UK-based pharmaceutical company ViiV Healthcare published the results from its two pivotal Phase III trials of its monthly HIV injection treatment at the 2019 Conference on Retroviruses and Opportunistic Infections (CROI), held on March 4-7 in Seattle, Washington, US.
The results investigated the efficacy and safety of cabotegravir/rilpivirine, the company’s once-monthly injection for treating human immunodeficiency virus (HIV).
HIV injections: ViiV Healthcare trials
Together, the ATLAS and Flair studies demonstrated the non-inferior efficacy and safety of cabotegravir/rilpivirine compared with daily antiretroviral therapy (ART) in both treatment-naïve and virally suppressed HIV-1 patients, while also showing patients receiving the once-monthly injection preferred it over daily ART.
With these strong results, GlobalData expects ViiV’s first-in-class injectable regimen to receive US Food and Drug Administration (FDA) approval in early 2020, providing HIV-1 patients with an attractive alternative to daily oral ART.
This latest two-drug ART from ViiV combines its investigational, long-acting integrase inhibitor (INI), cabotegravir, with Janssen ’s non-nucleoside reverse transcriptase inhibitor (NNRTI), rilpivirine (marketed separately under the brand name Edurant), in an injectable formulation that only requires administration every four weeks.
HIV injections: competition
Facing stiff competition from Gilead Sciences and others, ViiV has differentiated itself in the HIV market by focusing its efforts on developing two-drug, INI-based regimens, for a market long dominated by three- and four-drug regimens; Juluca (dolutegravir/rilpivirine) became the first success of this initiative when it was approved in 2017, and the company submitted the dolutegravir/lamivudine single-tablet regimen (STR) for regulatory approval in late 2018.
The comprehensive results published from the FLAIR study demonstrated that cabotegravir/rilpivirine was non-inferior in the viral suppression (HIV RNA <50 copies/ml) of treatment-naïve HIV-1 patients, compared with a once-daily regimen of Tivicay (dolutegravir) plus two nucleoside reverse transcriptase inhibitors (NRTIs).
These strong results in treatment-naïve patients will allow ViiV to pursue a broader label for cabotegravir/rilpivirine compared with that of Juluca, which can only be prescribed to virally suppressed patients. Trial participants also stated significantly higher satisfaction with the long-acting injectable regimen compared to their previous oral therapies, with 86.4% and 90.8% of ATLAS and FLAIR participants, respectively, preferring the injectable over once-daily, oral ART.
HIV injections: dosing regimen
The route of administration (ROA) and dosing regimen has proved favourable amongst patients, despite 24.7% of injections resulting in mild or moderate injection-site reactions (ISRs), and eight participants withdrawing due to ISRs across both Phase III trials. This alternative ROA, along with the reduced dosing frequency, sets this two-drug combination apart from the currently approved ART regimens.
Given the popularity shown in the trial and a potential boost to compliance rates, ViiV could set a premium price for this first-in-class product. However, there are some reasons for caution – although the long-acting injectable could provide more consistent compliance compared to daily STRs, the risks associated with missing a dose have not been thoroughly researched and could potentially have serious implications for the emergence of resistance or virologic failure.
GlobalData expects that cabotegravir/rilpivirine will achieve approval for the treatment of both treatment-naïve and virally suppressed HIV-1 patients. A broad indication paired with a dosing regimen favoured amongst many patients could result in ViiV’s cabotegravir/rilpivirine achieving blockbuster status within the next five years.
If ViiV is able to capitalise on this product’s unique characteristics, which have a clear emphasis on improving convenience and quality of life for patients receiving ART, it will certainly challenge Gilead’s STRs, notably recently approved Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide [TAF]) and Genvoya (elvitegravir/cobicistat/emtricitabine/TAF).
GlobalData believes the injectable cabotegravir/rilpivirine is a substantial threat to Gilead’s HIV portfolio of STR therapies, and if post-approval studies can demonstrate a viable application for using cabotegravir/rilpivirine for pre-exposure prophylaxis (PrEP), then revenues could soar even higher in the medium- and long-term future.