Latest results from KEYNOTE-181: Pembrolizumab versus chemotherapy as a second-line therapy for advanced oesophageal cancer

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Published: 15 Jul 2019
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Prof Jean-Philippe Metges - Centre Hospitalier Régional et Universitaire de Brest, Brest, France

Prof Jean-Philippe Metges speaks to ecancer at ESMO 21st World Congress on Gastrointestinal Cancer about the final results from the KEYNOTE-181 study, in which patients with advanced oesophageal cancer were administered pembrolizumab or chemotherapy as a second-line therapy.

He describes the design of the trial, including the patient population included in the trial and the outcomes assessed.

Prof Metges states that overall survival was improved in patients with adenocarcinoma and squamous cell carcinoma when administered pembrolizumab. Grade 3 - 5 toxicities and patient quality of life were also improved with pembrolizumab. However, no improvement was seen in progression-free survival.

He concludes by emphasising that this could be a new treatment option for patients with adenocarcinoma and squamous cell carcinoma due to the promising results this phase III trial has generated. 
 

It’s the final results of the phase III trial, which is an open phase III trial. We all know that the patient is going to receive chemotherapy or immunotherapy. It concerns patients with oesophageal cancer and it’s adenocarcinoma and squamous cell carcinoma. These patients have a progression after first line and clearly they have to be in a fit situation, meaning PS zero and one. This is a phase III trial so you have a randomisation between pembrolizumab, an immunotherapy, or chemotherapy and concerning the chemotherapy you have three options and this is the choice of the investigator between paclitaxel, docetaxel and irinotecan.

The primary endpoint is very easy to understand – overall survival – but you have, in fact, three co-primary endpoints – overall survival for the intent to treat group, overall survival for patients adenocarcinoma and squamous cell with a CPS superior to 10. CPS superior to 10 means it’s a count of immune cells and tumour cells and you have a count for a total. Then the third group is focussed on squamous cell carcinoma. So if you look to the results clearly you have a clear improvement in terms of overall survival in patients with adenocarcinoma and squamous cell carcinoma who have a CPS superior to 10 or equal and for patients with squamous cell carcinoma. If you move to PFS, it’s a secondary endpoint, you have no clear gain and if you move to side effects and especially side effects grade 3 and 5, remember it’s the worst, you have clearly an improvement in the arm with pembrolizumab versus chemotherapy. After it’s very important to look to quality of life for the patients and clearly you have an improvement for the patients with pembrolizumab.

Why is it important? Because when you speak about squamous cell and when you speak about adenocarcinoma this is the same place in the oesophageal area but it’s not the same histology and it’s not the same management due to the results in the literature. If you go to squamous cell carcinoma actually you have no phase III data trial results which tend to prove that you have any treatment for these patients after failure of first line. So if you arrive with a positive study for this kind of patient you have the first positive study and this is the case for squamous cell carcinoma.

So it’s difficult to know what our authorities in Europe, in the US and over abroad could have as final results – approval or not. But one thing is sure, this is a worldwide trial, that means that everybody in the world has put some patients in this trial – coming from the United States of America, coming from Europe, coming from Asia – and that means that we are not able to say, like previous studies not in oesophageal but, for example, in gastric, ‘Oh no, it’s Japanese people, it’s not the same in Caucasian.’ You have Caucasian and you have, clearly, Asian people.

The second point is, and it could be a surprise, the vast majority, about 60% of the patients, are squamous cell carcinoma. So it’s not a little subgroup of patients, that’s the majority of the patients who have been included in this study who have a squamous cell carcinoma.

So, in summary, we have a social decision for this kind of patient because for squamous cell carcinoma you have actually no approval for a drug and the drugs we give worldwide are based on expert opinion. In fact, we all know that the result of a positive phase III trial is clearly superior to expert opinion. So we wait but clearly this is a new option for adenocarcinoma CPS 10 but this is very new. We have a phase I and then a phase and then a phase. This is a phase III trial, this is not a phase I or phase II, this is a prospective open label phase III trial which is positive for squamous cell carcinoma and this is the first time.

Is there anything you would like to add?

I think I covered the fact that this is now the ball in the place of the authorities. The medical doctors have done their job, they have performed the study, the patients have signed and everybody is going to wait for now. You have a positive one. When you await results and you have not the results and you say, ‘Perhaps… It seems…’ No, that’s the final results. So we need actually to have the full publication because it’s a presentation in a congress, a world congress but it’s a presentation. After the paper, or rapidly, we need to have a response of the authorities because these patients are equal to the others and it’s not possible to say, ‘It’s difficult, you have nothing.’ and when you have nothing in terms of strategy or only an expert opinion, that’s lower in terms of poorer than a phase III trial.