Comment 1:
Commenter states: "This is an embarrassing typo, as it is obvious for anyone with expertize in this field that the correct units used to report PSA concentrations in blood in all published reports on the 4K-panel and all literature related to PSA are in ng/mL, and the cited PSA levels in "ng/dL" are completely clinically irrelevant."

Response 1:
Typographical error noted and corrected.

Comment 2:
Commenter states: "The 4K-panel test (commercialized by OPKO Health as the 4Kscore test) is an algorithm that is based on age, laboratory and clinical data into a calibrated risk score corresponding to an individual patient's risk of Gleason score =7 ("high-grade") prostate cancer at prostate biopsy."

Response 2:
The 4Kscore test was launched in March 2014 at OPKO's OurLab in Nashville, TN. After OPKO's acquisition of BioReference Laboratories the test was moved to BioReference lab in NJ. The test has also launched in Europe in September 2014 in partnership with Barnaclinic, a branch of Hospital Clinic de Barcelona. "The test consists of serum levels of four different prostate-derived kallikrein proteins: total PSA, free PSA, intact PSA and hK2. Levels of these biomarkers are combined with a patient's age and digital rectal exam (DRE) status using a proprietary algorithm to calculate the probability of a finding of aggressive prostate cancer" (http://investor.opko.com/releasedetail.cfm? ReleaseID=825596). The proprietary algorithm depends on the DRE. However, the use of DRE by primary care physicians has largely fallen into misuse, and may or may not be used by urologists. This reviewer has found no data that validates the proprietary algorithm when results of a DRE are not obtained.

Comment 3:
Commenter states they conducted a deliberate step-bystep evaluation of the association between the four kallikrein markers (4K-panel) in participants of the Swedish (Goteborg), Dutch (Rotterdam), and French (Tarn) arms of the large prospective European Randomized Screening for prostate Cancer (ERSPC)trial contributing cryopreserved serum, clinical and biopsy data spanning over more than a decade (1994- 2006). These studies include:

• 7500 men with PSA =3.0 ng/mL who had a sextant biopsy with over 1900 ERSPC patients having evidence of any grade prostate cancer at biopsy – allowed researchers opportunity to determine whether prediction of risk of PC at biopsy using a statistical model based on the 4K panel was accurate and could be independently replicated across multiple clinical settings using large, highly representative population-based cohorts of men aged 50-74 who were either previously unscreened, subject to previous PSA testing, having a previous negative biopsy, or had been subject to clinical work-up prior to biopsy.
• First report on 4K-panel was based on cryopreserved serum and data from 740 previously unscreened participants in the prospective Goteborg (Swedish arm of ERSPC) who had PSA =3.0 ng/mL and were followed up with DRE, TRU, and sextant biopsy.
• The next report was an evaluation of 4K-panel in 1241 recently screened participants in the Goteborg trial. These studies involved the technical evaluation of monoclonal antibodies vs recombinant Fab-capture to measure intact fPSA and hK2.
• The first change in assay protocols for intact fPSA and hK2 was in Vickers et al. (J Clin Oncol., 2010) based on 2914 previously unscreened men in ERSPC-Rotterdam with PSA =3.0 ng/mL who were followed up by DRE, TRUS, and a sextant biopsy. The change in assay protocols for intact fPSA and hK2 led us to build a new statistical model to predict prostate biopsy-outcome based on the 4kpanel testing in cryopreserved serum from the ERSPC-Rotterdam participants. The Rotterdam cohort was randomly divided 1:3 into a training and validation set. The validation set utilized a locked down, statistical model based on levels of the 4K-panel, age and DRE with model-based prediction compared with empirical biopsy outcome.
• Clinical practice changes during the early 2000s, e.g. use of =10-core prostate biopsy, changes in Gleason grading criteria for Gleason score =7 cancer (high grade), and cryopreservation of anticoagulated plasma rather than serum, led us to develop a new statistical model to predict risk of Gleason score =7 prostate cancer at =10-core prostate biopsy based on 4K-panel testing from 4765 biopsied 50-70 year old participants in the large, prospective randomized ProtecT-trail in UK who had a PSA =3.0 ng/mL. The 4K-panel enhanced cancer detection compared with PSA and age alone. AUC for the 4K-panel was 0.719 (95% CI: 0.704; 0.734) vs. 0.634 (95% CI: 0.617; 0.651) for PSA and age alone for any grade cancer, and 0.820 (95% CI: 0.802; 0.838) vs 0.738 (95% CI: 0.716; 0.761) for high-grade cancer. Using a 6% risk of high-grade cancer as illustrative cutoff, the 4K-panel model reduced the need for biopsy in 43% of mean with PSA=3.0 ng/mL, detected 90% high-grade cancers, and delayed diagnosis of 10% high-grade cancers.

Response 3:
The European studies prior to publication of the Bryant study (JNCI, 2015) use a different model/algorithm because both biopsy and grading practice changed in the late 1990's and early 2000's. Subsequent to the Bryant study, the algorithm was "locked down". Nevertheless, results of the pre- and post-Bryant model/algorithm change are not directly comparable.

Comment 4:
The commenter corrects a draft LCD statement: "the number of men undergoing biopsy could be reduced to half using 20% or greater risk of advanced cancer as a tentative threshold for biopsy" is incorrect. The tentative threshold for the decision curve analysis and biopsy reduction calculation in the report based on the ERSPC-Rotterdam data was based on a 20% or greater risk for any grade prostate cancer, a threshold used in all other ERSPC studies, corresponding to a risk of any grade prostate cancer lower than that in unscreened men aged 50-70 with PSA =4.0 ng/mL.

Response 4:
Error noted and corrected in the policy.

Comment 5:
The commenter states "the vast majority of cancers not detected using the 20% threshold for any grade cancers with Gleason score =6 are unlikely to be life threatening". The commenter reports evidence from a very large population-based cohort (Stattin et al, 2015) that men with elevated PSA (e.g., =3.0 ng/mL at age 60) and a low 4K-panel test (?7.5% 4K-panel risk for Gleason score =7 prostate cancer have a 0% probability at 5 years and less than 0.3% probability at 10 years risk for documented evidence of distant metastasis from prostate cancer", and states: "this is certainly ample time to follow up with subsequent PSA and 4K-panel testing to detect risk of developing aggressive disease and adds further support that a clinical decision to avoid prostate biopsy in a man with elevated PSA and a low 4K-panel result may be both safe and very reasonable.

Response 5:
The commenter's conclusions form a viable hypothesis for how the test could be used and that it does no harm. However, no prospective studies substantiate or prove this hypothesis.

Comment 6:
"All published studies related to the clinical models based on the f4K-panel used PSA =3.0 ng/mL as biopsy cut off, or relied upon clinical judgement for biopsy decision. It is also true that in all of our studies there are a small group of men with PSA =10 ng/mL, as one would expect to be the case for men referred to a urologist for a prostate cancer evaluation. With respect to men with a PSA =10 ng/mL, we conducted and reported a statistical analysis referring to the men with a PSA concentration from 10-25 ng/mL at the 2016 American Urological Association meeting in San Diego. Our study showed that the 4K-panel retains excellent discrimination for high-grade prostate cancer in men with high PSA (10-25 ng/mL)."

Response 6:
Only published, peer-reviewed data is acceptable for consideration of medical evidence. It appears that this observational data may further validate the assay, but does not demonstrate clinical utility (improved patient outcomes).

Comment 7:
"The Stattin et al. data provide clinically important health outcomes endpoints as well as insights into the long-term consequences of using the 4K panel as a risk stratification tool to make biopsy decisions in men with elevated PSA levels. Our study showed that for a 50 year old man with PSA =2.0 ng/mL and a ProtecTbased 4K-panel risk <5.0%, or a 60 year old man with PSA =3.0 ng/mL and 4K-panel risk <7.5%, the risk for documented evidence of distant metastatic cancer was 0% at 5 years and less than 0.3% at 10 years. This is far lower than the 20 year risk for metastatic prostate cancer of 3.8% for a 60 year old man with a PSA =2.0 ng/mL, who is not recommended for prostate biopsy according to any contemporary guidelines. The risk in the low 4K-panel group is in distinct contrast to 50 year old men with PSA =2.0 ng/mL and 4K-panel risk =5.0% to 50-year or 60-year old men with PSA =3.0 ng/mL and 4K-panel risk =7.5%. Their 10-year risk for metastases from prostate cancer is 2.4% and 5.6%, respectively, and obviously indicated a need for much closer monitoring of their prostate health."

Response 7:
Information noted.

Comment 8:
A commenter notes there are "numerous egregious errors" and disagrees with the draft policy review of research and conclusions regarding consistency of the algorithm (predictive model) in the studies cited:

• It is demonstrably false that the model has never been "locked down". In the study on the French ERSPC cohort (Benchikh et al, BMC, 2010) the abstract reads: "We applied a previously published predictive model". Similarly, in the Rotterdam ERPCS study (Gupta et al, BJC, 2010) the abstract states: "A previously published statistical model was applied". In both cases the model applied was the one built on a "training" set of the Rotterdam ERPSC cohort.
• The "LCD uses the Bryant study (JNCI, 2015) to "highlight" that the model has never been locked down. He states "But there was a very specific reason why the Bryant study was conducted, why a new model was generated and why that model was used in subsequent studies. The reason is that both biopsy and grading practice changed in the late 1990's and early 2000's. The commenter states that the model developed in the Rotterdam ERSPC was of value for demonstrating "proof of principle" and it should not be applied to contemporary patients. The decision to create a new model in the Bryant study using the ProtecT cohort- which involved at least 10 core biopsy and predominately modern grading practices – was not, as implied in the LCD, an arbitrary one, but a conscious choice to ensure contemporary clinical applicability. The model created using the Bryant data was then applied in all subsequent cohorts, including the Swedish community study, the Statin long-term follow-up study and the Parekh validation study."

Response 8:
As noted within the comments, studies prior to and subsequent to the Bryant study were not based on the same statistical model. Although the post-Bryant studies continue to refine the hypothesis, direct extrapolation with pre-Bryant studies cannot be made.

Comment 9:
The commenter refutes the LCD statement that the model was "validated with patients outside the intended use population". The commenter states that "the study population in the US prospective evaluation study is exactly the intended use population: US men for whom a urologist has decided that a prostate biopsy is indicated."

Response 9:
The intended use population was not defined in the Parekh study. Rather, consecutive patients referred for prostate biopsy at 26 US urology center for roughly 6-7 months were tested. "Because biopsy was indicated for all the men in our cohort, the biopsy-all strategy is equivalent to current practice in the USA."

Comment 10:
Regarding intended use population. The "inclusion of men with PSA levels >10 ng/mL, whom the reviewer feels "are at intermediate risk and should be biopsied" and the inclusion of men who have previously undergone a negative biopsy, the "primary goal of this trial was to assess the performance of the 4Kscore in a broad range of men who are being subjected to a biopsy" in the US today. "While we are not arguing that these men do not require a biopsy, we appreciate that many men may have a PSA > 10 ng/mL for benign reasons. For instance, in this trial we found that 35% (36/104) of men who were subjected to a biopsy for a PSA >10 ng/ml had no cancer found on their biopsy. However, men with a previous negative biopsy a frequently referred for a repeat biopsy. In this study, we found that 30% (60/199) of men with a prior negative biopsy were found to have prostate cancer, which is a significant number of men who may falsely assume they are cancer free due to have a previous negative biopsy. The reviewer's assumption that a test to assess the risk of prostate cancer would only be helpful among men with a PSA of 4-10 ng/mL who have never had a biopsy is unfounded as many men outside this definition are also subjected to a biopsy each year, and it is not always clear that they need one. The commenter agrees that it is appropriate to separately analyze the subgroup of PSA >10 ng/mL, reported at the 2016 AUA.

Response 10:
Regarding the intended use population for 4Kscore, among the numerous publications, there is no consistency in defining the intended use population. Furthermore, publications address the urologist as the intended user of the test. But there exists a risk for this test when used within primary care (PCP) setting. PCPs might misinterpret the intended use and order 4Kscore as a reflex test to determine which patient to refer to the urologist. The intended user based on the scientific validation is the urologist, not the PCP. Another important consideration is the DRE. Since DRE is infrequently performed by PCPs, and DRE status is integral to the 4K algorithm, no publications have been identified that assess the model/algorithm without inclusion of the DRE status.

Comment 11:
The commenter states that "any test that attempts to focus more on the detection of high-grade disease will run the risk of missing low grade disease. Finding the acceptable balance between these two is the ultimate goal of screening and any tests that are employed for this use. To this point, unlike other tests that provide only a negative or positive results, the 4Kscore provides a continuous risk assessment, allowing the patient and clinician to decide on what threshold merits a biopsy based on the goals and values of each individual patient and his provider. Through shared decision making, providers can decide with their patients what an acceptable level of missing cancer would be, as this number will differ between patients."

Response 11:
This policy was drafted to address the Medicare "reasonable and necessary" criteria for coverage for the intended user (urologists) cases implied in the research to date. The policy addresses the lack of demonstrated clinical utility (not reasonable and necessary). Numerous comments have emphasized that 4K score is a risk assessment tool, and its intended use is for screening. As a screening test, it should be noted per National Coverage Determination (NCD 210.1) for Prostate Cancer Screening Tests, prostate screening coverage is limited to digital rectal examination and prostate specific antigen (PSA) only. As a risk assessment tool, with intended use for screening, the 4Kscore test is excluded by statute from Medicare coverage.

Comment 12:
Commenter states: "PSA testing as a public health measure has not received widespread approval because of the associated harm, namely, the high rate of false positive PSA tests leading, to excess biopsies and the consequent ove-detection and over-treatment of indolent, low-risk prostate cancers that pose little threat to life and health. … A better solution than abandoning PSA testing altogether would be to develop ways to make the test more specific, with fewer false positive results. Especially valuable would be tests focusing on the detection of high-grade, potentially lethal prostate cancers that could minimize the over-detection of lowrisk cancers. Over the past 20 years, research conducted at memorial Sloan Kettering in collaboration with major medical centers in Europe has led to the development of the current 4Kscore test, which combines clinical and biomarker measures in an algorithm to predict the risk of high-grade, Gleason 7 or greater, cancer at biopsy. The clinical validity of this test has been documented across large populations of patients enrolled in prospective randomized trials of screening for prostate cancer. These 'retrospective, prospective studies' meet Simon's criteria to establish the clinical validity of a cancer biomarker, with specimens of stored blood collected from patients during a prospective screening trial available for biomarker measurement. In a series of such studies, the 4Kscore test showed a remarkable ability to detect high-grade cancers while eliminating the need for biopsy in a substantial proportion of patients."

Response 12:
This reviewer agrees there is a significant unmet need for a diagnostic biomarker(s) to replace PSA. However, with all due respect to this commenter, the clinical validity of 4Kscore has NOT been validated in retrospective, prospective studies. Simon's criteria are in regard to the development of clinical utility, not clinical validity. A retrospective, prospective clinical utility study involves the use of archived samples from a previously reported prospective controlled trial to demonstrate that treatment based on a test result in a specified patient population is associated with improved outcomes in a statistically and clinical significant manner versus a currently accepted standard of care. The chosen samples and study design must be sufficiently characterized and powered to permit definition of the indications for use and the intended use population for the test. Most of the 4K-panel (Europe)/4Kscore (US) studies to date have been based on data modeling. The Parekh et al study is a prospective validation study without specification of the intended use population (1370 prospectively enrolled men referred for prostate biopsy at 26 urology centers in US between October 2013 and April 2014), and NO PSA cutoff inclusion. In this study, 86 (8%) of men has PSA >10 ng/mL and 348 (34%) had PSA <4 ng/mL. From marketing materials and OPKO's Health's Analyst and Investor Day, June 15, 2016 webcast, OPKO is marketing this test as a broad screening test with no PSA cutoff. This reviewer reminds the reader that prostate screening is limited by federal statute to PSA and DRE, and therefore, not a Medicare benefit. Even more worrisome is Parekh et al's conclusion that 434 (43%) of biopsies would be avoided by use of the 4Kscore test. This makes the significant assumption that men with 4K <9% wouldn't get biopsied, and results in 24 of 231 (10.5%) of men with high-grade Gleason 7 cancer being missed.

Comment 13:
A PCP in Michigan states that the "4Kscore has dropped our biopsy rate by nearly 50% and has increased our positive biopsy rate as well by better patient selection. This is especially helpful in those patients who have already undergone previous biopsies showing benign disease. Also helps the patient decide whether to proceed with biopsy or not."

Response 13:
Anecdotal information only.

Comment 14:
The commenter states that he was an active investigator in the US 4Kscore Validation Study and the 4Kscore Retrospective Clinical Utility Study, and that the 4Kscore is a 'life-saving game changer".

Response 14:
Subjective statement and no published data submitted for review.

Comment 15:
Letters to Dr. Debra Patterson, Novitas Medicare Administrative Contractor provided to Palmetto GBA from BioReference Laboratories: Form letters signed by individuals affirming that in their personal experience the 4Kscore test allowed them to biopsy those men at greatest risk, and as shown in a recent clinical study by Konety et al., and that the biopsy rates fall significantly by up to 65%.

Response 15:
This reviewer received 22 form letters from BioReference Laboratories from individuals in prestigious academic and private urology practices. In some of the letters, the signers state that they were involved in the pivotal US clinical trial (Parekh et al) and the clinical utility (Konety et al) study. Neither study demonstrated clinical utility. Parekh et al, as stated above was a clinical validation study. Konety et al. is a retrospective decision-impact study. Konety et al was a retrospective study where "no restrictions were placed on the urologists in deciding which patients received the 4Kscore tests or in making decisions with the patient about whether to proceed with a prostate biopsy. The study was a questionnaire and subject to the biases of questionnaires. This reviewer also noted that 247 (24%) of men in Parekh had an abnormal DRE, while only 38 (6%) men in Konety had negative DRE, yet 576 (94%) were being considered for prostate biopsy before the 4Kscore. Also, 199 (20%) in Parekh had prior biopsy, while 315 (52%) men in Konety has prior negative biopsy. Our assessment is that the negative biopsy may actually be the more significant driver.

Comment 16:
Summary

Response 16:
In Summary:

• The PSA units and reference to the assay not being "locked down" will be corrected in the policy.
• The validation studies appear adequate to show the predictive accuracy of 4Kscore.
• However, there is no evidence of clinical utility. As stated above, the intended use population, the intended user and PSA cutoff for testing have never been defined. Current company marketing appears directed towards the PCP for automatic reflex testing without regard to PSA cutoff. Prospective studies must demonstrate that 4Kscore testing improves patient outcomes, or changes physician management that results in improved patient outcomes.
• Despite the absence of clinical utility to meet Medicare's reasonable and necessary criteria for coverage, this test is marketed as a "screening" test and would not be covered under NCD 210.1
• The NCCN has not endorsed 4Kscore. The NCCN says "… 4Kscore are potentially informative in patients who have never undergone biopsy or after a negative biopsy, and "consider…, 4Kscore…" and "Tests that improve specificity in the post-biopsy state ….4Kscore…should be considered in patients thought to be higher risk despite a negative prostate biopsy." Medicare has no requirement to cover biomarkers listed in NCCN.