Well tolerated, with a chance of a nodule
Regarding safety, LEN was well tolerated across treatment arms, though the oral LEN group had as many people develop resistance mutations as the other three groups combined. Still, that was only three people, with one each in the two subcutaneous arms and one in the control arm.
Two people developed resistance to LEN – one in the LEN SC plus BIC arm and one in the oral LEN plus Descovy arm. In the LEN SC plus BIC arm, the mutations Q67H and K70R emerged at week 10, following a mutation that’s common when people don’t take integrase inhibitors as they’re supposed to (M184M/I). This led Dr. Gupta to conclude that lack of adherence to the oral part of the regimen may have contributed to the development of resistance, rather than an issue with LEN SC itself.
In the oral LEN plus Descovy arm, mutation Q67H didn’t emerge until week 54, when pill counts and drug levels revealed that that participant hadn’t been taking his Descovy as prescribed. In both cases, viral loads in those participants returned to undetectable after switching to an integrase inhibitor–based three-drug regimen.
Most safety concerns were mild and included nausea, diarrhea, and vomiting. But that was for non–injection-site reactions. There were more side effects of that sort, with most of them being pain, hardening of the site, and swelling. But 11% of participants developed more serious side effects, including nodules. Only one nodule was considered a grade 3 reaction; that person didn’t leave the trial because of it.
“These phase 2 data from the ongoing CALIBRATE trial support the further evaluation of lenacapavir for treatment and prevention of HIV-1,” he said.
Finding the right partner
In short, the findings are promising, Dr. Gupta told this news organization . But the question now, as Gilead prepares to begin a phase 3 efficacy trial, is what would be a good combination with LEN SC?
“Lenacapavir in a two-drug regimen should work,” he said. “The question now, though, is you have to find a suitable, potent, second agent to pair it with.”
Indeed, the long-acting HIV treatment pipeline sustained a blow in December 2021 when the U.S. Food and Drug Administration halted all trials for Merck’s investigational, long-acting drug islatravir. This led Dr. Waters to tweet: “Is it just me or are the islatravir abstracts at #CROI2022 quite sad to read?” She ended the tweet with, “I just hope it recovers!”
Indeed, Merck and Gilead have entered into an agreement to codevelop lenacapavir and islatravir as a weekly oral tablet. Islatravir seemed like the obvious choice as a partner to lenacapavir if phase 3 trials are successful, said Dr. Gupta. But now, it’s anyone’s guess as to what will happen. And while it’s too soon to say that lenacapavir is a success, it does leave the field wondering about how to use LEN SC without another, equally long-acting agent.
“When I talk about LEN, I show a picture of a man standing solo at a party, leaning against the wall looking a bit lonely, with ‘lenacapavir’ written over his head,” she said in an interview. “Right now, lenacapavir is the only drug at the 6-monthly party. It’s going to need some other guests if that party is going to rock.”
The study was funded by Gilead Sciences. Dr. Gupta has received research funding from ViiV Healthcare and advisory board fees from Gilead Sciences and ViiV Healthcare. Dr. Waters has received speaker or advisory fees from Gilead Sciences, ViiV Healthcare, Merck, Janssen, Theratech, Sipla, and Mylan.
A version of this article first appeared on Medscape.com.