Background

Clinical studies have shown that integrase strand transfer inhibitors can be used to treat HIV-1 infection. Although the first-generation integrase inhibitors are susceptible to the emergence of resistance mutations that impair their efficacy in therapy, such resistance has not been identified to date in drug-naïve patients who have been treated with the second-generation inhibitor dolutegravir. During previous in vitro selection study, we identified a R263K mutation as the most common substitution to arise in the presence of dolutegravir with H51Y arising as a secondary mutation. Additional experiments reported here provide a plausible explanation for the absence of reported dolutegravir resistance among integrase inhibitor-naïve patients to date.

Results

We now show that H51Y in combination with R263K increases resistance to dolutegravir but is accompanied by dramatic decreases in both enzymatic activity and viral replication.

Conclusions

Since H51Y and R263K may define a unique resistance pathway to dolutegravir, our results are consistent with the absence of resistance mutations in antiretroviral drug-naive patients treated with this drug.

The correlation between quantitative human epidermal growth factor receptor (HER)-2 protein expression in primary breast cancers and the time to brain metastases in HER-2+ advanced breast cancer patients treated with trastuzumab was investigated. A strong relationship between the quantitative HER-2 protein expression level and the risk for brain relapse in HER-2+ advanced breast cancer patients was found.

Background.

Patients with human epidermal growth factor receptor (HER)-2+ breast cancer are at particularly high risk for brain metastases; however, the biological basis is not fully understood. Using a novel HER-2 assay, we investigated the correlation between quantitative HER-2 expression in primary breast cancers and the time to brain metastasis (TTBM) in HER-2+ advanced breast cancer patients treated with trastuzumab.

Methods.

The study group included 142 consecutive patients who were administered trastuzumab-based therapy for HER-2+ metastatic breast cancer. HER-2/neu gene copy number was quantified as the HER-2/centromeric probe for chromosome 17 (CEP17) ratio by central laboratory fluorescence in situ hybridization (FISH). HER-2 protein was quantified as total HER-2 protein expression (H2T) by the HERmark® assay (Monogram Biosciences, Inc., South San Francisco, CA) in formalin-fixed, paraffin-embedded tumor samples. HER-2 variables were correlated with clinical features and TTBM was measured from the initiation of trastuzumab-containing therapy.

Results.

A higher H2T level (continuous variable) was correlated with shorter TTBM, whereas HER-2 amplification by FISH and a continuous HER-2/CEP17 ratio were not predictive (p = .013, .28, and .25, respectively). In the subset of patients that was centrally determined by FISH to be HER-2+, an above-the-median H2T level was significantly associated with a shorter TTBM (hazard ratio, [HR], 2.4; p = .005), whereas this was not true for the median HER-2/CEP17 ratio by FISH (p = .4). Correlation between a continuous H2T level and TTBM was confirmed on multivariate analysis (HR, 3.3; p = .024).

Conclusions.

These data reveal a strong relationship between the quantitative HER-2 protein expression level and the risk for brain relapse in HER-2+ advanced breast cancer patients. Consequently, quantitative assessment of HER-2 protein expression may inform and facilitate refinements in therapeutic treatment strategies for selected subpopulations of patients in this group.

Background

Drug resistance poses a significant challenge for the successful application of highly active antiretroviral therapy (HAART) globally. Furthermore, emergence of HIV-1 isolates that preferentially utilize CXCR4 as a coreceptor for cell entry, either as a consequence of natural viral evolution or HAART use may compromise the efficacy of CCR5 antagonists as alternative antiviral therapy.

Methods

We sequenced the pol gene of viruses from 45 individuals failing at least six months of HAART in Durban, South Africa to determine the prevalence and patterns of drug resistance mutations. Coreceptor usage profiles of these viruses and those from 45 HAART-naive individuals were analyzed using phenotypic and genotypic approaches.

Results

Ninety-five percent of HAART-failing patients had at least one drug resistance mutation. Thymidine analog mutations (TAMs) were present in 55% of patients with 9% of individuals possessing mutations indicative of the TAM1 pathway, 44% had TAM2 while 7% had mutations common to both pathways. Sixty percent of HAART-failing subjects had X4/dual//mixed-tropic viruses compared to 30% of HAART-naïve subjects (p<0.02). Genetic coreceptor usage prediction algorithms correlated with phenotypic results with 60% of samples from HAART-failing subjects predicted to possess CXCR4-using (X4/dual/mixed viruses) versus 15% of HAART-naïve patients.

Conclusions

The high proportion of TAMs and X4/dual/mixed HIV-1 viruses among patients failing therapy highlight the need for intensified monitoring of patients taking HAART and the problem of diminished drug options (including CCR5 antagonists) for patients failing therapy in resource-poor settings.

Objectives

To evaluate the association between baseline (BL) replication capacity (RC) [RCBL] and immunologic/virologic parameters (at BL and after 48 weeks on therapy) in HIV-1 infected subjects initiating antiretroviral therapy.

Methods

RCBL was determined using a modified Monogram PhenoSense HIV drug susceptibility assay on plasma HIV-1 from 321 treatment-naïve subjects from ACTG384. Univariate and multivariable analyses were performed to determine the association of RCBL with BL and on-therapy virologic and immunologic outcomes.

Results

Higher RCBL was associated with lower baseline CD4 (CD4BL) (r=−0.23, p<0.0001), higher baseline HIV-1 (RNABL) (r=0.25, p<0.0001), higher CD4BL activation percent (r=0.23, p<0.0001) and lower CD4BL memory count (r=−0.21, p=0.0002).

In a multivariable model, week 48 CD4 increase (ΔCD448) was associated with lower CD4BL memory count and higher CD4BL naive percent (p=0.004, p=0.015, respectively). The interaction between CD4BL and RCBL was significant (p=0.018), with a positive association between RCBL and ΔCD448 in subjects with higher CD4BL, and a negative association at lower absCD4BL.

Conclusions

At baseline, higher RC was significantly associated with higher HIV-1 RNA, higher CD4 cell activation, lower CD4 cell count, and lower CD4 memory cell count. These factors may interact, directly or indirectly, to modify the extent to which CD4 recovery occurs in patients starting antiretroviral therapy at different baseline CD4 counts.

Background

Lapatinib plus capecitabine is an effective treatment option for trastuzumab-refractory HER2-positive metastatic breast cancer. We have investigated the correlation between quantitative measures of HER2, p95HER2, and HER3 and treatment outcomes using lapatinib and capecitabine.

Methods

Total HER2 (H2T), p95HER2 (p95), and total HER3 (H3T) expression were quantified in formalin-fixed paraffin-embedded samples using the VeraTag assays. Patients received lapatinib and capecitabine treatment following trastuzumab failure according to the Lapatinib Expanded Access Program. The association between the protein expression levels and clinical outcomes was analyzed.

Results

A total of 52 patients were evaluable. H2T level was significantly higher in responders (median 93.49 in partial response, 47.66 in stable disease, and 17.27 in progressive disease; p = 0.020). Longer time-to-progression (TTP) was observed in patients with high H2T [p = 0.018, median 5.2 months in high (>14.95) vs. 1.8 in low (<14.95)] and high H3T [p = 0.017, median 5.0 months in high (>0.605) vs. 2.2 in low (<0.605)]. Patients having both high H2T and high H3T had significantly longer TTP [adjusted hazard ratio (HR) 0.38 (95% CI 0.20–0.73), p = 0.004] and overall survival [adjusted HR 0.46 (95% CI 0.24–0.89), p = 0.020]. No significant association between p95 and response or survival was observed.

Conclusions

These data suggest a correlation between high HER2 and high HER3 expression and treatment outcome, while no significant difference was observed between clinical outcome and p95 expression level in this cohort of HER2-positive, trastuzumab-refractory metastatic breast cancer patients treated with lapatinib and capecitabine.

Percentages of activated T cells correlate with HIV-1 disease progression, but the underlying mechanisms are not fully understood. We hypothesized that HLA-DR+ CD38+ (DR+ 38+) CD4+ T cells produce the majority of HIV-1 due to elevated expression of CCR5 and CXCR4. In phytohemagglutinin (PHA)-stimulated CD8-depleted peripheral blood mononuclear cells (PBMC) infected with HIV-1 green fluorescent protein (GFP) reporter viruses, DR− 38+ T cells constituted the majority of CCR5 (R5)-tropic (median, 62%) and CXCR4 (X4)-tropic HIV-1-producing cells (median, 61%), although cell surface CCR5 and CXCR4 were not elevated in this subset of cells. In lymph nodes from untreated individuals infected with R5-tropic HIV-1, percentages of CCR5+ cells were elevated in DR+ 38+ CD4+ T cells (median, 36.4%) compared to other CD4+ T-cell subsets (median values of 5.7% for DR− 38− cells, 19.4% for DR+ 38− cells, and 7.6% for DR− 38+ cells; n = 18; P < 0.001). In sorted CD8− lymph node T cells, median HIV-1 RNA copies/105 cells was higher for DR+ 38+ cells (1.8 × 106) than for DR− 38− (0.007 × 106), DR− 38+ (0.064 × 106), and DR+ 38− (0.18 × 106) subsets (n = 8; P < 0.001 for all). After adjusting for percentages of subsets, a median of 87% of viral RNA was harbored by DR+ 38+ cells. Percentages of CCR5+ CD4+ T cells and concentrations of CCR5 molecules among subsets predicted HIV-1 RNA levels among CD8− DR/38 subsets (P < 0.001 for both). Median HIV-1 DNA copies/105 cells was higher in DR+ 38+ cells (5,360) than in the DR− 38− (906), DR− 38+ (814), and DR+ 38− (1,984) subsets (n = 7; P ≤ 0.031). Thus, DR+ 38+ CD4+ T cells in lymph nodes have elevated CCR5 expression, are highly susceptible to infection with R5-tropic virus, and produce the majority of R5-tropic HIV-1. PBMC assays failed to recapitulate in vivo findings, suggesting limited utility. Strategies to reduce numbers of DR+ 38+ CD4+ T cells may substantially inhibit HIV-1 replication.

The HIV gp41 N-trimer pocket region is an ideal viral target because it is extracellular, highly conserved, and essential for viral entry. Here, we report on the design of a pocket-specific d-peptide, PIE12-trimer, that is extraordinarily elusive to resistance and characterize its inhibitory and structural properties. d-Peptides (peptides composed of d-amino acids) are promising therapeutic agents due to their insensitivity to protease degradation. PIE12-trimer was designed using structure-guided mirror-image phage display and linker optimization and is the first d-peptide HIV entry inhibitor with the breadth and potency required for clinical use. PIE12-trimer has an ultrahigh affinity for the gp41 pocket, providing it with a reserve of binding energy (resistance capacitor) that yields a dramatically improved resistance profile compared to those of other fusion inhibitors. These results demonstrate that the gp41 pocket is an ideal drug target and establish PIE12-trimer as a leading anti-HIV antiviral candidate.

Objective

To assess the effect of pol replication capacity (RC) on the hazard ratio of progression to a composite endpoint of time to progression to <350 CD4+ cells/μL, initiation of therapy or death.

Methods

pol RC assays were performed after study closure in baseline samples obtained from 316 enrollees in a prospectively monitored cohort of treatment-naive adults with ≥450 CD4+ cells/μL and ≥1000 HIV-1 RNA copies/mL.

Results

The median RC was 79%. Patients with a lower RC had a lower median viral load (4.0 vs 4.2 Log HIV-1 RNA copies/mL, p=0.026) and a lower rate of protease inhibitor resistance 2% vs 8%, p=0.03). Otherwise, baseline demographic and laboratory characteristics were similar. The hazard ratio of progression to the composite endpoint was 0.73 (p=0.041) for persons with lower RC, 2.07 per 1.0 log10 higher viral load (p<0.001) and 0.86 per 50 cell/μL higher CD4+ cell count (p<0.001). The effect of lower RC was also significant in a separate analysis of time to initiation of therapy (p=0.04).

Conclusion

These results show that untreated patients with lower vs higher RC had a slower rate of progression as assessed by a composite outcome of time to CD4+ count ≤350 cells/μL, treatment initiation or death.

Background

The CPCRA 064 study examined the effect of structured treatment interruption (STI) of up to 4 months followed by salvage treatment in patients failing therapy with multi-drug resistant HIV. We examined the relationship between the reversion rate of major reverse transcriptase (RT) resistance-associated mutations and change in viral replication capacity (RC). The dataset included 90 patients with RC and genotypic data from virus samples collected at 0 (baseline), 2 and 4 months of STI.

Principal Findings

Rapid shift towards wild-type RC was observed during the first 2 months of STI. Median RC increased from 47.5% at baseline to 86.0% at 2 months and to 97.5% at 4 months. Between baseline and 2 months of STI, T215F had the fastest rate of reversion (41%) and the reversion of E44D and T69D was associated with the largest changes in RC. Among the most prevalent RT mutations, M184V had the fastest rate of reversion from baseline to 2 months (40%), and its reversion was associated with the largest increase in RC. Most rates of reversion increased between 2 months and 4 months, but the change in RC was more limited as it was already close to 100%. The highest frequency of concurrent reversion was found for L100I and K103N. Mutagenesis tree models showed that M184V, when present, was overall the first mutation to revert among all the RT mutations reported in the study.

Conclusion

Longitudinal analysis of combined phenotypic and genotypic data during STI showed a large amount of variability in prevalence and reversion rates to wild-type codons among the RT resistance-associated mutations. The rate of reversion of these mutations may depend on the extent of RC increase as well as the co-occurring reversion of other mutations belonging to the same mutational pathway.

Background

During the first two decades of the U.S. AIDS epidemic, and unlike some malignancies, breast cancer risk was significantly lower for women with human immunodeficiency virus (HIV) infection compared to the general population. This deficit in HIV-associated breast cancer could not be attributed to differences in survival, immune deficiency, childbearing or other breast cancer risk factors. HIV infects mononuclear immune cells by binding to the CD4 molecule and to CCR5 or CXCR4 chemokine coreceptors. Neoplastic breast cells commonly express CXCR4 but not CCR5. In vitro, binding HIV envelope protein to CXCR4 has been shown to induce apoptosis of neoplastic breast cells. Based on these observations, we hypothesized that breast cancer risk would be lower among women with CXCR4-tropic HIV infection.

Methods and Findings

We conducted a breast cancer nested case-control study among women who participated in the WIHS and HERS HIV cohort studies with longitudinally collected risk factor data and plasma. Cases were HIV-infected women (mean age 46 years) who had stored plasma collected within 24 months of breast cancer diagnosis and an HIV viral load ≥500 copies/mL. Three HIV-infected control women, without breast cancer, were matched to each case based on age and plasma collection date. CXCR4-tropism was determined by a phenotypic tropism assay. Odds ratios (OR) and 95% confidence intervals (CI) for breast cancer were estimated by exact conditional logistic regression. Two (9%) of 23 breast cancer cases had CXCR4-tropic HIV, compared to 19 (28%) of 69 matched controls. Breast cancer risk was significantly and independently reduced with CXCR4 tropism (adjusted odds ratio, 0.10, 95% CI 0.002–0.84) and with menopause (adjusted odds ratio, 0.08, 95% CI 0.001–0.83). Adjustment for CD4+ cell count, HIV viral load, and use of antiretroviral therapy did not attenuate the association between infection with CXCR4-tropic HIV and breast cancer.

Conclusions

Low breast cancer risk with HIV is specifically linked to CXCR4-using variants of HIV. These variants are thought to exclusively bind to and signal through a receptor that is commonly expressed on hyperplastic and neoplastic breast duct cells. Additional studies are needed to confirm these observations and to understand how CXCR4 might reduce breast cancer risk.

The recent availability of CCR5 antagonists as anti-human immunodeficiency virus (anti-HIV) therapeutics has highlighted the need to accurately identify CXCR4-using variants in patient samples when use of this new drug class is considered. The Trofile assay (Monogram Biosciences) has become the method that is the most widely used to define tropism in the clinic prior to the use of a CCR5 antagonist. By comparison, the MT-2 assay has been used since early in the HIV epidemic to define tropism in clinical specimens. Given that there are few data from direct comparisons of these two assays, we evaluated the performance of the plasma-based Trofile assay and the peripheral blood mononuclear cell (PBMC)-based MT-2 assay for the detection of CXCR4 use in defining the tropism of HIV isolates derived from clinical samples. The various samples used for this comparison were derived from participants of the Amsterdam Cohort Studies on HIV infection and AIDS who underwent consecutive MT-2 assay testing of their PBMCs at approximately 3-month intervals. This unique sample set was specifically selected because consecutive MT-2 assays had demonstrated a shift from negative to positive in PBMCs, reflecting the first emergence of CXCR4-using virus in PBMCs above the level of detection of the assay in these individuals. Trofile testing was performed with clonal HIV type 1 (HIV-1) variants (n = 21), MT-2 cell culture-derived cells (n = 20) and supernatants (n = 42), and plasma samples (n = 76). Among the clonal HIV-1 variants and MT-2 cell culture-derived samples, the results of the Trofile and MT-2 assays demonstrated a high degree of concordance (95% to 98%). Among consecutive plasma samples, detection of CXCR4-using virus was at or before the time of first detection by the MT-2 assay in 5/10 patients by the original Trofile assay and in 9/10 patients by the enhanced-sensitivity Trofile assay. Differences in the time to the first detection of CXCR4 use between the MT-2 assay (PBMCs) and the original Trofile assay (plasma) were greatly reduced by the enhanced-sensitivity Trofile assay, suggesting that sensitivity for the detection of minor CXCR4-using variants may be a more important determinant of discordant findings than compartmentalization. The similarities in performance of the enhanced-sensitivity Trofile and MT-2 assays suggest that either may be an appropriate methodology to define tropism in patient specimens.

Objective

To assess the effect of HIV coreceptor tropism (CRT) on the relative risk of progression to a composite outcome of CD4+ count ≤350 cells/μL, treatment initiation or death.

Methods

CRT assays were performed after study closure in baseline samples obtained from enrollees in a prospectively monitored cohort of treatment-naïve adults with ≥450 CD4+ cells/μL and ≥1,000 HIV-1 RNA copies/mL.

Results

Dual/mixed (D/M) and R5 CRT was detected in 32 and 282 patients, respectively. The baseline CD4+ count (617 vs 694 cells/μL; p=0.05) differed in patients with D/M versus R5 CRT. Otherwise, baseline laboratory characteristics were similar.

The relative risk of progression to the composite endpoint was 2.15 (p=0.002) for D/M versus R5 CRT, 2.07 per 1.0 log10 higher viral load (p<0.001) and 0.87 per 50 cell/μL higher CD4+ cell count (p<0.001). The effect of D/M CRT was also significant in separate analyses of time to initiation of antiretroviral therapy or CD4+ cell count ≤350.

Conclusion

Untreated patients with D/M rather than R5 CRT had a faster rate of disease progression, whether assessed by a composite outcome of time to CD4+ count ≤350, treatment initiation or death, or by separate analyses of time to CD4+ count ≤350 or treatment initiation.

Background

Current public health efforts often use molecular technologies to identify and contain communicable disease networks, but not for HIV. Here, we investigate how molecular epidemiology can be used to identify highly-related HIV networks within a population and how voluntary contact tracing of sexual partners can be used to selectively target these networks.

Methods

We evaluated the use of HIV-1 pol sequences obtained from participants of a community-recruited cohort (n=268) and a primary infection research cohort (n=369) to define highly related transmission clusters and the use of contact tracing to link other individuals (n=36) within these clusters. The presence of transmitted drug resistance was interpreted from the pol sequences (Calibrated Population Resistance v3.0).

Results

Phylogenetic clustering was conservatively defined when the genetic distance between any two pol sequences was <1%, which identified 34 distinct transmission clusters within the combined community-recruited and primary infection research cohorts containing 160 individuals. Although sequences from the epidemiologically-linked partners represented approximately 5% of the total sequences, they clustered with 60% of the sequences that clustered from the combined cohorts (O.R. 21.7; p=<0.01). Major resistance to at least one class of antiretroviral medication was found in 19% of clustering sequences.

Conclusions

Phylogenetic methods can be used to identify individuals who are within highly related transmission groups, and contact tracing of epidemiologically-linked partners of recently infected individuals can be used to link into previously-defined transmission groups. These methods could be used to implement selectively targeted prevention interventions.

Background:

Frequent methamphetamine use among recently HIV infected individuals is associated with transmitted drug resistance (TDR) to non-nucleoside reverse transcriptase inhibitors (NNRTI); however, the reversion time of TDR to drug susceptible HIV may exceed 3 years. We assessed whether recreational substance use is associated with detectable TDR among individuals newly diagnosed with HIV infection of unknown duration.

Design:

Cross-sectional analysis.

Methods:

Subjects were enrolled at the University California, San Diego Early Intervention Program. Demographic, clinical and substance use data were collected using structured interviews. Genotypic resistance testing was performed using GeneSeq™, Monogram Biosciences. We analyzed the association between substance use and TDR using bivariate analyses and the corresponding transmission networks using phylogenetic models.

Results:

Between April 2004 and July 2006, 115 individuals with genotype data were enrolled. The prevalence of alcohol, marijuana and methamphetamine use were 98%, 71% and 64% respectively. Only active methamphetamine use in the 30 days prior to HIV diagnosis was independently associated with TDR to NNRTI (OR: 6.6; p=0.002).

Conclusion:

Despite not knowing the duration of their HIV infection, individuals reporting active methamphetamine use in the 30 days prior to HIV diagnosis are at an increased risk of having HIV strains that are resistant to NNRTI.

Although combination antiretroviral therapy has resulted in a considerable improvement in the treatment of human immunodeficiency virus (HIV) type 1 (HIV-1) infection, the emergence of resistant virus is a significant obstacle to the effective management of HIV infection and AIDS. We have developed a novel phenotypic drug susceptibility assay that may be useful in guiding therapy and improving long-term suppression of HIV replication. Susceptibility to protease (PR) and reverse transcriptase (RT) inhibitors is measured by using resistance test vectors (RTVs) that contain a luciferase indicator gene and PR and RT sequences derived from HIV-1 in patient plasma. Cells are transfected with RTV DNA, resulting in the production of virus particles that are used to infect target cells. Since RTVs are replication defective, luciferase activity is measured following a single round of replication. The assay has been automated to increase throughput and is completed in 8 to 10 days. Test results may be useful in facilitating the selection of optimal treatment regimens for patients who have failed prior therapy or drug-naive patients infected with drug-resistant virus. In addition, the assay can be used to evaluate candidate drugs and assist in the development of new drugs that are active against resistant strains of HIV-1.

The Chinese hamster cell lines E36 and CHOK1 dramatically differ in susceptibility to amphotropic murine leukemia virus (A-MuLV) and gibbon ape leukemia virus (GALV); E36 cells are highly susceptible to both viruses, CHOK1 cells are not. We have previously shown that GALV can infect E36 cells by using both its own receptor, HaPit1, and the A-MuLV receptor, HaPit2. Given that the two cell lines are from the same species, the loss of function of both of these receptors in CHOK1 cells is surprising. Other studies have shown that CHOK1 cells secrete proteins that block A-MuLV entry into CHOK1 as well as E36, suggesting the two A-MuLV receptors are functionally identical. However, CHOK1 conditioned medium does not block GALV entry into E36, indicating the secreted inhibitors do not block HaPit1. HaPit1 and ChoPit1 therefore differ as receptors for GALV; ChoPit1 is either inactivated by secreted factors or intrinsically nonfunctional. To determine why GALV cannot infect CHOK1, we cloned and sequenced ChoPit1 and ChoPit2. ChoPit2 is almost identical to HaPit2, which explains why CHOK1 conditioned medium blocks A-MuLV entry via both receptors. Although ChoPit1 and HaPit1 are 91% identical, a notable difference is at position 550 in the fourth extracellular region, shown by several studies to be crucial for GALV infection. Pit1 and HaPit1 have aspartate at 550, whereas ChoPit1 has threonine at this position. We assessed the significance of this difference for GALV infection by replacing the aspartate 550 in Pit1 with threonine. This single substitution rendered Pit1 nonfunctional for GALV and suggests that threonine at 550 inactivates ChoPit1 as a GALV receptor. Whether native ChoPit1 functions for GALV was determined by interference assays using Lec8, a glycosylation-deficient derivative of CHOK1 that is susceptible to both viruses and that has the same receptors as CHOK1. Unlike with E36, GALV and A-MuLV exhibited reciprocal interference when infecting Lec8, suggesting that they use the same receptor. We conclude both viruses can use ChoPit2 in the absence of the inhibitors secreted by CHOK1 and ChoPit1 is nonfunctional.