BlueCross and BlueShield of Montana Medical Policy/Codes
Laboratory Testing for HIV Tropism
Chapter: Medicine: Tests
Current Effective Date: October 25, 2013
Original Effective Date: October 25, 2013
Publish Date: July 25, 2013
Description

HIV tropism testing can determine the predominant co-receptor protein used by the human immunodeficiency virus (HIV) to infect target cells. Tropism testing can help select patients for treatment with HIV co-receptor antagonists, such as Maraviroc, which block specific co-receptor proteins.

The human immunodeficiency virus (HIV-1), which causes acquired immunodeficiency syndrome (AIDS), uses co-receptor proteins (either CCR5 or CXCR4) on the surface of target cells to enter and infect the cells. The most commonly transmitted strains of HIV-1 bind to CCR5 and are said to have “tropism” for CCR5-expressing cells. Dual or mixed (D/M) tropic viruses can bind to either receptor type. It is estimated that around 85% of treatment-naïve patients harbor CCR5-tropic virus only, around 15% harbor D/M virus, and less than 1% are infected with CXCR4-tropic virus alone. CXCR4-tropic virus is associated with immunosuppression and later stages of disease. New, experimental drugs, termed co-receptor antagonists, have been designed to interfere with the interaction between HIV-1 and its co-receptors.

Maraviroc (Selzentry™, Pfizer) is the first co-receptor antagonist to be approved by the U.S. Food and Drug Administration (FDA). Maraviroc is a selective, slowly reversible, small-molecule antagonist of the interaction between human cell surface CCR5 and HIV-1 gp120, also necessary for HIV-1 cell infection. Blocking this interaction prevents CCR5-tropic HIV-1 entry into cells. However, CXCR4-tropic HIV-1 entry is not prevented. According to the label, maraviroc, in combination with other antiretroviral agents, is indicated for adult patients who:

  • are treatment experienced, or
  • are treatment naïve (approved as of November 24, 2009);
  • are infected with only CCR5-tropic detectable HIV-1;
  • have evidence of viral replication.

The FDA-approved full prescribing information for the drug states that “Tropism testing must be conducted with a highly sensitive and specific tropism assay that has demonstrated the ability to identify patients appropriate for [maraviroc] use.” This is because efficacy was not demonstrated in a Phase II study of maraviroc in patients with D/M or CXCR4-tropic HIV-1. Due to potential adverse effects (hepatic and cardiotoxicity), maraviroc should only be used in indicated patients.

HIV tropism testing is available by either phenotypic or genotypic methods. Tropism testing with a phenotypic assay, a cellular-based assay that functionally determines tropism, is available with the enhanced sensitivity Trofile™ (Monogram Biosciences, South San Francisco, CA) assay (ESTA). This phenotypic assay uses virus stocks pseudotyped with envelope sequences derived from patient plasma to infect cell lines engineered to express CCR5 or CXCR4 HIV-2 co-receptors. Genotypic tropism testing is based on sequencing the third variable (V3) loop of the HIV glycoprotein 120 gene, because the V3 loop interacts with the HIV co-receptor, and mutations in V3 are associated with measurable changes in HIV tropism. Tropism assignment is derived from the sequence data using a bioinformatic algorithm such as geno2pheno. Genotypic tropism assays are available from commercial and other laboratory sources. For example, Quest Diagnostics Inc. offers the HIV-1 Coreceptor Tropism test.

Policy

Each benefit plan, summary plan description or contract defines which services are covered, which services are excluded, and which services are subject to dollar caps or other limitations, conditions or exclusions.  Members and their providers have the responsibility for consulting the member's benefit plan, summary plan description or contract to determine if there are any exclusions or other benefit limitations applicable to this service or supply.  If there is a discrepancy between a Medical Policy and a member's benefit plan, summary plan description or contract, the benefit plan, summary plan description or contract will govern.

Medically Necessary

Blue Cross and Blue Shield of Montana (BCBSMT) may consider human Immunodeficiency Virus (HIV) tropism testing with the phenotypic assay or V3 population genotyping medically necessary for selecting patients for treatment with HIV co-receptor antagonists such as maraviroc when the patient:

  • has failed multiple antiretroviral treatment regimens (treatment experienced) with evidence of viral replication, OR
  • is treatment naïve.

Not Medically Necessary

BCBSMT considers HIV tropism testing without immediate plans to prescribe HIV co-receptor antagonists such as maraviroc not medically necessary. 

Investigational

BCBSMT considers HIV tropism testing using other assay techniques including but not limited to  genotypic or HIV V3 deep sequencing (synonyms: ultra-deep sequencing; pyrosequencing; next generation sequencing) experimental, investigational and unproven.

Repeat HIV tropism testing during co-receptor antagonist treatment or after failure with co-receptor antagonists is considered experimental, investigational and unproven.

HIV tropism testing to predict disease progression (irrespective of co-receptor antagonist treatment) is considered experimental, investigational and unproven.

Rationale

This policy was created with searches of the MEDLINE database through July 2012. The following is a summary of the key literature to date.

Literature Review

The approval by the U.S. Food and Drug Administration (FDA) of maraviroc is based on safety and effectiveness data from 3 studies in adult subjects infected with CCR5-tropic HIV-1: A4001027 and A4001028, in antiretroviral treatment-experienced adult patients and A4001026 in treatment-naïve patients.

Clinical studies in treatment-experienced patients

The Maraviroc versus Optimized Therapy in Viremic Antiretroviral Treatment-Experienced Patients (MOTIVATE) 1 and 2 trials assessed the efficacy of maraviroc in patients previously treated or resistant to 3 antiretroviral drug classes and with HIV-1 RNA levels exceeding 5,000 copies/mL. (1) MOTIVATE-1 was conducted in Canada and the United States, and MOTIVATE-2 in Australia, Europe, and the United States, using identical study designs. A total of 1,075 patients were randomized to 3 trial arms, and 1,049 received at least one dose of study drug: placebo (n=209), maraviroc once daily (n=414), or maraviroc twice daily (n=426). Selected subjects had only CCR5-tropic HIV-1 infections, as determined by the original Trofile assay for HIV tropism (see ‘Tropism Testing,’ following). At 48-weeks follow-up in an intention-to-treat analysis, 16% in the placebo group and 45% in both maraviroc-treated groups had HIV-1 RNA levels less than 50 copies/mL. The mean increase in CD-4 count from baseline was 60 in the placebo group compared to 120 in the maraviroc groups. Based on the early trial results and review by the FDA Antiviral Drugs Advisory Committee, the FDA concluded that, compared to placebo, maraviroc significantly reduced HIV RNA copy number, and significantly increased CD4 cells, both validated markers of improved health outcomes. (2) At nearly 2 years of follow-up (96 weeks), 81% to 87% of maraviroc-treated patients maintained these responses with no new or unexpected events impacting safety. (3)

In contrast, in a trial of 167 patients infected with dual- or mixed-tropic HIV-1, randomized to receive optimal therapy plus maraviroc or placebo, there was no difference in outcomes between treatment groups, indicating maraviroc treatment failure in patients harboring assay-detectable CXCR4-tropic HIV-1 populations. (4)

Clinical studies in treatment-naïve patients

The MERIT (Maraviroc versus Efavirenz in Treatment-Naive Patients) study is a randomized, double-blind, multicenter study in subjects infected with CCR5-tropic HIV-1 according to the original Trofile assay. Patients had plasma HIV-1 RNA levels of at least 2,000 copies/mL and did not have: 1) prior antiretroviral therapy for longer than 14 days, 2) an active or recent opportunistic infection or primary HIV-1 infection, or 3) resistance to zidovudine, lamivudine, or efavirenz. Subjects were randomized to 2 doses of either maraviroc or efavirenz, each in combination with zidovudine/lamivudine. In a pre-planned interim analysis, the lower dose of maraviroc failed to meet prespecified efficacy criteria and was discontinued. Patients were stratified by screening HIV-1 RNA levels and by geographic region. The median CD4 cell counts and mean HIV-1 RNA at baseline were similar for both treatment groups.

At 96 weeks, after re-analysis using results from an enhanced sensitivity Trofile assay (see ‘Tropism Testing,’ following), virologic response rates in both treatment arms were approximately equal, and there were fewer discontinuations due to adverse events in the maraviroc arm. (5)

Although most newly infected patients harbor CCR5-tropic HIV virus alone, a study of 150 individuals from 2 recent seroconverter cohorts documented 4% infection with detectable CXCR4-tropic virus (either mixed or, rarely, CXCR4-only), indicating that tropism analysis is necessary, even for the recently infected. (6)

Tropism testing

For the clinical studies of patients with treatment failure, tropism at enrollment and again at baseline was determined using the original phenotypic Trofile assay for 2,560 potential enrollees; 56% were CCR5-tropic only and were eligible for the clinical trials. Most other patients had dual/mixed HIV infection; CXCR4-infection alone is rare. Of the patients enrolled, 90% had CCR5-tropic virus at baseline, 4% had dual-mixed tropic virus, and 5% had non-typable virus infection.

Based on information presented to the FDA Antiviral Drugs Advisory Committee and on published assay validation data, (7) the original phenotypic Trofile assay had a turnaround time of 14 to 18 days, failed to work in 3–7% of patients, and required at least 1,000 copies/mL of HIV RNA. The assay was 100% effective in detecting model CXCR4-tropic or dual/mixed HIV present in a 10% mixture, and 83% effective at a 5% mixture. Validation studies also indicated 100% accuracy of results for 38 samples with known tropism, and 100% reproducibility including repeat assays using multiple operators, instrumentation, reagent lots, and conducted over a 14-day period. No false-positive results were obtained on samples that were HIV-negative but positive for either hepatitis B or C virus.

An enhanced sensitivity Trofile assay (ESTA) has replaced the original Trofile. The ESTA can detect CXCR4-tropic virus present at levels less than 0.3% of the total virus population, and at that level of virus or higher, the assay is stated to be 100% sensitive. (8) Total viral concentration of at least 1,000 copies/mL is required. However, ESTA remains limited by long turnaround time and the relatively high minimum level of viremia required, making it not useful in patients in virological failure with low viremia. Additionally, a small proportion of samples cannot be successfully phenotyped with either generation of the Trofile assay. (9)

The MERIT study of treatment-naïve patients was retrospectively reanalyzed using ESTA; approximately 15% of the subjects originally identified as CCR5-tropic had dual/mixed- or CXCR4-tropic virus by ESTA. Removing these from the analysis resulted, as already noted, in similar responses in both trial arms, indicating that maraviroc in a combination regimen is at least as good as another well-accepted combination regimen for treatment-naïve patients. (5)

Wilkin et al. used ESTA to re-analyze samples from 4 large cohort studies that had originally been evaluated for HIV tropism with the original Trofile assay. (10) Nine percent to 26% of patients with CCR5-tropic virus by the original Trofile assay had CXCR4-using virus by ESTA.

Tropism testing for treatment monitoring and at virologic failure

The prominent reason for individual treatment failure in the clinical studies was outgrowth of a minor CXCR4-tropic virus population not detected at screening. However, treatment failure with CCR5-tropic virus alone also occurred, indicating that resistance to CCR5 antagonists occurs independent of tropism. In vitro studies have provided extensive information on resistance; mechanisms may involve the ability of HIV to bind the CCR5 inhibitor-receptor complex. Resistance to CCR5 antagonists has been associated with increased affinity for CCR5, changes in the gp 120 V3 loop, and with other gp 120 (or other envelope) changes.

HIV-1 viral load is a strong prognostic indicator of HIV disease progression, and suppression of viral load is a critical goal of antiretroviral therapy. (9) Viral rebound (virologic failure) is typically followed by a reduction in CD4 cell count (immunologic failure), and if not adequately addressed by changes in treatment, by HIV-related events (clinical progression). Thus, success of any antiretroviral treatment regimen is monitored by measuring HIV-1 RNA level and CD4 cell count; significant changes direct patient management.

Viral strains transmitted in vivo are usually CCR5-tropic. (11) Over time and more often after antiretroviral treatment, detectable CXCR4-tropic virus emerges in about half of patients and is associated with rapid CD4 cell depletion and clinical disease progression. (12, 13) However, patients whose infection remains predominately CCR5-tropic can also experience disease progression. The significance of CXCR4-tropic virus emergence is unknown.

A concern regarding treatment with CCR5 co-receptor antagonists is that small, undetectable populations of CXCR4-tropic virus would be enriched and would accelerate disease progression. However, in a randomized, placebo-controlled Phase II study of maraviroc treatment of patients with D/M-tropic infections, there was no evidence that this was the case. (14) The association of CXCR4 tropism (defined with the original Trofile assay) with clinical progression has been shown to be independent of CD4 cell count and HIV-1 RNA level (adjusted hazard ratio 3.82, 95% CI: 1.69–8.60, p=0.001 compared to patients with CCR5-tropic infection only). (15)

Fatkenheuer et al. performed a post-hoc analysis of the virologic response according to tropism at baseline and at treatment failure (16) using pooled data from the MOTIVATE 1 and 2 trials. Virologic failure occurred in 53% of placebo-treated patients and in 22-23% in the maraviroc treatment arms. However, of the 133 treatment failures in the maraviroc groups, 76 (57%) had CXCR4 or D/M tropism compared to only 6 of 95 (6%) in the placebo group, (16) raising concerns that maraviroc treatment could lead to emergence of CXCR4-tropic subpopulations and more rapid development of clinical progression. This was not the case, as the CXCR4 maraviroc treatment failures were not associated with declines in CD4 cell counts nor with disease progression.

There currently is no recommended management change based on a CCR5 to CXCR4 tropism switch during treatment with maraviroc. Treatment failure is detected by increased viral load and decreased CD4 cell count, (9) indicating that maraviroc treatment can be discontinued. The most common mechanism of maraviroc treatment failure is emergence of a CXCR4-tropic viral population. However, this is not necessarily correlated with rapid clinical progression. (17) Aside from the specific situation of maraviroc treatment failure, CXCR4-topic virus infection has been associated with more rapid disease progression, compared to CCR5 infection, in several studies (e.g. see Wilkin et al. (10)), but current management recommendations are based on monitoring CD4 cell count and viral load, rather than viral tropism.

V3 population genotyping to determine tropism

The Trofile assay is a cell-based, functional (phenotypic) assay. Genotypic assays are based on the sequencing of the patient-derived HIV-1 gp 120 V3 domain, which determines the protein amino acid sequence for the major determinant of co-receptor binding. This sequencing method results in a V3 sequence that represents the average or dominant viral population sequence for each patient. The HIV V3 sequence is used to infer HIV-1 tropism using web-based bioinformatic interpretation tools developed from prior data. These are most often geno2pheno co-receptor (G2P; available online at: http://coreceptor.bioinf.mpi-inf.mpg.de/index.php ) (18) and position-specific scoring matrices. (19) Genotyping can be conducted on either viral RNA samples (plasma) or on proviral DNA (peripheral blood mononuclear cells), the latter allowing tropism determination in the context of undetectable viremia. (20) Other potential advantages of genotypic assays are reduced cost, shorter turnaround time, fewer sample failures. (21)

Early genotyping studies with comparisons to original Trofile assay results reached contradictory conclusions regarding the adequacy of genotyping for predicting CXCR4 co-receptor usage. Some of the variability in genotype-phenotype assay correlation may have been due to the lower sensitivity of the original Trofile assay, and some variability may have accrued from inclusion of samples containing HIV subtypes other than B (the dominant form in Europe, the Americas, Japan, Thailand, and Australia). Ultimately, the best indication against which tropism assay results should be compared is the virological outcome of patients who receive CCR5-antagonist medication. (22)

Table 1 summarizes the results of studies comparing V3 genotyping results to virologic outcomes after maraviroc treatment. Because most studies use G2P for interpretation, only these results are presented. Where reported, results of original Trofile and enhanced-sensitivity Trofile assay results are also shown. Only the study reported by Gonzalez-Serna was prospective; for the others, V3 genotyping was conducted retrospectively on banked samples. McGovern (2010) likely includes data reported by Harrigan (2009). Results depend on the false-positive rate (FPR) cutoff value chosen for the G2P algorithm. If the result provided by G2P for a specific V3 sequence is higher than the chosen cut-off, the prediction of HIV-1 co-receptor tropism is CXCR4. Because the G2P distributions for CCR5- and CXCR4-tropic viruses overlap, no cutoff value allows perfect classification. Using a higher cutoff value is considered a conservative choice because predictions of CXCR4-tropism are more likely to be true predictions; the trade-off is that some true CXCR4-tropic HIV infections will be falsely identified as CCR5-tropic. For example, a cutoff value of 5.75% was optimized retrospectively for the MOTIVATE trial data, (23) but for routine clinical practice, the European guidelines on HIV-1 tropism testing recommend a cut-off of 10% for sequencing of samples in triplicate, or a cut-off of 20% when only a single sequence is generated. (24)

The data in Table 1 indicate that, depending on the G2P cutoff value chosen, V3 sequencing results can be generated that are very similar in their ability to predict response to maraviroc to both the original Trofile and the enhanced sensitivity Trofile assays. The Gonzalez-Serna study reports somewhat different results, with lower sensitivity and higher specificity for maraviroc response using similar G2P cutoff values. This study prospectively enrolled patients attending the infectious disease service of a university hospital, as opposed to the other retrospective studies of carefully selected clinical trial participants, but was also much smaller. Sequencing in this study was not done in triplicate as it was in the other studies.

Table 2 summarizes studies that evaluated the results of V3 sequencing using ESTA as the reference standard; treatment outcomes were not considered in these analyses. All studies sequenced HIV V3 RNA from plasma (standard assay); 2 additionally sequenced HIV V3 DNA from whole blood, which targets proviral DNA (useful for patients with low plasma levels of virus). These studies are much smaller than the studies in Table 1, and largely, where it could be determined, did not test samples in triplicate. It is important to remember that the test performance characteristics reported in Table 2 cannot be compared to those reported in Table 1, as the reference standards differ. In general, the sensitivity results indicate that V3 genotyping detects somewhat fewer CXCR4-tropic viral samples than does ESTA; the specificity results indicate that the FPR is not high, i.e. few CCR5-tropic samples are identified as CXCR4-tropic. Assay concordance is relatively high. Where reported, genotyping results for proviral DNA appear very similar to those for RNA in paired samples from the same patient population.

Overall and based largely on the studies of tropism assays with reference to maraviroc treatment outcome (Table 1), the evidence suggests that HIV V3 genotyping classifies patients as well as Trofile assays. Genotyping has additional advantages of shorter turnaround time, ability to generate results for patients who cannot be assayed by Trofile, and more access to assay providers.

Table 1. Performance of HIV V3 genotyping, Trofile, and ESTA assays with reference to maraviroc treatment outcomes.

Study

N

Patients

RT-PCR repli-cates

Virologic Response Definition

V3 Genotyping algorithm

V3 Genotyping vs virologic response to MVC

Original Trofile vs virologic response to MVC

ESTA vs virologic response to MVC

McGovern 2010 (Abs) (25)

705

Drug-naïve patients from MERIT trial

3x

<50 copies/mL at week 48

G2P, FPR=5.75%

Sens=94%

Spec = 13%

NR

Sens=91%

Spec=22%

Harrigan 2009 (Abs) (26)

623

Treatment experienced patients from MOTIVATE and 1,029 studies

3x

<50 copies/mL or reduction > 2 log at week 8

G2P, FPR=5%


Sens=85%

Spec=36%


Sens=90%

Spec=31%

NR

Gonzalez-Serna 2011 (27)

73

Patients with persistent viral load and on treatment hiatus

1x

<50 copies/mL or reduction > 1 log on day 8

G2P clonal,

FPR=5%

FPR=10%




Sens=58%

Spec=89%



Sens = 68%

Spec = 83%

NR

NR

McGovern 2010 (28)

1,164

Treatment-experienced patients from MOTIVATE and 1,029 studies

3x

<50 copies/mL or reduction > 2 log at week 8

G2P, FPR=5%

Sens=89%

Spec=24%

Sens=92%

Spec=20%

NR

Abbreviations: RT-PCR, reverse-transcriptase polymerase chain reaction; ESTA, enhanced sensitivity Trofile assay; MVC, maraviroc; G2P, geno2pheno co-receptor system; FPR, false-positive rate (used as cutoff value); Sens, sensitivity; Spec, specificity; Conc, concordance; MERIT, (Maraviroc versus Efavirenz Regimens as Initial Therapy trial; MOTIVATE, Maraviroc Plus Optimized Therapy in Viremic Antiretroviral Treatment-Experienced Patients trials; NR, not reported

Table 2. Performance of HIV V3 genotyping with reference to enhanced sensitivity Trofile assay.

Study

N

Patients

RT-PCR repli-cates

V3 Genotyping algorithm

V3 genotyping vs ESTA

Sens

Spec

Conc

Prosperi 2010 (21)

55

Patients failing antiretroviral treatment

1x

G2P clonal, FPR=5.75% G2P clonal, FPR=10%

G2P clonal, FPR=5.75%

G2P clonal, FPR=10%

RNA: 55%



55%



DNA: 68%



67%

96%



79%



86%



71%

83%



71%



82%



71%

Svicher 2010 (20)

365

63% treatment-experienced patients

1x

G2P clonal, FPR=5%

G2P clonal, FPR=10%

49%



55%

96%



89%

81%



78%

Sanchez 2010 (29)

119

Naïve and treatment-experienced patients

1x (?)

G2P clonal, FPR=5%

G2P clonal, FPR=10%

37%



57%

93%



84%

79%



77%

Strang 2009 (Abs) (30)

79

Patients evaluated for maraviroc therapy

?

G2P,

FPR 1-20%

NR

NR

Range,

70-94%

Pou 2009 (Abs) (31)

31

Banked samples, pre- ART

3x

G2P

RNA: 40%

DNA: 36%

100%

100%

78%

77%

Abbreviations: RT-PCR, reverse-transcriptase polymerase chain reaction; ESTA, enhanced sensitivity Trofile assay; G2P, geno2pheno co-receptor system; FPR, false-positive rate (used as cutoff value); Sens, sensitivity; Spec, specificity; Conc, concordance; NR, not reported

Tropism testing by deep sequencing

Because of concern that standard V3 sequencing methods used for tropism testing, might miss clinically significant minor HIV variants, so-called “deep sequencing,” i.e., V3 sequencing using next generation sequencing methods has been investigated for utility in tropism testing. While standard sequencing essentially determines a population average V3 loop sequence, deep sequencing allows simultaneous sequencing and quantifying of thousands of individual V3 variants within a viral population, From this, the proportion of non-R5 variants in a given sample can be calculated. For example, Swenson et al. examined 859 samples from the MERIT trial to determine if deep sequencing could predict maraviroc response. (32) Patients identified as having CCR5 or non-CCR5 viral infections by either deep sequencing or ESTA had similar treatment outcomes. Where assay results differed in their predictions, it was not clear from outcomes which assay was the better standard. What is not known is what proportion of the viral population can be non-CCR5 for maraviroc treatment to remain effective, (33) although the results of one preliminary study suggest no more than 1-3% (34).  Other studies have also reported high concordance between deep sequencing and current tropism assays (22, 33).  Based on available information, the additional clinical utility of deep sequencing over current methods of HIV tropism determination has not yet been demonstrated.

Practice Guidelines and Position Statements

The European Consensus Group on clinical management of tropism testing states that tropism testing is indicated for patients who fail treatment or have unacceptable toxicity and a CCR5 inhibitor is being considered. (24) In the absence of evidence, the Group provides no guidance regarding tropism testing for newly diagnosed patients whose immediate treatment plan does not include a CCR5 inhibitor. In the absence of adequate data, the Group could provide no guidance regarding the question of testing treatment-naïve patients prior to the start of a regimen not including a CCR5 inhibitor, in anticipation of need for a fast change to a CCR5 inhibitor due to the toxicity of the initial treatment regimen. For patients with a plasma HIV RNA load >1,000 copies/mL, tropism testing can be done by Trofile ESTA or by population genotypic analysis of the V3 loop, indicating for both a moderate level of evidence based on well designed, nonrandomized trials or cohort studies with long-term clinical outcomes. For patients with a plasma HIV RNA load <1,000 copies/mL, genotyping is the preferred method.

The Health and Human Services Panel on Antiretroviral Guidelines for Adults and Adolescents Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents states that tropism assays should be used whenever the use of a CCR5 inhibitor is being considered (based on strong evidence from randomized trials with clinical outcomes) and possibly for patients who exhibit virologic failure during CCR5 inhibitor treatment (optional recommendation based on expert opinion, no data cited). (9) Other uses of tropism assays, e.g. for prognostic purposes or in case use of a CCR5 inhibitor is needed later do not have sufficient data to support a recommendation. ESTA is recognized as the more sensitive version of the original assay used in the qualifying maraviroc clinical trials. Genotyping is noted as apparently less sensitive, but based on 2 “recent studies,” possibly as accurate as phenotyping in predicting response to treatment. However, these guidelines do not yet cite all the large, published studies summarized in Table 1; rather, citing uncertainty of the evidence, they recommend phenotyping as the preferred method of tropism testing.

Other published, relevant guidelines have not been recently updated and do not include the most recent evidence.

Summary

Based on the evidence from the clinical studies used for FDA approval, and the labeled requirement for tropism testing immediately prior to initiating a course of maraviroc, HIV tropism testing using the enhanced sensitivity version of the phenotypic Trofile assay is considered medically necessary for both treatment-experienced and treatment-naïve patients who are being considered for immediate treatment with maraviroc.

The evidence comparing HIV V3 population genotyping to original Trofile and ESTA, using maraviroc response as the reference for all assays, strongly suggests that genotyping is equivalent to Trofile assays in selecting patients likely to respond to maraviroc, the outcomes of interest. Studies evaluating genotyping and using paired ESTA results for reference suggest that genotyping may be somewhat less sensitive for detecting CXCR4-topic samples, but these studies were smaller, and most did not test in triplicate. Based largely on the maraviroc response results, HIV V3 population genotyping is considered medically necessary for patients considering immediate maraviroc treatment.

Either phenotyping or genotyping may be used to determine tropism when considering maraviroc treatment; both are not required.

Currently, patient management decisions are based on monitoring of CD4 cell counts and HIV plasma viral load. Studies would be needed to support improved outcomes with additional tropism monitoring during treatment. Pending such studies, tropism testing during treatment with co-receptor antagonists is experimental, investigational and unproven. In addition, data are not available to support the use of phenotypic tropism testing to predict prognosis, or to determine tropism in advance of a possible need for a regimen change to a co-receptor antagonist later.  Finally, based on available information, the additional clinical utility of V3 deep sequencing (i.e., next generation sequencing) over current methods of HIV tropism determination has not yet been demonstrated.

Coding

Disclaimer for coding information on Medical Policies

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy.  They may not be all-inclusive.

The presence or absence of procedure, service, supply, device or diagnosis codes in a Medical Policy document has no relevance for determination of benefit coverage for members or reimbursement for providers.  Only the written coverage position in a medical policy should be used for such determinations.

Benefit coverage determinations based on written Medical Policy coverage positions must include review of the member’s benefit contract or Summary Plan Description (SPD) for defined coverage vs. non-coverage, benefit exclusions, and benefit limitations such as dollar or duration caps. 

Procedural Codes: 87999
References
  1. Gulick RM, Lalezari J, Goodrich J et al. Maraviroc for previously treated patients with R5 HIV-1 infection. N Engl J Med 2008; 359(14):1429-41.
  2. Katzenstein DA, Hammer SM, Hughes MD et al. The relation of virologic and immunologic markers to clinical outcomes after nucleoside therapy in HIV-infected adults with 200 to 500 CD4 cells per cubic millimeter. AIDS Clinical Trials Group Study 175 Virology Study Team. N Engl J Med 1996; 335(15):1091-8.
  3. Hardy WD, Gulick RM, Mayer H et al. Two-year safety and virologic efficacy of maraviroc in treatment-experienced patients with CCR5-tropic HIV-1 infection: 96-week combined analysis of MOTIVATE 1 and 2. J Acquir Immune Defic Syndr 2010; 55(5):558-64.
  4. Saag M, Goodrich J, Fatkenheuer G et al. A double-blind, placebo-controlled trial of maraviroc in treatment-experienced patients infected with non-R5 HIV-1. J Infect Dis 2009; 199(11):1638-47.
  5. Cooper DA, Heera J, Goodrich J et al. Maraviroc versus efavirenz, both in combination with zidovudine-lamivudine, for the treatment of antiretroviral-naive subjects with CCR5-tropic HIV-1 infection. J Infect Dis 2010; 201(6):803-13.
  6. Huang W, Toma J, Stawiski E et al. Characterization of human immunodeficiency virus type 1 populations containing CXCR4-using variants from recently infected individuals. AIDS Res Hum Retroviruses 2009; 25(8):795-802.
  7. Whitcomb JM, Huang W, Fransen S et al. Development and characterization of a novel single-cycle recombinant-virus assay to determine human immunodeficiency virus type 1 coreceptor tropism. Antimicrob Agents Chemother 2007; 51(2):566-75.
  8. Reeves JD, Coakley E, Petropoulos CJ et al. An enhanced-sensitivity Trofile HIV coreceptor tropism assay for selecting patients for therapy with entry inhibitors targeting CCR5: A review of analytical and clinical studies. J Viral Entry 2009; 3:94-102.
  9. Panel on Antiretroviral Guidelines for Adults and Adolescents. Guidelines for the use of antiretroviral agents in HIV-1-infected adults and adolescents. Department of Health and Human Services. Updated January-October 2011. Available online at: http://aidsinfonihgov. Last accessed November 2011.
  10. Wilkin TJ, Goetz MB, Leduc R et al. Reanalysis of coreceptor tropism in HIV-1-infected adults using a phenotypic assay with enhanced sensitivity. Clin Infect Dis 2011; 52(7):925-8.
  11. Philpott SM. HIV-1 coreceptor usage, transmission, and disease progression. Curr HIV Res 2003; 1(2):217-27.
  12. Moyle GJ, Wildfire A, Mandalia S et al. Epidemiology and predictive factors for chemokine receptor use in HIV-1 infection. J Infect Dis 2005; 191(6):866-72.
  13. Weber J, Piontkivska H, Quinones-Mateu ME. HIV type 1 tropism and inhibitors of viral entry: clinical implications. AIDS Rev 2006; 8(2):60-77.
  14. Pfizer, Inc. Selzentry™ (maraviroc) prescribing information. New York, NY; August 2007. Available online at: http://wwwviivhealthcarecom/products/~/media/Files/G/GlaxoSmithKline-Plc/Attachments/pdfs/products/us_selzentry_jul2011pdf  . Last accessed November 2011.
  15. Daar ES, Kesler KL, Petropoulos CJ et al. Baseline HIV type 1 coreceptor tropism predicts disease progression. Clin Infect Dis 2007; 45(5):643-9.
  16. Fatkenheuer G, Nelson M, Lazzarin A et al. Subgroup analyses of maraviroc in previously treated R5 HIV-1 infection. N Engl J Med 2008; 359(14):1442-55.
  17. Wilkin TJ, Gulick RM. CCR5 Antagonism in HIV Infection: Current Concepts and Future Opportunities. Annu Rev Med 2012; 63:81-93.
  18. Lengauer T, Sander O, Sierra S et al. Bioinformatics prediction of HIV coreceptor usage. Nat Biotechnol 2007; 25(12):1407-10.
  19. Jensen MA, Li FS, van 't Wout AB et al. Improved coreceptor usage prediction and genotypic monitoring of R5-to-X4 transition by motif analysis of human immunodeficiency virus type 1 env V3 loop sequences. J Virol 2003; 77(24):13376-88.
  20. Svicher V, D'Arrigo R, Alteri C et al. Performance of genotypic tropism testing in clinical practice using the enhanced sensitivity version of Trofile as reference assay: results from the OSCAR Study Group. New Microbiol 2010; 33(3):195-206.
  21. Prosperi MC, Bracciale L, Fabbiani M et al. Comparative determination of HIV-1 co-receptor tropism by Enhanced Sensitivity Trofile, gp120 V3-loop RNA and DNA genotyping. Retrovirology 2010; 7:56.
  22. Swenson LC, Moores A, Low AJ et al. Improved detection of CXCR4-using HIV by V3 genotyping: application of population-based and "deep" sequencing to plasma RNA and proviral DNA. J Acquir Immune Defic Syndr 2010; 54(5):506-10.
  23. Mcgovern R, Dong W, Mo T et al. Optimization of clinically relevant cut-points for the determination of HIV co-receptor usage to predict maraviroc responses in treatment experienced (TE) patients using population V3 genotyping. 12th European AIDS Conference Cologne, Germany 2009:Abstract PE3.4/8.
  24. Vandekerckhove LP, Wensing AM, Kaiser R et al. European guidelines on the clinical management of HIV-1 tropism testing. Lancet Infect Dis 2011; 11(5):394-407.
  25. McGovern R, Dong W, Zhong X et al. Population-based sequencing of the V3-loop is comparable to the enhanced sensitivity Trofile assay in predicting virologic response to maraviroc of treatment-naive patients in the MERIT trial. 17th Conference on Retroviruses and Opportunistic Infections; San Francisco, CA, Feb 27–March 2, 2010:Abstract 92.
  26. Harrigan PR, McGovern R, Dong W et al. Screening for HIV tropism using population-based V3 genotypic analysis: a retrospective virological outcome analysis using stored plasma screening samples from MOTIVATE-1. 5th International AIDS Symposium, 2009, Cape Town, S Africa:Abstract WELBA101.
  27. Gonzalez-Serna A, McGovern RA, Harrigan PR et al. Correlation of the virological response to short-term Maraviroc monotherapy with standard and deep sequencing-based genotypic tropism methods. Antimicrob Agents Chemother 2011.
  28. McGovern RA, Thielen A, Mo T et al. Population-based V3 genotypic tropism assay: a retrospective analysis using screening samples from the A4001029 and MOTIVATE studies. AIDS 2010; 24(16):2517-25.
  29. Sanchez V, Masia M, Robledano C et al. Performance of genotypic algorithms for predicting HIV-1 tropism measured against the enhanced-sensitivity Trofile coreceptor tropism assay. J Clin Microbiol 2010; 48(11):4135-9.
  30. Strang AL, Cameron J, Booth CL et al. Genotypic prediction of viral co-receptor tropism: correlation with enhanced Trofile. 15th Annual Conference of the British HIV Association 1-3 April 2009, Liverpool, UK:Abstract P95.
  31. Pou C, Cabrera C, Dalmau J et al. Co-Receptor Tropism Prediction in Chronically HIV-1-Infected Subjects with Suppressed Viremia. 7th European HIV Drug Resistance Workshop, Stockholm, Sweden; March 27–29, 2009:Abstract 82.
  32. Swenson LC, Mo T, Dong WW et al. Deep V3 sequencing for HIV type 1 tropism in treatment-naive patients: a reanalysis of the MERIT trial of maraviroc. Clin Infect Dis 2011; 53(7):732-42.
  33. Saliou A, Delobel P, Dubois M et al. Concordance between two phenotypic assays and ultradeep pyrosequencing for determining HIV-1 tropism. Antimicrob Agents Chemother 2011; 55(6):2831-6.
  34. Tsibris AM, Korber B, Arnaout R et al. Quantitative deep sequencing reveals dynamic HIV-1 escape and large population shifts during CCR5 antagonist therapy in vivo. PLoS One 2009; 4(5):e5683.
  35. Laboratory Testing for HIV Tropism. Chicago, Illinois:  Blue Cross Blue Shield Association Medical Policy Reference Manual (2012  March) Medicine 2.04.49.
History
July 2013  New 2013 BCBSMT medical policy.
BCBSMT Home
®Registered marks of the Blue Cross and Blue Shield Association, an association of independent Blue Cross and Blue Shield Plans. ®LIVE SMART. LIVE HEALTHY. is a registered mark of BCBSMT, an independent licensee of the Blue Cross and Blue Shield Association, serving the residents and businesses of Montana.
CPT codes, descriptions and material only are copyrighted by the American Medical Association. All Rights Reserved. No fee schedules, basic units, relative values or related listings are included in CPT. The AMA assumes no liability for the data contained herein. Applicable FARS/DFARS Restrictions Apply to Government Use. CPT only © American Medical Association.
Laboratory Testing for HIV Tropism