Tecentriq (atezolizumab) combined with chemotherapy failed to meet its primary endpoint of progression-free survival — the length of time during and after therapy in which the patient’s disease does not get worse — for the initial (first-line) treatment of PD-L1-positive individuals with metastatic triple-negative breast cancer (TNBC).
These are the findings of the multicenter Phase 3 IMpassion131 study (NCT03125902), which compared Tecentriq plus the chemotherapy paclitaxel to paclitaxel alone in 651 people with previously untreated, inoperable, locally advanced or metastatic TNBC. The study was sponsored by Genetech, a Roche subsidiary, which is developing the cancer immunotherapy treatment.
The participants received an 840-milligram intravenous (into-the-vein) dose of Tecentriq, or placebo, on days one and 15 of every 28-day cycle. It was given along with 90 mg per square meter of intravenous paclitaxel, administered on days one, eight, and 15 of every 28-day cycle until there was evidence of disease progression or unacceptable toxicity, up to a maximum of about 40 months (3.3 years).
The trial’s secondary endpoints included overall survival, objective response rate — the percentage of patients whose cancer shrinks or disappears after treatment — and duration of response. While the results for the secondary endpoint of overall survival show a negative trend, the data were incomplete at the time of this analysis. The company plans to continue the follow-up until the final analysis.
The Tecentriq combination demonstrated a safety profile consistent with the known safety profiles of the individual medicines, and no new safety signals were reported.
“While we are disappointed by the results from the IMpassion131 study, we are grateful for all the patients, families, and physicians who were involved in the study,” Levi Garraway, MD, PhD, Genentech’s chief medical officer and head of global product development, said in a press release. “Today’s results underscore the need to better understand the cancer and immune system interactions, including the chemotherapy backbone and associated regimens.”
“We remain committed to finding optimal treatments for all people living with this aggressive disease,” Garraway added.
The full trial results will be presented at a future scientific meeting after discussions with global health authorities, including the U.S. Food and Drug Administration and the European Medicines Agency. The results will inform current and future studies in TNBC with Tecentriq in combination with paclitaxel, the company said.
Tecentriq is an immune checkpoint inhibitor, a type of immunotherapy, that has been approved to treat different types of cancer, including non-small cell lung and bladder cancers.
The therapy is an antibody (a protein component of the immune system) designed to bind to the protein PD-L1 that’s produced by cancer cells, blocking it from interacting with its receptor found of the surface of immune cells, known as PD-1. Tecentriq prevents signals that allow cancer cells to evade being killed by immune cells.
In combination with the alternative chemotherapy agent Abraxane (nab-paclitaxel), Tecentriq is approved in the U.S. and the E.U. for people with advanced PD-L1-positive TNBC.
Both approvals were based on results from the IMpassion130 trial (NCT02425891), which demonstrated a statistically significant benefit in progression-free survival and, while not specifically tested, showed clinically meaningful improvements in overall survival compared with Abraxane alone.
Tecentriq, either alone or in combination with other medicines, is being investigated in multiple ongoing or planned Phase 3 trials in cancers of the lung, skin, and breast. It also is being evaluated in people with gastrointestinal, gynecological, and head and neck cancers.