A phase I/II study of oral all-trans-retinoic acid (ATRA; tretinoin), administered every other week alone and then in combination with interferon (IFN) alfa-2a, was undertaken to evaluate the activity, toxicity, and pharmacokinetics of this regimen in patients with human immunodeficiency virus (HIV)-associated Kaposi's sarcoma (KS).

PATIENTS AND METHODS

Thirteen patients with HIV-associated KS, eight of whom had more than 100 CD4 cells/microL, were entered. The protocol initially called for patients to receive 150 mg/m2/d of ATRA every other week. However, this regimen was associated with headaches, and the initial dose of ATRA was reduced to 40 mg/m2/d orally in three divided doses, increasing to a maximum of 100 mg/m2/d. After 12 weeks, IFN alfa-2a could be added.

RESULTS

The principal toxicities from ATRA were headaches (12 patients) and dry skin or lip (seven patients). Of 12 assessable patients, 10 had progressive disease and two had stable disease on ATRA alone. One of eight assessable patients who went on to receive ATRA plus IFN alfa-2a had partial response (PR). There were no overall changes in the serum HIV p24 antigen (Ag) level or CD4 count during treatment with ATRA alone. Peak ATRA levels decreased during the week of continuous ATRA therapy, but rebounded when treatment was resumed after a week without the drug.

CONCLUSION

Intermittent ATRA therapy was reasonably well tolerated and provided a means to circumvent the low plasma exposure found with continuous ATRA therapy. However, we were unable to document antitumor activity in patients with HIV-associated KS.