More than 2,400 registered participants attended the 4th Conference on Retroviruses and Opportunistic Infections, held in Washington, DC, from January 22-26, 1997. There were 842 abstracts, including 639 poster presentations. Major themes of the conference were: (1) various benefits of the newer combination therapies; (2) the effects of combination therapies on HIV in lymph tissues; (3) new HIV-related drug interactions; (4) new HIV therapies in the pipeline; (5) chemokine research; and (6) new insights into HIV/AIDS pathogenesis.

There is a conference Internet website at which all abstracts and selected audiovisual presentations of oral presentations are available; it will be maintained only through July 1997.

Treatments for HIV: Benefits of New Combination Therapies

HAART -- Highly Active Antiretroviral Therapy, Including a Protease Inhibitor

• AIDS-defining illnesses, hospitalizations and deaths have decreased in specified geographic locations
• Potent therapies reverse some cases of severe AIDS-related conditions, including cryptosporidial diarrhea, HIV-related wasting and Kaposi's sarcoma
• Improvements in immune function: Response to Mycobacterium avium normalizes in some patients; return of "naive" lymphocytes occurs in some patients after 3-12 months, but depends on the cells presence before HAART therapy was started
• Case reports of cytomegalovirus (CMV) retinitis and myelopathy (spinal cord disease) occur even after short-term HAART

The benefits of potent combinations including a protease inhibitor drug were documented in several poster presentations that described case reports of symptom resolution and disappearance of severe AIDS-related conditions. Improvements occurred over weeks to months, depending on the condition.

Cryptosporidial diarrhea

Eighteen patients from France, Australia or Rhode Island with chronic cryptosporidial diarrhea completely cleared the parasite from their stool, had no further diarrhea, discontinued their anti-diarrheal and pain medications, and gained weight after either ritonavir (Norvir) or indinavir (Crixivan) was added to their prior anti-HIV therapy. As expected, their HIV viral loads decreased markedly, while their CD4 cell counts increased.

Wasting syndrome

One injection drug-using (IDU) patient from Rhode Island with HIV-related wasting gained 30 pounds and had an improved appetite and energy level after indinavir was added to his prior therapy of d4T (Zerit) plus 3TC (Epivir).

Progressive multifocal leukoencephalopathy

Two patients from Minnesota and France with life-threatening progressive multifocal leukoencephalopathy (PML) brain disease had dramatic improvement in their disabilities (difficulty in speaking, controlling urination or walking) after indinavir or ritonavir was added to AZT (Retrovir) plus either 3TC or ddI (Videx). Magnetic resonance imaging (MRI) brain scans improved markedly as the patients' HIV viral loads decreased and CD4 counts increased.

Kaposi's sarcoma

One man with moderate Kaposi's sarcoma (KS) lesions experienced moderate clearing of his KS over a 6-month period after ritonavir, d4T and 3TC were instituted. (He was previously noncompliant with other anti-HIV regimens.) His HIV viral load decreased while his CD4 cell count increased. The poster showed serial photographs of his face and trunk, demonstrating marked improvement in his KS.

Certain HIV-related conditions do not seem to respond, at least initially, to HAART while others, for example cytomegalovirus (CMV), have been reported to occur within a month after starting HAART.

In the same abstract from France regarding resolution of cryptosporidial diarrhea, 2 patients who originally had microsporidial diarrhea still had the infection and diarrhea symptoms, even after prolonged triple HAART. The patients were assumed to be compliant with their medications. Improvements in HIV viral load and CD4 counts were not observed in those 2 patients. Similarly, 1 patient from Australia with microsporidial diarrhea, while initially responding to HAART with decreasing diarrhea, subsequently relapsed.

G. Pialoux, MD, and colleagues from the Pasteur Institute in Paris, reported 1 patient who developed difficulty walking because of spinal cord disease (HIV myelopathy) even after 7 weeks of HAART including indinavir, AZT and 3TC. His HIV viral load became undetectable (limit of detection 200 copies/mL). However, his cerebrospinal fluid (CSF) viral load was 6.1 log (1,262,653) copies/mL after 9 weeks of HAART. This discrepancy appears to be uncommon (see below). The authors suggest that the central nervous system (CNS) may be a sanctuary site for HIV. Indinavir, like other protease inhibitors, does not penetrate the CNS . The researchers are currently doing genotypic and phenotypic assays to measure HIV resistance to the 3 drugs.

Mark Jacobson, MD, and colleagues from AIDS Clinical Trials Group (ACTG) 266, reported on 5 patients who developed CMV retinitis (eye infection) 4-8 weeks after starting HAART. Their CD4 counts increased from fewer than 85 cells/mm³ before HAART to greater than 200 cells/mm³ at the time of CMV diagnosis. Normally, AIDS-related CMV retinitis occurs when the CD4 count is fewer than 50 cells/mm³. Before HAART, CMV retinitis occurred in none of 27 patients examined with a CD4 cell count greater than 100 cells/mm³. After HAART became widely available in March 1996, 7 of 49 (15%) newly diagnosed patients with CMV retinitis had CD4 counts greater than 100 cells/mm³.

J. Gilquin, MD, and colleagues, from Paris, reported 8 cases of first-episode CMV retinitis or detection of CMV in the blood within 10 weeks after starting HAART including either ritonavir or indinavir. This occurred despite overall clinical improvements, an anti-HIV effect and a greater than 5-fold increase in their mean CD4 counts from a baseline mean of 37 cells/mm³.

C. Michelet, MD, and colleagues, from Rennes, France, reported 2 cases of CMV retinitis (1 recurrent, 1 first-episode) within 1 month after starting combination therapy with d4T plus 3TC and either indinavir or ritonavir. After 4 weeks of triple therapy, the CD4 counts increased by 97 cells/mm³ from a mean baseline of 41 cells/mm³. Mean plasma HIV RNA viral loads decreased from a baseline of 330,000 copies/mL to undetectable (limit of detection 4,000 copies/mL). One of the 2 patients was found to have CMV in the blood at baseline.

These 3 reports of 15 AIDS patients who developed CMV disease or viremia within 4-10 weeks after starting HAART may be due to 1 or more of several factors:

1) These patients may have had subclinical ("silent") CMV in the blood or seeded in some organs prior to starting HAART (1 patient did have CMV in the blood before HAART), and HAART was unable to prevent additional CMV reproduction; or

2) After a certain threshold of immune compromise has been reached in people with AIDS, complete immune restoration may not be possible to prevent all types of opportunistic infections. Specifically, a return of "naive" lymphocytes (cells that respond to new infections) may not be possible (see BETA, June 1995, pages 44-45); or

3) Only 4-10 weeks of HAART is inadequate to allow for maximal immune restoration. David Ho, MD, calculated that the second phase decay (loss) of HIV from latently infected macrophages could be 4 weeks, and the time to 100% HIV eradication may be 3.1 years, if 1 trillion immune cells are infected. Two posters indicated that a reappearance of "naive" lymphocytes begins to occur after 3-12 months or more of HAART.

4) HAART may be causing an improved immune response to silent CMV that was already present, resulting in clinical CMV disease. This possibility is supported by the occurrence of Mycobacterium avium disease after HAART has been started, as described below.

Two posters from Harvard Medical School and the AIDS Research Program in Vancouver reported on the occurrence of Mycobacterium avium complex (MAC) lymph node infection and swelling in the neck or groin among 8 patients 1-3 weeks after starting HAART (usually including a protease inhibitor). The 3 patients from the Harvard study also developed fever. All 5 patients from the Vancouver study had negative blood cultures for MAC at the time of lymph node infection. AIDS-related MAC, before the era of HAART, was often detected in the blood. After HAART, the Vancouver group reported a median increase of 110 CD4 cells/mm³ and the Harvard group reported a significant increase in total white blood cells. These cases may seem to indicate that HAART either caused or did not prevent MAC; however, starting HAART may have improved the immune response leading to a more normalized and localized immune reaction to a pre-existing MAC blood infection. In the pre- HIV/AIDS era, MAC infection of a lymph node was more common, while blood infection was less common. The Harvard poster recommends that unrecognized or subclinical MAC infection should be sought before starting a patient on combination therapy with a protease inhibitor drug.

Researchers from Harvard Medical School observed 4 patients who developed a recurrence of a prior toxic ("allergic") reactions to sulfa medications (fever, sometimes with rash) within 7-21 days after starting protease inhibitor therapy. All had been taking trimethoprim-sulfamethoxazole (TMP-SMX; Bactrim, Septra) for Pneumocystis carinii pneumonia (PCP) prophylaxis and were stable after an earlier fever reaction to the drug resolved. No infectious cause of the fevers was found, and they disappeared (as did the rashes) after the TMP-SMX was stopped. All 4 had mean increases in their total white blood cell counts of 4,225 cells/mL. Baseline CD4 counts ranged from 33-88 cells/mm³. One patient whose CD4 count was reported after protease inhibitor therapy was initiated experienced an increase to 480 cells/mm³. Most were "memory" rather than "naive" cells. HAART may lead to an enhanced immune response that can be associated with certain hypersensitive, abnormal immune responses observed earlier during the patients' immune system decline.

Autran B and others. Dynamics of the CD4 T helper cell subset reconstitution after combined anti-retroviral therapies. Abstract and oral presentation 34.

Benhamou Y and others. Effects of triple antiretroviral therapies including a HIV protease inhibitor on chronic intestinal cryptosporidiosis and microsporidiosis in HIV-infected patients. Abstract and oral presentation 357.

Carr A and others. Resolution of antibiotic-resistant cryptosporidiosis and microsporidiosis with potent combination antiretroviral therapy. Abstract and poster presentation 688.

Connors M and others. HIV induces changes in CD4 plus T cell phenotype and repertoire that are not immediately restored by antiviral or immune-based therapies. Abstract and oral presentation 369.

Gilquin J and others. Acute CMV infection in AIDS patients receiving combination therapy including protease inhibitors. Abstract and poster presentation 354. Henry K and others. Documented improvement in late stage manifestations of AIDS after starting ritonavir in combination with two reverse transcriptase inhibitors. Abstract and poster presentation 356.

Ho DD. Can HIV be eradicated from an infected person? Opening plenary session and abstract S1.

Jacobson MA and others. Failure of highly active antiretroviral therapy (HAART) to prevent CMV retinitis despite marked CD4 count increase. Abstract and poster presentation 353.

Lederman M and others. Partial immune reconstitution after 12 weeks of HAART (AZT, 3TC, ritonavir) preliminary results of ACTG 315. Abstract and late breaker presentation LB13.

Mars ME and others. Protease inhibitors lead to a change of infectious diseases unit activity (France). Abstract and poster presentation 203.

Michelet C and others. Viral ocular involvement after initiation of antiprotease inhibitor therapy. Abstract and poster presentation 315.

Mileno MD and others. Resolution of AIDS-related opportunistic infections with additions of protease inhibitor treatment. Abstract and poster presentation 355.

Pialoux G and others. Central nervous system (CNS) as sanctuary of HIV 1 in patient treated with AZT plus 3TC plus indinavir. Abstract and poster presentation 233.

Phillips P and others. Mycobacterial lymphadenitis: can highly active antiretroviral therapy (HAART) unmask subclinical infection? Abstract and poster presentation 351.

Race E and others. Focal inflammatory lymphadenitis and fever following initiation of protease inhibitor in patients with advanced HIV-1 disease. Abstract and poster presentation 352.

Reimann K and others. Recurrence of trimethoprim-sulfamethoxazole hypersensitivity following initiation of protease inhibitor in patients with advanced HIV-1. Abstract and poster presentation 535.

Soucier H and others. Effect of antiretroviral therapy on CD8 plus CD38 plus mean fluorescence intensity and CD4 plus naive/memory T cells. Abstract and poster presentation 248.

Effects of Therapy on HIV in Lymph Tissues

• Combination therapy markedly decreases HIV in lymph tissue
• RNA mostly undetectable, as in blood plasma
• Traces of HIV DNA and unspliced RNA still present after months
• Decreased lymphocyte apoptosis
• Lymph gland changes correlate with response to anti-HIV drugs
• Lymph tissues in the colon represent an easy biopsy site
• Lymph tissue sampling from newborns may differentiate HIV acquired during pregnancy from that acquired during delivery and may also measure efficacy of therapy in preventing HIV transmission to newborns

Eleven abstracts addressed the concept of measuring HIV in lymph tissues as the next step in determining the effects of potent therapies on the presence and growth of the virus (see BETA, September 1996, page 9). This is an important concept, since 98-99% of all HIV is sequestered in lymph tissues. In general, when potent therapies for HIV, usually including a protease inhibitor, decreased the HIV RNA viral load in blood plasma to undetectable levels, RNA levels in lymph tissue were also undetectable. However, unspliced, "trapped" HIV messenger RNA was sometimes detected even after up to 18 months of therapy. Moreover, HIV proviral DNA, incorporated into human genes, was almost always present, except among those whose treatments started during primary infection (that group, however, still had HIV DNA in their blood mononuclear cells). Attempts to grow lymph cell proviral HIV in vitro were always unsuccessful, potentially indicating non-viable HIV genes. Also, decreased apoptosis (programmed cell death) was measured in lymph tissues following initiation of potent therapies.

Several abstracts addressed the question of where to biopsy lymph tissue. Past reports implied that easily accessible lymph nodes were obvious choices, including the tonsils or those in the neck or groin. Only a small piece of tissue is needed. The amount of lymphoid tissue throughout the gastrointestinal tract and internal genitourinary tract is 5-10 times larger in volume than the lymph nodes, so the gut may be another suitable location for biopsy. Many reports analyzed gut lymph tissue obtained during a sigmoidoscopy, the insertion of a flexible tube through the rectum approximately 7.5 inches into the sigmoid.

David Ho, MD, Martin Markowitz, MD, and colleagues from the Aaron Diamond AIDS Research Center, looked at gut lymph tissue samples for HIV RNA, DNA and its culturability, and compared their findings with those for blood. They examined a group of 36 recently infected HIV positive men treated with AZT plus 3TC plus either indinavir or ritonavir (see below). Despite undetectable HIV RNA in blood and a marked reduction of HIV RNA in lymph tissues after 5 months of therapy (and continuing until 17 months), a few patients did have unspliced, "trapped" HIV RNA in their lymph tissues, as measured by polymerase chain reaction (PCR). All lymph tissue samples were positive for HIV proviral DNA integrated among the human genes. Also, after combination therapy, mononuclear cells in semen were negative for HIV RNA, yet positive for HIV DNA, even after up to 17 months of therapy.

J.K.Wong, MD, and colleagues, from the University of California at San Diego, measured HIV levels in blood plasma and took groin lymph node biopsies from 5 patients taking AZT plus 3TC plus indinavir. After 3-12 months of triple therapy, 2 of 5 had undetectable HIV RNA viral loads in plasma (lower limit of detection 20 copies/mL). Their lymph nodes contained 50-100 copies of HIV RNA per gram of lymph tissue. Cultures of either lymph tissue or blood mononuclear cells showed no HIV growth. Analyses of the other 3 patients indicated that complete HIV viral suppression in blood plasma correlates with a greater than 3.5 log (3,100-fold) lower viral RNA level in lymph tissue. The authors also reported some regeneration of abnormal lymph node structure in those patients who had sustained viral load suppression. HIV DNA measurements were not reported.

W. Cavert and colleagues, from the University of Minnesota, presented data demonstrating a marked decrease in HIV RNA from tonsil biopsies of 10 HIV positive patients treated with AZT plus 3TC plus ritonavir for 24 weeks (patients had no prior anti-HIV therapy). They used in situ hybridization techniques and computerized quantitative image analysis to measure HIV viral load mononuclear cells and follicular dendritic cells (FDC, a pool of lymph cells that contain HIV antigen-antibody complexes), both of which are major lymph cell reservoirs for HIV.

After triple therapy for 6 months, the mean number of mononuclear cells actively producing HIV per gram (gm) of lymph tissue decreased from 310,000 cells/gm by greater than or equal to 2.2 log (158-fold). An actively productive cell was defined as one with greater than or equal to 20 HIV RNA copies per cell. In addition, 6 months of triple therapy decreased the mean pretreatment FDC-associated HIV RNA load from 150 million copies per gram by greater than or equal to 3.4 log (2,500-fold). Residual HIV RNA was detectable in most patients' mononuclear cells and/or FDC. Lymph tissue from all 10 patients also still showed residual HIV proviral DNA, although possibly in lower quantities than before treatment. The patients' mean blood plasma HIV RNA viral load in the patients decreased by approximately 2.6 log copies/mL (398-fold).

The best results of lymph tissue HIV sampling comes from a study of 15 patients who were started with combination anti-HIV therapy during acute retroviral syndrome (primary infection) (see BETA, September 1996, pages 11-12). C. Tamalet, MD, and colleagues, from Toulon General Hospital in France, treated patients with either AZT plus ddI plus 3TC or AZT plus 3TC plus saquinavir for up to 12 months. Six of 15 patients reached the 12-month point.

The mean baseline plasma HIV RNA viral load of 6 log copies/mL (1 million) decreased by 4 log copies/mL (10,000-fold) and became undetectable (limit of detection 200 copies/mL) in 4 of 6 after 12 months. The mean baseline lymph cell HIV RNA of 4.9 log copies per million cells decreased to undetectable levels in all 6 persons after 6 months, and persisted for 12 months. The mean baseline HIV RNA in blood mononuclear cells was 3 log copies per million cells, which decreased by 1.6 log copies per million cells (to undetectable in 4 of 6 persons) after 12 months. The mean baseline lymph cell HIV DNA of 4.9 log copies per million mononuclear cells became undetectable after 6-12 months in all 6 patients. However, blood mononuclear cell HIV DNA at baseline was 3.1 log copies per million cells and decreased by 2 log copies per million cells after 12 months. This indicates the persistence of HIV DNA in blood mononuclear cells after 12 months of potent combination therapy. However, lymph cell HIV DNA was not detected after only 6 months. Cultures of either plasma, blood mononuclear cells or lymph tissue mononuclear cells, while positive at baseline, were all persistently negative from the third month of treatment (in 12 of 12 patients) to the twelfth month (in 6 of 6 patients).

Donald Kotler, MD, and colleagues, reported the short-term effects of combination anti-HIV therapy on rectal lymph tissue in 12 patients. Four of 12 took antiretroviral therapy that included indinavir. After 7 days of treatment, their HIV RNA viral load decreased by 1.25 log copies/mL (17-fold) in both blood plasma and lymph tissue. CD4 cell counts increased by 40% in the blood and by 80% in the lymph tissue. Also, apoptosis of lymph tissue mononuclear cells decreased by 1.9 log (79-fold). Increased apoptosis induced by HIV is thought to be a part of the immune dysfunction in AIDS.

A decrease in apoptosis was also observed in blood mononuclear cells by A. Lafeuillade and colleagues, from Marseilles, France, in 10 HIV positive patients treated with the 4-drug combination of AZT plus ddI plus 3TC plus saquinavir for 6 months. (They had taken no prior anti-HIV therapy.) This was associated with a mean increase in blood CD4 counts of 140 cells/mm³ after 4 months and an even greater increase in lymph tissue CD4 cells. At the same time, HIV RNA became undetectable in blood plasma and decreased by greater than or equal to 3.5 log (3,100-fold) in lymph tissue mononuclear cells. Potent anti-HIV therapy can allow partial immune reconstitution in lymph nodes and is related to decreased apoptosis and increased lymphocyte proliferation.

Jonathan Schapiro, MD, and colleagues, from Stanford University, correlated the pathology of lymph node architecture with the degree of response to anti-HIV therapy. Ten HIV positive patients were treated with high dose (3,600-7,200 mg daily) saquinavir monotherapy for 24 weeks, extended up to 2 years. A longer sustained suppression of HIV viral load by saquinavir was correlated with a less pathologic lymph gland architecture. Conversely, a less sustained HIV viral load suppression by the drug was correlated with a more pathologic lymph gland architecture.

R.C. Hard, MD, and colleagues, from the Medical College of Virginia, have proposed that testing newborns' lymph node cells for HIV DNA may be able to distinguish between perinatal HIV transmission that takes place during pregnancy from transmission that occurs during delivery. A positive HIV DNA test by of newborn lymph cells suggests transmission prior to delivery. A negative test at birth associated with persistent HIV infection after 18 months would suggest HIV transmission during delivery. The researchers also state that such testing could also be used to determine whether specific anti-HIV drug regimens were successful in preventing perinatal HIV transmission.

Ongoing and new research using HIV markers in lymph tissue will further clarify the potential for complete HIV eradication in addition to new insights into the pathogenesis of HIV/AIDS.

Cavert W and others. Quantitative in situ hybridization measurement of HIV-1 RNA clearance kinetics from lymphoid tissue cellular compartments during triple-drug therapy. Abstract and late breaker presentation LB9.

Christopherson C and others. Evaluation of HIV-1 proviral DNA in patients with undetectable RNA. Abstract and oral presentation 752.

Hard RC and others. Tests of lymph node cells for HIV-1 to identify neonates infected in utero and to learn when zidovudine is most effective. Abstract and poster presentation 276.

Haase AT and others. Quantitative image analysis of HIV-1 infection in lymphoid tissue. Science 274:985-989. November 8, 1996.

Ho DD. Can HIV be eradicated from an infected person? Opening plenary session and abstract S1.

Kotler DP and others. Effects of combination antiretroviral therapy upon mucosal viral RNA burden and apoptosis. Abstract and late breaker presentation LB11.

Lafeuillade A and others. Four-drug combination: effect on viral load and immune reconstitution (blood and lymph nodes). Abstract and poster presentation 235.

Markowitz M and others. Recent HIV infection treated with AZT, 3TC and a potent protease inhibitor. Abstract and late breaker presentation LB8.

Schapiro JM and others. Lymph node histopathology in HIV-infected patients correlates with duration of response to antiretroviral therapy. Abstract and poster presentation 538.

Tamalet C and others. Viral load and genotypic resistance pattern in HIV-1 infected patients treated by a triple combination therapy including nucleoside and protease inhibitors initiated at primary infection. Abstract and poster presentation 592.

Wegner S and others. Rectal and lymph node biopsies in early stage HIV-1 infected patients. Abstract and oral presentation 748.

Wong JK and others. Reduction of HIV in blood and lymph nodes after potent antiretroviral therapy. Abstract and late breaker presentation LB10.

New Drugs and Drug Combinations

To understand drug combinations from the different drug classes, in addition to generic, brand and alphanumeric chemical names, please refer to the table Types and Names of Antiretroviral Drugs, this issue.

Indinavir plus Nevirapine plus 3TC Effective as "Salvage Therapy"

• Pilot study in Vancouver of 12 patients with advanced disease and prior therapy for 20 weeks
• Baseline median plasma HIV RNA viral load 5.17 log copies/mL decreased by 3.12 log, with 60% being undetectable (limit of detection 500 copies/mL)
• Baseline CD4 count 30 cells/mm³, increased by 90 cells/mm³
• 14% discontinued because of adverse effects (e.g., rash, nausea)
• Nevirapine 200 mg once daily for 2 weeks, then increased to twice daily; indinavir and 3TC both at standard doses

Harris M and others. A pilot study of indinavir, nevirapine and 3TC in patients with advanced HIV disease. Abstract and poster presentation 234.

Indinavir, AZT plus 3TC Effective for Advanced Disease

• Randomized, double-blind study of 320 patients for 24 weeks 27 months prior AZT therapy; no previous 3TC or protease inhibitor therapy
• Baseline median plasma HIV RNA 4.9 log (89,500) copies/mL, decreased by 2.2 log, with 65% being undetectable (limit of detection 500 copies/mL)
• Baseline median CD4 count 15 cells/mm³, increased by 84 cells/mm³ and still increasing at 48 weeks
• 6% discontinued because of adverse events
• 2-3% on indinavir had kidney stones
• Indinavir, AZT and 3TC taken at standard doses
• Study 039

Hirsch M and others. Indinavir in combination with zidovudine (ZDV) and lamivudine in ZDV-experienced patients with CD4 cell counts of 50 cells/mm³. Abstract and late breaker presentation LB7.

Indinavir plus 2 Nucleoside Analogs Effective in Advanced Disease

• Open-label, compassionate-use study in France of 496 patients for 24 weeks All had prior anti-HIV therapy but were protease inhibitor-naive
• 79% took indinavir plus 2 nucleoside analog drugs
• Baseline median plasma HIV RNA 129,000 copies/mL, decreased to 8,585 copies/mL among 264 patients completing 24 weeks of therapy
• Baseline median CD4 count 34 cells/mm³, increased to 96 cells/mm³ among 288 patients completing 24 weeks
• 4% withdrew because of indinavir toxicity; 11% because of stomach or intestinal toxicity;
• 3% developed a new AIDS-related illness

Rozenbaum W and others. Prospective follow-up of 406 (updated to 496) patients treated with antiretroviral regimen including indinavir. Abstract and poster presentation 239.

Indinavir plus d4T plus 3TC: another Option for Those with Prior Nucleoside Analog Treatment

• Open-label study in France of 145 patients for 6 months
• Extensive prior nucleoside analog drug therapy for a mean of 36 months, including 58% who were 3TC experienced and 32% who were d4T experienced
• d4T taken at 40 mg every 12 hrs; both indinavir and 3TC at standard doses
• Median baseline plasma HIV RNA 4.63 log copies/mL, decreased by 2.13 log to 2.5 log copies/mL
• Undetectable RNA viral load in 48% (limit of detection 200 copies/mL)
• Mean baseline CD4 count 84 cells/mm³, increased to 174 cells/mm³
• Mean body weight increase of 3 kg
• 28% incidence of new opportunistic infections; 2% incidence of death
• 44% were non-responders at 6 months with viral load decreases less than 1 log, although half of these were noncompliant with regimen
• 13% interrupted drug because of adverse events: sensory neuropathy (d4T, 6%); kidney stones (indinavir, 3%); nausea, vomiting or abdominal pain (2%)

de Truchis P and others. Combination therapy with d4T plus 3TC plus indinavir in nucleoside-experienced HIV-infected patients: an open-label study. Abstract and poster presentation 247.

Nelfinavir plus AZT plus 3TC Very Effective

• Double-blind, placebo-controlled study of 297 patients for 24 weeks
• No prior anti-HIV therapies, or AZT for less than 1 month
• AZT plus 3TC (standard doses) with or without nelfinavir, 500 or 750 mg 3 times daily with food
• Baseline mean plasma HIV RNA 152,511 copies/mL (range 1,052-1,600,000), decreased significantly by 2.3 log in the 500 mg nelfinavir arm and by 2.5 log in the 750 mg nelfinavir arm, but by only 1.4 log in the AZT plus 3TC arm
• Undetectable RNA in 65% of 500 mg nelfinavir arm (limit of detection 500 copies/mL)
• Undetectable RNA in 81% of 750 mg nelfinavir arm (limit of detection 500 copies/mL)
• 750 mg dose arm was significantly superior only if baseline HIV RNA was greater than 100,000 copies/mL
• Undetectable RNA in only 18% of AZT plus 3TC arm
• Baseline median CD4 count of 283 cells/mm³ (range 10-1,066), increased significantly in both nelfinavir arms, by 155 cells/mm³ in the 500 mg nelfinavir arm and by 160 cells/mm³ in the 750 mg arm, but only by 104 cells/mm³ in the AZT plus 3TC arm
• Diarrhea was the only grade 2 (moderate or severe) adverse event due to nelfinavir that occurred in more than 10% of participants: 12% in the 500 mg dose arm and 19% in the 750 mg arm. Diarrhea was not associated with weight loss, was ÒcontrollableÓ by anti-diarrheal medications, and led to patient discontinuation in less than 2%
• Other adverse events associated with nelfinavir that did not occur or rarely occurred in the AZT plus 3TC arm were flatulence (3-5%), anxiety (2%) and rash (1-3%); occurring almost equally frequently in all 3 were nausea (3-7%), vomiting (1-3%), headache (1-2%), weakness (1-2%), anemia (2-5%) and neutropenia (3-4%)
• Other studies of nelfinavir as monotherapy (Study 505) or in combination with d4T (Study 506) led to lesser viral load reductions than with the triple combination of nelfinavir plus AZT plus 3TC
• Nelfinavir is effective against AZT-resistant virus
• FDA approval of nelfinavir for adults and children is expected soon
• Study 511

Henry K and others. The safety of Viracept (nelfinavir mesylate) in pivotal Phase II/III double-blind randomized controlled trials as monotherapy and in combination with either d4T or AZT/3TC. Abstract and poster presentation 240.

Powderly W and others. The efficacy of Viracept (nelfinavir mesylate) in pivotal Phase II/III double-blind randomized controlled trials as monotherapy and in combination with d4T or AZT/3TC. Abstract and oral presentation 370.

Nelfinavir plus d4T plus ddI: Another Up-and-Coming Combination

• Pilot study of 22 patients for 12 weeks
• All were naive to ddI, d4T and protease inhibitors; 11 had used other anti-HIV drugs
• Median baseline plasma HIV RNA of 4.75 log copies/mL, decreased by 2.1 logs in 6 compliant patients
• Noncompliance occurred because of inconvenience of regimen (8), intercurrent illness (3) or vacation (1)
• Undetectable RNA in 83% (5 of 6) compliant patients
• Median baseline CD4 count of 315 cells/mm³ (range 70-709), increased by 200 cells/mm³ in compliant patients
• Adverse events included 1 case of grade 3 allergic reaction to nelfinavir and 1 case of grade 3 neutropenia with grade 4 liver enzyme elevations; 4 patients had mild fatigue; most patients had mild to moderate loose stools that did not require dose interruption
• Drugs used were d4T (40 mg twice daily), ddI (200 mg twice daily) and nelfinavir (750 mg every 8 hours)

Given the known synergism between d4T and ddI, and the benefits of combining nelfinavir with d4T, it would be reasonable to think that a triple cocktail using these 3 drugs would also be beneficial. Louise Pednault, MD, and colleagues, from the Princeton, NJ Continuing Care Center, reported on such a pilot study. While noncompliance was pronounced in the group of 22 patients, side effects were moderate. Further studies are indicated.

Pednault L and others. Stavudine (d4T), didanosine (ddI) and nelfinavir combination therapy in HIV-infected subjects: antiviral effect and safety in an ongoing pilot study. Abstract and poster presentation 241.

Nelfinavir plus Saquinavir Soft-Gel Combination Increases Saquinavir but Not Ritonavir Blood Levels

• Nelfinavir-indinavir combination increases levels of both drugs
• Other nelfinavir drug interactions have been described
• FDA approval for nelfinavir in adults and children is expected soon

Steven Kravcik, MD, and colleagues from Ottawa General Hospital, reported on the benefits of combining nelfinavir with saquinavir in a new soft-gel capsule (SGC) formulation. Combining 2 protease inhibitor drugs often allows a decrease in the dosage of one or both drugs. In 14 patients, nelfinavir 750 mg 3 times daily plus saquinavir-SGC 1,200 mg 3 times daily led to a 2.8-fold increase in blood levels of saquinavir. However, saquinavir-SGC did not affect the blood level of nelfinavir. A lower dose of saquinavir-SGC, 800 mg 3 times daily, might therefore be combined with nelfinavir.

After 12 weeks of combination therapy with nelfinavir plus saquinavir-SGC, the median plasma HIV RNA viral load reduction was 2.0 log, from a baseline of 39,917 copies/mL. Eight of 14 (57%) persons had undetectable viral loads (limit of detection 500 copies/mL). The median baseline CD4 count of 327 cells/mm³ increased by 118 cells/mm³.

Other double protease inhibitor combinations were reported by John Mellors, MD, from the University of Pittsburgh. Indinavir plus nelfinavir leads to a 1.8-fold increase in nelfinavir levels, while nelfinavir increases indinavir levels by 1.5-fold. Ritonavir also leads to an increase in nelfinavir levels, approximately 2.5-fold, without any changes in ritonavir levels caused by nelfinavir.

Other drug interactions with nelfinavir were described by Brad Kerr, MD, from Agouron Pharmaceuticals. Drug effects caused by nelfinavir are similar to those caused by indinavir. Nelfinavir increases blood levels of rifabutin 3-fold, thereby increasing the risk of uveitis (eye inflammation); 1 case of uveitis has been reported. When combining the 2 drugs, the rifabutin dose should be decreased by half. Since nelfinavir is metabolized by the CYP3A liver enzyme, other drugs also metabolized by CYP3A should be avoided. These include the antihistamine terfenadine (Seldane) and the calcium channel blockers. Nelfinavir also causes a 50% reduction in the levels of the birth control hormone ethinyl estradiol; to ensure effective contraception, the dose would have to be increased or another oral contraceptive would be indicated (i.e., norethindrone). When taken with nelfinavir, no dose modifications are necessary for each of the following drugs: azole antifungals including ketoconazole (Nizoral), fluconazole (Diflucan) and itraconazole (Sporanox); macrolide antibiotics including erythromycin, clarithromycin (Biaxin) and azithromycin (Zithromax); and nucleoside drugs including AZT, 3TC, d4T and ddI.

Agouron Pharmaceuticals. Agouron reports positive results from pivotal clinical trials of Viracept. News release. January 23, 1997.

Kerr B and others. Overview of the in vitro and in vivo drug interaction studies of nelfinavir mesylate, a new HIV-1 protease inhibitor. Abstract and oral presentation 373.

Kravcik S and others. Nelfinavir mesylate increases saquinavir soft-gel capsule exposure in HIV positive patients. Abstract and oral presentation 371.

Mellors J. Combination protease inhibitor therapy. Abstract and oral presentation S54.

Nelfinavir Resistance Does Not Confer Cross-Resistance to other Protease Inhibitors

One drawback of the current Food and Drug Administration (FDA)-approved protease inhibitor drugs is that resistance to one is often associated with to others (cross-resistance), particularly in the case of indinavir and ritonavir. Amy Patick, of Agouron Pharmaceuticals, suggested that initial resistance to nelfinavir does not necessarily confer cross-resistance to other protease inhibitor drugs including indinavir, ritonavir, saquinavir and 141W94 (an experimental drug made by Glaxo Wellcome). Nelfinavir may be the best protease inhibitor to use first. If resistance develops, there remains an option to switch to one of the other 3 available protease inhibitors. Data are still too limited to allow specific recommendations.

The report included 55 patients randomized to 4 arms: nelfinavir monotherapy, nelfinavir plus AZT plus 3TC, nelfinavir plus d4T, or AZT plus 3TC. The most commonly observed genetic mutation to nelfinavir after 44 weeks was at position 30. This was associated with phenotypic resistance to the drug. Resistance mutations associated with other protease inhibitors were only rarely observed. The most common genetic resistance mutation observed with ritonavir or indinavir (at position 184) did not occur with nelfinavir therapy. HIV strains that are highly resistant to nelfinavir were fully sensitive to indinavir, ritonavir, saquinavir and 141W94. There was a lower rate of nelfinavir resistance when the drug was taken in combination with other anti-HIV therapies.

In another group of patients, if 2 genotypic mutations in an HIV strain conferred resistance to indinavir, ritonavir or saquinavir, those HIV isolates were resistant to nelfinavir. In a separate analysis, 14 of 23 HIV viral isolates (61%) from AIDS patients who failed therapy with indinavir, ritonavir or saquinavir remained sensitive to nelfinavir. In December 1996 Agouron Pharmaceuticals submitted to FDA a New Drug Application for nelfinavir for adults and children.

Agouron Pharmaceuticals. Agouron reports positive results from pivotal clinical trials of Viracept. News release. January 23, 1997.

Patick A and others. Genotypic analysis of HIV-1 variants isolated from patients treated the protease inhibitor nelfinavir, alone or in combination with d4T or AZT and 3TC. Abstract and oral presentation 10.

Ritonavir plus d4T plus ddI as a First-Line Cocktail

• Open-label trial in France of 36 patients with CDC stage B HIV disease, followed for 24 weeks
• No prior HIV therapy
• Mean baseline plasma HIV RNA viral load of 4.83 log copies/mL, decreased by 2.5 log to 2.38 log copies/mL
• 14 of 17 (83%) had undetectable HIV RNA (limit of detection 200 copies/mL)
• Mean baseline CD4 count of 235 cells/mm³, increased to 377 cells/mm³
• 8 of 36 (22%) discontinued therapy because of nausea, diarrhea, rash (toxidermia), elevated muscle enzymes or anxiety
• 1 or more adverse events occurred in 80% including paresthesia (57%), diarrhea (47%), nausea and vomiting (39%), weakness (25%), mouth symptoms (14%), fever (11%) and skin rash (11%)

The adverse effects profile and discontinuation rate of this triple combination may preclude widespread popularity among patients.

Saimot AG and others. Ritonavir, stavudine (d4T), didanosine (ddI) as a triple combination treatment in antiretroviral-naive patients. Abstract and poster presentation 246.

Loviride in Combination with Nucleoside Analogs: Viral Load Benefits only for Patients without Prior Antiretroviral Therapy

Study 1

• CAESAR trial
• Patients had prior experience with nucleoside analog drugs
• Double-blind, placebo-controlled trial of 1,892 patients for 52 weeks; trial interrupted by independent Data Safety and Monitoring Board
• All patients continued current therapy AZT monotherapy (62%) or AZT plus ddI or AZT plus ddC then were randomized to receive 3TC plus loviride, 3TC plus placebo or dual placebo
• HIV RNA viral load levels decreased and CD4 cell counts increased
• Progression to new AIDS illness or death occured in 8% taking 3TC plus loviride, 9% taking 3TC plus placebo and 17% taking dual placebo. The difference is significant only for 3TC groups; the addition of loviride conferred no added benefits. There was also a significantly decreased risk of death for any AZT/3TC arm
• Loviride dosage 100 mg every 8 hours; 3TC at standard dose

Study 2

• AVANTI 1 trial
• Participants had no prior antiretroviral therapy
• Randomized, double-blind comparative trial of 106 patients for 52 weeks
• 2 arms: AZT plus 3TC (at standard doses) or AZT plus 3TC plus loviride 100 mg every 8 hours
• Median HIV RNA viral load at baseline of 4.8 log copies/mL, decreased by 1.3 log in the AZT plus 3TC group and by 1.6 log in the AZT plus 3TC plus loviride group (a statistically significant difference)
• Undetectable viral load (limit of detection 500 copies/mL) in 11% of AZT plus 3TC arm and 20% of loviride arm
• Median baseline CD4 count of 270 cells/mm³, increased by 55 cells/mm³ in the AZT plus 3TC arm and by 98 cells/mm³ in the AZT plus 3TC plus loviride arm
• Serious adverse events occurred in 15 (30%) on the AZT plus 3TC arm and 25 (50%) on the AZT plus 3TC plus loviride arm
• Withdrawal from study occurred in 11 (22%) on the AZT plus 3TC arm and 6 (12%) on the loviride arm
• Clinical endpoints were 1 death in the AZT plus 3TC arm; there were no deaths in loviride arm

These 2 studies using loviride in combination with nucleoside analogs indicate a potential benefit in viral load reductions after 1 year on loviride-containing regimens for patients who have never taken prior antiretroviral therapy.

Cooper D and others. The CAESAR trial final results. Abstract and oral presentation 367.

Rozenbaum W and others. Avanti 1: a randomized, double blind, comparative trial to evaluate the efficacy, safety and tolerance of combination antiretroviral regimens for the treatment of HIV-1 infection: AZT/3TC vs AZT/3TC/loviride in anti-retroviral naive patients. Abstract and oral presentation 368.

ABT-378: a Promising New Protease Inhibitor

• New drug has 10 times the potency of ritonavir in vitro
• Little cross-resistance with other protease inhibitors
• Once or twice daily dosing possible, if given with low-dose ritonavir

Harvey S. Bartnof has been a member of the Scientific Advisory Committee at the San Francisco AIDS Foundation since 1987.