Pembrolizumab benefits persist at nearly 8 years in TNBC | ASCO 2026

At ASCO 2026, final analysis data from the phase 3 KEYNOTE-522 trial confirmed that adding pembrolizumab to neoadjuvant chemotherapy followed by adjuvant pembrolizumab produces durable, long-term survival benefits in patients with high-risk, early-stage triple-negative breast cancer (TNBC).

With a median follow-up of nearly 8 years, the 7-year event-free survival rate reached 78.3% in the pembrolizumab arm versus 69.8% with chemotherapy alone. Overall survival also favored pembrolizumab, with a 7-year rate of 85.1% compared with 77.2% in the placebo group. The benefit held across prespecified subgroups, including patients stratified by PD-L1 expression, nodal status, and disease stage.

Managed Healthcare Executive^® spoke with study author Javier Cortes, MD, PhD, of the International Breast Cancer Center in Barcelona, Spain, about what these mature data mean for clinical practice and where pembrolizumab fits as the TNBC treatment landscape continues to evolve with antibody-drug conjugates and novel biomarker-guided strategies.

This interview has been edited for length and clarity.

MHE: With nearly 8 years of follow-up now available, what stands out most to you about the durability of benefit seen with pembrolizumab in KEYNOTE-522?

I think that KEYNOTE-522 established the standard of care in patients with early triple-negative breast cancer, but it's always important to try to understand how the follow-up is going. Sometimes, something that we observed from the very beginning is, afterwards, less impressive than it was before. This was clearly not the case in KEYNOTE-522, but the other way around. We always want to cure more patients, and this is something that we need time to demonstrate. Why? Because when patients develop metastasis, the new and better treatments we have might improve overall survival at the end. So, the point is, can we cure more patients? Can we decrease the number of patients who develop metastasis? That's something that, with this 86-month follow-up, we have demonstrated that it not only continues to be like that, but also the absolute number has slightly increased. I think that is very, very good news.

MHE: The survival benefit appeared generally consistent across PD-L1 status, nodal status, and stage. Do these findings further solidify pembrolizumab plus chemotherapy as the standard of care for high-risk early-stage TNBC?

Triple-negative breast cancer is always an aggressive disease, and it is a disease to treat intensively. I think that we cannot say, “This is a smaller triple-negative breast cancer [tumor], and we can maybe do less treatment,” because triple-negative breast cancer is something that we have to treat very, very well from the very beginning. Basically, we have stage II or stage III, and here is where pembrolizumab improves outcomes, and you said very nicely before that it is not just about the stage; it's not just about the nodal involvement — node-positive or node-negative — it's true that it’s not only about PD-L1 either. It is about all of these patients who might benefit to the same degree from pembrolizumab, and the other important aspect is that the strategy should be complete — it should be prior to surgery and after surgery as well.

MHE: How do these mature overall survival data change the conversation around pathologic complete response as a surrogate endpoint in TNBC?

In TNBC, pathological response, in my opinion, continues to be a good surrogate marker. It's true that the two most important long-term outcomes are invasive disease-free survival and overall survival. I would also like to add distant disease-free survival, or metastasis-free survival — I would prefer this compared with invasive disease-free survival. Nevertheless, in triple-negative breast cancer, usually when we have a patient with a pathological complete remission (PCR), we know that the prognosis of this patient is much better than for patients who did not achieve PCR. To conclude, we want to demonstrate long-term outcomes, but in the meantime, if we observe this improvement in PCR, that's something important to try to approve the drug earlier, and they will have the impact and benefit afterwards.

MHE: As the TNBC landscape evolves with antibody-drug conjugates and other immunotherapy approaches, where do you see KEYNOTE-522 fitting into the future treatment paradigm?

That’s a great question. I think that, as you said, treatments are getting better and better. But many patients continue to die or continue to develop metastasis. If we have one out of a million patients who are not cured, we have to continue working on this, and I think that the KEYNOTE-522 is the standard of care — so platinum-based chemotherapy plus pembrolizumab — is the standard of care, and we have to build on top of that.

First, we have to understand that the antibody-drug conjugates are here to stay. And we are exploring in many trials — in the neoadjuvant setting, in the adjuvant setting, after no PCR, etc. — how these antibody-drug conjugates will act in the prognosis of triple-negative breast cancer. It does not mean that we are going to remove pembrolizumab, we're going to add to it. Second, it's true that we also have ongoing clinical trials for patients who achieved a pathological remission to understand if we have to continue or not with pembrolizumab. But it is very, very important to remark that today, unless we have these data, the standard of care should be to continue with pembrolizumab.

My last comment is that the antibody-drug conjugates will be here, I think, in the coming maybe 2 to 3 years. Pembrolizumab is also here, but we need to understand much better if we can also de-escalate chemotherapy. So, would it be the possible that some patients with pembrolizumab could be cured without so much intense chemotherapy? That's another important aspect. So, in my opinion, pembrolizumab is the standard of care along with chemotherapy. We have to escalate in some patients, but in other patients, we might de-escalate at least the chemotherapy.

MHE: Is there anything else you’d like to add?

One final comment to consider is how to incorporate novel technologies into early triple-negative breast cancer? I'm not just talking about how to have better MRIs or PET scans. I'm talking about liquid biopsy, for example, ctDNA. How can we follow-up our patients better to try to diagnose micrometastatic disease before seeing the micrometastatic disease? There are ongoing clinical trials, and we have seen clinical trials like c-TRACK — but unfortunately, at the time we observed ctDNA positivity, we also saw micrometastatic and macrometastatic disease. So, I think that the new technologies, including artificial intelligence, everything has to help us treat patients in a more efficient way. And it's not just the same for everyone, so can we optimize, can we target, and can we tailor the treatments better? That's something we have to try to learn in the future.