Use of archival versus newly collected tumor samples for assessing PD-L1 expression and overall survival: an updated analysis of KEYNOTE-010 trial.

BACKGROUND: In KEYNOTE-010, pembrolizumab versus docetaxel improved overall survival (OS) in patients with programmed death-1 protein (PD)-L1-positive advanced non-small-cell lung cancer (NSCLC). A prespecified exploratory analysis compared outcomes in patients based on PD-L1 expression in archival versus newly collected tumor samples using recently updated survival data. PATIENTS AND METHODS: PD-L1 was assessed centrally by immunohistochemistry (22C3 antibody) in archival or newly collected tumor samples. Patients received pembrolizumab 2 or 10 mg/kg Q3W or docetaxel 75 mg/m2 Q3W for 24 months or until progression/intolerable toxicity/other reason. Response was assessed by RECIST v1.1 every 9 weeks, survival every 2 months. Primary end points were OS and progression-free survival (PFS) in tumor proportion score (TPS) ≥50% and ≥1%; pembrolizumab doses were pooled in this analysis. RESULTS: At date cut-off of 24 March 2017, median follow-up was 31 months (range 23-41) representing 18 additional months of follow-up from the primary analysis. Pembrolizumab versus docetaxel continued to improve OS in patients with previously treated, PD-L1-expressing advanced NSCLC; hazard ratio (HR) was 0.66 [95% confidence interval (CI): 0.57, 0.77]. Of 1033 patients analyzed, 455(44%) were enrolled based on archival samples and 578 (56%) on newly collected tumor samples. Approximately 40% of archival samples and 45% of newly collected tumor samples were PD-L1 TPS ≥50%. For TPS ≥50%, the OS HRs were 0.64 (95% CI: 0.45, 0.91) and 0.40 (95% CI: 0.28, 0.56) for archival and newly collected samples, respectively. In patients with TPS ≥1%, OS HRs were 0.74 (95% CI: 0.59, 0.93) and 0.59 (95% CI: 0.48, 0.73) for archival and newly collected samples, respectively. In TPS ≥50%, PFS HRs were similar across archival [0.63 (95% CI: 0.45, 0.89)] and newly collected samples [0.53 (95% CI: 0.38, 0.72)]. In patients with TPS ≥1%, PFS HRs were similar across archival [0.82 (95% CI: 0.66, 1.02)] and newly collected samples [0.83 (95% CI: 0.68, 1.02)]. CONCLUSION: Pembrolizumab continued to improve OS over docetaxel in intention to treat population and in subsets of patients with newly collected and archival samples. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01905657.

Pembrolizumab as first-line therapy for patients with PD-L1-positive advanced non-small cell lung cancer: a phase 1 trial.

Background: Pembrolizumab improved survival as first- and second-line therapy compared with chemotherapy in patients with highly programmed death ligand 1 (PD-L1) expressing advanced non-small cell lung cancer (NSCLC). We report the long-term safety and clinical activity of pembrolizumab as first-line therapy for patients with advanced NSCLC and the correlation between PD-L1 expression and efficacy. Patients and methods: In the open-label phase 1b KEYNOTE-001 trial, treatment-naive patients with advanced NSCLC whose tumors expressed PD-L1 (≥1% staining, assessed using a prototype assay) were randomly assigned to intravenous pembrolizumab 2 or 10 mg/kg every 3 (Q3W) or 2 (Q2W) weeks. Response was assessed per central RECIST v1.1 every 9 weeks in all patients who received ≥1 pembrolizumab dose. Using pre-treatment tumor tissue, a clinical assay quantified the percentage of tumor cells expressing PD-L1 as tumor proportion score (TPS). Results: Between 1 March 2013 and 18 September 2015, 101 patients received pembrolizumab 2 mg/kg Q3W (n = 6), 10 mg/kg Q3W (n = 49), or 10 mg/kg Q2W (n = 46). Of these, 27 (26.7%) had TPS ≥50%, 52 (51.5%) had TPS 1%-49%, and 12 (11.9%) had TPS <1%. The objective response rate (ORR) was 27% (27/101, 95% CI 18-37) and median overall survival was 22.1 months (95% CI 17.1-27.2). In patients with PD-L1 TPS ≥50%, ORR, 12-month PFS, and 12-month OS were higher [14/27 (51.9%; 95% CI 32%-71%), 54%, and 85%, respectively] than the overall population [27/101 (26.7%; 95% CI 18.4%-36.5%), 35%, 71%]. Pembrolizumab was well tolerated, with only 12 (11.9%) patients experiencing grade 3/4 treatment-related adverse events and no treatment-related deaths. Conclusions: Pembrolizumab provides promising long-term OS benefit with a manageable safety profile for PD-L1-expressing treatment-naive advanced NSCLC, with greatest efficacy observed in patients with TPS ≥50%. Clinical trial name and number: KEYNOTE-001 (ClinicalTrials.gov, NCT01295827).

Safety and antitumor activity of the anti-PD-1 antibody pembrolizumab in patients with recurrent carcinoma of the anal canal.

Background: Safety and efficacy of pembrolizumab, a humanized programmed death 1 monoclonal antibody, was assessed in KEYNOTE-028, a multicohort, phase Ib trial for patients with programmed death ligand 1 (PD-L1)-positive advanced solid tumors. We report results for the cohort of patients with advanced anal carcinoma. Patients and methods: Patients with PD-L1-positive tumors (≥1%) received intravenous pembrolizumab 10 mg/kg once every 2 weeks for up to 2 years or until confirmed progression or unacceptable toxicity. Response was assessed every 8 weeks for the first 6 months and every 12 weeks thereafter per Response Evaluation Criteria In Solid Tumors, version 1.1. Primary endpoints were safety and overall response rate per investigator review. Secondary endpoints included progression-free survival, overall survival, and response duration. Data cutoff date was 1 July 2015. Results: Of the 43 patients with advanced anal carcinoma evaluable for PD-L1 expression, 32 (74%) had PD-L1-positive tumors as assessed with the 22C3 prototype assay, of whom 25 were enrolled between April and September 2014. Sixteen patients (64%) experienced treatment-related adverse events; the most common ones were diarrhea and fatigue in four patients (16%) each and nausea in three patients (12%). There were no treatment-related deaths or discontinuations as of the data cutoff date. Among the 24 patients with squamous cell carcinoma histology, four had confirmed partial response, for an overall response rate of 17% [95% confidence interval (CI), 5%-37%) and 10 (42%) had confirmed stable disease, for a disease control rate of 58%. One additional patient with non-squamous histology had confirmed stable disease. Conclusion: In this population of patients with PD-L1-positive advanced squamous cell anal carcinoma, pembrolizumab demonstrated a manageable safety profile and encouraging antitumor activity. These data support further study of pembrolizumab for this patient population. ClinicalTrials.gov: NCT02054806.

Critical values: ASCP practice parameter. American Society of Clinical Pathologists.

Appropriate use of critical values improves patient outcome by ensuring that physicians are promptly notified of immediate life-threatening conditions. Conversely, overuse squanders resources and actually may impair patient outcome. A generic critical values list derived from interlaboratory surveys is an excellent starting point, but every laboratory must customize its list to meet the needs of the organization that it serves. Category-specific and once-per-period critical values can limit superfluous reporting, but they make the critical values list more complicated. Strict semantic interpretation of critical limits is appropriate. The best ways to report critical values are by telephone and by alphanumeric pager. When required, repeat analysis should precede critical value reporting. Laboratories should avoid reporting invalid results (due to poor specimen integrity, for example) as critical values. An institutional committee initially should approve, and periodically should review and revise, the critical values policy.

Laboratory diagnosis and monitoring of diabetes mellitus.

The American Diabetes Association emphasizes fasting plasma glucose (FPG) levels, rather than the oral glucose tolerance test (OGTT), to diagnose diabetes mellitus. The diagnostic cutoff for FPG is 126 mg/dL (7.0 mmol/L). A 2-hour plasma glucose level of 200 mg/dL (11.1 mmol/L) or more during an OGTT or a random plasma glucose level of 200 mg/dL (11.1 mmol/L) or more also is diagnostic of diabetes. The 100-g, 3-hour OGTT remains the "gold standard" for gestational diabetes mellitus (GDM). Two of 4 samples exceeding cutoffs (fasting, > or = 105 mg/dL [5.8 mmol/L]; 1 hour, > or = 190 mg/dL [10.5 mmol/L]; 2 hours, > or = 165 mg/dL [9.2 mmol/L]; 3 hours, > or = 145 mg/dL [8.0 mmol/L]) indicate GDM. An effective GDM screening test is plasma glucose 1 hour after a 50-g oral glucose load. Tight control, which requires self-monitoring of blood glucose, reduces microvascular complications for patients with type 1 or type 2 diabetes. Patients with well-controlled diabetes have glycohemoglobin concentrations of 7% AIc (0.07 AIc/A) or less. Microalbuminuria indicates early, reversible, diabetic nephropathy. The random urine albumin-creatinine ratio is a convenient effective screening test. Albumin-creatinine ratios in the 0.03 to 0.30 (g/g) range indicate microalbuminuria.

Sensitivity, specificity, and reproducibility of four measures of laboratory turnaround time.

The authors studied the performance of four measures of laboratory turnaround time: the mean, median, 90th percentile, and proportion of tests reported within a predetermined cut-off interval (proportion of acceptable tests [PAT]). Measures were examined with the use of turnaround time data from 11,070 stat partial thromboplastin times, 16,761 urine cultures, and 28,055 stat electrolyte panels performed by a single laboratory. For laboratories with long turnaround times, the most important quality of a turnaround time measure is high reproducibility, so that improvement in reporting speed can be distinguished from random variation resulting from sampling. The mean was found to be the most reproducible of the four measures, followed by the median. The mean achieved acceptable precision with sample sizes of 100-500 tests. For laboratories with normally rapid turnaround times, the most important quality of a measure is high sensitivity and specificity for detecting whether turnaround time has dropped below standards. The PAT was found to be the best measure of turnaround time in this setting but required sample sizes of at least 500 tests to achieve acceptable accuracy. Laboratory turnaround time may be measured for different reasons. The method of measurement should be chosen with an eye toward its intended application.

Immunohistologic demonstration of myocardial proteins with applications.

The authors used antibodies specific for creatine kinase MB isoenzyme (CK-MB) and myosin light chain-1 (MLC-1) for immunohistologic staining. At appropriate dilutions of antibody, frozen sections of human heart muscle were positive for both CK-MB and MLC-1, whereas sections of human skeletal muscle were negative for both proteins. Staining for both CK-MB and MLC-1 also was demonstrated in an immature teratoma. Furthermore, staining was localized to the rhabdomyosarcomatous elements within the teratoma; other components of the tumor did not stain for CK-MB or MLC-1. Biopsies of skeletal muscle revealed that regenerative, but not intact normal or degenerating, fibers also contained CK-MB and MLC-1. Immunohistologic stains for CK-MB and MLC-1 may be useful as tumor markers and as markers for regenerative muscle fibers.

An algorithm for finding the linear region in a nonlinear data set.

Finding the linear reportable range is an important procedure for each method in clinical chemistry. One is often called upon to limit the reportable range in order to find the linear region. Limiting the reportable range by visual techniques is subjective, may introduce bias and is not programmable. Using Kroll and Emancipator's polynomial method for linearity, we compare the residuals of a test to determine whether eliminating a point from one end or the other of the data set worsens or improves the data sets' linearity. In an example of urinary cortisol, the root mean squares of the residuals improve by 2% when the lowest point is removed, 39% when the highest point is removed and 82% when the two highest points are removed. The latter data set is the most linear.

Low bias in assayed values of lipoprotein antigens--lipoprotein(a) and apolipoproteins A-I and B--in midday postprandial blood specimens compared with morning fasting specimens.

Two-hour postprandial specimens have a -14% proportional bias for lipoprotein(a) [Lp(a)], a -0.035 g/L systematic bias for apolipoprotein (apo) A-I, and a -9% proportional bias for apo B, compared with values in 12-h fasting specimens. Although a physiological hemodilution appears to account for a portion of these biases, other major factors must be implicated for Lp(a) and apo B. Even after dilutional effects are controlled for, assayed values of Lp(a) are 11-13% lower, and assayed values of apo B are 8-9% lower, in postprandial specimens than in fasting specimens. Therefore, the time of collection of a blood sample relative to the last meal can significantly affect assayed values of lipoprotein antigens. Further studies are needed to determine whether these observations result from a physiological sequestering of lipoproteins in the postprandial state or from negative interferences affecting the assays of lipoprotein antigens.

A quantitative measure of nonlinearity.

Quantitative measures of the nonlinearity of an analytical method are defined as follows: the "(dimensional) nonlinearity" of a method is the square root of the mean of the square of the deviation of the response curve from a straight line, where the straight line is chosen to minimize the nonlinearity. The "relative nonlinearity" is defined as the dimensional nonlinearity divided by the difference between the maximum and minimum assayed values. These definitions may be used to develop practical criteria for linearity that are still objective. Calculation of the nonlinearity requires a method of curve-fitting. In this article, we use polynomial regression to demonstrate calculations, but the definition of nonlinearity also accommodates alternative nonlinear regression procedures.

A theoretical evaluation of linearity.

The measure of linearity is an important part of the evaluation of a method. According to the NCCLS guidelines (Document EP6-P), results of a linearity experiment are fit to a straight line and judged linear either by visual evaluation, which is subjective, or by the lack-of-fit test. This approach depends on the precision of the method, is not necessarily conclusive, and fails to be quantitative. We define linearity as a measure of how well a first-order (linear) polynomial fits the data compared with a higher-order (nonlinear) polynomial. The major property of a linear polynomial is that the first derivative is a constant. The nonlinearity of a method can be measured by the difference between these two polynomials (first-order and higher-order) at specific values or, as an average, the root-mean difference. This approach is independent of the precision of the assay and is conclusive, quantitative, and objective.

Bromide interference: is less really better?

Increased serum bromide may result from the ingestion of various drugs and from environmental exposures. Chloride methods that are less susceptible to bromide interference have a clinical disadvantage in that they are less likely to arouse suspicion in cases of bromide toxicity. When there is a clinical suspicion of bromide toxicity, differences among various analyzers in the amount of interference caused by bromide may be exploited to confirm this suspicion and to estimate the concentration of bromide in serum.

Analytical versus clinical sensitivity and specificity in pregnancy testing.

A typical urine pregnancy test with the enzyme-linked immunoassay for human chorionic gonadotropin (Tandem Icon human chorionic gonadotropin) was performed as was a qualitative serum radioimmunoassay for human chorionic gonadotropin when the positive cutoff for the latter was set at 30 IU/L. There was 99.5% concordance between the two methods when performed on 871 simultaneous urine and serum specimens. Although the serum radioimmunoassay can detect levels of human chorionic gonadotropin as low as 10 IU/L, in this study the majority of patients with serum levels between 10 and 30 IU/L were not pregnant on clinical follow-up. Of nine patients with adequate clinical follow-up, a negative urine pregnancy test result, and a serum human chorionic gonadotropin level between 10 and 30 IU/L, only one proved to be pregnant. The Tandem Icon human chorionic gonadotropin urine test is sufficient for routine pregnancy testing and to rule out the need for immediate intervention in cases of ectopic pregnancy.

Comparison of two automated nephelometers.

The intercalibration precision and linearity were determined for two representative analytes, apolipoprotein A1 (apo A1) and immunoglobulin G (IgG), on the Beckman Array and the Behring Nephelometer 100 (BN-100). For two of nine samples analyzed, poor precision was observed for IgG with the Array. The poor precision for these two samples is attributed to large systematic shifts. A statistical non-linearity was observed for apo A1 with the BN-100, but this non-linearity does not exclude use of this assay for clinical diagnosis. Method comparisons were done for 12 analytes: apo A1, apo B, IgG, IgA, IgM, IgE, C3, C4, albumin, C-reactive protein, alpha-1-antitrypsin, and ceruloplasmin. These comparisons showed proportional biases of > 10% for seven of 12 analytes. Furthermore, correlation coefficients were < 0.96 for seven of 12 analytes. We conclude that comparing results obtained from the two different nephelometers is of only limited value for the individual patient.

In vitro inactivation of bacterial endotoxin by human lipoproteins and apolipoproteins.

A chromogenic Limulus amebocyte lysate assay was used to measure the recovery of 1 endotoxin unit of endotoxin per ml. Purified human high-density lipoprotein, low-density lipoprotein, and apolipoprotein A1 (apo A1) at a maximum concentration of 1 g of protein per liter reduced the recovery to less than 40% of baseline in a both dose- and time-dependent manner and in the absence of other serum components. Furthermore, the lapine fever response to a dose of 1 ml of 5-ng/ml endotoxin per kg was reduced by greater than 0.5 degrees C (P less than 0.005) when the solution was preincubated in vitro with 0.5 g of apo A1 per liter. By the Limulus test, a maximum concentration of 0.01 g of apolipoprotein B (apo B) per liter (which contained deoxycholate, a known endotoxin-disaggregating agent) reduced recovery to 0% in a dose- but not time-dependent manner. In heat-inactivated (56 degrees C, 1 h) normal human serum, high-density lipoprotein cholesterol (P less than 0.005) and apo A1 (P less than 0.05) correlated inversely with endotoxin recovery, but, paradoxically, apo B correlated directly with endotoxin recovery (P less than 0.05), while low-density lipoprotein cholesterol showed no significant correlation. INTRALIPID alone had no effect on endotoxin recovery. Addition of a maximum of 10 g of INTRALIPID per liter to 0.0042 g of apo B per liter increased endotoxin recovery from approximately 30 to 80% (P less than 0.001), but addition of INTRALIPID to 0.25 g of apo A1 per liter decreased recovery from approximately 30 to 20% (P less than 0.001). We conclude that (i) lipoproteins are endotoxin inactivators; (ii) this ability of lipoproteins may be modulated by their lipid component (lipid-endotoxin interaction); (iii) apo A1 is capable of directly inactivating endotoxin (protein-endotoxin interaction).

Diagnosis of ectopic pregnancy by the rate of increase of choriogonadotropin in serum: diagnostic criteria compared.

We compare three methods for using the rate of change of human choriogonadotropin (hCG) concentration in serum to diagnose ectopic pregnancy. With Method I, the lower limit for the rate of increase of serum hCG in normal pregnancy is 66% per 48 h. With Method II, a different lower limit of normal is specified for each of four discrete sampling intervals of hCG. With Method III, the lower limit of normal is determined by a continuous discriminant function of the initial hCG concentration. If the initial hCG concentration is less than or equal to 2000 int. units/L (Second International Standard), all three methods have acceptable diagnostic efficiencies, and there are no statistically significant differences among conclusions from the methods. None of the three methods performs satisfactorily if the initial hCG concentration is greater than 2000 int. units/L. We recommend Method I because it is simpler than the other two.

Secretion of creatine kinase MB isoenzyme by an immature teratoma with predominant rhabdomyosarcomatous elements.

A 37-year-old man with metastatic immature (malignant) teratoma with prominent rhabdomyosarcomatous elements had markedly increased activity of creatine kinase (EC 2.7.3.2) MB in serum. There was no electrocardiographic evidence of infarction or ischemia, and autopsy revealed no myocardial infarction, significant coronary atherosclerosis, myocarditis, or invasion of the heart by tumor. A high proportion of the creatine kinase activity in a homogenate of the tumor was attributable to the MB isoenzyme. Persistent increases of creatine kinase-MB and an unusually high MB isoenzyme activity, out of proportion to total creatine kinase activity, may indicate a nonmyocardial origin of this isoenzyme.

Hidden and classical 19S IgM rheumatoid factor in a juvenile rheumatoid arthritis patient.

Hidden 19S IgM rheumatoid factors (RF), i.e., 19S IgM RF which can be detected in the IgM containing fraction after acid gel filtration of serum, are found in 59-68% of patients with juvenile rheumatoid arthritis (JRA). Their presence generally correlates with disease activity. We describe a 12 year-old female with a polyarticular onset of JRA who, during her first 15 months of disease, was seronegative but had hidden RF titers of 1:128----1:256. Inhibition studies on her hidden RF showed specificity for HIgG greater than RIgG and equal specificity for the human IgG subclasses (IgG1 = IgG3). In the second and third year of disease, she became seropositive with RF titers varying from 1:40 to 1:320 while her hemolytic titers on her IgM fractions were decreased from 1:128 to 1:32. Inhibition studies now demonstrated a higher avidity for RIgG; and HIgG3 inhibited more than HIgG1. These studies documented for the first time a JRA patient who early in the disease was negative for RF and positive for hidden RF, and who later became seropositive.