On CROI were presented the latest data of the effectiveness and safety of fostemsavir

In Seattle were released the latest information about studies of fostemsavir - a drug for the treatment of HIV infection of a fundamentally new type. Fostemsavir (FTR) is the first in its class prodrug of the Temsavir attachment inhibitor (TMR). TMR binds to HIV-1 by blocking the gp120 protein, by which the virus binds to the CD4 receptor and coreceptor located on the surface of T-lymphocytes and prevents cell infection.

At the Conference on Retroviruses and Opportunistic Infections (CROI), a poster was presented with data from the study 205889 (AI438011, NCT01384734), which is the conditional name for the recently completed phase 2b CI using different dosages among participants with HIV-1 who had previously been treated.

The developer published the results of the effectiveness of fostemsavir by the 192nd week and general data on the safety of the drug.

More than 250 adult patients took part in the presented studies, 200 of which were randomly divided into 4 FTR groups depending on the dosage of the drug. They were asked to take 400 or 800 mg of the drug twice a day, or 600 or 1200 mg once a day. The reference group (REF) included 51 participants. The latter took atazanavir / ritonavir [ATV / r] 300/100 mg, raltegravir (RAL, 400 mg twice daily) and tenofovir (TDF, 300 mg).

According to the study, after an interim analysis at week 48, those who were randomized to FTR switched to open-label FTR at 1200 mg per day with raltegravir and tenofovir. REF members stayed on ATV / r + RAL + TDF.

The average time spent by patients on FTR was 4.5 years (maximum 5.6), and for REF, 2.9 years. Indicators of virologic suppression (HIV-1 RNA <50 kopecks / ml) and average increase in CD4 counts (+279.9 and +263.7 cells / µl) between FTR and REF up to 192 weeks were comparable.

Most side effects were mild and unsystematic. However, in the REF group, adverse reactions of 2-4 degrees or 3-4 degrees were more common than in the FTR (39% versus 12%; 33% versus 18%, respectively). Also in the FTR group there were fewer people who decided to discontinue treatment due to side effects (4% versus 12% for REF), and none of the participants stopped taking therapy for reasons related to FTR. The most common reactions associated with the study drug were headache and nausea.

Thus, according to preliminary estimates, the combination of FTR with RAL + TDF showed high safety comparable to the ATV / r scheme with RAL + TDF. Moreover, in the FTR group, fewer side effects related to classes 2-4 were recorded, as well as adverse reactions of classes 3-4, leading to discontinuation of treatment.

In addition, despite a longer median exposure (4.5 versus 2.9 years), by 192 weeks the FTR group had comparable viral suppression rates to ATV / r.

These results confirm the current assessment of the FTR currently undergoing Phase III clinical trials in adult patients with limited therapeutic treatment options (≤2 remaining ART classes) due to resistance, tolerance problems or contraindications (NCT02362503).