A pill for him promises a new era for contraception

Researchers have completed the first human trial of YCT-529, a once-daily, non-hormonal male birth control pill that blocks sperm production by targeting the retinoic acid receptor-alpha. The Phase 1a study in 16 men found no major safety issues, setting the stage for longer trials to measure its effect on sperm counts.

Read the full article at https://www.paperleap.com/blog/articles/a-pill-for-him-promises-a-new-era-for-contraception-0cccc9

Episode Transcript

Speaker 1 (00:00):
Welcome to the paper Leap podcast, where a science takes
the mic. Each episode, we discuss cutting edge research, groundbreaking discoveries,
and the incredible people behind them, across disciplines and across
the world. Whether you're a curious mind, a researcher, or
just love learning, you're in the right place before we start.

(00:21):
Don't forget to subscribe so you never miss an insight.
All the content is also available on paper leap dot com. Okay, ready,
let's start. For decades, conversations about birth control have mostly
centered on women's options pills, patches, injections, implants, and intrauterine devices. Men,

(00:43):
on the other hand, have had to choose between two extremes,
condoms which can fail more often than we'd like, and vasectomy,
a surgical step that's meant to be permanent. Now a
new contender is stepping onto the stage, and it's not hormonal.
In early twenty twenty five, researchers led by nog And
Monoets and A Kosh Bakshef from Your Choice Therapeutics in

(01:06):
San Francisco, in collaboration with sciences from Quotient Sciences in
the UK and Insight in the US, published results in
communications medicine from the first human trial of YCT five
two nine, a once a day, non hormonal male contraceptive pill.
The trial might mark the start of a long awaited

(01:27):
shift in reproductive responsibility, one where men can take an active,
reversible role in preventing pregnancy without hormones. So what's different
about YCT five two nine. While most male birth control
research over the past half century has revolved around hormones,
altering testosterone levels to suppress sperm production. While these approaches

(01:50):
can work, they tend to bring alongside effects like acne,
weight gain, and mood changes. YCT five two nine takes
a different route. It tarts gets retinoic acid receptor alpha,
or RR, a key player in how the body uses
vitamin A to produce and mature sperm. If you block

(02:10):
this receptor in the testes, sperm production halts, but the
rest of the body's functions stay largely unaffected. Animal studies
with mice and monkeys showed that this effect was both
highly effective and reversible, which is crucial for a contraceptive.
The phase one A trial enrolled sixteen healthy men, all
of whom had already undergone a vasectomy. This allowed scientists

(02:34):
to focus on safety without worrying about unplanned pregnancies just yet.
Participants received single doses of YCT five two nine, ranging
from ten to one hundred and eighty milligrams, either on
an empty stomach or after a high fat breakfast, while
some got a placebo for two weeks after taking the pill.
Researchers monitored everything they did think of heart function, hormone levels,

(02:58):
markers of inflammation, mood, sexual desire, and any adverse effects.
The results no significant safety issues, vital signs, testosterone and
other hormone levels, and mood scores stayed steady. Most side effects,
like mild headaches or temporary colds, were random and not
tied to the drug. One participant had a brief irregular

(03:21):
heart rhythm detected by continuous ECG monitoring, but it was
mild symptom free and cleared up on its own. YCT
five two nine reached peak blood levels between four and
ten hours after swallowing, and it stuck around for more
than two days, with the half life of about fifty
one to seventy six hours. Food slightly increased absorption, but

(03:44):
not in a way that raised safety concerns. Even the
smallest tested dose brought blood concentrations into the range that
had proven effective in animal studies. That means that, at
least in theory, a daily pill could maintain the drug
at steady sperm blocking levels. Because YCT five two nine
is non hormonal, it didn't affect testosterone, follicle stimulating hormone,

(04:08):
lutinizing hormone, or sex hormone binding globulin. That's important. These
hormones control much more than reproduction, and avoiding their disruption
could mean fewer side effects than traditional hormone based male contraception.
The pill also didn't mess with sexual desire or function,
a crucial detail for a drug intended to be taken

(04:28):
long term by healthy people. Nearly half of pregnancies in
the US and worldwide are unintended. That's not just a statistic.
It's a reflection of a gap in reproductive responsibility and choice.
Many men say they want to share that responsibility, but
their options have been stuck in the twentieth century. The

(04:49):
last big push for non hormonal male birth control, for instance,
compounds like Gossip Pole or when eighteen four four six
fizzles out decades ago due to safety problems. YCT five
two nine may be the first in a new generation
of candidates to pass the first most critical test, showing
that it's safe enough to keep studying. The team is

(05:11):
already running a Phase one B two a trial where
men will take YCT five two nine daily for either
twenty eight or ninety days. This time, sperm counclill be
measured to see if the drug delivers on its main promise,
temporarily shutting down sperm production while keeping everything else running smoothly.
If all goes well, YCT five two nine could one

(05:33):
day sit on pharmacy shelves next to the female pill,
a small capsule representing a big cultural shift. For the
first time, men could have a reliable, reversible hormone freeway
to take control of their fertility. Of course, there's a
long road between a promising phase one trial and a
product you can pick up at your local drug store,

(05:54):
but as this research shows, that road might finally be
open for travel, and who knows, a decade from now,
couples might be sharing birth control in the most literal
sense by each taking their own pill. That's it for
this episode of the paper Leaf podcast. If you found
it thought provoking, fascinating, or just informative, share it with

(06:17):
the fellow science nerd. For more research highlights and full articles,
visit paperleaf dot com. Also make sure to subscribe to
the podcast. We've got plenty more discoveries to unpack. Until
next time, Keep questioning, keep learning,