BARCELONA, SPAIN – A genomic test developed by Reveal Genomics has shown potential in a retrospective validation study to be able to identify early-stage, triple-negative breast cancer (TNBC) patients likely to benefit from neoadjuvant taxane-carboplatin chemotherapy.
The test, which Reveal calls TNBCDX and markets currently for research use, may help some TNBC patients avoid more toxic regimens if further validated, according to oncologists at the European Society for Medical Oncology Congress in Barcelona after seeing the initial data presented on Saturday.
The company hopes to standardize the TNBCDX test and begin selling it for clinical use by next year. Reveal CSO Aleix Prat said in an email that the company plans to market the test as a tool that can "help … physicians de-escalate and escalate systemic therapy" for TNBC patients, which is "a topic of high interest in the [oncology] community."
TNBC accounts for 10 percent to 20 percent of breast cancers. Compared to hormone receptor- or HER2-positive breast cancers, TNBC is more aggressive, more likely to recur after treatment, and has worse survival rates. Unlike other breast cancer subtypes, the absence of targetable biomarkers on triple-negative breast tumor cells makes it harder to identify tailored therapies for patients.
The standard treatment for TNBC is a neoadjuvant anthracycline-based regimen comprising doxorubicin-cyclophosphamide or epirubicin-cyclophosphamide for four cycles, followed by a taxane for four cycles. Merck's PD-1 inhibitor Keytruda (pembrolizumab) is often added to this regimen. However, while highly effective against cancer, anthracyclines are associated with cardiotoxicity, which can cause progressive and permanent heart damage.
Previous studies have demonstrated encouraging efficacy of anthracycline-free regimens such as taxane-carboplatin in treating TNBC. However, given these are nonstandard regimens, oncologists are interested in identifying biomarkers that can help them identify those who will benefit from the treatments or should receive standard anthracycline-based regimens instead. In a presentation at the ESMO Congress, Miguel Martin Jimenez, chair of medical oncology at the Hospital General Universitario Gregorio Marañón in Madrid, shared results from a validation study in which researchers used Barcelona-based Reveal Genomics' TNBCDX test to do just that.
The TNBCDX multigene expression test is designed similarly to Reveal's HER2DX test for early-stage HER2-positive breast cancer. Reveal's HER2DX is being evaluated prospectively in two clinical studies: the pivotal ECOG-ACRIN CompassHER2 pCR trial in HER2-positive breast cancer and a study in collaboration with Dana-Farber Cancer Institute evaluating the test's turnaround time and clinical feasibility.
The TNBCDX test is performed using a baseline pretreatment core biopsy and comprises two gene signatures: a 10-gene signature tracking tumor infiltration and another four-gene signature assessing tumor cell proliferation. Those signatures are combined with information about a patient's tumor size and nodal stage and are analyzed using two different machine-learning algorithms. These algorithms then generate a score predicting the likelihood that a patient will experience a pathologic complete response following neoadjuvant taxane-based chemotherapy in the absence of anthracycline, cyclophosphamide, and Keytruda and a score predicting the patient's risk of relapse.
To validate the TNBCDX test, Jimenez and collaborators analyzed data from two studies — the Phase II WSG-ADAPT-TN study in Germany and the MMJ-CAR2014-01 study in Spain — involving 418 TNBC patients. In WSG-ADAPT-TN, patients received gemcitabine or carboplatin neoadjuvant therapy, and those that did not achieve a pathologic complete response had additional anthracycline-based chemotherapy. In MMJ-CAR2014-01, patients received carboplatin and docetaxel neoadjuvant therapy. Both studies enrolled patients with stage I through stage III TNBC. Jimenez and colleagues' primary goal was to use data from these studies to retrospectively evaluate the association between the two TNBCDX scores and efficacy outcomes in patients, including overall survival.
The researchers found that the TNBCDX score was significantly associated with pathologic complete response rates in both studies. The pathologic complete response rates for patients with predicted high-, medium-, and low-TNBCDX pathologic complete response scores were 57.2 percent, 43.9 percent, and 16.7 percent, respectively. The TNBCDX risk of relapse score was also significantly associated with distant disease-free survival and with overall survival, and those associations remained statistically significant after accounting for patients' pathologic complete response status.
Based on this data, Jimenez concluded that oncologists "have a new tool to individualize neoadjuvant therapy for our patients."
Lisa Carey, a professor of breast cancer research at the University of North Carolina School of Medicine, characterized the validation data on TNBCDX as "promising" but cautioned that the analysis was retrospective and observational, that some patients received adjuvant therapy and some did not, and that none received immune checkpoint inhibitors. She acknowledged that the test has the potential to help doctors decide which patients need an anthracycline-based neoadjuvant regimen and which don't but suggested that it should be "validated in an immune checkpoint inhibitor-treated cohort," since TNBC patients commonly have such therapies added on.
As the company works to further validate the test ahead of a projected commercial launch in 2025, Reveal's Prat said the firm will release more data on TNBCDX soon, including an analysis from the Phase II NeoPACT trial of neoadjuvant Keytruda with carboplatin and docetaxel in TNBC patients.