Clinical UM Guideline
|Subject:||Tropism Testing for HIV Management|
|Guideline #:||CG-LAB-03||Current Effective Date:||07/09/2013|
|Status:||Reviewed||Last Review Date:||05/09/2013|
Human immunodeficiency virus (HIV) enters cells by a complex process that involves attachment to the CD4 receptor followed by binding to either the chemokine receptor 5 (CCR5) or chemokine receptor 4 (CXCR4) molecules and fusion of the viral and cell membranes. The CCR5 coreceptor antagonist (inhibitor) antiretroviral drug, maraviroc (Selzentry ®, ViiV Healthcare, Research Triangle Park, NC; Pfizer Manufacturing Deutschland GmbH), prevents HIV entry into target cells by binding to the CCR5 receptor. The phenotypic coreceptor tropism assay test, Trofile® (Monogram Biosciences, Inc., South San Francisco, CA) is performed to identify HIV viral tropism (e.g. CCR5, CXCR4, or dual/mixed-tropic) to assist in selection of individuals for a CCR5 antagonist.
This document addresses the use of the coreceptor tropism assay (Trofile) test in the management of individuals with HIV-1 infection.
HIV tropism testing with the phenotypic coreceptor tropism assay (Trofile) is considered medically necessary in an HIV-1 infected individual for either of the following indications:
Not Medically Necessary:
HIV tropism testing with the phenotypic coreceptor tropism assay is considered not medically necessary for all other indications, including, but not limited to the following:
The following codes for treatments and procedures applicable to this document are included below for informational purposes. A draft of future ICD-10 Coding (effective 10/01/2014) related to this document, as it might look today, is included below for your reference. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.
Molecular pathology procedure, Level 1 (eg, identification of single germline variant [eg, SNP] by techniques such as restriction enzyme digestion or melt curve analysis)
|042||Human immunodeficiency virus [HIV] disease|
|V08||Asymptomatic human immunodeficiency virus [HIV] infection status|
|V58.83||Encounter for therapeutic drug monitoring|
|V65.44||Human immunodeficiency virus [HIV] counseling|
|ICD-10 Diagnosis||ICD-10-CM draft codes; effective 10/01/2014:|
|B20||Human immunodeficiency virus [HIV] disease|
|O98.711||Human immunodeficiency [HIV] disease complicating pregnancy, first trimester|
|O98.712||Human immunodeficiency [HIV] disease complicating pregnancy, second trimester|
|O98.713||Human immunodeficiency [HIV] disease complicating pregnancy, third trimester|
|O98.719||Human immunodeficiency [HIV] disease complicating pregnancy, unspecified trimester|
|O98.72||Human immunodeficiency [HIV] disease complicating childbirth|
|O98.73||Human immunodeficiency [HIV] disease complicating the puerperium|
|Z21||Asymptomatic human immunodeficiency virus [HIV] infection status|
|Z71.7||Human immunodeficiency virus [HIV] counseling|
The human immunodeficiency virus (HIV-1), which causes acquired immunodeficiency syndrome (AIDS), uses coreceptor 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. Over the course of infection, CXCR4 using HIV-1 clones emerge in some infected individuals. Viruses in many untreated individuals eventually exhibit a shift in coreceptor tropism from CCR5 to either CXCR4 or both CCR5 and CXCR4 (i.e., dual- or mixed-tropic; D/M tropic). This shift is temporally associated with a more rapid decline in CD4 T-cell counts (DHHS, 2013). Coreceptor antagonists have been designed to interfere with the interaction between HIV-1 and its coreceptors.
The U.S. Department of Health and Human Services Guidelines for the Use of Antiretroviral Agents in HIV-1 Infected Adults and Adolescents (DHHS, 2013) includes a number of factors for the clinician to consider when initiating a combination antiretroviral regimen for an antiretroviral therapy-naïve individual. Regimen selection should be individualized, including "coreceptor tropism assay if considering maraviroc (MVC)." "In clinical trials, NNRTI-, PI-, INSTI-, or CCR5 antagonist-based regimens have all resulted in suppression of HIV RNA levels and CD4 cell increased in the large majority of patients."
Initial antiviral treatment of adult HIV-1 infection consists of dual nucleoside or nucleotide analogue reverse transcriptase inhibitors (nRTI), such as tenoflovir/emtricitabine or abacavir/lamivudine, plus a key third agent. While recommended third agents include efavirenz, atazanavir, darunavir, or raltegravir, maraviroc is considered an acceptable alternative agent (Thompson, 2012).
Maraviroc is the first coreceptor antagonist drug 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 glycoprotein 120 (gp120), necessary for HIV-1 cell infection. Blocking this interaction prevents CCR5-using HIV-1 strains from entry into cells. However, CXCR4-using HIV-1 strains are not prevented. On November 20, 2009, the FDA approved a supplemental new drug application (NDA) to expand the indication for maraviroc to include combination antiretroviral treatment of therapy-naïve adults (i.e. who have never taken anti-HIV drugs) infected with CCR5-tropic HIV-1 virus. The expanded indication is based on safety and efficacy data collected through 96 weeks from the large, double-blind, prospective randomized MERIT trial (Maraviroc versus Efavirenz in Treatment-Naive Patients) which compared combination therapy of maraviroc/zidovudine/lamivudine to the combination therapy regimen of efavirenz/zidovudine/lamivudine (Cooper, 2010). Presently, there is no data available in the pediatric population; therefore, maraviroc should not be used in individuals less than 16 years of age (Selzentry Product Information, 2013).
For the clinical studies of individuals 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 individuals had dual/mixed HIV infection; CXCR4-infection alone is rare. Of the individuals 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 (Whitcomb, 2007), the original phenotypic Trofile assay had a turnaround time of 14 to 18 days, failed to work in 3%-7% of individuals, 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.
A more sensitive, second-generation assay replaced the original Trofile assay. The assay examines the complete gp160 region of the HIV-1 envelope protein. According to information from Monogram Biosciences, the enhanced sensitivity Trofile can detect CXCR4-tropic virus present at levels less than 0.3% of the total virus population, and at that level of virus, the assay is 100% sensitive. Viral load must be at least 1,000 copies/ml to determine viral tropism. Supportive data, however, have not yet been published. No information could be found on turnaround time; it is assumed to be unchanged from the original assay, i.e., 14-18 days.
The enhanced sensitivity Trofile assay became available after week 48 analysis of the phase III treatment-naïve MERIT trial (Maraviroc versus Efavirenz in Treatment-Naïve Patients); approximately 15% of the subjects identified as CCR5-tropic using the original assay had dual/mixed- or CXCR4-tropic virus by the enhanced sensitivity assay. Reanalysis of the data at week 96 of the MERIT study using the enhanced sensitivity assay screening results reduced the number of maraviroc virologic failures with dual/mixed- or CXCR4-tropic virus to 12 compared to 24 of the 311 subjects when screening with the original Trofile HIV tropism assay (Selzentry, Product Information, 2013).
Based on the clinical studies used for the FDA approval, and the labeled requirement for tropism testing prior to initiating a course of maraviroc, HIV tropism testing using the Trofile assay is recommended for both treatment-experienced and treatment-naïve individuals who are being considered for immediate treatment with maraviroc. Because maraviroc requires twice-daily dosing and requires a tropism assay prior to use, and experience with regimens other than zidovudine/lamivudine is limited, the DHHS Panel recommends maraviroc plus zidovudine/lamivudine as another option for use in antiretroviral-naïve individuals. "Although zidovudine/lamivudine was used as the NRTI backbone in the MERIT trial, pending further data, many clinicians favor the combination of maraviroc with tenofovir/emtricitabine or abacavir/lamivudine (Level of Evidence CIII)" (DHHS, 2013).
The U.S. Department of Health and Human Services Guidelines for the Use of Antiretroviral Agents in HIV-1 Infected Adults and Adolescents (DHHS, 2013) recommends the use of coreceptor tropism assays in clinical practice as follows:
In addition, the DHHS guidelines state: "A tropism assay may potentially be used in clinical practice for prognostic purposes or to assess tropism before starting ART if future use of a CCR5 antagonist is anticipated (e.g., a regimen change for toxicity). Currently, sufficient data do not exist to support these uses."
The Antiretroviral Treatment of Adult HIV Infection - 2012 Recommendations of the International Antiviral Society-USA Panel (Thompson, 2012) states "Drugs that block CCR5 have durable antiretroviral activity only if the individual is infected with HIV that uses CCR5 exclusively and not CXCR4. The use of these drugs thus requires receptor tropism screening. Maraviroc is the only currently approved CCR5 attachment inhibitor."
Acquired Immunodeficiency Syndrome (AIDS): A disease of the body's immune system caused by the human immunodeficiency virus (HIV). AIDS is characterized by the death of CD4 cells (an important part of the body's immune system), which leaves the body vulnerable to life-threatening conditions, such as infections and cancers.
Antagonist: Block the binding of an agonist (a substance that binds to a specific receptor and triggers a response in the cell) at a receptor site. Coreceptor antagonists prevent the HIV virus from attaching to CD4 coreceptor.
CD4 cells: A type of infection-fighting white blood cell that carries the CD4 receptor on its surface; also known as helper T cell or CD4 lymphocyte. CD4 cells coordinate the immune response, which signals other cells in the immune system to perform their special functions. The number of CD4 cells in a sample of blood is an indicator of the health of the immune system. HIV infects and kills CD4 cells, which leads to a weakened immune system.
Chemokine receptor 5 (CCR5): A protein on the surface of some immune system cells. It is one of two coreceptors that HIV can use along with the CD4 receptor to bind to and enter host cells.
Coreceptor: A protein on the surface of a cell that serves as a second binding site for a virus or other molecule. Although the CD4 protein is HIV's primary receptor, the virus must also bind to either the CCR5 or CXCR4 coreceptor to get into a host cell.
Human Immunodeficiency Virus (HIV): The virus that causes Acquired Immunodeficiency Syndrome (AIDS). HIV is in the retrovirus family, and two types have been identified: HIV-1 and HIV-2. HIV-1 is responsible for most HIV infections throughout the world, whereas HIV-2 is found primarily in West Africa.
Treatment-experienced: A term used to describe HIV-infected individuals who are currently being treated with anti-HIV drugs or who have taken anti-HIV drugs in the past.
Treatment failure: A broad term that describes failure of an anti-HIV treatment to adequately control HIV infection. The three types of HIV treatment failure are virologic, immunologic, and clinical failure. Factors that contribute to treatment failure include poor adherence, drug resistance, and drug toxicity.
Treatment-naïve: A term used to describe HIV-infected individuals who have never taken anti-HIV drugs.
Viral load (VL): The amount of HIV RNA in a blood sample, reported as number of HIV RNA copies per milliliter of blood plasma; also known as HIV RNA. The VL provides information about the number of cells infected with HIV and is an important indicator of HIV progression and of how well treatment is working.
Viral tropism: Refers to which type of coreceptor HIV uses when binding to a cell during infection. HIV can bind to the CXCR4 coreceptor (X4-tropic) or to the CCR5 coreceptor (R5-tropic) on a cell surface. Although the virus often prefers one coreceptor to the other, it also can be dual/mixed-tropic HIV that can bind to either coreceptor. Viral tropism may switch, or change from preference of one coreceptor to the other, during the course of an HIV infection.
Virologic failure: The inability of anti-HIV drug treatment to reduce viral load or to maintain suppression of viral load. Virologic failure is the most common type of treatment failure and may lead to immunologic and clinical failure.
Government Agency, Medical Society, and other Authoritative Publications:
|Web Sites for Additional Information|
Coreceptor Tropism Assay
|Reviewed||05/09/2013||Medical Policy & Technology Assessment Committee (MPTAC) review. Minor format changes. Updated Discussion, References, and Web Sites for Additional Information.|
|Reviewed||05/10/2012||Medical Policy & Technology Assessment Committee (MPTAC) review. Updated Description, Discussion, Coding and References.|
|01/01/2012||Updated Coding section with 01/01/2012 CPT changes.|
|Revised||05/19/2011||MPTAC review. Revised criterion to clarify that HIV tropism testing is medically necessary in an individual prior to initiating a combination antiretroviral drug regimen with a coreceptor antagonist, and in an individual who has experienced virologic failure while receiving therapy that contains a CCR5 inhibitor. Removed not medically necessary statement for coreceptor tropism assay testing in the absence of antiretroviral treatment failure. Updated Discussion and References. Added Definitions and Web Sites for Additional Information.|
|Revised||05/13/2010||MPTAC review. Revised document title to Tropism Testing for HIV Management. Revised Clinical Indications, removing indications for phenotypic and genotypic assays used in HIV-1 management other than the coreceptor tropism assay test, Trofile™. Updated Discussion/General Information, Coding, References, and Index.|
|Revised||08/27/2009||MPTAC review. Revised/clarified medically necessary criteria for genotypic and phenotypic assays for drug resistance testing and for tropism testing with the coreceptor tropism assay based on DHHS guidelines. Clarified not medically necessary criterion for use of other coreceptor (genotypic) assay techniques. Updated Discussion and References.|
|Revised||05/21/2009||MPTAC review. Revisions as follows: 1) Subject/title to Phenotypic and Genotypic Assays in HIV Management; 2) Medically necessary criteria for HIV-treated individuals who have experienced virologic failure during antiretroviral therapy (ART), adding "defined as HIV RNA levels ≥500 but <1,000 copies/mL;" and criterion for testing pregnant women; 3) Revised not medically necessary criterion for individuals who have plasma HIV RNA levels of <500 copies/mL. Updated Discussion and References.|
|Revised||05/15/2008||MPTAC review. Revised/renamed document number to CG-LAB-03. Addition of medically necessary and not medically necessary criteria for HIV tropism testing with the coreceptor assay (Trofile™). Discussion, Coding, and References updated.|
|Revised||11/29/2007||MPTAC review. Addition of medically necessary criteria for HIV drug resistance testing through phenotype and genotype assays: In individuals with recently acquired HIV infection; and, in individuals with established HIV infection prior to initiating ART. Addition of timeframe criterion: HIV resistance testing is considered not medically necessary in individuals greater than four weeks after discontinuation of ART. Discussion and References updated.|
|Revised||12/07/2006||MPTAC review. Clarification of when concurrent genotypic and phenotypic assays are medically necessary. Concurrent genotypic and phenotypic testing is considered not medically necessary in all other situations. Coding updated; removed CPT 0023T deleted 12/31/2005.|
|Revised||09/14/2006||MPTAC review. Added concurrent testing by genotypic and phenotypic assay is duplicative. Updated References.|
|01/01/2006||Updated Coding section with 01/01/2006 CPT/HCPCS changes|
|11/22/2005||Added reference for Centers for Medicare and Medicaid Services (CMS) – National Coverage Determination (NCD).|
|Revised||09/22/2005||MPTAC review. Revision based on Pre-merger Anthem and Pre-merger WellPoint Harmonization.|
Last Review Date
|WellPoint Health Networks, Inc.|
|2.12.03||Phenotypic and Genotypic Resistance Assays in HIV Management|