Professor David Isenberg, Arthritis Research UK Professor of Rheumatology, chats to WPR about how the introduction of certain biologic drugs has been overhauling the treatment of psoriatic arthritis – and assesses the impact of the genetic profile of the patient.
WHAT ARE THE MAJOR SIGNPOSTS OF PSORIATIC ARTHRITIS?
Psoriasis is a skin rash which can cause ‘slivery-red’ areas of inflammation and may be accompanied by arthritis, that leads to swollen and painful joints. Psoriasis is a fairly common condition and the effects can vary considerably for each patient. You can get someone who has a small rash on their elbow, or someone who has a psoriatic rash covering 80 per cent of their body.
There is conflicting information on how likely it is that a person with psoriasis will develop arthritis. Currently, it is believed that somewhere between 7.5 and 25 per cent of people with psoriasis will experience arthritis.
DO WE KNOW ANY MORE ABOUT THE CONDITION’S SPECIFIC TRIGGERS?
At present, we don’t know why people develop psoriasis or why some go on to develop arthritis. Sometimes, confusingly, arthritis comes first and psoriasis appears later. It’s hard to say how common that is and it’s difficult to pin down specific triggers.
WHEN DOES CONFUSION PLAGUE ITS DIAGNOSIS?
I don’t think that there’s much confusion, except when the arthritis comes first. A patient may develop swollen fingers, wrists or knees, for example, but they don’t have a rash, and then six months later the psoriasis rash appears. This scenario is difficult to anticipate.
WHAT CAN BE EXPECTED REGARDING THE PROGRESSION AND LONG-TERM IMPACT OF PSORIATIC ARTHRITIS?
Treatment of psoriatic arthritis has changed radically with the introduction of biologic drugs, that inhibit specific components of the immune system. These drugs have made some previously untreatable cases much more manageable.
Years ago, before drugs were developed to target individual cells, there was a limited number of immunosuppressant drugs, and they would only control around 70 per cent of patients’ symptoms. The remaining 30 per cent of people with psoriatic arthritis would be very difficult to treat.
In the last 15 to 20 years, the drugs to control arthritis symptoms have arrived, and in the last two to four years a newer range of drugs can control psoriasis. These new drugs are also biologic, but with different targets, which are also key in the development of psoriasis.
WHAT ARE THE CARDIOVASCULAR RISKS?
People who have psoriasis have a small increase in prevalence of angina, high blood pressure, and coronary intervention; where you are looking to see if there is a reduction in blood flow in vessels in the heart. It’s only a small increase, but it’s there.
WITH A VARIED SELECTION OF MEDICATION OPTIONS AVAILABLE, WHAT ARE YOUR RECOMMENDED CHOICES?
It depends on the extent of the rash and arthritis. In mild cases, creams and anti-inflammatory drugs can be used. In very severe cases, we’ll often use the anti-TNF drugs, and in between, a lot of patients are treated with methotrexate, which has been around for 60 years, and it can treat skin and arthritis.
HAVE THERE BEEN ANY RECENT REVELATIONS IN RELATION TO RESEARCH AND TREATMENT?
For the treatment of psoriasis, there are biologic drugs which block molecules known as IL17 or IL12/23. By targeting these molecules, you can block the inflammation process that occurs in psoriasis and psoriatic arthritis.
HOW IMPORTANT IS THE PHARMACIST’S ROLE IN THE TREATMENT PROCESS?
It’s very important that pharmacists co-ordinate with physicians and help to ensure that the best possible treatment for our patients is provided.
HOW CAN HEALTHCARE PROFESSIONALS HELP PSORIATIC ARTHRITIS PATIENTS MAINTAIN A HIGH QUALITY OF LIFE?
I think that a big part of being a good healthcare professional is being sympathetic, getting to know your patients well, introducing the appropriate drugs at the right time, and referring the patients rapidly to secondary care and rheumatologists.
HAVE YOU EVER WITNESSED ANY UNUSUAL CASES?
It’s very striking that the anti-TNF drugs are in some cases great for arthritis and sometimes not so good for the skin, and in other cases the opposite is true.
One suspects it must be down to genetic reasons; that the genetic profile of the patient forecasts the effectiveness of the drug in treating both the psoriasis and arthritis.
Some people don’t respond to the anti-TNFs at all. With rheumatoid arthritis, you have five different biologics to work with, and it can be frustrating when a patient needs a disease-modifying drug, and there is no way of knowing which one will work.
IT MUST BE TRIAL AND ERROR? HOW LONG DOES IT TAKE TO KNOW IF ONE WORKS OR NOT?
Trial and error, exactly. The drugs can take a while to take effect and a minimum of four to six months is needed. I had a patient who was in his 70s and had experienced rheumatoid arthritis since his 60s. He had been on a new biologic drug for two months and said he wanted to stop taking it as it was not working.
I wrote a letter to the biologic clinic asking for his treatment to be changed. Unfortunately, his wife was suffering with dementia and he missed his appointment. Four months later, he came in and had a huge smile on his face, as the drug he had originally disliked was now working well.