With the world focused on the outcome of clinical trials for a COVID-19 vaccine, new research may add a new layer of complexity to a trial process that mainly uses male animals and male humans in the development stages for drugs.

A team of researchers at the University of Sydney have found that female mice put on more liver fat than males in response to six-hour fasts, emphasising the growing need for the inclusion of both sexes in scientific research.

The research results raise questions around Australia’s clinical trial process, which does not require drugs that will be used by both men and women to be tested on both sexes at the preclinical and early clinical stages.

This has serious implications for investors in Australian biotech companies, which could be missing bigger opportunities by leaving females out of the research process.


Female mice get slimmer, male mice get bigger

Female mice not only put on more liver fat in response to the fasting period, but seemed to be better at using it, according to the research which was published last week in the The Journal of Physiology.

Male mice on the other hand ate more, got bigger and had larger livers.

Researchers fasted mice for six hours each night over four weeks, in research that was tapping into the growing interest in fasting as a way to deal with obesity. They chose night because this is the active phase of the mice, mimicking daytime fasting in humans.

The study said increasing the fasting phase during the day after eating can help to restore and repair the body after a meal and could be useful for researchers looking at diabetes, kidney disease, and high blood pressure particularly among women.


The male mouse bias

The paper noted that most studies exploring food restrictions and obesity used male mice.

“By highlighting the different responses to fasting in male and female mice, we are showing the importance of including both sexes in preclinical studies,” said Samantha Solon-Biet, a senior author on the University of Sydney research paper.

Male animal bias in the earliest stages of research is common in all areas of preclinical research.

A 2018 paper by Catholic University of Korea professor Suk Kyeong Lee found that 50 per cent of studies between 1979 and 2009 only used male mice.

She found that for diseases that affect more women than men, such as anxiety, depression, thyroiditis, hypertension and stroke, and multiple sclerosis, less than half of studies into the conditions used female animals.

“Experimental results obtained from research using only one sex are sometimes extrapolated to both sexes without thorough justification,” Lee wrote.

“Between years 1997 and 2000, the US Food and Drug Administration (FDA) suspended 10 prescription drugs producing severe adverse effects on the market.

“Eight of the 10 drugs caused greater health risks in women. Serious male biases in basic, preclinical, and clinical research were the main reason for the problem.”

Until 1993, the US FDA explicitly forbade women of childbearing age from participating in clinical trials, to avoid a repeat of the deformities suffered by babies whose mothers were given Thalidomide for morning sickness — even though that was a registered drug that had already passed clinical trials.

But in the US in 2016, the National Institutes of Health implemented a policy that required sex be included as a biological variable in pre-clinical research. The European Commission is moving in the same direction.


Et tu Australia?

The cost of running clinical trials is escalating every year.

This means that flaws in the trial process could cost investors millions of dollars with no return or deliver a drug that isn’t as good as it could be.

Late last year a paper in the Medical Journal of Australia said ignoring differences between the sexes across the research lifecycle — from grant submissions through to clinical translation — could compromise the accuracy of science.

Lee said the same thing, that sex bias “might cause enormous economic loss” as well as fatalities.

The Therapeutic Goods Administration (TGA) does not have rules around including women in trials or female representation in preclinical studies.

Women tend to only be included in trials at the phase two human stage, once preclinical studies and the phase one safety study have concluded. The final stage of clinical trials is a phase three, before drug registration.

The reason given for the lack of women at earlier stages, by industry leaders from Bill Ketelbey — chair of Alzheimer’s aspirant Actinogen (ASX:ACW) to Jane Kelly — the CEO of contract research organisation CMAX, is that regulations to protect women in the case of an unexpected pregnancy still make it too expensive and too arduous to include women at phase one.

The counter argument, by researchers such as Dr Zoe Wainer — head of public health and medical director at Bupa, and industry professionals such as Opyl (ASX:OPL) boss Michelle Gallaher, is that if drugs aren’t tested on women from the start how are we to know whether they are truly safe and truly effective.

Actinogen has been assiduous in collating the research, from preclinical right through to today, on its novel Alzheimer’s treatment — a disease that disproportionately affects women.

It shows the majority of animal studies used male subjects.

But Ketelbey also illustrates what a cash strapped biotech is up against, when they need to get a trial done on time and on budget.

“Our early human studies, in fact, we wanted an equal selection of males and females,” he explained.

“Our preference was an equal selection. In the multiple ascending dose study it turned out for simple practical logistic reasons, that in fact more men were available at the particular time that the study was done, it was just circumstance that we ended up with more men than women … we didn’t expect any difference at that point in time.”

The FDA and the European and Australian regulators require companies to prove drugs are safe and work in men and women to be allowed to market them to both sexes.

But with even Panadol untested on pregnant women yet widely recommended to them, and as the mouse data from Sydney shows, companies could be missing expensive flaws as well as a bigger opportunity entirely by not bringing females in sooner.