SABCS 2019: Keytruda Shows Promising Data in Triple-Negative Breast Cancer While Tecentriq Fails to Meet Endpoint

Compiled by Fan Dongdong

Currently, Roche’s Tecentriq is the only approved tumor immunotherapy for the treatment of triple-negative breast cancer (TNBC); however, recent clinical data on Merck Sharp & Dohme’s Keytruda in refractory TNBC appear poised to change this landscape.

On December 12, at the 42nd Annual San Antonio Breast Cancer Symposium (SABCS 2019), MSD announced the latest subgroup analysis data from the phase 3 clinical trial KEYNOTE-522. The results showed that 64.8% of patients with triple-negative breast cancer (TNBC) in the Keytruda plus chemotherapy group achieved a pathological complete response (pCR), defined as the absence of cancer cells in surgically resected tissue, compared with 44.1% in the chemotherapy-alone group.

These data further support the Keytruda-related data for TNBC treatment released in September, which showed that 64.8% of patients receiving the Keytruda-chemotherapy combination achieved pathological complete response, compared with 51.2% in the chemotherapy-alone group.

Furthermore, the KEYNOTE-522 study also demonstrated that patients receiving Keytruda in combination with chemotherapy had a 37% lower risk of postoperative disease recurrence compared to those receiving chemotherapy alone; however, this result was not statistically significant. Roy Baynes, Chief Medical Officer and Head of Global Clinical Development at MSD, stated that the results appeared very promising at this relatively early stage of the trial. Although Keytruda did not demonstrate a significant benefit in preventing recurrence, achieving a pathological complete response is generally considered a “favorable predictor” of non-recurrence.

Unlike Keytruda, the latest developments for Roche’s Tecentriq are not optimistic. On the same day, Roche also released new data (from the NeoTRIPaPDL1 study), showing that treatment with Tecentriq following chemotherapy did not enable patients with triple-negative breast cancer (TNBC) to achieve a pathological complete response. Among patients who received Tecentriq after chemotherapy but before surgery, 43.5% showed no signs of cancer cells post-surgery, compared to 40.8% in the chemotherapy-only group, with no statistically significant difference observed between the two groups.

As Roche seeks to advance the market approval process for Keytruda, this outcome will undoubtedly disadvantage the company. This past October, NICE in England rejected Tecentriq-Abraxane, despite the regimen being considered a cost-effective treatment option for triple-negative breast cancer (TNBC). While UK regulators acknowledged that the combination delayed disease progression by 2.5 months compared with placebo plus chemotherapy in patients whose tumors expressed the PD-L1 biomarker, they deemed the clinical data insufficient relative to other chemotherapeutic agents, including paclitaxel and docetaxel. NICE’s rejection has compelled Roche to either supplement its submission with new data or consider offering deeper discounts.

Reference source: Merck’s Keytruda notches win in triple-negative breast cancer as Roche’s Tecentriq falls short