Keytruda Plus Chemotherapy Improves Survival Outcome in Metastatic Triple-Negative Breast Cancer

First-line treatment with Keytruda (pembrolizumab) in combination with chemotherapy improves progression-free survival in patients with locally recurrent, inoperable or metastatic triple-negative breast cancer (mTNBC), according to data presented at the 2020 ASCO Virtual Scientific Program.

In an interview with CURE®’s sister publication, OncLive®, Dr. Javier Cortes, head of the breast cancer program at IOB Institute of Oncology, Madrid and Barcelona, went into greater detail about the updated progression-free survival (PFS) (the time from the start of treatment until disease worsened) and safety data from the KEYNOTE-355 study.

In patients who are PD-L1 positive and have a CPS score of 10 or more, the median PFS was 9.7 months with the combination of Keytruda and chemotherapy, compared to 5.6 months with placebo and chemotherapy, which, according to Cortes, is both statistically significant and of great clinical importance.

When it came to safety, Cortes noted, patients who received Keytruda and chemotherapy did not experience more treatment-related side effects than the placebo arm, and only saw a slightly higher percentage of immune-related side effects.

Transcription:

So, at ASCO, we presented the first primary endpoint, and also safety. Remember that the first co-primary end point of this study was progression free survival (PFS). Firstly, in patients with PDL1, and a CPS score of 10 or more, this primary endpoint was clearly met with a hazard ratio of 0.65, which is not only statistically significant, but also of great clinical importance, in my opinion. The median progression free survival moved from 5.6 months with placebo and chemotherapy to 9.7 months with pembrolizumab and chemotherapy.

So, regarding the activity and in conclusion, pembrolizumab plus chemotherapy improved progression free survival in patients with a CPS score of 10 or more (and we’re still talking about PD-L1 positive patients.)

Regarding toxicity, (there are) maybe two key messages. The first one: the patients who received pembrolizumab and chemotherapy did not have more treatment-related adverse events or treatment-related grade 3 to 5 adverse events.

These grade 3 to 5 adverse events were observed in 67% of patients with placebo and chemo, and 68% of patients with pembrolizumab and chemo.

However, when we look at the immune-related adverse events, obviously patients who receive pembrolizumab and chemotherapy have more adverse events compared with placebo and chemotherapy. Grade 3 and 4 (no grade 5 events) were observed in 5.2% of patients treated with pembrolizumab-based therapy and zero percent of patients who received placebo and chemotherapy.

Basically, these adverse events consisted of hypothyroidism, 3% (grade 3 and 4), or hyperthyroidism, 1.1% (grade 3 and 4). So (we found) no more adverse events, (only) slightly more immune-related adverse events.