Evolution of genotypic and phenotypic resistance during chronic treatment with the fusion inhibitor T-1249.

T-1249 is a peptide HIV fusion inhibitor (FI) previously under development for use in FI-naive and experienced patients. Here we present prospectively planned longitudinal analyses of FI resistance during 48 weeks of T-1249 dosing in patients with extensive prior FI exposure. T1249-105 was a single-arm rollover study in patients with prior resistance to enfuvirtide (ENF) and 10 days of T-1249 functional monotherapy exposure. The phenotype and genotype of plasma virus envelopes were analyzed at baseline and at study weeks 8, 16, and 48. At study entry, viruses had a geometric mean decrease in susceptibility to ENF of 51.8-fold but to T-1249 of 1.8-fold; extensive genotypic resistance to ENF was observed. A median viral load response of - 1.5 log(10) copies/ml was observed at week 2 that was partially sustained (- 0.5 log(10) copies/ml) through 48 weeks. Resistance to T-1249 gradually increased to a geometric mean 92.7-fold decrease from FI-naive baseline; this occurred concomitant with further evolution of gp41 amino acids 36-45, most commonly the G36D (n = 6, 16%) or N43K (n = 9, 24%) substitutions. A novel substitution, A50V (n = 12, 32%), was also common, as were the N126K and S138A substitutions in heptad-repeat 2 (HR-2). These data point toward a primary role for the gp41 36-45 locus in modulating FI binding and suggest that residues in HR-2 may contribute in a more limited manner to development of peptide FI resistance. These data also point toward a substantial genetic barrier and fitness cost to development of resistance to next-generation fusion inhibitors.

Structured antiretroviral treatment interruptions in chronically HIV-1-infected subjects.

The risks and benefits of structured treatment interruption (STI) in HIV-1-infected subjects are not fully understood. A pilot study was performed to compare STI with continuous highly active antiretroviral therapy (HAART) in chronic HIV-1-infected subjects with HIV-1 plasma RNA levels (VL) <400 copies per ml and CD4(+) T cells >400 per microl. CD4(+) T cells, VL, HIV-1-specific neutralizing antibodies, and IFN-gamma-producing HIV-1-specific CD8(+) and CD4(+) T cells were measured in all subjects. STIs of 1-month duration separated by 1 month of HAART, before a final 3-month STI, resulted in augmented CD8(+) T cell responses in all eight STI subjects (P = 0.003), maintained while on HAART up to 22 weeks after STI, and augmented neutralization titers to autologous HIV-1 isolate in one of eight subjects. However, significant decline of CD4(+) T cell count from pre-STI level, and VL rebound to pre-HAART baseline, occurred during STI (P = 0.001 and 0.34, respectively). CD4(+) T cell counts were regained on return to HAART. Control subjects (n = 4) maintained VL <400 copies per ml and stable CD4(+) T cell counts, and showed no enhancement of antiviral CD8(+) T cell responses. Despite increases in antiviral immunity, no control of VL was observed. Future studies of STI should proceed with caution.

Evaluation of distinct blood lymphocyte populations in human immunodeficiency virus type 1-infected subjects in the absence or presence of effective therapy.

Virus reservoirs can persist in human immunodeficiency virus type 1 (HIV-1)-infected subjects despite effective plasma virus suppression. To compare viral dynamics in the absence and presence of antiretroviral therapy, blood mononuclear cells from 19 subjects with high plasma RNA levels and 18 subjects following prolonged virus suppression were examined, by use of in situ hybridization, to detect virus RNA expression before and after in vitro T cell activation. This approach reveals circulating lymphocytes expressing HIV-1 RNA before activation and an increase in cells with detectable HIV-1 RNA transcription after in vitro activation. The frequencies of these 2 cell populations are strongly correlated with plasma virus load and appear to be stable once a new steady state is established during therapy. The frequency of viral RNA-positive cells is equivalent to the frequency of cells that produce infectious virus. Thus, in HIV-1-infected subjects there are distinct virus reservoirs comprising both latent and replication-active cells.

AIDS-related malignancies.

In the US over one million persons are currently infected with the HIV, over half a million have had AIDS, and over 300,000 have died from AIDS. Worldwide, it is estimated that more than 17 million people are currently infected with HIV, and over 1,200,000 cases of AIDS have been reported to the World Health Organization. By some estimates, up to 40% of patients with AIDS will ultimately develop some form of cancer. Non-Hodgkin's lymphoma, Kaposi's sarcoma and invasive cervical cancer have a higher incidence in persons with HIV infection and all three are AIDS-defining illnesses. In addition, several reports suggest that a number of other malignancies may occur at an increased incidence in persons with HIV infection, including squamous-cell carcinoma of the head, neck and anus, plasmacytoma, melanoma, small-cell lung cancer, basal-cell cancer, and germ-cell tumours. Clinicians should become familiar with HIV-related malignancies as their incidence is expected to further increase as more effective therapies for HIV and associated opportunistic infections allow patients to live longer in an advanced state of immunodeficiency. In the current article, we will review the clinical and therapeutic aspects of the most common AIDS-related malignancies including non-Hodgkin's and Hodgkin's lymphomas, Kaposi's sarcoma and anogenital epithelial neoplasias.

Treatment of HIV infection with cytoreductive agents.

Advances in antiretroviral therapy have resulted in significant improvement in virological markers and clinical end points. However, studies have demonstrated that HIV can be recovered from patients in whom HIV RNA has been undetectable for prolonged periods of time, suggesting that the elimination half-life of latently infected cells may be longer than previously speculated. When used in the appropriate setting, cytoreductive agents may help expedite the elimination of the long-lived viral reservoir, and result in shorter administration of antiviral agents. In this article we discuss the potential use of cytoreductive agents as adjunctive therapy to antiretrovirals. In addition, we review those agents most likely to impact the viral reservoir and describe ongoing clinical trials designed to define the effect of cytoreductive therapy on those reservoirs. If a positive effect is demonstrated, these agents could ultimately be a powerful addition to the potent drugs currently being used to block HIV replication.

Improved gastrointestinal tolerance and palatability of didanosine in adults by the use of pediatric power formulation.

Administration of didanosine (ddI) as buffered tablets is complicated by its poor palatability. The tolerance and palatability of pediatric powder ddI in an adult population of subjects with HIV infection as compared with buffered ddI tablets was compared. Twenty HIV-infected, were enrolled in a randomized crossover trial. Subjects took one of the two randomly assigned formulations for 4 weeks and then were crossed over to the alternative treatment. Twenty subjects were enrolled, and all of them completed the study. Of the 16 subjects, 10 reported that taking the ddI tablets affected the quality of their lives negatively. Of the participants, 18 (905) rated the pediatric formulation as 6 (better) or 2 (much better) than the buffered tablets. Preference was based on better taste and ease to swallow, although none of these 18 patients reported difficulties taking the pediatric formulation. In contrast, 19 of the 20 subjects reported difficulties taking the buffered tablets during the study period, including poor taste, trouble swallowing them, and diarrhea. Tolerance and palatability of ddI demonstrate marked improvement by the use of the pediatric powder, which suggests that the administration of ddI can markedly enhanced by the use of pediatric formulation.

CD34+CD38-lin- cord blood cells develop into dendritic cells in human thymic stromal monolayers and thymic nodules.

Thymic dendritic cells (DCs) appear to have distinct biologic and functional properties compared with DCs in other tissues. Currently, little is known about human thymic DCs because they have been difficult to isolate and culture in vitro. Here, we report that human thymic stroma can support the development of primitive human hemopoietic stem cells into mature DCs without cytokine or serum supplementation. Coculture of CD34+CD38-lineage (lin)- and CD34+CD38+lin- umbilical cord blood cells with thymic stromal monolayers induced 43 +/- 17-fold and 32 +/- 16-fold expansions, respectively, of umbilical cord blood progenitors and also generated large numbers of cells with the morphologic, phenotypic, and functional characteristics of mature DCs. These cells expressed class I and class II MHC, CD1a, CD2, CD4, CD11c, CD40, CD45, CD80, CD83, and CD86 and were potent stimulators of allogeneic T cell activation. Primitive hemopoietic progenitors also developed into mature DCs in a novel tissue culture system of thymic nodules wherein thymic epithelial cells and fibroblasts were grown in nodular aggregates in vitro. These results demonstrate that human thymic stroma efficiently supports the development of CD34+CD38-lin- cord blood cells into mature DCs. In addition, the culture conditions described in this report are useful systems for studying the ontogeny of human DCs in thymic microenvironments.

Neutralizing and infection-enhancing antibody responses to human immunodeficiency virus type 1 in long-term nonprogressors.

Serum antibodies from human immunodeficiency virus type 1 (HIV-1)-infected long-term non-progressors (LTNPs) and non-LTNPs were evaluated for virus neutralization and infection enhancement in vitro. Sera from LTNPs had higher average titers of neutralizing antibodies to HIV-1 strains IIIB and MN and more frequently neutralized primary isolates from progressors (14.9% vs. 1.3%, P = .002). Replication-competent HIV-1 was isolated from peripheral blood mononuclear cells and lymph nodes of 3 LTNPs. All viruses from LTNPs had a non-syncytium-inducing phenotype, were resistant to neutralization by autologous serum obtained at the time of virus isolation, and showed little evidence of a heightened sensitivity to neutralization by heterologous sera. Complement-mediated, antibody-dependent enhancement (C'-ADE) of HIV-1IIIB and primary isolates was equally prevalent for sera from LTNPs and non-LTNPs. Results indicate that LTNPs produce vigorous serum antibody responses and that long-term nonprogression is not associated with homologous neutralization or the absence of C'-ADE.

Disseminated Nocardia farcinica infection in an AIDS patient.

This report describes an AIDS patient presenting with disseminated Nocardia farcinica infection diagnosed by percutaneous kidney biopsy. The isolate was initially identified as Nocardia asteroides. Though Nocardia asteroides remains sensitive to most antimicrobial agents, Nocardia farcinica is resistant to gentamicin, tobramycin and cephalosporins and is indistinguishable from Nocardia asteroides by regular laboratory methods. In view of the rising incidence of infections with Nocardia farcinica, third-generation cephalosporins should not be used in the initial management of Nocardia infections, and all isolates should be submitted for antibiotic susceptibility testing.

Th1 and Th2 cell-associated cytokines in experimental visceral leishmaniasis.

In experimental Leishmania donovani infection in BALB/c mice, initial susceptibility gives way to T-cell-dependent acquired resistance and eventual control over visceral infection. Since various cytokines appear to underlie the host response to Leishmania infection, we examined infected liver tissue for gene expression of cytokines associated with Th1 (gamma interferon [IFN-gamma] and interleukin-2 [IL-2]) and Th2 cells (IL-4 and IL-10). By Northern (RNA) blot analysis, only IFN-gamma mRNA expression was detected in livers of infected euthymic mice. To determine whether activation of Th1 cells develops selectively in this model, qualitative PCR analysis was used. These results indicated that mRNAs for IFN-gamma, IL-2, IL-4, and IL-10 were all induced by L. donovani infection. The potentially negative Th2 cell-associated response did not appear to play a functional role, however, since resistance was acquired, anti-IL-4 monoclonal antibody treatment did not accelerate control over visceral infection, and serum immunoglobulin E levels remained low. As judged by PCR analysis, IL-4 and IL-10 mRNAs were also expressed under three other conditions without apparent effect: in naive euthymic mice treated with IL-2, which induces leishmanicidal activity; in rechallenged immune mice, which resist reinfection; and in nude mice, which fail to control L. donovani. These results suggest that, like other Leishmania species, L. donovani infection may trigger a potentially suppressive Th2 cell-associated cytokine response. However, in T-cell-intact mice able to control L. donovani, this response either is insufficient to influence outcome or more likely is overshadowed by the Th1 cell response.

Role and effect of IL-2 in experimental visceral leishmaniasis.

In experimental visceral leishmaniasis, acquired resistance is T cell-dependent, involves IFN-gamma-activated macrophages, and is expressed in the tissues by granuloma formation. Resistance also correlates with Ag-stimulated IL-2 secretion; therefore, Leishmania donovani-infected BALB/c mice were treated with anti-IL-2 mAb or rIL-2 to determine the host defense effect of IL-2. In control mice, intracellular hepatic infection peaked at 2 wk and then declined coincident with granuloma development. In contrast, liver parasite burdens in anti-IL-2-treated mice continued to increase until after 4 wk, at which time mature granuloma formation was inhibited. Treatment of mice with continuously administered IL-2 reduced liver burdens by > 50% and led to marked accumulation of granuloma mononuclear cells. The IL-2-responsive mechanism was T cell-dependent and required both L3T4+ and Lyt-2+ cells. IL-2 enhanced IFN-gamma mRNA expression in vivo and was required for IFN-gamma secretion in vitro, and anti-IFN-gamma mAb administration abolished the antimicrobial effect of exogenous IL-2. These results: 1) identify the activity of endogenous IL-2 in both antileishmanial resistance and granuloma formation; 2) demonstrate that exogenous IL-2 can enhance the granulomatous tissue reaction; and 3) indicate that IL-2 treatment stimulates intracellular antimicrobial activity largely via the induction of IFN-gamma.

Plasma-cell dyscrasia with polyneuropathy. The spectrum of POEMS syndrome.

BACKGROUND: The POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome and osteosclerotic myeloma (polyneuropathy and sclerotic bone lesions) may both be manifestations of plasma-cell dyscrasia, but the interrelation of these diseases is not clear. We therefore set out to define the clinical spectrum of disease in patients with plasma-cell dyscrasia and polyneuropathy who have the complete or incomplete form of the POEMS syndrome or osteosclerotic myeloma. METHODS: Among 2714 patients with plasma-cell dyscrasia who were identified between 1973 and 1989, we reviewed the cases of those with polyneuropathy and plasma-cell dyscrasia who fulfilled the criteria for the POEMS syndrome or osteosclerotic myeloma. RESULTS: Thirty-eight patients (1.4 percent) with a median age of 51 years were identified, 22 of whom were male. By definition, all had polyneuropathy (37 combined sensorimotor, and 1 primarily motor). Other findings included osteosclerotic bone lesions (82 percent), skin abnormalities (58 percent), lymphadenopathy (42 percent), papilledema (37 percent), peripheral edema (29 percent), hepatomegaly (24 percent), splenomegaly (21 percent), and ascites (11 percent). Thirty-three patients (87 percent) had an abnormal M protein in serum or urine (17 had IgA lambda, and 12 IgG lambda). Five patients fulfilled all the criteria for the POEMS syndrome. The estimated five-year survival in the 38 patients was 60 percent, which was significantly better than the 20 percent survival in 869 patients with multiple myeloma (P < 0.05). The clinical course was similar among the patients with the complete form of the POEMS syndrome and those with the incomplete form. CONCLUSIONS: Plasma-cell dyscrasia with polyneuropathy is a rare multisystem disease that often presents with osteosclerotic bone lesions. The differentiation of the POEMS syndrome from so-called osteosclerotic myeloma with peripheral neuropathy appears to have no clinical value.

POEMS syndrome with idiopathic flushing mimicking carcinoid syndrome.

POEMS syndrome, a rare multisystem disease, is a variant of osteosclerotic myeloma and is characterized by polyneuropathy, organomegaly, endocrinopathy, monoclonal proteins, and skin changes. Presented herein is a case of POEMS syndrome with flushing. The flushing was intermittent, involving the face and upper third of the trunk, and was associated with hypotension and bronchospasm. Final diagnosis was made by biopsy examination of an axillary lymph node, which showed angiofollicular hyperplasia that stained strongly and selectively for lambda light chains. The patient had most of the typical features of POEMS syndrome but was unique in that her most striking finding was carcinoid-like flushing. The flushing improved with steroid therapy, as did some of the other clinical features of her disease. This case suggests that idiopathic flushing can be added to the skin changes observed in POEMS syndrome.