Amid rising concern of resistance, Pfizer limits supply of Paxlovid for combination studies — report
As concerns mount over the potential development of resistance to Pfizer’s Covid-19 pill Paxlovid, the company has declined to supply researchers with the antiviral for use in combination studies, according to a Bloomberg report.
Pfizer confirmed to Endpoints News that it’s evaluating a “multi-pronged strategy” that includes thinking ahead to second-generation antivirals and combination therapies. However, the pharma giant has not begun any clinical trials, according to a spokesperson.
“I would also note that we are continuing to monitor the data, but we have not seen any resistance emerge to date in patients treated with Paxlovid,” the spokesperson said in an emailed statement.
But the threat is there, according to scientists, including a Rutgers University team which reported a couple months ago that “as more people take Paxlovid, we will expect drug resistance to emerge.”
The news comes as reports pour in from patients experiencing a rebound of their Covid-19 symptoms after completing a five-day course of Paxlovid. In some cases, Covid patients are even testing negative and then positive again.
Well thought Covid was over, finished a 5 d Paxlovid, felt well, X2 neg antigen tests. 5 d later up this AM lots of rinorrhea, sore throat, antigen test screaming +. So either this post-Paxlovid relapse is real, something unique to BA.2.12 (although can’t confirm)…or something
— Prof Peter Hotez MD PhD (@PeterHotez) May 18, 2022
The FDA said earlier this month that it’s aware of the re-emergence of symptoms in some patients, and — despite Pfizer CEO Albert Bourla suggesting a second treatment for some patients — recommended against a prolonged or repeated treatment course.
In a White House briefing on Wednesday, NIAID director Anthony Fauci said the NIH is in discussions with Pfizer regarding potential studies to determine if a longer course of the antiviral is necessary.
“We’re going to be planning what studies we’re going to be doing relatively soon, within the next few days,” he said.
White House Covid-19 response coordinator Ashish Jha pointed out that roughly 2% of patients in clinical trials experienced a rebound of symptoms in the Paxlovid group, compared to about 1.5% in the placebo group. But that was when the Delta variant was prevalent.
“The question is, is this more common with Omicron?” Jha said. “We’re actually doing a lot of work right now to try to sort that out … It is hard to know exactly how often it happens.”
Meanwhile, Bloomberg reported that Pfizer has declined to provide supplies of Paxlovid to multiple groups — including the nonprofit Drugs for Neglected Diseases Initiative — looking to see if combining the drug with other agents can help hedge resistance.
Pfizer told Bloomberg that it’s allocating resources “in a way that maximizes availability of our overall supply, to help ensure access to patients as quickly as possible.”
“For our part, we are committed to well-controlled, hypothesis-driven clinical studies that can provide data that will be accepted by global regulatory agencies and therefore maximize the potential benefit for patients,” a spokesperson told Endpoints. “Additional studies of Paxlovid are underway or are being explored, and we will continue to share information as we have it.”