Evaluation of a didanosin-containing regimen including genotypic resistance testing: an open-label, multicenter study

To show Didanosin in a new formulation as a once-a-day capsula as a well-tolerated and effective HIV-therapy when used in a protease sparing regimen including genotypic resistance pattern in blood, semen and cerebrospinal fluid before and during treatment.

Two groups of 58 patients, each containing 9 patients who had not been previously treated with any antiretroviral medication, and 49 patients heavily pretreated for 3,7 (DDI group) and 2,8 (non-DDI group) years, have been followed up for at least half a year. A group of 24 patients taking a special combination of Didanosin plus Efavirenz and Stavudine have been analysed with genotypic resistance testing concerning viral load response and resistance pattern under therapy.

Suppression of plasma HIV-1 RNA to <50 copies/mL and <500 copies/mL in the DDI group was achieved in 74% and 84% of the pretreated patients, respectively, and in 100% of the naive patients after 24 weeks. In the non-DDI group suppression was achieved in 59% and 69% of the pretreated patients, respectively, and in also 100% of the naive patients. The viral load reduction in the DDI containing regimen at week 24 was 1.7 log subset 10 for the pretreated and 3,4 log subset 10 for the naive patients. In the non-DDI group, the reduction was 1.5 for the pretreated and 4,0 for the naive patients. CD4 cell counts increased from 440 to 517 cells/microL at week 24 for the pretreated, and from 171 to 289 for the naive patients in the DDI containing regimen. In the other group, cells increased from 396 to 406 for the pretreated and from 155 to 321 for the naive patients. In each group, 12 patients discontinued treatment; 4 patients in the DDI group and 7 patients in the non-DDI group because of adverse events. There were no AIDS-defining events in the antiretroviral-treated patients in both groups. 16 patients of the special combination group (DDI, D4T and EFV) were evaluated for more than 24 weeks. Suppression of HIV-1 RNA to <50 copies /mL were found in 75% of the naive and 43% of the pretreated patients. No relevant mutations were found during treatment.

The new formulation of Didanosin as a once-a-day capsula in a protease sparing regimen was well-tolerated, effective in reducing viral load and in preventing AIDS-defining events. The combination of DDI, D4T and EFV proved to be a potent therapy without developing relevant mutations.