Kiniksa Pharmaceuticals might have been in the headlines for attempting to curb Covid-19 infections, but yesterday’s results from the phase III Rhapsody trial for rilonacept in recurring pericarditis had a bigger impact on its shares. The IL-1 antagonist showed impressive efficacy, producing a 96% reduction versus placebo in the risk of the reoccurrence of a pericarditis event, complete with a p value of 0.0001, causing the stock to close up 13%. Such was rilonacept’s effectiveness the median time to a recurrence could not be calculated owing to a lack of events. Unsurprisingly, a filing is being prepared for later this year. Knocking it out of the park on efficacy now means rilonacept’s addressable patient population could be higher than previously thought. Analysts at Wedbush had approximated 3,000 US patients, comprising the refractory category. Yesterday, the company upped that to 14,000, pulling in multiple relapsing and steroid-dependent patients. If this proves to be the case then the $5m that Kiniksa paid Regeneron back in 2017 for the pericarditis indication will look like a very shrewd investment.