The rationale for this combination in heavily pretreated patients stemmed from findings that suggested that HIV isolates resistant to 3TC were more susceptible to adefovir; that some NNRTI-resistant strains may still be suscpetible to efavirenz; that some NRTI-resistant strains may be inhibited by abacavir. The investigators followed 5 patients who had plasma viral loads between 400,000 and 2 million copies/ml, with CD4 counts ranging from 8 to 70 cells/mm³. The patients were heavily pretreated, with at least 7 years of prior antiretroviral therapy. They averaged 19 months on regimens containing at least one PI. Most had experience with all NRTIs, and had hepatotoxicity. Three of the 5 patients had at least a 0.4 log drop in plasma HIV RNA over 24 weeks. Two rebounded quickly; one of these initally did well, but developed pancreatitis attributed to human growth hormone, but had to be taken off drugs and didn't suppress after he could restart the meds. One patient who had an initial drop in plasma viral load, had a recurrence of CMV retinitis, went on foscarnet, and then had a 3.7 log plasma viral load drop overall. One patient, who had refractory thrush, was able to discontinue antifungal therapy without recurrence while on this combination. All patients noted transient lightheadedness, one had insomnia. One had to discontinue adefovir because of nephrotoxicity. No patient had a rash or hypersensitivity reaction. In summary, this small series suggests that for some very advanced patients, the use of the combination of abacavir, efavirenz, and adefovir may result in HIV suppression for at least 6 months, without undue toxicity.