JCO Editorial Fellow Dr. Peter Li and JCO Associate Editor Dr. Andrew Ko discuss the ASCO 25 Simultaneous Publication paper "Lenvatinib Plus Pembrolizumab and Chemotherapy Versus Chemotherapy in Advanced Metastatic Gastroesophageal Adenocarcinoma: The Phase III Randomized LEAP-015 Study."

The guest on this podcast episode has no disclosures to declare.

Dr. Peter Li: Hello, everyone, and welcome to our 2025 ASCO Annual Meeting Series where we cover some of the top JCO papers published simultaneously with their abstract presentation at this year's meeting. I'm your host, Dr. Peter Li, JCO Editorial Fellow, and I'm joined by Dr. Andrew Ko, JCO Associate Editor, to discuss the Journal of Clinical Oncology article and abstract presentation "Lenvatinib Plus Pembrolizumab and Chemotherapy Versus Chemotherapy in Advanced Metastatic Gastroesophageal Adenocarcinoma: The Phase III Randomized LEAP-015 Study."

Now, let's start off with the relevance of this article. Andrew, can you please explain this to our listeners?

Dr. Andrew Ko: Sure. Thanks, Peter. So, this was a very large international study evaluating the combination of lenvatinib and pembrolizumab. And just for context, that combination has been approved for use in other solid tumor types. It's FDA approved for renal cell carcinoma, for example, and endometrial carcinoma. But this study was looking specifically at this combination together with a chemotherapy backbone - so either FOLFOX or CAPOX - and comparing that to what at the time was a standard of care, which was just standard chemotherapy by itself. So, this very large study was intending to look at this particular novel combination. And we can get into some of the nuances of this study because the way that the experimental, the combination arm, was designed was perhaps a little bit more on the unusual side and led to maybe some imbalance in terms of how we think about the respective arms.

Dr. Peter Li: Okay. We can definitely talk more about that as we go on.

So, what are some of the key results of this study, and how do you think this will impact practice in the future?

Dr. Andrew Ko: That's a good question. Technically, it was not a positive study. Well, it was positive in the sense that the co-primary endpoints - which included both progression-free survival and overall survival - so, progression-free survival, it did technically meet its endpoint, both in terms of the overall population and the preplanned subgroup analysis of patients who had a PD-L1 CPS of greater than or equal to 1. So, there was a PFS benefit with the experimental combination - the lenvatinib, pembrolizumab, plus chemotherapy - compared to chemotherapy alone. I will say the benefit was on the more modest side. So, if you even look at the medians, it was not a marked difference. If you look at the hazard ratios, they did meet statistical significance. On the other hand, this did not translate into a benefit for overall survival.

So, when you ask, "Well, is this going to inform practice?" I'd have to say no. It highlights, I think, that JCO does want to publish articles that aren't necessarily going to be practice-changing, but that I think offer a lot of insights into trial design and important aspects of investigating novel treatments, even if they don't end up moving the needle in routine clinical practice.

Dr. Peter Li: I totally agree with you. I mean, it was significant in terms of progression-free survival, but again, not clinically significant. And then overall survival, the interventional arm actually appeared to do slightly worse overall.

Can you make some comments on the strengths and the weaknesses of this study, and where do you see us going from here?

Dr. Andrew Ko: So, I think a couple of things worth highlighting in this study, very well designed, more than 800 patients in total. So, first of all, as I mentioned at the beginning, the combination was a little bit unique in terms of patients enrolled to the experimental arm got the combination of lenvatinib, pembrolizumab, together with chemotherapy for a very finite duration. So, that period of chemotherapy they received was only three months. And per protocol, patients then just segued to, quote unquote “maintenance treatment” with just the lenvatinib and pembrolizumab combination. Whereas patients on the control arm, meaning chemotherapy alone, would continue chemotherapy basically in perpetuity until their disease progressed or intolerable toxicity. So, there really was an imbalance in terms of, if you think that chemotherapy or continuing chemotherapy beyond that initial three-month period of time may be significant, that could have had some impact on the robustness or the efficacy of the experimental arm. There were some other aspects in terms of perhaps some differences in the rates of post-progression treatment, in other words, patients going on to receive second-line treatment.

I think the other very relevant aspect, Peter, in this study was that the control arm - and no fault of the investigators - but the control arm at the time the study was ongoing just consisted of chemotherapy, FOLFOX CAPOX, by itself, without an immune checkpoint inhibitor, right? And we clearly know, based on results of several large phase III studies, and it's now in standard clinical practice, that we routinely use chemotherapy plus an immune checkpoint inhibitor. Certainly for patients with CPS PD-1/PD-L1 scores that are, well, you could argue greater than 1, or perhaps greater than 5 or 10. But the point being that the control arm of the study probably doesn't reflect what is currently used in clinical practice. And that's just always a challenge in clinical trial design, right? That when a study is designed and when it rolls out, you're always at risk in a rapidly changing and moving field that the standard of care may evolve during the lifetime of that particular trial, which is what I think you see in LEAP-015.

Dr. Peter Li: Totally understand. And the survival we see from this study is also roughly similar to the combination of immuno-chemotherapy that is the standard of care today, which is, the authors mentioned, 12 to 14 months.

Thank you so much, Andrew, for your input and for speaking about the JCO article "Lenvatinib Plus Pembrolizumab and Chemotherapy Versus Chemotherapy in Advanced Metastatic Gastroesophageal Adenocarcinoma: The Phase III Randomized LEAP-015 Study."

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