EFFICACY OF TRIPLE COMBINATION THERAPY WITH ZIDOVUDINE (ZDV) PLUS ZALCITABINE (DDC) PLUS LAMIVUDINE (3TC) VERSUS DOUBLE (ZDV+3TC) COMBINATION THERAPY IN PATIENTS PREVIOUSLY TREATED WITH ZDV+DDC

Objective: To evaluate the immunological and virological efficacy of t riple combination therapy with zidovudine (ZDV) plus zalcitabine (ddC) plus lamivudine (3TC) and a double (ZDV+3TC) combination therapy in p atients previously treated with ZDV plus ddC. Design: A 6-month follow -up open-label randomized study was undertaken in 46 HIV-1-infected pa tients previously treated for at least 6 months with ZDV plus ddC, who were allocated to receive either ZDV/ddC/3TC (n = 15) or ZDV/3TC (n = 15) or to continue with the ZDV/ddC regimen (control group; n = 16). Methods: Changes in CD4+ cell counts and plasma viral load (VL) were a nalysed with analysis of variance. Sequencing of the reverse transcrip tase gene was performed in a subset of 3TC-treated patients. Results: Mean CD4+ cell counts increased significantly above baseline in both 3 TC regimens whereas counts decreased in the control group. Significant plasma VL reduction was achieved in both 3TC combination therapy grou ps at weeks 4 and 24 compared with the control group. Coexistence of m utations conferring resistance to ZDV and 3TC were found in patients f rom both 3TC treatment groups. Conclusions: Both therapy strategies, s witching ddC to 3TC or adding 3TC, significantly improved the virologi cal and immunological efficacy compared with continuing ZDV/ddC. Our r esults support the use of 3TC in patients previously treated with the ZDV/ddC combination.