Gilead has reported new head-to-head data between its drugs for HIV pre-exposure prophylaxis (PrEP) to try to encourage uptake of newly-approved Descovy.
Descovy (emtricitabine/tenofovir alafenamide) claimed its FDA approval for PrEP last week – becoming only the second drug for this use since Gilead’s Truvada (emtricitabine/tenofovir disoproxil fumarate) got a green light in 2012.
Gilead wants to move quickly to transition people taking Truvada for PrEP over to the new drug before Truvada generics start to reach the market next year. It says new results from the DISCOVER trial show that can be done safely and with significant improvements on measures of bone and kidney toxicity.
The new results – presented at the IDWeek 2019 conference in Washington DC – involved a subgroup of 905 patients in DISCOVER who were taking Truvada for PrEP at enrolment into the trial, and were than assigned either to continue on their current drug or swap to Descovy.
One analysis showed that patients on Descovy had statistically significant improvements in lab measures of kidney function as early as four weeks after switching that were maintained out to 48 weeks, and also reported fewer drug-related adverse reactions and were less likely to discontinue therapy.
A second analysis focused on bone mineral density (BMD) data – a known side effect of Truvada – and showed that patients who swapped to Descovy experienced statistically significant improvements in BMD of the hip and spine compared with those who continued on the older drug.
The prevalence of bone weakening (osteopenia) in the spine was also reduced from 0.6% in the Truvada group to 0.4% with Descovy
SVB Leerink’s Geoffrey Porges thinks that the BMD data will be the main “ammunition” for Gilead as it tries to make a case for Descovy and could result in “substantial switching”.
The new drug has a slightly more restrictive label because it excludes cis-gender women, but that group is thought to account for only around 7-10% of Truvada’s PrEP sales, estimated to account for $2bn out of its $3bn total sales.
Gilead also presented results looking at the impact of PrEP on new HIV diagnoses between Truvada’s approval in 2012 and 2017 in US metropolitan areas, showing that there was a 15% decline in areas where use of PrEP was highest.
The analysis predicts that if PrEP use among individuals at high risk of HIV could reach 50% by 2022, it would result in a 40% decline in the rate of new diagnoses.