MSD/Merck’s once-weekly phase 2 study stopped - NNRTI MK-8507

[Jim Allen]

Not many details yet but seems the MK-8507 study has stopped due to concerns.
Shame.

Full article on i-base can be found here:
https://i-base.info/htb/41647

In Short:

MSD/Merck’s once-weekly phase 2 study stopped due to safety concerns with NNRTI MK-8507: islatravir studies continue

On 18 November 2021, a press release from MSD/Merck included top line concerns about an investigational NNRTI currently being studied with islatravir as a component of once-weekly oral ART.

The statement reports decreases in total lymphocyte and CD4 counts in participants receiving MK-8507 + islatravir that were dose-related to the NNRTI and were sufficient for dosing to be stopped.

[Mightysure]

Well that's not good news.  Hopefully they can figure out why that is happening and fix the issue if it is fixable.

[Jim Allen]

Islatravir on Hold

14th Feb 2022: https://www.poz.com/article/treatment-islatravir-hold

In Short:

Islatravir is being tested as a component of once-weekly HIV treatment and as a once-monthly pill or once-yearly implant for pre-exposure prophylaxis (PrEP).

Some HIV-positive people in treatment trials saw a drop in their CD4 T-cell counts, while HIV-negative volunteers in PrEP trials experienced a decrease in total lymphocytes. In December, the Food and Drug Administration placed a partial clinical hold on seven studies of daily oral islatravir plus doravirine and a full clinical hold on six studies of islatravir PrEP and injectable islatravir.

[Loa111]

Do scientists then try to reengineer drugs like this if they don't work as expected or are but on hold? Or does it tend to be game over?

[Jim Allen]

I suppose it will depend on the cause, and if it can be addressed.

This is what Merck said:

Speaking with advocates, Michael Robertson, MD, of Merck Research Laboratories, said researchers are working to understand what’s causing the side effect and whether islatravir can move forward.

[Jim Allen]

https://www.poz.com/article/merck-will-study-lower-dose-longacting-islatravir

Merck plans to start new clinical trials of a lower dose of its experimental antiretroviral islatravir for HIV treatment, which has been on hold due to unexpected safety concerns. But studies of islatravir for monthly pre-exposure prophylaxis (PrEP) will be discontinued, the company announced this week.

[leatherman]

unexpected safety concerns

Crikey! an HIV med that lowers cd4s?
yes, that would be a safety (and efficacy) issue for me.