BlueCross and BlueShield of Montana Medical Policy/Codes
BRAF Gene Mutation Testing To Select Melanoma Patients for BRAF Inhibitor Targeted Therapy
Chapter: Genetic Testing
Current Effective Date: April 18, 2013
Original Effective Date: April 18, 2013
Publish Date: January 18, 2013
Description

Overall incidence rates for melanoma have been increasing for at least 30 years; in 2011, more than 70,000 new cases will be diagnosed.  In advanced (Stage 4) melanoma, the disease has spread beyond the original area of skin and nearby lymph nodes.  Although only a small proportion of cases are stage IV at diagnosis, prognosis is extremely poor; 5-year survival is about 15-20%.  Dacarbazine has long been considered the treatment standard for systemic therapy, but has disappointingly low response rates of only 15 to 25% and median response durations of 5-6 months; less than 5% of responses are complete.  Temozolomide has similar efficacy with the exception of a much greater ability to penetrate the central nervous system.  Combination regimens increase response rates, but not overall survival.  Very recently, ipilimumab was approved by the US Food and Drug Administration (FDA) for the treatment of patients with unresectable or metastatic melanoma.  For the first time, a survival advantage was demonstrated in previously treated patients: median survival on ipilimumab was 10 months versus 6.4 months on control medication.  However, side effects of ipilimumab can include severe and fatal immune-mediated adverse reactions, especially in patients who are already immune-compromised.

Mutations in the BRAF kinase gene are common in tumors of patients with advanced melanoma, and result in constitutive activation of a key signaling pathway that is associated with oncogenic proliferation.  In general, 50-70% of melanoma tumors harbor a BRAF mutation and of these, 80% are positive for BRAFV600E.  Thus, 40-60% of advanced melanoma patients might respond to a BRAF inhibitor targeted to this mutated kinase.

Two companies developed targeted BRAF inhibitors that have proceeded to phase III clinical trials in melanoma patients.  Vemurafenib (trade name Zelboraf®, also known as PLX4032 and RO5185426) was co-developed under an agreement between Roche (Genentech) and Plexxikon.  Vemurafenib was developed using a fragment-based, structure-guided approach that allowed the synthesis of a compound with high potency to inhibit the BRAF V600E mutated kinase, and significantly lower potency to inhibit most of many other kinases tested.  Preclinical studies demonstrated that vemurafenib selectively blocked the RAF/MEK/ERK pathway in BRAF mutant cells and caused regression of BRAF mutant human melanoma xenografts in murine models.  Paradoxically, preclinical studies also showed that melanoma tumors with the BRAF wild type gene sequence could respond to mutant BRAF-specific inhibitors with accelerated growth, suggesting that it might be harmful to administer BRAF inhibitors to patients with BRAF wild type melanoma tumors.  Potentiated growth in BRAF wild type tumors has not yet been confirmed in melanoma patients as the supportive clinical trials were enrichment trials, enrolling only those patients with tumors positive for the BRAFV600E mutation.

Dabrafenib (also known as GSK2118436 or SB-590885) is a BRAF inhibitor developed by GlaxoSmithKline and, as of October 2011, is under study in a phase III clinical trial.  As few publications detailing preclinical or clinical studies for dabrafenib are available, and neither drug nor companion test (developed by bioMérieux) have as yet been submitted to the FDA, this policy will focus on the the vemurafenib companion test.

The FDA Centers for Devices and Radiological Health (CDRH), for Biologics Evaluation and Research (CBER), and for Drug Evaluation and Research (CDER) developed a draft guidance on in vitro companion diagnostic devices, released on July 14, 2011, to address the “emergence of new technologies that can distinguish subsets of populations that respond differently to treatment.”  As stated, the FDA encourages the development of treatments that depend on the use of companion diagnostic devices, “when an appropriate scientific rationale supports such an approach.”  In such cases, the FDA intends to review the safety and effectiveness of the companion diagnostic test as used with the therapeutic treatment that depends on its use.  The rationale for co-review and approval is the desire to avoid exposing patients to preventable treatment risk.

While the guidance is not yet finalized, it represents the FDA’s current thinking on the topic and likely the direction given to sponsors of applicable treatments and companion diagnostics in development at the same time this guidance was being prepared.  Important points from the guidance include that a new therapeutic product and its corresponding companion diagnostic test should be developed together, and that both diagnostic test and therapeutic product should be approved or cleared at the same time by the FDA.  While the guidance allows for the development of competitor companion tests, those tests must be submitted to the FDA for review and approval or clearance.

Vemurafenib and a Class III companion diagnostic test, the cobas® 4800 BRAF V600 Mutation Test, were co-approved by the FDA in August, 2011.  The test is approved as an aid in selecting melanoma patients whose tumors carry the BRAFV600 mutation for treatment with vemurafenib.  Vemurafenib is indicated for the treatment of patients with unresectable or metastatic melanoma with BRAFV600 mutation.  The vemurafenib full prescribing information states that confirmation of the BRAFV600 mutation using an FDA-approved test is required for selection of patients appropriate for therapy.   

There is an FDA-approved BRAF testing kit that is intended to be used to select patients for vemurafenib treatment.  There are also commercial labs that perform BRAF testing using non-FDA approved testing.  The vemurafenib full prescribing information states that confirmation of the BRAFV600E mutation using an FDA-approved test is required for selection of patients appropriate for therapy.  The intent of the FDA-approval of this testing kit was to minimize the potential for inappropriate treatment based on an inaccurate test.

The phase III clinical trial selected all patients with a BRAFV600  mutation.  The majority of these mutations were BRAFV600E mutations and a small number (19/675, 2.8%) were BRAFV600K mutations.  The authors stated that patients with the BRAFV600K also appeared to respond to vemurafineb, but no formal subgroup analysis was performed.  Therefore, the results of the trial refer primarily to patients with the BRAFV600E mutation.  The efficacy of vemurafineb for patients with other mutations, including the BRAFV600K, is less certain.

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.

Coverage

Testing for the BRAFV600 mutation in tumor tissue of patients with stage IIIC or IV melanoma may be considered medically necessary to select patients for treatment with vemurafenib.

Testing for the BRAFV600 mutation for all other patients with melanoma, including, but not limited to, use in patients with lesser stage melanoma, is considered experimental, investigational and unproven.

Rationale

Literature Review

This policy is based on a 2011 Special Report by the Blue Cross Blue Shield Association (BCBSA) Technology Evaluation Center (TEC).  For the TEC Special Report, the MEDLINE database was searched (via PubMed) for articles using the terms “PLX4032,” “vemurafenib,” “V600E,” and “BRAF inhibitor,” all coupled with the term “melanoma.”  The reference lists of relevant study publications and review articles were also examined.  The meeting abstracts for the 2011 annual meeting of the American Society of Clinical Oncology were searched using the MEDLINE search terms.  If available, virtual presentations and slides were reviewed for key abstracts.  The “grey literature” was consulted in the form of drug and laboratory test approval information released by the FDA, ongoing clinical trials from ClinicalTrials.gov, and online searches for status and ancillary information.  The most recent searches included the period through September, 2011.  Following is a summary of the key publications and regulatory documents to date.

The components of the evidence evaluation are analytic validity, clinical validity, and clinical utility, as defined in the methods of the Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Working Group.

Analytic Validity

The analytic validity of a genetic test is its ability to accurately and reliably measure the genotype (or analyte) of interest in the clinical laboratory, and in specimens representative of the population of interest.  Submission to the Office of In Vitro Diagnostics of the FDA for marketing clearance or approval of a diagnostic test requires an extensive demonstration of the analytic validity of the test.  Data for cleared or approved tests are summarized in the kit insert (prepared by the manufacturer) and in the Summary of Safety and Effectiveness of the test (prepared by the FDA and publicly available).

The cobas® 4800 BRAF V600 Mutation Test is a real-time polymerase chain reaction (PCR) test intended for the qualitative detection of the BRAFV600E mutation specifically in DNA that has been extracted from formalin-fixed paraffin-embedded (FFPE) human melanoma tissue.

Correlation of cobas 4800 BRAF V600 Mutation Test results to Sanger sequencing was tested in the Phase III trial of vemurafenib on 596 consecutive patients, of which 449 were evaluable.  The percent agreement of the BRAF V600 mutation test with Sanger sequencing is shown in the first line of Table 1 (below) when only V600E results were counted as positive.  The cobas 4800 BRAF V600 Mutation Test detected 27 V600 mutations (primarily V600K) that were not V600E by Sanger Sequencing.  Limited evidence suggests that patients with V600K mutated tumors may also respond to vemurafenib.

Tumor specimens from the patients enrolled in the phase II trial were also sequenced by Sanger sequencing.  Specimens that were invalid by Sanger, or that were identified as V600K mutation or as V600 wild type by Sanger, were re-sequenced by the more sensitive 454 pyrosequencing method to resolve differences.  Correlation to 454 pyrosequencing was 100% if V600K-positive samples were counted as true positives (see Table 1).

Regulatory documents contain additional data detailing the evaluation of analytic sensitivity and specificity, cross reactivity, interference, reproducibility, repeatability, and additional studies of test robustness.  In general, correlation with sequencing and extensive analytic validation data support that the test is a sensitive, specific, and robust assay for the detection of the V600E mutation in FFPE melanoma specimens.  Patients with V600K mutations will also be identified as positive, although it is not clear that all patients with V600K mutations will be positive.  There is very limited evidence that patients with V600K mutations may respond to vemurafenib.  Infrequently, patients with V600E2 and V600D mutations may also be detected.  Additionally, the method is available as a kit and is partially automated, which should result in wide access and rapid turnaround time relative to the reference standard of sequencing.

Table 1.  Correlation of Vemurafenib trial companion test results with Sanger sequencing.

Definition of Positive

Positive% Agreement

Negative% Agreement

Overall % Agreement

Phase III trial

Only V600E

97.3

84.6

90.9

All V600

87.7

95.4

90.6

V600E + V600K

92.7

95.2

91.1

Phase II trial

Only V600E

92.4

 

 

V600E + V600K

100

 

 

Clinical Validity and Utility

The clinical validity of a genetic test is its ability to accurately and reliably predict the clinically defined disorder or phenotype of interest; the clinical utility of a genetic test is the evidence of improved measurable clinical outcomes, and its usefulness and added value to patient management decision-making compared with current management without genetic testing.

When a treatment is developed for a specific biological target that characterizes only some patients with a particular disease, and a test is co-developed to identify diseased patients with that target, clinical validity and clinical utility studies are no longer separate and sequential.  Rather, the clinical studies of treatment benefit, which use the test to select patients, provide evidence of both clinical validity and clinical utility.  The primary evidence of clinical validity and utility for the cobas® 4800 BRAF V600 Mutation Test is provided by the Phase III clinical trial of vemurafenib.  In addition, evidence from Phase I and Phase II trials is supportive.  All trials were enrichment trial designs, in which all patients were positive for a V600 mutation (with a few exceptions in the Phase I trial).  The justification for this was both efficiency and possibly potential for harm to patients with BRAF wild type tumors.

Phase III Clinical Trial 

This comparative trial, also known as BRIM-3, randomly assigned 675 patients to either vemurafenib (960 mg twice daily orally) or dacarbazine (1,000 mg/m2 body surface area by IV infusion every three weeks) to determine whether vemurafenib would prolong the rate of overall or progression-free survival, compared to dacarbazine.  All enrolled patients had unresectable, previously untreated stage IIIC or IV melanoma with no active CNS metastases.  Melanoma specimens from all patients tested positive for the BRAFV600E mutation on the cobas 4800 BRAF V600 Mutation Test.  Included were 19 patients with BRAFV600K mutations and one with a BRAFV600D mutation.

Tumor assessments including computed tomography (CT) were performed at baseline, at weeks 6 and 12, and every 9 weeks thereafter.  Tumor responses were determined by the investigators according to the RECIST, version 1.1.  Primary endpoints were the rate of overall survival and progression-free survival.  An interim analysis was planned at 98 deaths and a final analysis at 196 deaths; the published report is the interim analysis, reporting 118 deaths.  The median survival had not been reached; results are summarized in Table 2 (below).  Adverse events in the vemurafenib group included grade 2 or 3 photosensitivity skin reactions in 12% of patients, and cutaneous squamous cell carcinoma in 18% of patients.  The data and safety monitoring board determined that both co-primary endpoints had met prespecified criteria for statistical significance and recommended that patients in the dacarbazine group be allowed to cross over and receive vemurafenib.  The results of this trial comprised the data supporting the efficacy and safety of vemurafenib for submission to the FDA, and established the safety and effectiveness of the cobas 4800 BRAF V600 Mutation Test, resulting in co-approval of drug and companion test.

Table 2.  Phase III trial comparing vemurafenib to dacarbazine (BRIM-3) in patients with BRAFV600-positive advanced melanoma tumors

Vemurafenib

Dacarbazine

Overall Survival, N evaluable

336

336

Median, months (95% CI)

Not Reached

Not Reached

6 months

84% (95% CI: 78-89%)

65% (95% CI: 56-73%)

HR (95% CI)

0.37 (95% CI: 0.26-0.55)

 

p value

<0.001

 

Progression-Free Survival, N evaluable

275

274

Median, months

5.3

1.6

HR (95% CI)

0.26 (95% CI, 0.20-0.33)

 

p value

<0.001

 

Response, N evaluable

219

220

Objective Response Rate, % (95% CI)

48% (95% CI: 42 to 55%)

5% (95% CI: 3 to 9%)

Phase II Clinical Trial

A Phase II trial, also known as BRIM-2, is currently ongoing at 13 centers.  All patients were selected with the cobas 4800 BRAF V600 Mutation Test; 122 cases had BRAFV600E–positive melanoma and 10 cases were positive for BRAFV600K.  The early results of this trial have been published only as a meeting abstract and a meeting slide presentation.  The target overall response rate (primary outcome) was 30%, with a lower boundary of the 95% confidence interval (CI) of at least 20%.  At a median follow-up of 10 months, this target was met with an overall response rate of 53% by IRC (95% CI: 44-62%).  At 10 months, 27% of patients were still on treatment; the majority of discontinuations were due to disease progression.  The most common adverse events of any grade were arthralgias (58%), skin rash (52%), and photosensitivity (52%).  The most common grade 3 adverse event was squamous cell carcinoma; these were seen in about 25% of patients, tended to occur in the first two months of treatment, and were managed with local excision.  There were very few grade 4 adverse events.

Phase I Clinical Trial

The major goals of this trial were to first determine the maximum dose in a dose-escalation phase, then determine the objective response rate and monitor toxicity.  This trial used a PCR assay that was likely a prototype of the final test; only a brief description of the assay was provided in the publication.  In the dose-escalation phase, five patients with metastatic melanoma tumors who did not have the BRAFV600E mutation received 240 mg or more vemurafenib twice daily (final recommended dose is 960 mg twice daily); of these, none responded.  In the extension phase of the trial, 26 of 32 patients with the BRAFV600E mutation responded (81%; 24 partial, two complete responses).

Ongoing Clinical Trials

Despite impressive response rates in the Phase I trial, the duration of response to vemurafenib was limited to between 2 and 18 months suggesting the development of resistance; in some patients with BRAFV600E-positive tumors there was no response at all, which was interpreted as primary resistance.  Investigations of the mechanisms of resistance have reported evidence of different molecular mechanisms potentially responsible for resistance in different patients.  It is likely that combined inhibition of BRAF and other key molecular targets, and the use of different combinations in different patients, will be needed in the future.  For example, a clinical trial is already underway combining treatment with vemurafenib and a MEK inhibitor in patients who have already been treated with vemurafenib (NCT01271803).

As noted, the BRAF inhibitor dabrafenib is currently in phase II and III clinical trials (NCT01227889; NCT01266967), and is expected to be submitted to the FDA, along with a companion diagnostic test, relatively quickly.

Summary

A large proportion of patients with advanced melanoma have a mutation in the BRAF gene.  The Phase III clinical trial of vemurafenib in melanoma patients positive for the BRAFV600E mutation reported a benefit in overall survival and progression-free survival for vemurafenib treatment.  These results, which are corroborated by earlier trials, support the clinical validity and clinical utility of the cobas 4800 BRAF V600 Mutation Test, the companion diagnostic test for vemurafenib.  Using the test to select patients for treatment results in improved outcomes compared to the usual standard of care, dacarbazine.  Thus, this test, and any other tests approved by the FDA to detect the BRAFV600E mutation to select advanced melanoma patients for vemurafenib treatment, may be considered medically necessary.

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. 

ICD-9 Codes
172.0-172.9
ICD-10 Codes
C43.0-C43.9
Procedural Codes: 81210
References
  1. Sondergaard JN, Nazarian R, Wang Q et al.  Differential sensitivity of melanoma cell lines with
  2. King AJ, Patrick DR, Batorsky RS et al.  Demonstration of a genetic therapeutic index for tumors expressing oncogenic BRAF by the kinase inhibitor SB-590885.  Cancer Res 2006; 66(23):11100-5.
  3. Takle AK, Brown MJ, Davies S et al.  The identification of potent and selective imidazole-based inhibitors of B-Raf kinase.  Bioorg Med Chem Lett 2006; 16(2):378-81.
  4. Gogas HJ, Kirkwood JM, Sondak VK. Chemotherapy for metastatic melanoma: time for a change?  Cancer 2007; 109(3):455-64.
  5. Teutsch SM, Bradley LA, Palomaki GE et al.  The Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Initiative: methods of the EGAPP Working Group.  Genet Med 2009; 11(1):3-14.
  6. Bollag G, Hirth P, Tsai J et al.  Clinical efficacy of a RAF inhibitor needs broad target blockade in BRAF-mutant melanoma.  Nature 2010; 467(7315):596-9.
  7. BRAFV600E mutation to the specific Raf inhibitor PLX4032.  J Transl Med 2010; 8:39.
  8. Joseph EW, Pratilas CA, Poulikakos PI et al.  The RAF inhibitor PLX4032 inhibits ERK signaling and tumor cell proliferation in a V600E BRAF-selective manner.  Proc Natl Acad Sci U S A 2010; 107(33):14903-8.
  9. Yang H, Higgins B, Kolinsky K et al.  RG7204 (PLX4032), a selective BRAFV600E inhibitor, displays potent antitumor activity in preclinical melanoma models.  Cancer Res 2010; 70(13):5518-27.
  10. Flaherty KT, Puzanov I, Kim KB et al.  Inhibition of mutated, activated BRAF in metastatic melanoma.  N Engl J Med 2010; 363(9):809-19.
  11. Johannessen CM, Boehm JS, Kim SY et al.  COT drives resistance to RAF inhibition through MAP kinase pathway reactivation.  Nature 2010; 468(7326):968-72.
  12. Nazarian R, Shi H, Wang Q et al.  Melanomas acquire resistance to B-RAF(V600E) inhibition by RTK or N-RAS upregulation.  Nature 2010; 468(7326):973-7.
  13. Vultur A, Villanueva J, Herlyn M.  Targeting BRAF in advanced melanoma: a first step toward manageable disease.  Clin Cancer Res 2011; 17(7):1658-63.
  14. FDA.  Draft guidance for industry and food and drug administration staff: in vitro companion diagnostic devices.  2011; Available at www.fda.gov .
  15. Blue Cross and Blue Shield Association Technology Evaluation Center (TEC).  BRAF gene mutation testing to select melanoma patients for BRAF inhibitor therapy.  TEC Assessments 2011; Volume 26, Tab TBA.
  16. Chapman PB, Hauschild A, Robert C et al.  Improved survival with vemurafenib in melanoma with BRAF V600E mutation.  N Engl J Med 2011; 364(26):2507-16.
  17. Ribas A, Kim KB, Schuchter LM et al.  BRIM-2: An open-label, multicenter phase II study of vemurafenib in previously treated patients with BRAF V600E mutation-positive metastatic melanoma.  J Clin Oncol 2011; 29 (Suppl):Abstract 8509.
  18. ACS. American Cancer Society, Cancer Facts and Figures 2011.  2011; Available at www.cancer.org .
  19. BRAF Gene Mutation Testing To Select Melanoma Patients for BRAF Inhibitor Targeted Therapy.  Chicago, Illinois: Blue Cross Blue Shield Association (2011 November) Surgery 2.04.77.
History
January 2013 New 2013 BCBSMT medical policy.  
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BRAF Gene Mutation Testing To Select Melanoma Patients for BRAF Inhibitor Targeted Therapy