It’s my pleasure to be invited to talk about some of the recent advances in the treatment of head and neck cancer. I basically want to concentrate on three that I think have really come to the forefront in incredible ways of changes in the way we do handle head and neck cancer. The most appealing one and the most active one at this point, where much research is going on, is the immunotherapy of head and neck cancer tumours. It’s not only head and neck cancer tumours but other tumours too that are involved with this but obviously my area of expertise is with the head and neck cancer tumours. We’re talking about not chemotherapy, not anything that directly damages or attacks the tumour cells, but what enhances the immune system to recognise the tumour cells and for them to do the actual activity in destroying the tumour cells.
The most frequent mechanism for that is something called checkpoint inhibitors where the medication that we administer allows the immune cells of the body to recognise the tumour cells and to destroy them in a very, very effective way. One way of performing that and to find out if this tumour is indeed sensitive to this type of checkpoint inhibitor is to test the tumour cells for something called PD-L1 which is the pathway by which the tumour cell tries to turn off the recognition of the immune cell from recognising it as a tumour and thereby protecting itself. But this interferes with that pathway and the PD-L1 pathway is the checkpoint inhibitor pathway and it’s something that has been incredibly effective in tumours that demonstrate indeed they do contain PD-L1 and we actually get something called the CPS score to find out what percentage of the tumour cells are sensitive to this route. The higher the number of cells as far as percentage-wise, the more effective this type of therapy is.
We’ve been performing that for more advanced tumour stages and we’ve been seeing remarkable results in those tumours that demonstrate PD-L1 activity. The main drug that we use is something called pembrolizumab and that’s very effective in our hands in addressing these particular tumours. Recent research that is going on with this shows more and more that this has been an effective route to treat these tumours. We can talk about it a bit more if we have any additional questions but there’s again significant research.
Another area that has been incredibly active and very helpful for us is performing… Many of the tumours that occur at this point, especially in the area of the oropharynx, the oropharynx being the palatine tonsils, the lingual tonsils at the base of the tongue and also the rest of the oropharynx and the base of the tongue and the back of the throat. Many of these tumours, more and more, are not being caused as frequently by smoking and drinking exposure, smoking and alcohol exposure, but by HPV, human papilloma virus, exposure.
We have discovered more recently, in the past year or so, and again additional research is going on with this, that we can actually measure something called the ctDNA which is the circulating tumour DNA, the DNA that comes from the HPV that is causing this tumour. We can evaluate the titres of that in the bloodstream before treatment and can follow the progress, hopefully the positive progress, that our treatment plan has against decreasing the titres of these ctDNA, of the circulating tumour DNA. So if we obtain these titres before treatment and actually perform these titres either postoperatively, after an operation, to determine if there is eradication of that type of DNA, or as we treat them with either immunotherapy or chemotherapy or radiation, we can determine the progress in our treatment and the elimination of the tumour cells by following the titres in these tumour patients.
So these are two areas that really a lot of research has been performed and will continue to be done and we find very promising. For instance, with the HPV ctDNA, the circulating tumour DNA, if we perform a surgery on them, and nowadays there are a certain amount of patients who can fall into the realm of undergoing transoral robotic surgery for this, which is a less invasive way of handling these tumours if they are at the proper stage, the comparison of the preoperative ctDNA to the postoperative ctDNA really gives us an effective method of knowing if the entire tumour has been removed, both from the primary site and also from any of the potential lymph nodes that may be involved with metastatic disease in the neck too. So often the ctDNA will go down to zero immediately after the operation which obviously portends an excellent result from the operation.
We have been following these patients, again this is relatively short-term follow-up because this hasn’t been noted until most recently, but we also noticed that if there’s an increase in the ctDNA that one must be very concerned about the recurrence of tumour that may not be as clinically evident as with our examinations or even some of our radiographic studies. So this too is what we think is a very sensitive way of determining recurrent tumour by doing this blood test.