已收大量訂單的阿斯特捷利康和牛津大學攜手研發的新冠肺炎疫苗AZD1222因志願參加者出現嚴重副作用第三期試驗宣告暫停
牛津疫苗疑現嚴重負面反應 試驗暫停 AZN盤後瀉8%
MoneyDJ新聞
2020-09-09
英國藥廠阿斯特捷利康(AstraZeneca、AZN)和牛津大學攜手研發的新冠肺炎疫苗，在後期臨床試驗中，有名英國受試者疑似出現嚴重的負面反應，阿斯特捷利康宣布臨床試驗全面暫停。消息一出，該公司的美國存託憑證(ADR)盤後重挫8%。
Yahoo Finance報價顯示，8日美股正常盤，阿斯特捷利康上漲2.11%、收54.71美元。盤後暴跌8.14%、報50.25美元。
CNBC、STAT 8日報導，阿斯特捷利康聲明稿表示：「試驗時只要出現原因不明的疾病，就會有此種例行動作，以確保試驗倫理，目前狀況仍在調查當中」。有數種情況可列入疑似的嚴重負面反應，如入院、危及生命、甚至死亡，目前仍不清楚該名受試者的病況，消息人士透露，該受試者應會康復。
阿斯特捷利康表示會加快檢討速度，希望對試驗時間表的衝擊程度，能降至最低。現在只有三家疫苗廠進入第三階段(最終階段)的臨床試驗，分別是阿斯特捷利康、輝瑞(Pfizer)、Moderna。阿斯特捷利康8月底才在美國啟動第三階段人體試驗，稍早該公司已在英國、巴西、南非開始第二、三階段人體試驗。
一名匿名的內情人士表示，阿斯特捷利康疫苗出現嚴重負面反應，影響該公司疫苗實驗，也拖累別家疫苗廠的臨床試驗。阿斯特捷利康的疫苗，使用改良過的腺病毒(adenovirus)當作載體，運送新冠肺炎病毒的遺傳物質進入人體，此一技術未用於任何核准上市的疫苗，只用於試驗性的伊波拉疫苗。
7月份阿斯特捷利康公布初步試驗結果，當時數據顯示疫苗耐受性優異、沒有嚴重的負面後果，常見副作用為疲勞、頭痛等。美國政府5月表示，撥款12億美元給阿斯特捷利康，以取得至少3億劑疫苗。
牛津疫苗引發雙重免疫反應
BBC News、Barron`s、MarketWatch先前報導，牛津大學和英國藥廠阿斯特捷利康共同研發的新冠肺炎疫苗，初步試驗結果7月20日發布在知名醫學期刊《刺胳針》。結果顯示參與試驗的1,077人，接種後均誘發抗體和T細胞(T-cell)，能對抗新冠肺炎病毒。
《刺胳針》報告問世同時，阿斯特捷利康發布新聞稿表示，疫苗在所有受試者身上均誘發T細胞反應。90%受試者接種一次就出現中和抗體(neutralizing antibody)，只有10個人需要二度接種，之後所有人均產生中和抗體。兩種情況下，受試者體內的中和抗體水位，都和新冠肺炎康復患者差不多。與此同時，疫苗只引發了輕微溫和的副作用。
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AstraZeneca Covid-19 vaccine study put on hold due to suspected adverse reaction in participant in the U.K.
SEPTEMBER 8, 2020
Alarge, Phase 3 study testing a Covid-19 vaccine being developed by AstraZeneca and the University of Oxford at dozens of sites across the U.S. has been put on hold due to a suspected serious adverse reaction in a participant in the United Kingdom.
A spokesperson for AstraZeneca, a frontrunner in the race for a Covid-19 vaccine, said in a statement that the company’s “standard review process triggered a pause to vaccination to allow review of safety data.”
In a follow-up statement, AstraZeneca said it initiated the study hold. The nature of the adverse reaction and when it happened were not immediately known, though the participant is expected to recover, according to an individual familiar with the matter.
The spokesperson described the pause as “a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials.” The spokesperson also said that the company is “working to expedite the review of the single event to minimize any potential impact on the trial timeline.”
An individual familiar with the development said researchers had been told the hold was placed on the trial out of “an abundance of caution.” A second individual familiar with the matter, who also spoke on condition of anonymity, said the finding is having an impact on other AstraZeneca vaccine trials underway — as well as on the clinical trials being conducted by other vaccine manufacturers.
Clinical holds are not uncommon, and it’s unclear how long AstraZeneca’s might last. But the progress of the company’s trial — and those of all Covid-19 vaccines in development — are being closely watched given the pressing need for new ways to curb the global pandemic. There are currently nine vaccine candidates in Phase 3 trials. AstraZeneca’s is the first Phase 3 Covid-19 vaccine trial known to have been put on hold.
Researchers running other trials are now looking for similar cases of adverse reactions by combing through databases reviewed by a so-called Data and Safety Monitoring Board, the second person said.
AstraZeneca only began its Phase 3 trial in the U.S. in late August. The U.S. trial is currently taking place at 62 sites across the country, according to clinicaltrials.gov, a government registry, though some have not yet started enrolling participants. Phase 2/3 trials were previously started in the U.K., Brazil, and South Africa.
There are a number of different reactions that can qualify as suspected serious adverse reactions, symptoms that require hospitalization, life-threatening illness and even death. It was also not immediately clear which clinical trial the adverse reaction occurred in, though a clear possibility is the Phase 2/3 trial underway in the U.K.
While it’s still unclear how severe and rare the adverse event may be, the finding could impact how quickly efficacy data from the U.K. trial will be available. Those data are considered integral to any bid to seek an emergency use authorization for the vaccine from the U.S. Food and Drug Administration — and potentially jeopardize President Trump’s efforts to fast-track a vaccine ahead of the November election.
A Phase 1/2 study published in July reported that about 60% of 1,000 participants given the vaccine experienced side effects. All of the side effects, which included fever, headaches, muscle pain, and injection site reactions, were deemed mild or moderate. All of the side effects reported also subsided during the course of the study.
The vaccine — known as AZD1222 — uses an adenovirus that carries a gene for one of the proteins in SARS-CoV-2, the virus that causes Covid-19. The adenovirus is designed to induce the immune system to generate a protective response against SARS-2. The platform has not been used in an approved vaccine, but has been tested in experimental vaccines against other viruses, including the Ebola virus.
The Phase 3 trial in the U.S. aims to enroll about 30,000 participants at 80 sites across the country, according to a release last week from the National Institutes of Health.
It was not immediately clear what steps were being taken at study sites across the U.S. in response to the hold. Clinical holds in ongoing studies often involve a pause in recruiting new participants and dosing existing ones, unless it’s deemed in the interest of participant safety to continue dosing.
In the statement from AstraZeneca, the company spokesperson noted that “in large trials illnesses will happen by chance but must be independently reviewed to check this carefully.” The spokesperson also said the company is “committed to the safety of our participants and the highest standards of conduct in our trials.”
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