Showing posts with label challenge. Show all posts
Showing posts with label challenge. Show all posts

Tuesday, October 24, 2023

Scientists deliberately gave women Zika--challenge trials for diseases whose incidence has dropped too far for conventional clinical trials

 Nature has the story (despite the somewhat inflammatory headline).

Scientists deliberately gave women Zika — here’s why. ‘Human challenge’ results suggest that such trials could be used to test vaccines when Zika incidence is low.  by Mariana Lenharo, Nature, 21 October 2023

"For the first time, scientists have deliberately infected people with Zika virus to learn whether such a strategy could help to test vaccines against the pathogen.

The virus can cause severe birth abnormalities in babies born to parents infected during pregnancy. It also has been associated with neurological problems in adults, although those cases are rare. But infected study participants had only mild symptoms, and none became pregnant during or immediately after the trial. The results raise hopes that ‘human challenge’ programmes — in which volunteers are exposed to a pathogen in a controlled setting — could make it feasible to test vaccines at a time when Zika incidence is low.

“This is a great scientific gain in terms of the development of a vaccine,” said Rafael Franca, an immunologist at the Oswaldo Cruz Foundation in Ribeirão Preto, Brazil. The results are scheduled to be presented today at the annual meeting of the American Society of Tropical Medicine and Hygiene in Chicago, Illinois.

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"In 2022, after a long process to address ethical concerns around the study, Durbin and her team recruited 28 healthy women, aged 18 to 40, who were neither pregnant nor lactating. All agreed to be admitted to a research facility and remain there until they were no longer infectious; they stayed at the unit for 9 to 16 days. They were tested for pregnancy several times before receiving the virus, to avoid the risk of congenital problems associated with Zika, and were counselled to use birth control for at least two months after the study.

Hope for smaller trials

The researchers injected 20 participants with one of two strains of Zika virus and eight with placebo. All of the participants who received the virus were infected; of those, 95% developed a rash — a common symptom of Zika — and 65% had joint pain. None of the placebo recipients had those symptoms.

Durbin says the findings indicate that the two strains of Zika administered in the trial can be safely and effectively used to infect participants in a Zika vaccine trial. She estimates that the controlled human infection model could be used in a phase III clinical trial for vaccine efficacy with as few as 50 to 100 participants. “With the challenge model, where you have 100% of infections, you could get an efficacy result with many fewer people” than in a conventional trial, says Durbin.

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The new study represents a turnaround in the thinking about challenge trials. In early 2017, a report by researchers convened by the National Institute of Allergy and Infectious Diseases and the Walter Reed Army Institute of Research concluded that the risks of a human-infection study for Zika, at that time, surpassed the potential benefits.

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But “from that time to now, we learnt a lot,” says Palacios. “Now we know that the risk of the virus being transmitted to another person through sexual relationships is limited and something that can be controlled,” he says. And regulators have signalled that they might consider data from human challenge trials in vaccine development, “in particular for those diseases that don’t have enough incidence to test in the field.”

Despite the low number of Zika cases, researchers say that it’s important to continue the efforts to develop a vaccine, because the virus might make a comeback. “Infections are much lower than they were during the epidemic in 2016. However, they are still occurring,” says Neil French, an infectious-disease specialist at the University of Liverpool, UK, who is involved in a Zika vaccine-development project. “The justification for a vaccine remains strong.”

Friday, September 22, 2023

Support for hepatitis C human challenge studies, in The Lancet Gastroenterology & Hepatology

 Here's a call for action, in The Lancet Gastroenterology & Hepatology:

Joint statement in support of hepatitis C human challenge studies by Harvey J Alter, Eleanor Barnes, Mia J Biondi, Andrea L Cox, Jake D Eberts, Jordan J Feld, T Jake Liang, Josh Morrison, Charles M Rice, Naglaa H Shoukry, David L Thomas, Jennifer Van Gennip, Charles Weijer, on behalf of other signatories †, Published:September 20, 2023 DOI:https://doi.org/10.1016/S2468-1253(23)00314-X

"We, the 121 undersigned, believe that human challenge studies among adult volunteers will be critical in the development of hepatitis C vaccines.

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"Despite the advent of safe and highly effective direct-acting antiviral (DAA) treatments, the ongoing toll of hepatitis C remains high among low-income and middle-income countries and vulnerable populations such as people who inject drugs. Millions of new infections occur annually, outpacing cures in some regions,1 with progress further disrupted by the COVID-19 pandemic. Without a change in strategy and the development of new tools, we will not reach the ambitious goal set out by WHO of elimination of viral hepatitis as a public health threat by 2030. This will require an effective hepatitis C vaccine—“the best insurance for the future”, as highlighted by a recent announcement of the White House national hepatitis C elimination programme.2

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"Human challenge studies for a hepatitis C vaccine could accelerate vaccine development dramatically. The effort to establish the model and test an initial vaccine candidate could take as little as 3 years. If that candidate fails, subsequent studies to test others could provide evidence of efficacy as quickly as 1 year.

"It is only because of the remarkably effective treatments that we can now consider human challenge studies for hepatitis C. With DAAs, cure rates of people without cirrhosis are reliably over 98%, with highly effective salvage regimens for the few who do not respond to a first course of therapy.5,  6 We are confident that in the era of DAAs, human challenge studies can be done in accordance with the highest ethical and safety standards. Healthy volunteers providing fully informed consent would be infected for at most 6 months before treatment and would be free to go about their lives with the right to request treatment and withdrawal from a study at any time. Acute infection causes no or few symptoms in most, and unlike in most challenge studies, where the risk of transmission necessitates quarantine of participants, the risk of passing hepatitis C to others is very low in day-to-day life.

"The impact of a vaccine would be enormous: reducing transmission, preventing cirrhosis, and most importantly, markedly reducing the rate of liver cancer, the world's second-most deadly cancer in terms of total fatalities.7 The global success of hepatitis B vaccine in achieving these goals exemplifies the importance of an effective hepatitis C vaccine. With the prospect of such a significant advance, we have confidence that people will volunteer to participate in hepatitis C challenge studies, and with such a strong team of experts worldwide, we are confident this approach will lead to the development of a successful hepatitis C vaccine."

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Here's the full list of 121 signers of the letter

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1Day Sooner has a related web page with some background: https://www.1daysooner.org/hepatitis-c-open-letter

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Earlier related posts:

Monday, May 15, 2023

Saturday, August 26, 2023

Challenge trials for a Hepatitis C vaccine

 The Journal Clinical Infectious Diseases has a special supplement on challenge trials (human infection trials) of a Hep C vaccine (now that Hep C is a curable disease):

Volume 77, Issue Supplement_3, 15 August 2023

SUPPLEMENT ARTICLES

T Jake Liang and others
Clinical Infectious Diseases, Volume 77, Issue Supplement_3, 15 August 2023, Page S215, https://doi.org/10.1093/cid/ciad343
Annette Rid and others
Clinical Infectious Diseases, Volume 77, Issue Supplement_3, 15 August 2023, Pages S216–S223, https://doi.org/10.1093/cid/ciad382
Jake D Eberts and others
Clinical Infectious Diseases, Volume 77, Issue Supplement_3, 15 August 2023, Pages S224–S230, https://doi.org/10.1093/cid/ciad350

The perspectives of former challenge study participants and a survey of other potential volunteers can inform the design of hepatitis C virus controlled human infection models, including on topics such as transparency, volunteer safety and risk, and compensation.

Alyssa Bilinski and others
Clinical Infectious Diseases, Volume 77, Issue Supplement_3, 15 August 2023, Pages S231–S237, https://doi.org/10.1093/cid/ciad379

Saturday, June 24, 2023

Challenge trial for Covid in England reveals airborne superspreaders

 Nature has a news story about a Lancet Microbe paper reporting the challenge trial. See links to and excerpts from both below.

Here's the Nature story:

What makes a COVID superspreader? Scientists learn more after deliberately infecting volunteers. A rigorous study identifies ‘supershedders’ who spew huge amounts of virus into the air — despite having only mild symptoms. by Saima Sidik

"A study of people who were intentionally infected with SARS-CoV-2 has provided a wealth of insights into viral transmission — showing, for example, that a select group of people are ‘supershedders’ who spew vastly more virus into the air than do others1.

"The publication describes data from a controversial ‘challenge study’, in which scientists deliberately infected volunteers with the virus that causes COVID-192. Although the approach drew opposition, the work has now yielded data on questions central to public health, such as whether the severity of symptoms correlates with how contagious people are and whether home COVID-19 tests can play a part in reducing viral spread.

...

"Challenge studies are “very bold”, says Gandhi. Some people argue that it’s unethical to give people an infection that can cause severe illness, but the research design comes with benefits. Challenge studies can substantially speed up vaccine testing, and they’re the only way to understand certain aspects of COVID-19, such as the stage before people test positive or develop symptoms.

"Researchers inoculated 34 healthy young participants by squirting a known quantity of viral particles up their noses. Eighteen developed infections and spent at least 14 days confined to hospital rooms. Each day, researchers measured viral levels in the participants’ noses and throats, in the air, and on the participants’ hands and various surfaces in the rooms.

...

"Of the 18 participants who developed infections, 2 shed 86% of the airborne virus detected over the course of the entire study — even though both had only mild symptoms. Previous research3 has provided evidence for the existence of superspreaders who infect large numbers of people. But whether such people are also ‘supershedders’ who emit copious amounts of virus, or simply have many social contacts, was up for debate

..

"None of the participants emitted a detectable level of virus into the air before testing positive, and only a small proportion of them left detectable virus on their hands, on surfaces or on masks that they donned temporarily.

"By the time they tested positive, most participants had already experienced mild symptoms, such as tiredness or muscle aches. That means that if people test as soon as they detect symptoms, rapid tests “can be a powerful tool” for controlling viral spread, says infectious-disease researcher Christopher Brooke at the University of Illinois at Urbana-Champaign.

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And here's the original paper:

Jie Zhou, Anika Singanayagam, Niluka Goonawardane, Maya Moshe, Fiachra P Sweeney, Ksenia Sukhova, Ben Killingley, Mariya Kalinova, Alex J Mann, Andrew P Catchpole, Michael R Barer, Neil M Ferguson, Christopher Chiu, Wendy S Barclay, Viral emissions into the air and environment after SARS-CoV-2 human challenge: a phase 1, open label, first-in-human study, The Lancet Microbe, 2023, ISSN 2666-5247, https://doi.org/10.1016/S2666-5247(23)00101-5. (https://www.sciencedirect.com/science/article/pii/S2666524723001015)

"After controlled experimental inoculation, the timing, extent, and routes of viral emissions was heterogeneous. We observed that a minority of participants were high airborne virus emitters, giving support to the notion of superspreading individuals or events. Our data implicates the nose as the most important source of emissions. Frequent self-testing coupled with isolation upon awareness of first symptoms could reduce onward transmissions."


Saturday, February 18, 2023

Compensation for participating in clinical trials

 Here's an opinion piece from Medpage Today:

It's Time to Pay Clinical Trial Participants More — Accelerating trial enrollment can catalyze access to much-needed medications  by Gunnar Esiason 

He writes:

"Most people I know with cystic fibrosis have participated in at least one, if not several clinical trials. 

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"Participating in a trial can be like working for a company that hasn't invested in its employees in a long time. In this case, the employees are clinical trial participants. The pay is low despite the time required to participate in research and the growing number of trials that need participants.

"From 2019-2022, the number of registered clinical trials grew by 25%opens in a new tab or window globally -- yet participant pay remains arbitrary and inconsistentopens in a new tab or window between studies. It's almost like mismatched supply and demand curves, where participants are in high demand but unwilling to participate.

"Increasing trial participant pay might be a path toward alleviating the participant supply crunch in trials hungry for patients. One key benefit of increasing pay for patients could be substantial: namely, speeding up clinical trials through a more competitive enrollment process.

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"More than 80% of clinical trials fail to enroll on time, leading to costs of anywhere from $600,000 to $8 million per dayopens in a new tab or window and making trials take up to twice as longopens in a new tab or window.

"And yet it has been shownopens in a new tab or window that moderately increasing pay can motivate participation without being an "unjust inducement." In other words, patients are encouraged to participate -- but not coerced to do so.

"If increasing participant pay can accelerate trial enrollment, then a safe and effective drug can reach the market faster and therefore reduce the amount of time products remain in the pre-revenue stage. The return on investment for study sponsors who increase participant pay should be clear from a business perspective.

"From a patient perspective, even a marginal improvement in time to accessing new drugs is something worth celebrating. For patients, we pay the cost of delays with our health."

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Some earlier related posts:

Thursday, October 29, 2020

Paying participants in challenge trials of Covid-19 vaccines, by Ambuehl, Ockenfels, and Roth

"we note that increasing hourly pay by a risk-compensation percentage as proposed in the target article provides compensation proportional to risk only if the risk increases proportionally with the number of hours worked. (Some risky tasks take little time; imagine challenge trials to test bulletproof vests.) "