First-in-human Phase I study of EZN-4176, a locked nucleic acid antisense oligonucleotide to exon 4 of the androgen receptor mRNA in patients with castration-resistant prostate cancer.

BACKGROUND: Prostate cancer remains dependent of androgen receptor (AR) signalling, even after emergence of castration resistance. EZN-4176 is a third-generation antisense oligonucleotide that binds to the hinge region (exon 4) of AR mRNA resulting in full-length AR mRNA degradation and decreased AR protein expression. This Phase I study aimed to evaluate EZN-4176 in men with castration-resistant prostate cancer (CRPC). METHODS: Patients with progressing CRPC were eligible; prior abiraterone and enzalutamide treatment were allowed. EZN-4176 was administered as a weekly (QW) 1-h intravenous infusion. The starting dose was 0.5 mg kg(-1) with a 4-week dose-limiting toxicity (DLT) period and a 3+3 modified Fibonacci dose escalation design. After determination of the DLT for weekly administration, an every 2 weeks schedule was initiated. RESULTS: A total of 22 patients were treated with EZN-4176. At 10 mg kg(-1) QW, two DLTs were observed due to grade 3-4 ALT or AST elevation. No confirmed biochemical or soft tissue responses were observed. Of eight patients with <5 circulating tumour cells at baseline, a conversion to <5 was observed in three (38%) patients. The most common EZN-4176-related toxicities (all grades) were fatigue (59%), reversible abnormalities in liver function tests ALT (41%) and AST (41%) and infusion-related reactions including chills (36%) and pyrexia (14%). CONCLUSION: Activity of EZN-4176 at the doses and schedules explored was minimal. The highest dose of 10 mg kg(-1) QW was associated with significant but reversible transaminase elevation.

Is the use of insulin lispro safe in pregnancy?

OBJECTIVE: To provide a review of the use and safety of insulin lispro during pregnancy. METHODS: This is a review of the available literature on the use of insulin lispro in pregnancy. A MEDLINE search was performed which included published manuscripts and abstracts in the English language to June 2001. RESULTS: The extensive search revealed that data on insulin lispro use during pregnancy are limited. Most of the reports on the use of insulin lispro during pregnancy demonstrated improvement of glycemic control, an increase in patient satisfaction, decreased hypoglycemic episodes, improved maternal and neonatal outcomes, and no deterioration in retinal status. However, there were two reports where it was suggested that there was an association with the use of insulin lispro in pregnancy and increased risk for the development of congenital anomalies and/or development or progression of diabetic retinopathy. CONCLUSIONS: Preliminary data suggest that insulin lispro does not have adverse maternal or fetal effects during pregnancy in women with diabetes. The use of insulin lispro during pregnancy results in improved glycemic control, fewer hypoglycemic episodes, improved patient satisfaction, improved maternal and neonatal outcomes and no deterioration in retinal status. There is no evidence that the use of insulin lispro during pregnancy results in an increased rate of congenital malformations. A prospective randomized clinical trial is imperative for further evaluation of any possible association with the use of insulin lispro during pregnancy and an increased rate of congenital malformations or change in retinal status.

Leptin in the ovine fetus correlates with fetal and placental size.

OBJECTIVE: The purpose of this study was to detect the presence of leptin and its receptor in ovine fetal tissues and to examine the relationship between circulating leptin concentrations and fetal and placental weights on gestational day 138 (GD138) of ovine pregnancy (term, 145 days). STUDY DESIGN: Pregnant sheep (n = 18) were instrumented on GD 110 to facilitate measurement and chronic reduction of uterine blood flow and produce intrauterine growth restriction. Four animals that served as controls were euthanized on GD 138 to obtain fetal tissues to determine the presence of ovine leptin and its receptor by reverse transcriptase-polymerase chain reaction. Seven instrumented animals were randomized into the control group, and 7 instrumented animals were randomized into the uterine blood flow restricted group (reduction equaled approximately 50% on GD 138). Maternal and fetal blood samples were obtained on day 138 to measure plasma leptin concentrations, and animals were euthanized for the determination of fetal morphometrics and placental weight. RESULTS: Expression of RNA for ovine leptin and its receptor were observed in fetal liver, skeletal muscle, kidney, heart, and placenta. Fetal body weight, ponderal index, and placental weight were significantly decreased by approximately 40% in the blood flow restricted group as compared with controls. Fetal leptin concentrations were increased by 45% in the uteroplacental blood flow restricted group (P =.01). Maternal leptin concentrations were not significantly different between the 2 groups and did not correlate with fetal concentrations. Fetal leptin concentrations had an inverse relationship with uterine blood flow (r = -0.73; P =.004), fetal body weight (r = -0.78; P =.002), and placental weight (r = -0.68; P =.01). CONCLUSION: Ovine fetal tissues express RNA for leptin and its receptor. Circulating leptin concentrations in the ovine intrauterine growth restriction fetus were significantly elevated on gestational day 138 compared with controls. Fetal leptin concentrations were inversely related to uterine blood flow and fetal and placental weight. These findings suggest that fetal leptin may be involved in an adaptive response to intrauterine growth restriction.

Is insulin lispro associated with the development or progression of diabetic retinopathy during pregnancy?

OBJECTIVE: This study was designed to determine whether there is an association between the use of insulin lispro during pregnancy and the development or progression of diabetic retinopathy. STUDY DESIGN: This observational cohort study included women with type 1 diabetes mellitus (n = 12) who were enrolled in our diabetes mellitus in pregnancy program and were treated with insulin lispro during pregnancy. We compared these women with a historical cohort (n = 42) who were treated with regular insulin during pregnancy. All patients underwent ophthalmologic examinations before 24 weeks' gestation and post partum, and retinopathy was graded according to a previously defined scale. RESULTS: Whereas none of the patients in the insulin lispro group showed any change in retinopathy status, 6 patients in the regular insulin group (14%) demonstrated changes in retinopathy status. Mild background retinopathy (change from grade 0 to 1) developed in 3 of these patients, and extensive proliferative retinopathy developed in 1 patient after normal results of the baseline examination (change from grade 0 to 6). Two patients had progression of retinopathy--1 had progression from background retinopathy to mild proliferative retinopathy (change from grade 2 to 4) and 1 had progression from mild proliferative retinopathy to extensive proliferative retinopathy (change from grade 4 to 6). CONCLUSIONS: These preliminary findings provide no evidence that insulin lispro treatment during pregnancy is associated with the development or progression of diabetic retinopathy.

[Comparative analysis of the proliferative capacity of cholesteatomas]. / Análisis comparativo de la capacidad proliferativa del colesteatoma.

Cholesteatomas of the middle ear are frequently aggressive and produce bone destruction. Stimulation of the surrounding inflammatory tissue and autocrine mechanisms could be responsible for the keratinocytic dysregulation of cholesteatomas, as well as for abnormal proliferation patterns. The proliferative capacity of human cholesteatoma of the middle ear was studied through the kinetics of the epithelial cells of cholesteatomas and external ear canal. The APAAP method was used to study the monoclonal antibody MIB-1, which recognizes an antigen of cells in the division phase. Biopsies taken from the outer ear canal (n = 7) revealed an MIB-1 level (the ratio of MIB-1 positive cells to all cells) of 7.6% +/- 2.2%. Cholesteatoma samples (n = 13) showed an MIB-1 level of 17.4% +/- 8.9%, and heterogeneity of the proliferative areas. Epithelial invaginations into the surrounding stroma were characterized by intense mitotic activity. The results confirmed a statistically significant increase in keratinocytes in the cholesteatomas, with an MIB-1 level 2.3 times higher than that of meatal keratinocytes. PCNA, a nuclear proliferation antigen which expresses the growth phase of cells in normal and tumoral tissue, was determined in 15 biopsies of meatal skin and 7 specimens of cholesteatoma in the phase of infection and 8 non-infection. Although the number of proliferative cells changed depending on the site of the cholesteatorna, the amount of PCNA-positive cells was significantly higher in the cholesteatoma (2.5-15, mean 9.3) than in normal skin (1-2.8, mean 1.5) (p < 0.001). Finally, AgNOR (argyrophyllic nucleolar organizer regions), which express proliferative activity, were determined in 12 specimens of meatal skin and in 19 acquired and 2 congenital cholesteatomas. A mean of 3.71 AgNOR dots were counted in the cholesteatomas and 1.54 dots in meatal skin specimens. The immunohistological study with three different markers expressing cellular proliferative capacity showed hyperproliferation associated with keratinocyte dysregulation in cholesteatoma samples, which could explain the clinically aggressive and destructive behavior of these lesions.

Análisis comparativo de la capacidad proliferativa del colesteatoma / Comparative analysis of the proliferative capacity of cholesteatomas

Los colesteatomas de oído medio presentan frecuentemente un comportamiento invasivo asociado a una destrucción ósea. Los estímulos inflamatorios del tejido conjuntivo subyacente, así como mecanismos autocrinos podrían ser responsables de la disregulación de los queratinocitos del colesteatoma y de los patrones anormales de proliferación. El presente trabajo refleja los estudios realizados para determinar la capacidad proliferativa del colesteatoma humano de oído medio. Para ello se han llevado a cabo investigaciones comparativas entre la cinética de las células epiteliales del colesteatoma y de la piel del conducto auditivo extemo (CAE). Por una parte, se utilizó el anticuerpo monoclonal MIB-1, que reconoce, un antígeno celular de células en división, mediante la técnica inmunológica de la APAAP (alcalina-fosfatasa-anti-alcalina-fosfatasa). Las biopsias de piel de CAE (n = 7) revelaron un nivel MIB 1 (cociente de células MIB 1 positivas y el total de células) de 7,6% ± 2,2%. Las muestras de colesteatoma (n = 13) presentaron un nivel del 17,4% ± 8,9% y una heterogenicidad de áreas epiteliales proliferativas. Los conos epiteliales con crecimiento hacia el estroma subyacente mostraron una actividad mitótica alta. Estadísticamente, los resultados confirman un incremento altamente significativo de queratinocitos en el colesteatoma, presentando un nivel 2,3 veces más alto de expresión MIB-1 en comparación con los queratinocitos de la piel meatal. Por otra parte, se compararon 15 biopsias de piel de CAE con 7 muestras de colesteatoma en fase de infección y 8 sin infección, determinándose el PCNA, el antígeno de proliferación del núcleo celular, capaz de expresar células en fase de crecimiento, tanto en tejido normal como en tejido neoplásico. Aunque el número de células proliferativas variaba según la zona del colesteatoma, el número de células positivas al PCNA era superior en el epitelio colesteatomatoso en comparación con la piel normal de CAE. El rango en piel normal osciló entre 1 y 2,8 (media de 1,5), mientras que en el colesteatoma los valores se hallaban entre 2,5 y 15 (media 9,3), siendo la diferencia estadísticamente significativa (p < 0,001). Finalmente se determinaron las AgNOR (regiones nucleolares organizadoras argirofílicas), como expresión de una actividad proliferativa en 12 biopsias de CAE y en 19 colesteatomas adquiridos y 2 congénitos. Se contabilizaron una media de 3,71 puntos ('dots') AgNOR en los colesteatomas y 1,54 puntos en las biopsias de piel del CAE, demostrando los colesteatomas una proliferación mayor. El estudio histológico con tres marcadores diferentes capaces de expresar la proliferación celular objetiva la marcada hiperproliferación del colesteatoma humano en oído medio, con una disregulación de los queratinocitos, que explica su comportamiento clínico agresivo y destructor (AU)

Cholesteatomas of the middle ear are frequently aggressive and produce bone destruction. Stimulation of the surrounding inflammatory tissue and autocrine mechanisms could be responsible for the keratinocytic dysregulation of cholesteatomas, as well as for abnormal proliferation patterns. The proliferative capacity of human cholesteatoma of the middle ear was studied through the kinetics of the epithelial cells of cholesteatomas and external ear canal. The APAAP method was used to study the monoclonal antibody MIB-1, which recognizes an antigen of cells in the division phase. Biopsies taken from the outer ear canal (n = 7) revealed an MIB-1 level (the ratio of MIB-1 positive cells to all cells) of 7.6% ± 2.2%. Cholesteatoma samples (n = 13) showed an MIB-1 level of 17.4% ± 8.9%, and heterogeneity of the proliferative areas. Epithelial invaginations into the surrounding stroma were characterized by intense mitotic activity. The results confirmed a statistically significant increase in keratinocytes in the cholesteatomas, with an MIB-1 level 2.3 times higher than that of meatal keratinocytes. PCNA, a nuclear proliferation antigen which expresses the growth phase of cells in normal and tumoral tissue, was determined in 15 biopsies of meatal skin and 7 specimens of cholesteatoma in the phase of infection and 8 non-infection. Although the number of proliferative cells changed depending on the site of the cholesteatorna, the amount of PCNA-positive cells was significantly higher in the cholesteatoma (2.5-15, mean 9.3) than in normal skin (1-2.8, mean 1.5) (p < 0.001). Finally, AgNOR (argyrophyllic nucleolar organizer regions), which express proliferative activity, were determined in 12 specimens of meatal skin and in 19 acquired and 2 congenital cholesteatomas. A mean of 3.71 AgNOR dots were counted in the cholesteatomas and 1.54 dots in meatal skin specimens. The immunohistological study with three different markers expressing cellular proliferative capacity showed hyperproliferation associated with keratinocyte dysregulation in cholesteatoma samples, which could explain the clinically aggressive and destructive behavior of these lesions (AU)

A phase I study of sequential vinorelbine followed by paclitaxel.

BACKGROUND: In vitro experiments suggest that administration of vinorelbine preceding paclitaxel results in synergistic cytotoxic effects. A phase I dose escalation trial of vinorelbine daily x 3 with paclitaxel on day 3 repeated every 28 days in metastatic breast cancer patients was completed. PATIENTS AND METHODS: Female patients, PS 0-2, without evidence of CNS disease or prior neuropathies were treated with vinorelbine at dose levels 7, 10, 13 mg/m2 per day and paclitaxel over three hours at dose levels of 135, 175, and 200 mg/m2. RESULTS: Twenty-eight patients with six dose levels were studied. At dose level 1, patients developed intolerable but reversible neutropenia. Subsequent dose levels required filgrastim. Dose limiting toxicities were myalgia and fatigue at vinorelbine 13 mg/m2/day and paclitaxel 200 mg/m2. Neuropathy was minor. Twelve of twenty-five patients with measurable disease had a rapid response which did not correlate with dose level. CONCLUSIONS: Sequential administration of these two agents demonstrates activity in breast cancer patients. Phase II dosing on this schedule should be vinorelbine 13 mg/m2/day x 3 and paclitaxel 175 mg/m2. With proper selection of patients, concern about neurologic toxicity should not impede future trials of vinorelbine with paclitaxel.

Ig V gene mutation status and CD38 expression as novel prognostic indicators in chronic lymphocytic leukemia.

Cellular immunophenotypic studies were performed on a cohort of randomly selected IgM(+) B-chronic lymphocytic leukemia (B-CLL) cases for which Ig V(H) and V(L) gene sequences were available. The cases were categorized based on V gene mutation status and CD38 expression and analyzed for treatment history and survival. The B-CLL cases could be divided into 2 groups. Those patients with unmutated V genes displayed higher percentages of CD38(+) B-CLL cells (>/=30%) than those with mutated V genes that had lower percentages of CD38(+) cells (<30%). Patients in both the unmutated and the >/=30% CD38(+) groups responded poorly to continuous multiregimen chemotherapy (including fludarabine) and had shorter survival. In contrast, the mutated and the <30% CD38(+) groups required minimal or no chemotherapy and had prolonged survival. These observations were true also for those patients who stratified to the Rai intermediate risk category. In the mutated and the <30% CD38(+) groups, males and females were virtually equally distributed, whereas in the unmutated and the >/=30% CD38(+) groups, a marked male predominance was found. Thus, Ig V gene mutation status and the percentages of CD38(+) B-CLL cells appear to be accurate predictors of clinical outcome in B-CLL patients. These parameters, especially CD38 expression that can be analyzed conveniently in most clinical laboratories, should be valuable adjuncts to the present staging systems for predicting the clinical course in individual B-CLL cases. Future evaluations of new therapeutic strategies and drugs should take into account the different natural histories of patients categorized in these manners.

Secondary hemochromatosis as a long-term complication of the treatment of hematologic malignancies.

The increased cure rate of hematologic malignancies including the use of bone marrow transplantation has focused attention on the chronic toxicity and quality of life of the survivors. We have observed five patients who have been diagnosed with clinically significant iron overload, presumably due to packed red blood cell transfusions, >/=12 months after transplant for a hematologic malignancy. In these patients, there is no history of veno-occlusive disease or family history of hemochromatosis. The allotransplant patient has been free of chronic graft versus host disease. Family screening has been negative. No patient developed clinically significant endocrinopathy, arthropathy, or cardiac disease. The patients have been treated with phlebotomy to bring the transferrin saturation and ferritin levels to normal. The long-term follow-up of patients treated for a hematologic malignancy should include analysis of hepatitis C virus and iron status. This may prevent the development of clinically significant chronic liver disease and possibly malignancy.

Acquired factor VIII inhibitors--successful treatment with an oral outpatient regimen.

A rare cause of a spontaneous, life threatening coagulopathy in adults is the development of autoantibodies to factor VIII. We recently had the opportunity to treat seven patients with this disorder. After stabilization, they were given a regimen consisting of prednisone and oral cyclophosphamide. All patients had a complete response to treatment. The median time to response was three weeks. Durable remissions were achieved, making this oral regimen an acceptable treatment for this disorder.

Clonal expansion within the CD4+CD57+ and CD8+CD57+ T cell subsets in chronic lymphocytic leukemia.

The role of T cells in chronic lymphocytic leukemia (CLL) has not been extensively investigated, since the most prominent cellular abnormality in CLL involves the clonal expansion of B cells. In this study we have undertaken a comprehensive analysis of the CD4+ and CD8+ T cell repertoire in a population of CLL patients (n = 19) and age-matched controls (n = 22). The TCR repertoire analysis was performed using a multiplex PCR assay for CDR3 length, an approach that allows for the detection of underlying oligoclonality in complex T cell populations. We established that oligoclonality was substantially more frequent in both the CD4+ and CD8+ T cell populations of CLL patients than in the age-matched controls (p < 0.001). Using three-color FACS analysis with a panel of TCRV segment-specific mAbs, we also established that oligoclonal expansions are predominantly found in the CD57+ subset of both the CD4+ and CD8+ T cell populations. The frequency of the CD57 marker on CD4+ T cells was increased in the setting of CLL (% CD57 = 14.8 +/- 13.0%) compared with that in normal controls (% CD57 = 3.3 +/- 3.0%; p < 0.001). An elevated frequency of CD4+CD57+ T cells was correlated with more advanced disease. Similarly, the most extreme oligoclonal expansions of CD4+CD57+ T cells occurred in CLL patients who had progressed beyond Rai stage 0. These data document profound alterations in the T cell repertoire of CLL patients and point to a role for clonal T cell populations in the pathogenesis of this disease.

Rearrangement and expression of MDM2 oncogene in chronic lymphocytic leukemia.

Since trisomy 12 is the most common chromosome abnormality found in CLL and MDM2 has been mapped to this chromosome, we examined the possible association of MDM2 in the pathogenesis of CLL. A rearrangement of the MDM2 gene was observed in 4 of 11 peripheral blood mononuclear cells (PBMC) from patients with CLL by Southern blot hybridization. Expression of MDM2 was detected in all of the CLL samples examined by Northern blot. However, neither gross amplification nor overexpression of the MDM2 gene was found in CLL. The data suggest that MDM2 may play a role in the pathogenesis of CLL and may help to explain how abnormalities of chromosome 12 are related to CLL.

Synergistic neutralization of human immunodeficiency virus type 1 by combinations of human monoclonal antibodies.

The ability of antibodies to the V3 region and the CD4-binding domain (CD4bd) of human immunodeficiency virus type 1 (HIV-1) to act in synergy to neutralize HIV has been demonstrated previously. However, synergy between antibodies to other HIV-1 epitopes has not been studied. We have used 21 combinations of human monoclonal antibodies (MAbs) directed against different epitopes of the gp120 and gp41 proteins of HIV-1 to evaluate their ability to act in synergy to neutralize HIV-1. Combinations of anti-V3 and anti-CD4bd antibodies, anti-V3 and anti-gp120 C-terminus antibodies, anti-CD4bd and anti-C-terminus antibodies, anti-V3 and anti-gp41 antibodies, and anti-CD4bd and anti-gp41 antibodies were tested. Our results show that some, but not all anti-V3 antibodies can act in synergy with anti-CD4bd antibodies. In addition, for the first time, antibodies to the C-terminus region have been found to act in synergy with the anti-CD4bd antibodies. Various anti-CD4bd MAbs also act in synergy when used together. The use of such cocktails of human MAbs for passive immunization against HIV-1 may prove to be important for therapy in postexposure settings and for prevention of maternal-fetal transmission of the virus. The results also provide information on the types of antibodies that should be elicited by an effective vaccine.

Human monoclonal antibodies to the V3 loop of HIV-1 gp120 mediate variable and distinct effects on binding and viral neutralization by a human monoclonal antibody to the CD4 binding site.

Interactive effects between human monoclonal antibodies specific for the V3 loop (257-D and 447-D) and an epitope within the CD4 binding site (F105) of HIV-1 gp120 were evaluated for neutralization of viral cytopathogenicity and binding to HIV-infected cells. Regardless of antibody pair, only additive effects were observed in neutralization of MN and SF2 virus though each antibody alone had potent neutralizing activity on these strains. Significant cooperativity was observed between F105 and 447-D in neutralization of RF. Relatively high concentrations (> 100 micrograms/ml) of each individual antibody are required for partial neutralization (25--40%) of RF. Coincubation with 10 micrograms/ml of each antibody increased neutralization activity 3--4-fold more than predicted for additive effects alone. No enhancement was seen upon coincubation of F105 with 257-D which does not neutralize RF. Antibody interactions with native antigen on HIV-infected cells was measured by flow cytometry. Results were consistent with neutralization results in the majority of flow cytometry experiments; however, enhanced binding did not necessarily predict enhanced neutralization. These data support the notion that either a conformational change occurs with binding of V3 loop antibodies which enhances the binding and neutralizing activity of antibodies directed to the CD4 binding site of gp120 or vice versa, or new antigenic sites are exposed by the V3 loop antibodies on cell surfaces and virions. Of importance, cooperativity is observed even at very low antibody concentrations.

Repertoire of neutralizing human monoclonal antibodies specific for the V3 domain of HIV-1 gp120.

HIV infection induces antibodies that mediate neutralization of cell-free virus and may protect against viral infection. Neutralizing human mAb that bind to the third hypervariable domain (V3) of gp120 have been generated from PBL of HIV-seropositive subjects. Twelve such mAb recognize 9 different epitopes spanning an 11 amino acid stretch at the tip of the V3MN loop. The epitopes of an additional two mAb have not been precisely determined but occur within a 15-mer peptide around the tip of the V3 loop. Eleven of 13 mAb are reactive with at least one other V3 peptide besides MN, indicating that cross-reactivity is a common phenomenon amongst anti-V3 antibodies. All the mAb achieved 50% neutralization of HIVMN at antibody concentrations of 12 to 4700 ng/ml. Two mAb, which recognized epitopes at the top of the V3 loop, GPGR and GRAF, neutralized strains as divergent as MN and IIIB. The affinities of all mAb tested were shown to be substantially higher for the rgp120 than for a 23-mer peptide from the V3 loop of the homologous strain. A significant inverse correlation was demonstrated between affinities and the 50% neutralizing doses for HIVMN.

Neutralization of diverse human immunodeficiency virus type 1 variants by an anti-V3 human monoclonal antibody.

The third variable region (V3) of the HIV-1 gp120 envelope glycoprotein is thought to induce potent neutralizing antibodies which are generally defined as type specific and reactive with individual viral isolates. In contrast, the CD4-binding domain is thought to induce neutralizing antibodies that are group specific and capable of neutralizing all isolates of HIV-1. However, in this study, we used a panel of human monoclonal antibodies to these regions of gp120 which displays specificities and neutralizing activities that challenge these tenets. In particular, we used a human monoclonal antibody to the V3 domain with exceptionally potent and broad neutralizing activity against many diverse HIV-1 isolates. The anti-CD4-binding domain antibodies, on the other hand, showed a more restricted pattern of activity.

The absence of Tat sequences in tissues of HIV-negative patients with epidemic Kaposi's sarcoma.

OBJECTIVE: Tat, an essential regulatory protein of HIV, acts as a growth factor for Kaposi's sarcoma (KS)-derived cells in culture. We tested the hypothesis that HIV-negative epidemic KS patients who are also at high risk for HIV disease might have been infected with a defective HIV-1 virus that retained the ability to express Tat. METHODS: We evaluated the presence of Tat sequences in KS tissue and peripheral blood mononuclear cells (PBMC) of HIV-1-negative individuals with epidemic KS who had risk factors for HIV infection by polymerase chain reaction using specific primers for the Tat region of HIV-1. RESULTS: No evidence for the presence of Tat-1 sequences or for Tat-expressing defective HIV-1 virus was found. CONCLUSION: These results suggest that HIV-1 Tat does not play a role in the initiation of KS in HIV-1-negative individuals. Tat might play an indirect role in epidemic KS in HIV-infected patients.