Image of Dr Teresa Tsakok, a dermatologist at Guy's and St Thomas'

A BRC-funded study published in JAMA Dermatology looked at how a blood test can be used to predict how well patients respond to a drug. We sat down with author Dr Teresa Tsakok to put this research into the wider context of work at St John’s Institute of Dermatology towards personalising treatment for psoriasis.

Psoriasis has a huge impact on patients’ lives. Aside from the physical discomfort of inflamed and flaking skin, the condition has a huge psychological impact, especially where patients have tried several treatments with little success.

Biologics have been game-changing in treating the condition. For some patients with severe psoriasis, these treatments bring huge benefits, mimicking naturally occurring signalling molecules to reduce inflammation, rather than just relieving symptoms. Yet at the moment, we are using them in a ‘one-size fits all’ way, at a cost of approximately £10,000 per year per patient.

Each patient has different individual characteristics such as genetics, body size, gender, ethnicity and smoking or alcohol habits. We know that these factors can affect how patients respond to medicines, and we want to work out how to use this to tailor our treatment to each patient.

Our team at St John’s Institute of Dermatology are working towards personalising treatment for psoriasis – trying to predict who will respond best to different treatments, and monitoring how patients are responding, so we can adjust doses or try a new treatment altogether in an informed way, rather than trial and error.

One key piece of this puzzle is looking at levels of a biologic drug in patients’ bloodstreams, and how this affects their outcomes. Why is this important? If a patient doesn’t respond or stops responding to a biologic therapy, we don’t know if that’s because the drug doesn’t work, or because we are not giving them a dose that is high enough. On the flipside, if we’re giving a patient a higher dose than required, they might experience more side effects without added benefit. And routinely giving certain patients even just a bit too much, means we’re wasting money. For common diseases like psoriasis, and expensive drugs like ustekinumab, even small gains in efficiency could represent big savings for the NHS.

So it was exciting for us to confirm that in patients being treated with ustekinumab for severe psoriasis, measuring levels of the drug in the blood early on does give us an idea of whether the treatment will be successful down the line. This is the largest study using ‘real-world’ data from psoriasis patients in NHS clinics across the country, so we hope it’s a reliable finding.

This is a first step, but it has already sparked other research looking at implementing drug levels into clinical practice – you can read more about my colleague Dr Satveer Mahil’s work here. In another project, I’m looking at anti-drug antibodies produced by some patients as part of an immune response against the biologic. 40-70% of patients on a common biologic called adalimumab develop these anti-drug antibodies, which can mean that the drug stops working. This can be hugely distressing for patients.

The power of this type of research will eventually be in integrating lots of different steps – perhaps including a patient’s genetic factors. Team work is going to be key. But we hope that this work will make a huge difference to patients down the line.

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