting," and the company identified "a specific subset of patients wherein the risk of recurrence was over-reported."

Agendia did not name the reagent developer, noting that the provider is "a respected third-party vendor" whose reagents are "widely used in both commercial and academic laboratories." As such, it is possible that the results of genetic tests provided by other companies may be impacted by this batch of reagents.

Agilent manufactures the microarrays that underlie the MammaPrint test and Agendia also has a supply agreement with Asuragen for RNARetain, a molecular fixative that preserves fresh tissue samples ahead of analysis.

Asuragen President Rollie Carlson told Pharmacogenomics Reporter that Agendia had confirmed that the recent issues regarding MammaPrint "were not associated with RNARetain RNA stabilization reagent." RNARetain is the diagnostic version of the Ambion RNAlater research reagent.

Since MammaPrint is an in vitro diagnostic multivariate index assay approved by the US Food and Drug Administration, Agendia informed the agency of the cause and effect of this error in result reporting, as well as how the company has resolved the problem, Herklots said.

"Patient care is our top priority and we are committed to providing healthcare professionals and patients with accurate, reliable MammaPrint results," Herklots added.

MammaPrint is a microarray-based diagnostics that determines breast cancer patients' risk of disease recurrence based on a 70-gene signature panel. The test identifies early-stage breast cancer patients as either being at low risk or at high risk of distant recurrence following surgery, independent estrogen receptor status, and any prior treatment.

If MammaPrint determines a patient is at low risk of recurrence, then she may be given tamoxifen to further reduce her risk. If she is deemed at high risk by the test, then she might need chemotherapy.

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