Dr Ravindra Uppaluri - Dana-Farber Brigham Cancer Center, Boston, USA
The study I’ll be presenting at AACR is the phase III KEYNOTE-689 clinical trial which tested the addition of pembrolizumab to standard of care versus standard of care alone in stage 3 or 4a locally advanced head and neck cancer patients.
The trial was focussed on the locally advanced head and neck cancer setting where the standard of care for over 20 years for a large percent of patients has been to provide surgery up front followed by adjuvant therapy based on surgical pathology from the surgery. This paradigm was established, as I mentioned, about two decades ago and there have been really no significant advances for these patients. We continue to struggle with suboptimal outcomes and severe toxicities in these patients. So KEYNOTE-689 really addresses this sort of pressing need to improve the outcomes for these patients.
What was the study design?
The study design, honestly, to start I’ll say that it’s a very novel approach in the way we set it up. It was based on phase II data that Doug Adkins, my medical oncology colleague at WashU, and I had initially generated where we first asked the question over a decade ago of whether delivering perioperative immunotherapy was safe, number one, and would also lead to satisfactory outcomes. In fact, in our phase II study compared to historical data we saw intriguing clinical outcomes and also pathologic responses in the resected tumour.
Based on this study, KEYNOTE-689 was further designed to specifically address this question in a randomised phase III fashion. So the study design involves patients with locally advanced head and neck cancer, stage 3 or 4, are randomised 1:1 to either receive standard of care therapy which is surgery followed by adjuvant therapy, which is either radiation or radiation plus chemotherapy, or to the pembrolizumab arm where pembrolizumab plus standard of care is tested where patients receive two cycles of neoadjuvant pembrolizumab, surgery, which is then followed by adjuvant therapy, again dictated by pathologic findings, and concurrent and maintenance pembrolizumab with the adjuvant treatment. So that was the overall trial design.
What were the results of the study?
Let me tell you a little bit first about the endpoints of the study. The primary endpoint of the study was event free survival in the experimental arm versus standard of care arm. The event free survival, or EFS, is defined as disease progression, any recurrence or death after randomisation. The secondary endpoints included major pathologic response, or what’s called MPR, which is defined as having 10% of less residual invasive cancer in the primary resected tumour and any tumour involved lymph nodes. Overall survival was also another secondary endpoint. Finally, of course, we tested safety of this pembrolizumab plus standard of care approach compared to standard of care alone.
The findings of the study were really significant and overall we believe will lead to a new standard of care for these patients. What we found was that after a median follow-up of 38.3 months, number one, the general characteristics of the patients in both arms were balanced. What we found, number one, is that nearly 90% of patients underwent planned surgery in both arms. So the introduction of neoadjuvant pembrolizumab did not alter the surgical plan for patients at all. So this is a very reassuring finding. For the primary endpoint we found that patients who had received pembrolizumab had longer event free survival regardless of their PD-L1 scores, a common biomarker used in these types of studies. Median event free survival across all patients was 51.8 months with pembrolizumab and 30.4 months without after a median of 38.3 months of follow-up. This was highly significant.
For the secondary endpoints, as expected because we delivered neoadjuvant pembrolizumab, we saw significantly higher rates of major pathologic response in the surgical specimens across all patients who received neoadjuvant pembrolizumab. Finally, for the overall survival secondary endpoint, this was at this initial analysis not significant at the first interim analysis and additional follow-up is ongoing.
What is the significance of these results and what is next for this study?
The significance of the study is really impactful for the field of head and neck cancer in the sense that, as I mentioned earlier, the current standard of care has been in place for over 20 years and our hope was that the results would offer a new alternative for our patients. In fact, the data really strongly support that. So, really, neoadjuvant pembrolizumab followed by surgery and adjuvant pembrolizumab concurrent with and after postoperative radiotherapy or chemoradiotherapy represents a new standard of care in the treatment of patients with locally advanced head and neck cancer that’s surgically resectable.
For future studies I really think the study really opens up the door for thinking about this novel trial design approach in head and neck cancer patients. The neoadjuvant component allows potential de-intensification of adjuvant therapy and I think that’s an important area to investigate. An additional area to study is the contribution of components, that is our study, KEYNOTE-689, delivered pembrolizumab in the neoadjuvant and adjuvant setting and the question is which one is important or are both important?
It really, again as I said, is a new age for head and neck cancer and thinking about these surgical patients which really haven’t been addressed at all in the previous immunotherapy, immune checkpoint inhibitor, clinical trials. So it’s a really exciting time for head and neck cancer.
Is there anything else you would like to add?
I think it’s really important to highlight, and we use this phrase very commonly, that head and neck cancer management for these locally advanced patients really takes a village to manage these patients. There’s contribution from multiple specialities – medical oncology, radiation oncology, surgical oncology already we talked about, and lots of different ancillary services. This trial in particular really highlights that interaction and, given that it represents a new standard of care, really emphasises the importance of close multidisciplinary collaboration in taking care of these patients.
Finally, I’d like to say that this trial wouldn’t have been possible without hundreds of patients from all over the world and I’m excited to see the findings applied to patients and improving patient outcomes for these difficult to treat cancers.
