The European Agency for the Evaluation of Medicinal Products (EMEA) has issued a precautionary statement for those on the combination of abacavir (Ziagen), lamivudine (3TC, Epivir) and tenofovir (Viread), which can be downloaded here. A similar statement was issued in the United States last week by GlakoSmithKline.
The EMEA suggests that this combination should not be used as a new treatment regimen, and that anyone currently on this combination should be frequently monitored with an ultrasensitive viral load test (
This comes after high rates of early virogical failure were seen in the now-terminated GlaxoSmithKline-sponsored study ESS30009, first reported here.
ESS30009 compared once daily abacavir/lamivudine/efavirenz with abacavir/lamivudine/tenofovir.
After 12 weeks, 30/63 (48%) still on abacavir/lamivudine/tenofovir therapy had not achieved a viral load below 50 copies/ml or a viral load reduction of less than 2 logs, compared with 3/62 (5%) on abacavir/lamivudine/efavirenz.
Resistance data from 14 patients who had not responded to the tenofovir arm shows that all 14 had the M184V mutation associated with lamivudine resistance, and 8/14 (57%) had the K65R mutation associated with abacavir and tenofovir resistance.
The EMEA’s scientific committee, the CPMP, has asked tenofovir’s manufacturers Gilead, and GlaxoSmithKline who market both abacavir and lamivudine, for further studies explaining this interaction, as well as the final interim study report for ESS30009 and other relevant studies, including a pilot study from Farthing et al. which also found high rates of virological non-response in patients on abacavir/lamivudine/tenofovir.