Concerning news from one of Glaxosmithkline’s biggest cancer hopes: second-quarter sales of the Parp inhibitor Zejula dipped 5% versus the previous three months, the company said yesterday. Executives blamed Covid-19, which has caused cancer diagnoses and debulking surgeries to decline. This seems plausible, although these issues did not hit Astrazeneca and Merck & Co’s rival Parp inhibitor, Lynparza, which grew 6% quarter on quarter, it was announced today. More worrying is that Glaxo was expecting demand to rise on the back of a recent label expansion that saw Zejula approved in an all-comers, front-line maintenance setting. This was viewed by analysts as an advantage over Lynparza, which is restricted to patients with a specific genetic signal in this use. True, these new approvals only happened in May so it is too early to draw firm conclusions: Glaxo said Zejula’s share of first-line Parp sales jumped from 14% in April to 21% in May. It should be remembered that Lynparza is also approved in other tumour types. But Glaxo was always going to struggle to compete against a much bigger product backed by two pharma giants. Zejula’s performance in the coming quarters will be scrutinised for further signs of distress.