First-line Avelumab plus Chemotherapy in Patients with Advanced Solid Tumors: Results from the Phase Ib/II JAVELIN Chemotherapy Medley Study.

PURPOSE: Chemotherapy can potentially enhance the activity of immune checkpoint inhibitors by promoting immune priming. The phase Ib/II JAVELIN Chemotherapy Medley trial (NCT03317496) evaluated first-line avelumab + concurrent chemotherapy in patients with advanced urothelial carcinoma or non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: Avelumab 800 or 1,200 mg was administered continuously every 3 weeks with standard doses of cisplatin + gemcitabine in patients with urothelial carcinoma, or carboplatin + pemetrexed in patients with nonsquamous NSCLC. Dual primary endpoints were dose-limiting toxicity (DLT; phase Ib) and confirmed objective response (phase Ib/II). RESULTS: In phase Ib, urothelial carcinoma and NSCLC cohorts received avelumab 800 mg (n = 13 and n = 6, respectively) or 1,200 mg (n = 6 each) + chemotherapy. In evaluable patients with urothelial carcinoma treated with avelumab 800 or 1,200 mg + chemotherapy, DLT occurred in 1/12 (8.3%) and 1/6 (16.7%), respectively; no DLT occurred in the NSCLC cohort. In phase II, 35 additional patients with urothelial carcinoma received avelumab 1,200 mg + chemotherapy. Across all treated patients, safety profiles were similar irrespective of avelumab dose. Objective response rates (95% confidence internal) with avelumab 800 or 1,200 mg + chemotherapy, respectively, across phase Ib/II, were 53.8% (25.1-80.8) and 39.0% (24.2-55.5) in urothelial carcinoma, and 50.0% (11.8-88.2) and 33.3% (4.3-77.7) in NSCLC. CONCLUSIONS: Preliminary efficacy and safety findings with avelumab + chemotherapy in urothelial carcinoma and NSCLC were consistent with previous studies of similar combination regimens. Conclusions about clinical activity are limited by small patient numbers. SIGNIFICANCE: This phase Ib/II trial evaluated avelumab (immune checkpoint inhibitor) administered concurrently with standard first-line chemotherapy in patients with advanced urothelial carcinoma or advanced nonsquamous NSCLC without actionable mutations. Efficacy and safety appeared consistent with previous studies of similar combinations, although patient numbers were small.

Avelumab Plus Talazoparib in Patients With Advanced Solid Tumors: The JAVELIN PARP Medley Nonrandomized Controlled Trial.

Importance: Preclinical data suggest that poly(ADP-ribose) polymerase (PARP) inhibitors have synergistic activity when combined with immune checkpoint inhibitors (ICIs); however, it is unknown which tumor types or molecular subtypes may benefit from this combination. Objective: To investigate responses associated with the combination of avelumab and talazoparib in different tumor types and/or molecular subtypes. Design, Setting, and Participants: In this phase 1b and 2 basket nonrandomized controlled trial, patients with advanced solid tumors were enrolled in the following cohorts: non-small cell lung cancer (NSCLC); DNA damage response (DDR)-positive NSCLC; triple-negative breast cancer (TNBC); hormone receptor-positive, human epidermal growth factor receptor 2 (ERBB2)-negative, DDR-positive breast cancer; recurrent, platinum-sensitive ovarian cancer (OC); recurrent, platinum-sensitive, BRCA1/2-altered OC; urothelial cancer; metastatic castration-resistant prostate cancer (mCRPC); DDR-positive mCRPC; and BRCA1/2- or ATM-altered solid tumors. Data were analyzed between June 17, 2021, and August 6, 2021. Interventions: All patients in phases 1b and 2 received avelumab plus talazoparib. Main Outcomes and Measures: The phase 1b primary end point was dose-limiting toxic effects. The phase 2 primary end point was objective response, measured as objective response rate (ORR). Secondary end points included safety, time to response, duration of response (DOR), progression-free survival, time to prostate-specific antigen progression and PSA response of 50% or greater (for mCRPC), cancer antigen 125 response (for OC), pharmacokinetics, immunogenicity, and biomarkers. Results: A total of 223 patients (mean [SD] age, 63.2 [11.0] years; 117 [52.5%] men) were treated, including 12 patients in phase 1b and 211 patients in phase 2. The recommended phase 2 dose was avelumab 800 mg every 2 weeks plus talazoparib 1 mg once daily. In phase 2, the ORR was 18.2% (95% CI, 5.2%-40.3%) in patients with TNBC; 34.8% (95% CI, 16.4%-57.3%) in patients with HR-positive, ERBB2-negative, and DDR-positive BC; and 63.6% (95% CI, 30.8%-89.1%) in patients with platinum-sensitive, BRCA1/2-altered OC. Responses occurred more frequently in patients with BRCA1/2-altered tumors. Durable responses were observed in patients with TNBC (median [range] DOR, 11.1 [3.4-20.4] months); HR-positive, ERBB2-negative, and DDR-positive BC (median [range] DOR, 15.7 [3.9 to ≥20.6] months); and BRCA1/2-altered OC (median DOR not reached; range, 5.6 to ≥18.4 months). The most common grade 3 or greater treatment-related adverse events were anemia (75 patients [33.6%]), thrombocytopenia (48 patients [21.5%]), and neutropenia (31 patients [13.9%]). Conclusions and Relevance: This nonrandomized controlled trial found that ORRs for avelumab plus talazoparib were comparable with those with PARP inhibitor or ICI monotherapy. Prolonged DOR in patients with TNBC; HR-positive, ERBB2-negative, and DDR-positive BC; and BRCA1/2-altered OC warrant further investigation in randomized clinical trials. These data highlight the importance of prospective patient selection in future studies of ICI and PARP-inhibitor combinations. Trial Registration: ClinicalTrials.gov Identifier: NCT03330405.

Avelumab Plus Talazoparib in Patients With BRCA1/2- or ATM-Altered Advanced Solid Tumors: Results From JAVELIN BRCA/ATM, an Open-Label, Multicenter, Phase 2b, Tumor-Agnostic Trial.

Importance: Nonclinical studies suggest that the combination of poly(ADP-ribose) polymerase and programmed cell death 1/programmed cell death-ligand 1 inhibitors has enhanced antitumor activity; however, the patient populations that may benefit from this combination have not been identified. Objective: To evaluate whether the combination of avelumab and talazoparib is effective in patients with pathogenic BRCA1/2 or ATM alterations, regardless of tumor type. Design, Setting, and Participants: In this pan-cancer tumor-agnostic phase 2b nonrandomized controlled trial, patients with advanced BRCA1/2-altered or ATM-altered solid tumors were enrolled into 2 respective parallel cohorts. The study was conducted from July 2, 2018, to April 12, 2020, at 42 institutions in 9 countries. Interventions: Patients received 800 mg of avelumab every 2 weeks and 1 mg of talazoparib once daily. Main Outcomes and Measures: The primary end point was confirmed objective response (OR) per RECIST 1.1 by blinded independent central review. Results: A total of 200 patients (median [range] age, 59.0 [26.0-89.0] years; 132 [66.0%] women; 15 [7.5%] Asian, 11 [5.5%] African American, and 154 [77.0%] White participants) were enrolled: 159 (79.5%) in the BRCA1/2 cohort and 41 (20.5%) in the ATM cohort. The confirmed OR rate was 26.4% (42 patients, including 9 complete responses [5.7%]) in the BRCA1/2 cohort and 4.9% (2 patients) in the ATM cohort. In the BRCA1/2 cohort, responses were more frequent (OR rate, 30.3%; 95% CI, 22.2%-39.3%, including 8 complete responses [6.7%]) and more durable (median duration of response: 10.9 months [95% CI, 6.2 months to not estimable]) in tumor types associated with increased heritable cancer risk (ie, BRCA1/2-associated cancer types, such as ovarian, breast, prostate, and pancreatic cancers) and in uterine leiomyosarcoma (objective response in 3 of 3 patients and with ongoing responses greater than 24 months) compared with non-BRCA-associated cancer types. Responses in the BRCA1/2 cohort were numerically higher for patients with tumor mutational burden of 10 or more mutations per megabase (mut/Mb) vs less than 10 mut/Mb. The combination was well tolerated, with no new safety signals identified. Conclusions and Relevance: In this phase 2b nonrandomized controlled trial, neither the BRCA1/2 nor ATM cohort met the prespecified OR rate of 40%. Antitumor activity for the combination of avelumab and talazoparib in patients with BRCA1/2 alterations was observed in some patients with BRCA1/2-associated tumor types and uterine leiomyosarcoma; benefit was minimal in non-BRCA-associated cancer types. Trial Registration: ClinicalTrials.gov Identifier: NCT03565991.

A Phase II Study of Talazoparib after Platinum or Cytotoxic Nonplatinum Regimens in Patients with Advanced Breast Cancer and Germline BRCA1/2 Mutations (ABRAZO).

PURPOSE: To assess talazoparib activity in germline BRCA1/2 mutation carriers with advanced breast cancer. PATIENTS AND METHODS: ABRAZO (NCT02034916) was a two-cohort, two-stage, phase II study of talazoparib (1 mg/day) in germline BRCA mutation carriers with a response to prior platinum with no progression on or within 8 weeks of the last platinum dose (cohort 1) or ≥3 platinum-free cytotoxic regimens (cohort 2) for advanced breast cancer. Primary endpoint was confirmed objective response rate (ORR) by independent radiological assessment. RESULTS: We enrolled 84 patients (cohort 1, n = 49; cohort 2, n = 35) from May 2014 to February 2016. Median age was 50 (range, 31-75) years. Triple-negative breast cancer (TNBC) incidence was 59% (cohort 1) and 17% (cohort 2). Median number of prior cytotoxic regimens for advanced breast cancer was two and four, respectively. Confirmed ORR was 21% [95% confidence interval (CI), 10-35; cohort 1] and 37% [95% CI, 22-55; cohort 2]. Median duration of response was 5.8 and 3.8 months, respectively. Confirmed ORR was 23% (BRCA1), 33% (BRCA2), 26% (TNBC), and 29% (hormone receptor-positive). The most common all-grade adverse events (AE) included anemia (52%), fatigue (45%), and nausea (42%). Talazoparib-related AEs led to drug discontinuation in 3 (4%) patients. In an exploratory analysis, longer platinum-free interval was associated with higher response rate in cohort 1 (0% ORR with interval <8 weeks; 47% ORR with interval >6 months). CONCLUSIONS: Talazoparib exhibited promising antitumor activity in patients with advanced breast cancer and germline BRCA mutation.

Safety, virology and pharmacokinetics of oseltamivir in infants with laboratory-confirmed influenza: a Phase I/II, prospective, open-label, multicentre clinical trial.

BACKGROUND: The influenza antiviral oseltamivir is not licensed for infants aged <1 year in most countries outside the United States. More information is needed on oseltamivir safety at different dosing levels in this vulnerable age group. METHODS: In this prospective, observational, non-randomized study, infants aged <1 year with laboratory-confirmed influenza were treated with oral oseltamivir for 5 days. Cohorts 1, 2 and 3 (aged 91-364, 31-90 and 0-30 days, respectively), received twice-daily dosages of 3, 2.5 and 2 mg/kg, respectively. Assessments included pharmacokinetics, on-treatment adverse events, resistance testing and viral shedding. RESULTS: A total of 65 patients were enrolled: 40, 20 and 5 in cohorts 1, 2 and 3, respectively. Systemic exposure to oseltamivir carboxylate (active metabolite) reached therapeutic levels in all patients, with an adequate safety margin. On-treatment adverse events (n=48) were reported by 32 patients (49%). At least one adverse event was reported by 43%, 65% and 40% of infants in cohorts 1, 2 and 3, respectively; most frequently vomiting and diarrhoea. Eight serious adverse events were reported, all of which were considered unrelated to treatment by the investigator. No deaths occurred and no patient had treatment withdrawn. Oseltamivir resistance mutations were detected in eight patients. CONCLUSIONS: Oseltamivir dosages of 2-3 mg/kg were well tolerated in infants aged <1 year and achieved therapeutic exposure levels. The current study supports the adoption of a universal dosing recommendation for infants. Clinicaltrials.gov unique identifier NCT00988325.

Safety, tolerability, and pharmacokinetics of intravenous oseltamivir: single- and multiple-dose phase I studies with healthy volunteers.

There is an unmet need for an intravenous (i.v.) neuraminidase inhibitor, particularly for patients with severe influenza who cannot take oral medication. Two phase I pharmacokinetic and safety studies of i.v. oseltamivir were carried out in healthy volunteers. The first was an open-label, randomized, four-period, two-sequence, single-dose trial of 100 mg, 200 mg, and 400 mg oseltamivir i.v. over 2 h and a 75-mg oral dose of oseltamivir. The second was a double-blind, placebo-controlled, parallel-group, multiple-dose study in which participants were randomized to 100 mg or 200 mg oseltamivir or placebo (normal saline) i.v. over 2 h every 12 h for 5 days. Exposure to the active metabolite oseltamivir carboxylate (OC) after dosing achieved with 100 mg oseltamivir administered i.v. over 2 h was comparable to that achieved with 75 mg administered orally. Single i.v. doses of oseltamivir up to 400 mg were well tolerated with no new safety signals. Multiple-dose data confirmed good tolerability of 100 mg and 200 mg oseltamivir and showed efficacious OC exposures with 100 mg i.v. over 2 h twice daily for 5 days. These results support further exploration of i.v. oseltamivir as an influenza treatment option for patients unable to take oral medication.

A systems analysis of mutational effects in HIV-1 protease and reverse transcriptase.

The development of a quantitative understanding of viral evolution and the fitness landscape in HIV-1 drug resistance is a formidable challenge given the large number of available drugs and drug resistance mutations. We analyzed a dataset measuring the in vitro fitness of 70,081 virus samples isolated from HIV-1 subtype B infected individuals undergoing routine drug resistance testing. We assayed virus samples for in vitro replicative capacity in the absence of drugs as well as in the presence of 15 individual drugs. We employed a generalized kernel ridge regression to estimate main fitness effects and epistatic interactions of 1,859 single amino acid variants found within the HIV-1 protease and reverse transcriptase sequences. Models including epistatic interactions predict an average of 54.8% of the variance in replicative capacity across the 16 different environments and substantially outperform models based on main fitness effects only. We find that the fitness landscape of HIV-1 protease and reverse transcriptase is characterized by strong epistasis.

Differences in reversion of resistance mutations to wild-type under structured treatment interruption and related increase in replication capacity.

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.

Comparison of standard PCR/cloning to single genome sequencing for analysis of HIV-1 populations.

To compare standard PCR/cloning and single genome sequencing (SGS) in their ability to reflect actual intra-patient polymorphism of HIV-1 populations, a total of 530 HIV-1 pro-pol sequences obtained by both sequencing techniques from a set of 17 ART naïve patient specimens was analyzed. For each specimen, 12 and 15 sequences, on average, were characterized by the two techniques. Using phylogenetic analysis, tests for panmixia and entropy, and Bland-Altman plots, no difference in population structure or genetic diversity was shown in 14 of the 17 subjects. Evidence of sampling bias by the presence of subsets of identical sequences was found by either method. Overall, the study shows that neither method was more biased than the other, and providing that an adequate number of PCR templates is analyzed, and that the bulk sequencing captures the diversity of the viral population, either method is likely to provide a similar measure of population diversity.

Principal component analysis of general patterns of HIV-1 replicative fitness in different drug environments.

To detect general patterns and temporal trends of HIV-1 resistance, we apply principal component analysis (PCA) to in vitro fitness data. Twenty-eight thousand virus samples, obtained between 2002 and 2008, were assayed for fitness in 16 to 21 selective environments. Fitness measurements are based on replication capacity (RC), which quantifies in vitro viral replication in a single cycle of infection. RC is determined both in the absence of drugs and in the presence of 6-7 nucleoside analog reverse transcriptase inhibitors (NRTIs), 3-4 non-nucleoside reverse transcriptase inhibitors (NNRTIs), and 6-9 protease inhibitors (PIs). PCA shows remarkable structure in RC across the different environments, which reveals differences in the patterns of resistance and cross-resistance between drugs or between drug classes. To probe the causes of the observed patterns, we develop a model to generate simulated data and subject these simulated data to an equivalent analysis. By comparing the outcomes of PCA on the original and the simulated data, we quantify which part of the total variance of the original data is due to non-specific effects, class-specific effects, and drug-specific effects of resistance mutations. We find that relative fitness is mainly drug-independent and that drug-specific effects are substantially bigger than class-specific effects for NRTIs, but not for NNRTIs or PIs. The observed patterns remain remarkably stable over the period of observation. Comparison with known potent combination therapies suggests that PCA helps to identify combinations that act synergistically in preventing the emergence of resistance.

An evolutionary model-based algorithm for accurate phylogenetic breakpoint mapping and subtype prediction in HIV-1.

Genetically diverse pathogens (such as Human Immunodeficiency virus type 1, HIV-1) are frequently stratified into phylogenetically or immunologically defined subtypes for classification purposes. Computational identification of such subtypes is helpful in surveillance, epidemiological analysis and detection of novel variants, e.g., circulating recombinant forms in HIV-1. A number of conceptually and technically different techniques have been proposed for determining the subtype of a query sequence, but there is not a universally optimal approach. We present a model-based phylogenetic method for automatically subtyping an HIV-1 (or other viral or bacterial) sequence, mapping the location of breakpoints and assigning parental sequences in recombinant strains as well as computing confidence levels for the inferred quantities. Our Subtype Classification Using Evolutionary ALgorithms (SCUEAL) procedure is shown to perform very well in a variety of simulation scenarios, runs in parallel when multiple sequences are being screened, and matches or exceeds the performance of existing approaches on typical empirical cases. We applied SCUEAL to all available polymerase (pol) sequences from two large databases, the Stanford Drug Resistance database and the UK HIV Drug Resistance Database. Comparing with subtypes which had previously been assigned revealed that a minor but substantial (approximately 5%) fraction of pure subtype sequences may in fact be within- or inter-subtype recombinants. A free implementation of SCUEAL is provided as a module for the HyPhy package and the Datamonkey web server. Our method is especially useful when an accurate automatic classification of an unknown strain is desired, and is positioned to complement and extend faster but less accurate methods. Given the increasingly frequent use of HIV subtype information in studies focusing on the effect of subtype on treatment, clinical outcome, pathogenicity and vaccine design, the importance of accurate, robust and extensible subtyping procedures is clear.

Human immunodeficiency virus type 1 protease-correlated cleavage site mutations enhance inhibitor resistance.

Drug resistance is an important cause of antiretroviral therapy failure in human immunodeficiency virus (HIV)-infected patients. Mutations in the protease render the virus resistant to protease inhibitors (PIs). Gag cleavage sites also mutate, sometimes correlating with resistance mutations in the protease, but their contribution to resistance has not been systematically analyzed. The present study examines mutations in Gag cleavage sites that associate with protease mutations and the impact of these associations on drug susceptibilities. Significant associations were observed between mutations in the nucleocapsid-p1 (NC-p1) and p1-p6 cleavage sites and various PI resistance-associated mutations in the protease. Several patterns were frequently observed, including mutations in the NC-p1 cleavage site in combination with I50L, V82A, and I84V within the protease and mutations within the p1-p6 cleavage site in combination with D30N, I50V, and I84V within the protease. For most patterns, viruses with mutations both in the protease and in either cleavage site were significantly less susceptible to specific PIs than viruses with mutations in the protease alone. Altered PI resistance in HIV-1 was found to be associated with the presence of Gag cleavage site mutations. These studies suggest that associated cleavage site mutations may contribute to PI susceptibility in highly specific ways depending on the particular combinations of mutations and inhibitors. Thus, cleavage site mutations should be considered when assessing the level of PI resistance.

Antiretroviral drug susceptibility among drug-naive adults with recent HIV infection in Rakai, Uganda.

OBJECTIVE: To analyze antiretroviral drug susceptibility in HIV from recently infected adults in Rakai, Uganda, prior to the availability of antiretroviral drug treatment. METHODS: Samples obtained at the time of HIV seroconversion (1998-2003) were analyzed using the GeneSeq HIV and PhenoSense HIV assays (Monogram Biosciences, Inc., South San Francisco, California, USA). RESULTS: Test results were obtained for 104 samples (subtypes: 26A, 1C, 66D, 9A/D, 1C/D, 1 intersubtype recombinant). Mutations used for genotypic surveillance of transmitted antiretroviral drug resistance were identified in six samples: three had nucleoside reverse transcriptase inhibitor (NRTI) surveillance mutations (two had M41L, one had K219R), and three had protease inhibitor surveillance mutations (I47V, F53L, N88D); none had nonnucleoside reverse transcriptase inhibitor (NNRTI) surveillance mutations. Other resistance-associated mutations were identified in some samples. However, none of the samples had a sufficient number of mutations to predict reduced antiretroviral drug susceptibility. Ten (9.6%) of the samples had reduced phenotypic susceptibility to at least one drug (one had partial susceptibility to didanosine, one had nevirapine resistance, and eight had resistance or partial susceptibility to at least one protease inhibitor). Fifty-three (51%) of the samples had hypersusceptibility to at least one drug (seven had zidovudine hypersusceptibility, 28 had NNRTI hypersusceptibility, 34 had protease inhibitor hypersusceptibility). Delavirdine hypersusceptibility was more frequent in subtype A than D. In subtype D, efavirenz hypersusceptibility was associated with substitutions at codon 11 in HIV-reverse transcriptase. CONCLUSION: Phenotyping detected reduced antiretroviral drug susceptibility and hypersusceptibility in HIV from some antiretroviral-naive Ugandan adults that was not predicted by genotyping. Phenotyping may complement genotyping for analysis of antiretroviral drug susceptibility in populations with nonsubtype B HIV infection.

Quantitation of HER2 expression or HER2:HER2 dimers and differential survival in a cohort of metastatic breast cancer patients carefully selected for trastuzumab treatment primarily by FISH.

The selection of patients with HER2-positive breast cancer for treatment with trastuzumab is based on the measurement of HER2 protein expression by immunohistochemistry, or the presence of HER2 gene amplification by fluorescence in situ hybridization (FISH). By using multivariate analyses, we investigate the relationship between quantitative measurements of HER2 expression or HER2:HER2 dimers and objective response (Response Evaluation Criteria in Solid Tumors), time to progression, and breast cancer survival after trastuzumab treatment in a cohort of patients with metastatic breast cancer who were primarily selected for treatment by FISH. The VeraTag assay, a proximity-based assay designed to quantitate protein expression and dimerization in formalin-fixed, paraffin-embedded tissue specimens, was used to measure HER2 protein expression and HER2:HER2 dimer levels. In a Cox proportional hazards analysis, higher HER2 expression or HER2:HER2 dimer levels were both correlated with longer survival (P=0.0058 and P=0.016, respectively) after treatment with trastuzumab in a population of patients that were either FISH-positive (90%) or immunohistochemistry 3+ (10%). Patients with higher levels of HER2 expression or HER2:HER2 dimers seemed to derive little benefit from the addition of concomitant chemotherapy to trastuzumab, whereas those with lower levels benefited significantly [interaction test P=0.43 (HER2 expression), P=0.27 (HER2:HER2 dimers)]. These data suggest that more quantitative or functional measurements of HER2 status may facilitate the development of more personalized treatment strategies for patients with metastatic breast cancer.

Prevalence, genotypic associations and phenotypic characterization of K65R, L74V and other HIV-1 RT resistance mutations in a commercial database.

BACKGROUND: Nucleoside reverse transcriptase inhibitor (NRTI)-associated mutations (NAMs) can affect response to treatment with NRTIs and might also result in HIV-1 with reduced replication capacity. METHODS: A large commercial HIV-1 database (n=60,487) was analysed for the prevalence of NAMs, antiviral drug susceptibilities and viral replication capacity. RESULTS: Thymidine analogue mutations (TAMs) and M184V were the most commonly observed NAMs (>25%). L74V/I was detected in 11% of isolates. K65R was detected in 3.3% of isolates and its frequency remained stable from 2003 to 2006, similar to trends observed for other NAMs. TAMs were rarely observed in combination with K65R, but frequently associated with L74V/I. HIV-1 with K65R or L74V/I alone were fully susceptible to zidovudine and stavudine. K65R was associated with reduced susceptibility to tenofovir, didanosine, abacavir and lamivudine; L74V/I was associated with reduced susceptibility to abacavir and didanosine. The addition of M184V to either K65R or L74V/I improved susceptibility to tenofovir, zidovudine and stavudine, but reduced susceptibility to abacavir, didanosine and lamivudine. Other NAMs commonly associated with K65R were A62V, S68G and Y115F; their NRTI susceptibilities were similar to those of viruses containing K65R alone. The replication capacity for HIV-1 with M184V/I or K65R was significantly reduced compared with wild-type (median 68%/ and 72%, respectively; P<0.0001), whereas replication capacity for HIV-1 with L74V or TAMs was not significantly reduced (88% and 97%, respectively). CONCLUSIONS: These results demonstrate a relative stability in the prevalence of HIV-1 clinical isolates with NAMs from 2003 to 2006. Differences between the genotypic patterns, phenotype and replication capacity associated with common NAMs are described.

Development of an HIV-1 reference panel of subtype B envelope clones isolated from the plasma of recently infected individuals.

We have developed an HIV-1 reference panel of 20 subtype B envelope clones isolated from the plasma of recently infected individuals. It is widely accepted that a prophylactic vaccine against HIV-1 requires the development of novel immunogens that are capable of eliciting broadly protective neutralizing antibody responses. Historically, patient serum has been screened for such antibodies by assaying against laboratory strains, but these viruses typically have increased neutralization sensitivity compared with primary isolates. To create a more standardized and relevant assay system for vaccine evaluation, we have developed a panel of primary envelopes derived from the plasma of individuals with documented acute/early subtype B HIV-1 infection occurring between 2000 and 2004. The HIV-1 envelopes from this panel vary in mode of transmission, coreceptor tropism, fusogenicity, and overall sensitivity to neutralization. These envelope sequences represent a broad spectrum of subtype B genetic diversity with an average pairwise genetic distance of 12% and a range from 10% to 19%. This well-characterized HIV-1 envelope panel should be a valuable resource for optimizing and standardizing vaccine assessment and improving vaccine design.

Phenotypic susceptibility to didanosine is associated with antiviral activity in treatment-experienced patients with HIV-1 infection.

OBJECTIVE: We investigated the relationship between human immunodeficiency virus (HIV) phenotypic susceptibility to didanosine and the antiviral activity of didanosine (ddI) in the JAGUAR study. METHODS: Baseline plasma HIV phenotypic susceptibility to ddI was assessed using a phenotype assay of patients randomized to receive ddI or placebo for 4 weeks in addition to their current regimen. Phenotypic susceptibility scores (PSSs) were then calculated for each sample. Associations between PSS and week 4 reductions in plasma HIV-1 RNA load or virologic response were assessed using linear regression and Jonckherre's test and the Wilcoxon and Cochran-Armitage tests, respectively. RESULTS: In the ddI arm, a significant association between reduction in viral load and continuous PSS was observed (P<.0001). Using distinct categories, an increasing fold change (FC) in susceptibility to ddI was strongly associated with smaller reductions in plasma HIV-1 RNA load (P<.0001). The proportion of virologic responders was 83% (15/18) for patients with a ddI FC < or =1.3, 50% (33/66) for patients with an FC of 1.3-2.2, and 29% (4/14) for patients with an FC > or =2.2 (P=.0008). After we determined these findings, 3 ddI FC categories were defined using 1.3 and 2.2 as thresholds. CONCLUSIONS: The relationship between phenotypic susceptibility to ddI and reduction in plasma HIV-1 RNA load describes a continuum. The establishment of a lower clinical cutoff at 1.3 and an upper clinical cutoff at 2.2 are clinically relevant.

A novel substrate-based HIV-1 protease inhibitor drug resistance mechanism.

BACKGROUND: HIV protease inhibitor (PI) therapy results in the rapid selection of drug resistant viral variants harbouring one or two substitutions in the viral protease. To combat PI resistance development, two approaches have been developed. The first is to increase the level of PI in the plasma of the patient, and the second is to develop novel PI with high potency against the known PI-resistant HIV protease variants. Both approaches share the requirement for a considerable increase in the number of protease mutations to lead to clinical resistance, thereby increasing the genetic barrier. We investigated whether HIV could yet again find a way to become less susceptible to these novel inhibitors. METHODS AND FINDINGS: We have performed in vitro selection experiments using a novel PI with an increased genetic barrier (RO033-4649) and demonstrated selection of three viruses 4- to 8-fold resistant to all PI compared to wild type. These PI-resistant viruses did not have a single substitution in the viral protease. Full genomic sequencing revealed the presence of NC/p1 cleavage site substitutions in the viral Gag polyprotein (K436E and/or I437T/V) in all three resistant viruses. These changes, when introduced in a reference strain, conferred PI resistance. The mechanism leading to PI resistance is enhancement of the processing efficiency of the altered substrate by wild-type protease. Analysis of genotypic and phenotypic resistance profiles of 28,000 clinical isolates demonstrated the presence of these NC/p1 cleavage site mutations in some clinical samples (codon 431 substitutions in 13%, codon 436 substitutions in 8%, and codon 437 substitutions in 10%). Moreover, these cleavage site substitutions were highly significantly associated with reduced susceptibility to PI in clinical isolates lacking primary protease mutations. Furthermore, we used data from a clinical trial (NARVAL, ANRS 088) to demonstrate that these NC/p1 cleavage site changes are associated with virological failure during PI therapy. CONCLUSIONS: HIV can use an alternative mechanism to become resistant to PI by changing the substrate instead of the protease. Further studies are required to determine to what extent cleavage site mutations may explain virological failure during PI therapy.

Development and characterization of a novel single-cycle recombinant-virus assay to determine human immunodeficiency virus type 1 coreceptor tropism.

Most human immunodeficiency virus type 1 (HIV-1) strains require either the CXCR4 or CCR5 chemokine receptor to efficiently enter cells. Blocking viral binding to these coreceptors is an attractive therapeutic target. Currently, several coreceptor antagonists are being evaluated in clinical trials that require characterization of coreceptor tropism for enrollment. In this report, we describe the development of an automated and accurate procedure for determining HIV-1 coreceptor tropism (Trofile) and its validation for routine laboratory testing. HIV-1 pseudoviruses are generated using full-length env genes derived from patient virus populations. Coreceptor tropism is determined by measuring the abilities of these pseudovirus populations to efficiently infect CD4+/U87 cells expressing either the CXCR4 or CCR5 coreceptor. Viruses exclusively and efficiently infecting CXCR4+/CD4+/U87 cells are designated X4-tropic. Conversely, viruses exclusively and efficiently infecting CCR5+/CD4+/U87 cells are designated R5-tropic. Viruses capable of infecting both CXCR4+/CD4+/U87 and CCR5+/CD4+/U87 cells are designated dual/mixed-tropic. Assay accuracy and reproducibility were established by evaluating the tropisms of well-characterized viruses and the variability among replicate results from samples tested repeatedly. The viral subtype, hepatitis B virus or hepatitis C virus coinfection, and the plasma viral load did not affect assay performance. Minority subpopulations with alternate tropisms were reliably detected when present at 5 to 10%. The plasma viral load above which samples can be amplified efficiently in the Trofile assay is 1,000 copies per ml of plasma. Trofile has been automated for high-throughput use; it can be used to identify patients most likely to benefit from treatment regimens that include a coreceptor inhibitor and to monitor patients on treatment for the emergence of resistant virus populations that switch coreceptor tropism.

Differential impact of thymidine analogue mutations on emtricitabine and lamivudine susceptibility.

The impact of drug resistance-associated mutations on subsequent antiretroviral therapy is an important consideration in managing treatment-experienced, HIV-1-infected patients. Lamivudine (3TC) and emtricitabine (FTC) are structurally related nucleoside reverse transcriptase inhibitors (NRTIs) approved for use in HIV-1-infected individuals. To evaluate whether susceptibility differences exist between lamivudine and emtricitabine, the phenotypic impact of common NRTI resistance-associated mutations was compared in HIV-1 from patient samples with paired FTC and 3TC susceptibility results. FTC phenotypic susceptibility was more greatly impacted than 3TC susceptibility in the presence of thymidine analogue mutations (TAMs), as the mean fold-change values were higher for FTC than for 3TC in groups of samples containing TAMs (P < 0.001 for 6 of 7 groups). For samples with K65R, L74I/V, or Q151M mutations, the phenotypic impact was similar, as the mean fold-change was not significantly different between drugs. Although the long-term clinical significance of these differences is unclear, they may suggest differential efficacy in some patients with prior NRTI experience, especially those with HIV harboring TAMs.