As data near, U.K. rethinks AstraZeneca COVID-19 antibody deal

The U.K. government has rethought plans to buy one million doses of an anti-SARS-CoV-2 antibody in development at AstraZeneca, according to anonymous sources quoted by Bloomberg. News of the rethink comes shortly before AstraZeneca is due to deliver late-phase data on the candidate.

AstraZeneca agreed to provide the U.K. with one million doses of its long-acting COVID-19 antibody AZD7442 in November. Back then, the U.K. government framed the in-principle agreement as part of a push to access “treatments that protect our vulnerable, particularly those who cannot receive a vaccine,” such as people who are immunocompromised.

Since then, the U.K. has seen (PDF) data that “indicates lower protection in vaccinated adults who are immunosuppressed,” leading it to prioritize the vaccination of the household contacts of people with severe immunosuppression.

Yet, despite new evidence validating the thinking behind the original deal, the U.K. is now reportedly reconsidering whether to buy the doses as planned. The original statement to disclose the deal said the U.K. would procure the doses if AZD7442 met “robust safety and effectiveness standards.” Trials that will show whether AZD7442 meets those standards are set to read out soon. 

AstraZeneca has completed dosing in phase 2/3 trials of AZD7442 in prophylaxis and post-exposure prophylaxis settings. Data from the post-exposure prophylaxis study are due in the first half of the year, with the results of the prophylaxis study set to follow before the end of 2021. AstraZeneca was still dosing in an outpatient treatment setting phase 2/3 as of its latest update, but the shorter-term endpoints used in the trial mean data from that study could still drop in the first half of the year.

The two prophylaxis clinical trials offer AstraZeneca a chance to differentiate AZD7442 from other anti-SARS-CoV-2 antibodies. AstraZeneca has used half-life extension technologies to try to develop a product that provides protection against COVID-19 for up to 12 months. If its efficacy and durability are validated in the clinic, AZD7442 could offer a lifeline for people who are only partly protected by COVID-19 vaccines. 

That opportunity for anti-SARS-CoV-2 antibodies remains untapped. So far, antibodies have mainly been used to treat people who are infected with the coronavirus. In that setting, uptake has lagged below expectations. Other antibody developers are targeting the prophylaxis opportunity but, while Regeneron already has data in the setting, AstraZeneca may have an edge in terms of durability. 

Yet, in the U.K., where two-thirds of the population have already received the first dose of a COVID-19 vaccine, the potential benefits of AZD7442 may no longer hold enough allure to convince the government to follow through on its agreement with AstraZeneca.