A combination of chemotherapy and immunotherapy slows disease progression in patients with metastatic triple-negative breast cancer, according to results published Saturday (October 20) in the New England Journal of Medicine and presented the same day at the European Society for Medical Oncology 2018 Congress in Munich. The treatment—Roche’s immune checkpoint inhibitor atezolizumab (Tecentriq) alongside chemotherapy—was somewhat more effective in patients whose tumors were positive for the protein PD-L1 than for other types of tumors
The study “is a big deal and has been the buzz of the breast cancer research world,” Larry Norton, an oncologist at Memorial Sloan Kettering Cancer Center who was not involved in the work, tells The New York Times.
Chemotherapy alone is the standard treatment for triple-negative breast cancers—those that lack receptors for estrogen and progesterone and do not overproduce the HER2 receptor—but cancers quickly become resistant to chemo. Once the cancer spreads, patients often survive 18 months or fewer.
In the new treatment cocktail, the chemotherapy and immunotherapy work as a team. First, the chemotherapy “roughens up the surface” of the tumor cells, according to the study’s lead author, Peter Schmid of Queen Mary University of London and St. Bartholomew’s Hospital, in speaking with CNN. “We are using chemotherapy to tear away the tumor’s ‘immune-protective cloak,’ to expose it, enabling people’s own immune system to get at it.” Then the checkpoint inhibitor takes the brakes off the immune system so that it more readily attacks the now-susceptible tumors.
In the study, 451 patients with triple-negative breast cancer received chemotherapy plus Tecentriq and an equal number of patients received chemotherapy plus a placebo. The researchers initially planned to study the length of time the drug cocktail prevented patients’ cancers from progressing—growing, that is. They later decided to study overall survival as well and expanded the number of study participants in order to do so.
Overall, patients treated with the Tecentriq cocktail lasted 1.7 months longer without disease progression than those who got the placebo cocktail; the median time without progression was 7.2 months in those receiving the drug cocktail, compared with 5.5 months in patients receiving the placebo. Patients with PD-L1–positive tumors receiving Tecentriq gained an extra 2.5 months without disease progression (7.5 months without disease progression in those receiving the cocktail versus 5 months among those receiving the placebo).
According to the preliminary survival results, patients given Tecentriq also lived 3.7 months longer than those receiving the placebo, though the authors note that this life extension was not statistically significant. Patients who received the combination treatment lived a median of 21.3 months, while those who got the placebo lived 17.6 months. According to estimates reported in the paper, patients with PD-L1–positive tumors who received the Tecentriq cocktail lived 10.5 months longer than those who received the placebo (25.5 months versus 15 months). Again, these data are preliminary, so the authors could not determine whether the treatment was responsible for the difference.
“These results are a massive step forward,” Schmid says in a press release.