Surgical pathologists could gain new tool to diagnose many types of cancers
It might soon be possible to determine the HER2 status of breast cancer patients from blood samples rather than tissue biopsies. If this new technology proves feasible, it would give surgical pathologists and medical laboratories a different, and possibly less complex, methodology to use when assessing a case of breast cancer.
In its report about the study, Medscape Medical News, wrote that “HER2 status derived from circulating tumor cells (CTCs) from breast cancer patients was generally concordant with that derived from tumor tissue” and that “CTCs could prove to be an alternative to biopsies for assessing tumor tissue for biomarker status.”
“The basic idea is that circulating tumor cells (CTCs) can provide real-time information about a patient’s current disease state, acting as a ‘liquid biopsy,’” commented Siminder Kaur Atwal, Ph.D., who is a Senior Research Associate at Genentech. “They are much less invasive than tumor biopsies because they can be detected from a blood draw and don’t require surgical intervention.”
The research was conducted by scientists at Genentech. As most pathologists and clinical laboratory managers know, Genetech is owned by Roche Holdings, Ltd., and manufactures Herceptin, the drug used to treat breast cancer patients who are positive for the HER2 mutation.
The study’s First Author is Siminder Kaur Atwal, Ph.D., who presented her research group’s findings at the 4th American Association for Cancer Research International Conference on Molecular Diagnostics in Cancer Therapeutic Development (AACR-MDCTD).
Giving Pathologists the Option of a ‘Liquid Biopsy’
In the abstract of the presentation made at the AACR-MDCTD conference, the group wrote, “Evaluation of cancer biomarkers from blood and other accessible tissues could significantly enable biomarker assessment by providing a relatively noninvasive source of representative tumor material. Circulating tumor cells (CTCs) isolated from blood of metastatic cancer patients hold significant promise in this regard.”
According to Atwal, “CTCs can also provide real-time information about the disease, acting as a liquid biopsy, and it can be done with a simple blood draw,” she explained. “CTCs can also tell you the current status of the patient’s disease, which may be different from archival tissue.
“In addition, comparing CTCs collected prior to treatment with those collected during repeated sampling allows biomarkers to be monitored during the course of treatment. CTCs present a very intriguing opportunity to look at biomarkers, obviating the need for biopsy,” she said.
Research into the use of CTCs in cancer diagnosis is not a new concept. According to the Medscape article, “Previous research has looked at using CTCs for diagnosis, prognostic indicators, and predicting response to therapy. CTCs have been discovered in men with early-stage prostate cancer and one study demonstrated that the detection of CTCs after treatment might indicate that the patient is more likely to develop metastases, and so might warrant repeat and aggressive chemotherapy.”
Using Circulating Tumor Cells for Cancer Diagnosis
In their abstract, the group explains how they conducted their research, “We determined HER2 status by IF and FISH in CTCs from metastatic breast cancer patients and in the majority of patients (89%) found concordance with HER2 status from patient tumor tissue, while in a subset of patients (11%), HER2 status had changed from the primary tumor at diagnosis.
“Surprisingly, we found CTC counts to be higher in ER+ patients in comparison to HER2+ and triple negative patients despite their more aggressive phenotype,” wrote Atwal. “This may be explained by our findings that the basal-like molecular subtype of breast cancer has low EpCAM expression and a more mesenchymal phenotype and CTCs will likely not be efficiently captured using EpCAM alone in tumors that arise from this subtype.”
Atwal concludes the abstract by saying, “Our data suggests that molecular characterization from captured CTCs is possible and can inform us of the patients’ current biomarker status. In this regard, CTCs hold significant promise as a source of tumor material to facilitate clinical biomarker evaluation.”
Circulating tumor cells are attracting plenty of attention from biotech companies and academic researchers for a simple reason. CTCs offer the promise of a cancer diagnosis tool which is much more patient friendly. First, a blood specimen is much less invasive to collect than a tissue specimen. Patients are quick to appreciate that advantage.
Second, there is the potential for this technology to result in diagnostic tests for cancer which allow early detection of cancer by looking for CTCs in blood specimens. Were the accuracy of such yet-to-be developed pathology tests to be demonstrated, it could justify mass screening for selected cancers. This would also be a patient-friendly development if these CTC-based assays could accurately detect cancer in its earliest stages.
On both points, Wall Street investors recognize the potential for medical laboratory tests based on CTCs to become “big sellers” in the clinical marketplace. For that reason, ample funding seems to be available to support research into circulating tumor cells as a useful, accurate biomarker for certain types of cancers.
CTCs as “liquid biopsies” also represent another line of technology which, if developed to its full potential, could provide anatomic pathologists with a powerful tool to diagnose cancer without the need to collect a tissue specimen from the patient.