Merck ( MRK Quick Quote MRK - Free Report) announced that it will evaluate a lower dose of its HIV candidate islatravir in a phase III program several months after the FDA put studies on the candidate on clinical hold last year.
In December 2021, the
FDA had placed a clinical hold on studies evaluating oral islatravir, a nucleoside reverse transcriptase translocation inhibitor for the treatment and prevention of HIV-1 infection.
The decision was taken based on observations of decreases in total lymphocyte and CD4+ T-cell counts in some study participants in previous clinical studies on islatravir.
While six studies on islatravir were placed on full clinical hold, seven were put on partial clinical hold. Merck was evaluating islatravir as a treatment for HIV-1 infection in combination with other antiretrovirals. With the FDA’s clinical hold in place, no new studies have been initiated on islatravir.
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However, now the new phase III studies will evaluate a once-daily oral combination of doravirine 100 mg and a lower dose of islatravir (DOR/ISL). While one study will evaluate DOR/ISL in previously untreated adults with HIV-1 infection, two studies will begin on DOR/ISL to evaluate it as a switch in antiretroviral therapy in adults with HIV-1 infection who are virologically suppressed. The FDA has reviewed and agreed to the plan.
In 2021, Merck collaborated with
Gilead ( GILD Quick Quote GILD - Free Report) to evaluate the combination of islatravir with the latter’s lenacapavir to develop long-acting HIV treatment options. Gilead and Merck also initiated a phase II study, evaluating the combination of a once-weekly treatment regimen of islatravir and lenacapavir in people living with HIV who are virologically suppressed on antiretroviral therapy. Back in December, all dosing of participants in the abovementioned phase II study was also stopped. However, the study will now resume with a lower dose of islatravir
Meanwhile, for all the above studies, the partial clinical hold remains valid for doses higher than those considered for the revised phase III clinical program.
However, Merck has decided to discontinue the development of the once-monthly oral islatravir for the prevention of HIV infection, also called pre-exposure prophylaxis or PrEP
GSK ( GSK Quick Quote GSK - Free Report) is another key player in the HIV market other than Merck and Gilead. GSK’s Apretude, a long-acting injectable form of cabotegravir drug, was approved by the FDA in December 2021 for PrEP.
An oral formulation of cabotegravir, with the trade name of Vocabria, is already approved in combination with
J&J’s ( JNJ Quick Quote JNJ - Free Report) Edurant (oral rilpivirine) for the short-term treatment of HIV-1 infection. A combination of long-acting injectable cabotegravir and J&J’s Edurant is approved as Cabenuva for the treatment of HIV-1 infection in virologically suppressed adults.
Cabenuva has been co-developed by J&J’s pharmaceutical subsidiary, Janssen and GSK’s HIV subsidiary, ViiV Healthcare.
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