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Since the discovery of human immunodeficiency virus (HIV) in 1983, significant progress has been made toward the discovery, development, and licensing of anti-HIV drugs. In vitro screens against whole virus are now being complemented by screens against specific viral targets, resulting in the development of clinical candidates acting at several critical stages of the viral life cycle. Despite these advances, clinical therapy remains largely palliative. In addition, it has recently been recognized that HIV resistance to most drugs may pose even greater obstacles. Moreover, emerging data on immunopathogenesis raise the possibility that even if virus was eliminated from an infected individual, the patient's immune system might not be capable of restoration to normal function. In the face of such obstacles, deeper insights into the pathogenic mechanisms of disease, aggressive exploitation of those mechanisms for therapeutic gain, and continued commitment of both public and private sectors to support and collaborate in this research are needed.

Randomized clinical trials are being conducted and/or sponsored by all scientific divisions of the National Institute of Allergy and Infectious Diseases (NIAID). External committees to review the progress of ongoing trials and to make recommendations to the Institute concerning continuation or termination are an integral part of many of these trials. These committees have evolved considerably from the ad hoc committees, called together when a need arose, which were used beginning in the mid 1970s. Currently, there are many monitoring committees operating for NIAID-sponsored trials. They function in a variety of ways, based partially on historical precedent and partially on the specialized requirements of the particular trial; there is no 'standard operating procedure' for the Institute, or even for divisions within the Institute. One of the major issues faced in establishing the data and safety monitoring board for AIDS treatment trials was access to the meetings of this board and to the reports of interim data that the board reviewed. After much discussion, procedures were established that restrict such access to a very limited group of programme and statistical centre staff. These procedures, while remaining controversial, appear necessary to ensure confidentiality and the integrity of the clinical trials process.

Infections and malignancies account for most deaths in patients with AIDS and will continue to do so as long as HIV-induced immunosuppression is progressive and irreversible. Co-trimoxazole has emerged as the preferred agent for prevention of Pneumocystis carinii pneumonia. As appropriate broad-spectrum agents are developed, multiple opportunistic pathogen prophylaxis could become effective.

Infections and malignancies account for most deaths in patients with AIDS--and will continue to do so as long as HIV-induced immunosuppression is progressive and irreversible. Options available for prevention and improved management of such diseases are changing as new agents emerge, new combinations of agents are developed, and new indications for available agents are identified.

In a single decade, the pandemic of human immunodeficiency virus (HIV) infection has become an international health, social, and economic emergency. Early and effective intervention is urgently needed for both prevention of HIV infection and for the amelioration of clinical disease. Results of therapeutic trials have suggested expanding the population for which chemotherapy is indicated. In this paper, we first review the findings from selected recent drug trials, using zidovudine and pentamidine as examples. We then discuss six issues that we believe to be crucial for future epidemiologic research in the service of vaccine and drug development: 1. To identify which complications of HIV infection most urgently require development of new therapies, we must characterize the frequency and severity of specific medical events (outcomes) in persons taking a variety of treatments. 2. Currently, acquired immunodeficiency syndrome (AIDS) therapeutic trials gauge the effectiveness of new therapies by their impact on such clinical parameters as the time to development of AIDS or death. These approaches take too long to provide information. We urgently need to identify surrogate markers of clinical outcome that will be useful in the early assessment of treatment efficacy. 3. Progress in vaccine development is being retarded because we do not have enough data from natural history studies on host immunologic responses to suggest that a given response is protective. We therefore need to identify natural correlates of immunity, which can help set priorities in vaccine development. 4. Discovery that a therapy works in the setting of a clinical trial is only a first step in intervention. We must also assess the impact of new therapies on the health of the public, evaluating access to health care, compliance, and other barriers to treatment. 5. Clinical trials are usually associated with the effort to prevent disease in infected persons. However, other trials are needed to assess efforts to interrupt viral transmission through use of condoms, use of virucides, and treatment of sexually transmitted diseases, and by effecting specific behavioral changes. 6. Traditional methods of conducting clinical therapeutic research may not be adequate to address urgent questions in the AIDS/HIV epidemic. We must develop innovative clinical research methods, including better use of data from observational studies, to infer what we can about the effect of treatment on the clinical course.

Recent advances in delineating the molecular biology of human immunodeficiency virus type 1 (HIV-1) have led to innovative approaches to development of a vaccine for acquired immunodeficiency syndrome (AIDS). However, the lack of understanding of mechanisms of protective immunity against HIV-1, the magnitude of genetic variation of the virus, and the lack of effective animal models for HIV-1 infection and AIDS have impeded progress. The testing of AIDS vaccines also presents challenges. These include liability concerns over vaccine-related injuries; identification of suitable populations for phase 3 efficacy studies; balancing the ethical obligation to counsel research subjects to avoid high-risk behavior with the necessity to obtain vaccine efficacy data; and the effect of vaccine-induced seroconversion on the recruiting and welfare of trial volunteers. Several candidate AIDS vaccines are nevertheless currently under development, and some are undergoing phase 1 clinical trials. Rapid progress will depend on continued scientific advancement in conjunction with maximum use of resources, open information and reagent exchange, and a spirit of international collaboration.

Suramin was given to ten outpatients with acquired immunodeficiency syndrome (AIDS) presenting as Kaposi's sarcoma (KS) or as an AIDS-related complex (ARC). Side-effects associated with the administration of 6.2 g of suramin over 5 weeks included fevers, rashes, urinary abnormalities, and transient rises in hepatic aminotransferases. Peak serum levels of over 100 micrograms/ml were attained. There was evidence of HTLV-III infectivity and replication in lymphocytes from four patients before therapy. The detectable virus level fell in each case by the time of the last dose, and in three cases it became undetectable at the end of therapy. In each case, viral replication was again detected in the weeks or months following the administration of suramin. Despite this in-vivo virustatic effect, no significant clinical or immunological improvement was observed using this short-term regimen. However, the results provide a rationale for investigating longer-term regimens.