Clinical efficacy of atezolizumab plus bevacizumab and chemotherapy in KRAS-mutated non-small cell lung cancer with STK11, KEAP1, or TP53 comutations: subgroup results from the phase III IMpower150 trial

Background

The efficacy of atezolizumab (A) and/or bevacizumab (B) with carboplatin/paclitaxel (CP) chemotherapy was explored in the phase III, randomized IMpower150 study in patients with non-squamous non-small cell lung cancer (NSCLC) according to KRAS mutations (mKRAS) and co-occurring STK11, KEAP1, or TP53 mutations.

Methods

Mutation status was determined by circulating tumor DNA next-generation sequencing. Overall survival (OS) and progression-free survival (PFS) were analyzed in a mutation-evaluable intention-to-treat population (MEP; n=920) and SP263 (programmed cell death ligand 1 (PD-L1)) biomarker-evaluable population (n=774).

Results

Within the mKRAS population (24.5% of MEP), ABCP showed numerical improvements vs BCP in median OS (19.8 vs 9.9 months; HR 0.50; 95% CI 0.34 to 0.72) and PFS (8.1 vs 5.8 months; HR 0.42; 95% CI 0.29 to 0.61)—greater than with ACP (OS: 11.7 vs 9.9 months; HR 0.63; 95% CI 0.43 to 0.91; PFS: 4.8 vs 5.8 months; HR 0.80; 95% CI 0.56 to 1.13) vs BCP. Across PD-L1 subgroups in mKRAS patients, OS and PFS were longer with ABCP vs BCP, but OS with ACP was similar to BCP in PD-L1-low and PD-L1-negative subgroups. Conversely, in KRAS-WT patients, OS was longer with ACP than with ABCP or BCP across PD-L1 subgroups. KRAS was frequently comutated with STK11, KEAP1, and TP53; these subgroups conferred different prognostic outcomes. Within the mKRAS population, STK11 and/or KEAP1 mutations were associated with inferior OS and PFS across treatments compared with STK11-WT and/or KEAP1-WT. In mKRAS patients with co-occurring mSTK11 and/or mKEAP1 (44.9%) or mTP53 (49.3%), survival was longer with ABCP than with ACP or BCP.

Conclusions

These analyses support previous findings of mutation of STK11 and/or KEAP1 as poor prognostic indicators. While clinical efficacy favored ABCP and ACP vs BCP in these mutational subgroups, survival benefits were greater in the mKRAS and KEAP1-WT and STK11-WT population vs mKRAS and mKEAP1 and mSTK11 population, suggesting both prognostic and predictive effects. Overall, these results suggest that atezolizumab combined with bevacizumab and chemotherapy is an efficacious first-line treatment in metastatic NSCLC subgroups with mKRAS and co-occurring STK11 and/or KEAP1 or TP53 mutations and/or high PD-L1 expression.

831 Exact Shapley values for explaining complex machine learning based molecular tests of checkpoint inhibitors: potential utility for patients, physicians, and translational research

Background

Modern machine learning (ML) models based on highly multivariate attribute sets (e.g. unbiased -omics data) can be very successful at generating clinically useful predictions, but at the price of less transparency in how individual attributes are used to make those predictions. In short, ML test algorithms tend to be ”black boxes”. Shapley values (SVs)1 describe the relative importance of the attributes used within a multivariate test to the generation of the test result for an individual patient.2 While typically the calculation of SVs is computationally prohibitive, our ML architecture permits the generation of SVs for large patient cohorts. In this study, we evaluate SVs for the Anti-PD-L1 Response Test (ART), that was shown in independent validation to predict outcomes for patients treated with atezolizumab,3 for the POPLAR Ph2 and OAK Ph3 studies of non-small cell lung cancer (NSCLC) patients .4 5

Abstract 831 Figure 1

Radar plots illustrating the values of the 10 most important SVs for test classification generation for two samples classified as poor (A and B) and two samples classified as good (C and D). Positive SVs are shown in red and negative SVs are shown in blue

Abstract 831 Figure 2

Heatmaps of the SVs for samples classified as poor showing two subgroups (top and bottom, separated by horizontal line) with different patterns of SVs for (A) POPLAR and (B) OAK

Abstract 831 Figure 3

Heatmaps of the SVs for samples classified as good showing three subgroups, top, middle, and bottom, separated by horizontal lines) with different patterns of SVs for (A) POPLAR and (B) OAK

Methods

ART results, Good or Poor had been produced for 262 patients in POPLAR (NCT01903993) and 786 patients in OAK (NCT02008227). Exact SVs were generated for each pretreatment serum sample for each of the 93 attributes (proteomic features) used in the test. The distribution of SVs across the cohort was investigated to assess the relative importance of each feature to test classification. Subgroups of patients with similar patterns of SVs were identified using t-sne plots and ML methods in the POPLAR cohort and validated in the OAK cohort.

Results

The SV distributions showed that the features influencing ART classification most were similar in both POPLAR and OAK. The relative importance of features to test classification differed between patients (figure 1), but subgroups of patients within test classification groups showed similar patterns of SVs (figures 2 and 3). Such patient subgroups, identified within POPLAR, were also found in the OAK cohort and were associated with differences in outcome and/or differences in patient characteristics.

Conclusions

SVs can explain how complex ML-based tests combine molecular attributes to produce individual patient results. Exact SVs can be obtained for certain ML architectures used in molecular test development, revealing the overall relative importance of attributes used in such molecular tests. Subgrouping of patients with the same test classification by different patterns of SVs is possible. This may reveal different biologies contributing to a Good or Poor phenotype and inform translational studies.

Trial Registration

ClinicalTrials

gov NCT01903993 and NCT02008227

References

Shapley L. A value for n-person games. Contributions to the Theory of Games. 1953;2.28:307–317.

Roder J, Maguire L, Georgantas R, Roder H. Explaining multivariate molecular diagnostic tests via Shapley values. BMC Med Inform Decis Mak 2021;21(1):211.

Kowanetz M, Leng N, Roder J, et al. Evaluation of immune-related markers in the circulating proteomic and their association with atezolizumab efficacy in patients with 2L+ NSCLC. J Immunother Cancer 2018;6(Suppl1):114.

Fehrenbacher L, Spira A, Ballinger M, et al. Atezolizumab versus docetaxel for patients with previously treated non-small-cell lung cancer (POPLAR): a multicentre, open-label, phase 2 randomised controlled trial. Lancet 2016;387(10030):1837–1846.

Rittmeyer A, Barlesi F, Waterkamp D, et al. Atezolizumab versus docetaxel in patients with previously treated non-small-cell lung cancer (OAK): a phase 3, open-label, multicenter randomized controlled trial. Lancet 2017;389(10066):255–265.

Ethics Approval

The OAK study that was done in 194 academic medical centers and community oncology practices across 31 countries worldwide. The study was done in full accordance with the guidelines for Good Clinical Practice and the Declaration of Helsinki. All patients gave written informed consent.The POPLAR trial was done at 61 academic medical centers and community oncology practices across 13 countries in Europe and North America. The study was done in full accordance with the guidelines for Good Clinical Practice and the Declaration of Helsinki. Protocol (and modification) approval was obtained from anindependent ethics committee for each site. Patients gave written informed consent.

26 Validation of the Primary Immune Response (PIR) test in advanced non-small cell lung cancer (NSCLC): blinded retrospective analyses from the POPLAR and OAK trials

Background

Biomarkers of immune checkpoint inhibitor (ICI) efficacy can be used for patient selection. PD-L1 expression in tumor tissue is used to determine eligibility for combination or monotherapy in 1st line NSCLC.1, 2 The liquid-biopsy mass spectrometry-based PIR test was developed to capture the role of patient biology on ICI outcomes.3 The test, stratifying patients into Resistant, Intermediate, and Sensitive groups, was associated with outcome on nivolumab treatment in 2nd line NSCLC patients.3 In this study, we blind validated PIR classifications in two large clinical studies (POPLAR4 and OAK5) of advanced NSCLC patients treated in the second or third line with atezolizumab.

Methods

Pretreatment serum samples from patients assigned to receive atezolizumab in the two studies (POPLAR (NCT01903993) and OAK (NCT02008227)) underwent PIR testing blinded to all clinical data. Association of test classification, as Sensitive vs Not Sensitive (Resistant+Intermediate) and Resistant vs Not Resistant (Sensitive+Intermediate), with overall survival (OS) and progression-free survival (PFS) was investigated using Cox proportion hazards models in univariate and multivariate analysis.

Results

PIR classifications were generated for 133 (POPLAR) and 403 (OAK) samples; the remaining available samples failed test QC, mainly due to hemolysis. PIR classified the POPLAR samples as 53 (40%) Resistant, 25 (19%) Intermediate, 55 (41%) Sensitive and the OAK samples as 154 (38%) Resistant, 89 (22%) Intermediate, and 160 (40%) Sensitive. In both cohorts, OS and PFS were better in the Not Resistant vs Resistant group (figure 1). OS and PFS were superior in the Sensitive vs Not Sensitive group in the POPLAR cohort, while OS was better and PFS showed indications of superiority in the OAK cohort (figure 2). Multivariate analysis within the OAK cohort showed that test classification predicted OS when adjusted for baseline factors, including PD-L1 negative vs positive, with hazard ratio 0.51 (95% confidence interval (CI) 0.40–0.65) for Resistant vs Not Resistant and 0.65 (CI: 0.50–0.83) for Sensitive vs Not Sensitive.

Abstract 23 Figure 1

Kaplan-Meier plots of OS and PFS by test classification Resistant vs Not Resistant for the POPLAR and OAK cohorts

Abstract 23 Figure 2

Kaplan-Meier plots of OS and PFS by test classification Not Sensitive vs Sensitive for the POPLAR and OAK cohorts

Conclusions

The PIR test stratified outcomes for patients treated with atezolizumab in second and third line NSCLC even when adjusted for PD-L1 expression. The combination of both tumor and host biomarkers appears to provide a more specific prognosis of NSCLC treated with ICIs.

Trial Registration clinicaltrials.gov NCT01903993 and NCT02008227

References

Roy S Herbst, Giuseppe Giaccone, Filippo de Marinis et al. Atezolizumab for first-line treatment of PD-L1-selected patients with NSCLC. N Engl J Med 2020 Oct 1;383(14):1328–1339

Tony S K Mok, Yi-Long Wu, Iveta Kudaba et al. Pembrolizumab versus chemotherapy for previously untreated, PD-L1-expressing, locally advanced or metastatic non-small-cell lung cancer (KEYNOTE-042): a randomised, open-label, controlled, phase 3 trial. Lancet 2019 May 4;393(10183):1819–1830.

Muller M, Hummelink K, Hurkmans D, et al. A serum protein classifier identifying patients with advanced non-small cell lung cancer who derive clinical benefit from treatment with immune checkpoint inhibitors. Clin Cancer Res 2020;26(19):5188–5197.

Fehrenbacher L, Spira A, Ballinger M, et al. Atezolizumab versus docetaxel for patients with previously treated non-small-cell lung cancer (POPLAR): a multicentre, open-label, phase 2 randomised controlled trial. Lancet 2016;387(10030):1837–1846.

Rittmeyer A, Barlesi F, Waterkamp D, et al. Atezolizumab versus docetaxel in patients with previously treated non-small-cell lung cancer (OAK): a phase 3, open-label, multicenter randomized controlled trial. Lancet 2017;389(10066):255–265.

Ethics Approval

The OAK study was done in 194 academic medical centers and community oncology practices across 31 countries worldwide. The study was done in full accordance with the guidelines for Good Clinical Practice and the Declaration of Helsinki. All patients gave written informed consent.The POPLAR trial was done at 61 academic medical centers and community oncology practices across 13 countries in Europe and North America. The study was done in full accordance with the guidelines for Good Clinical Practice and the Declaration of Helsinki. Protocol (and modification) approval was obtained from an independent ethics committee for each site. Patients gave written informed consent.

28 Predictions of outcomes and benefit of immune checkpoint inhibitor treatment in NSCLC require information on both tumor and host biology

Background

Immunotherapy has become a key element in the arsenal of treatments for advanced non-small cell lung cancer (NSCLC). The anti-PD-L1 Response Test (ART), based on mass spectrometry of pretreatment serum, captures the effect of host biology on outcomes after atezolizumab (A) therapy. It stratified outcomes on A and was predictive of benefit of A over docetaxel (D) in a blinded, retrospective study of 2nd and 3rd line NSCLC patients in the POPLAR Ph2 clinical study.1 Our current work applies the test to the larger OAK NSCLC Ph3 clinical study2 to investigate the interplay between tumor PD-L1 expression and ART classifications in predicting outcomes and benefit from A therapy.

Methods

Pretreatment serum samples from 823 of the 850 patients in the OAK study (NCT02008227) were analyzed with ART blinded to all clinical data. The ART assigns a result of Good or Poor corresponding to better or worse outcomes on A. Association of test classification with overall survival (OS) within and between treatment arms was investigated using Cox proportion hazards models overall and within PD-L1 subgroups defined by SP142 assay.3

Results

Test classifications were generated for 786 (96%) samples; the remaining samples failed test QC, mainly due to hemolysis. A Good classification was assigned to 359 (46%) samples and a Poor classification to 427 (54%) samples. Overall, OS was better for the Good subgroup than the Poor subgroup within both arms, arm A (hazard ratio (HR)=0.52 (95% Confidence Interval (CI): 0.41–0.66)) and arm D (HR=0.54 (CI:0.43–0.68)). The test was not predictive of benefit of A over D, but was prognostic for both A and D. Patients classified as Good had better outcomes than those classified as Poor in both treatment arms for all PD-L1 subgroups investigated (figure 1). Benefit of A vs D was found in both test classification groups for PD-L1 positive patients (table 1).

Abstract 28 Figure 1

Kaplan-Meier plots of OS by test classification, Good and Poor, and treatment arm, A and D, within PD-L1 subgroups

Abstract 28 Table 1

Hazard ratios between A and D by test classification group and PD-L1 subgroup

Conclusions

Information on both tumor and host are essential to predict outcomes of immunotherapy and chemotherapy in NSCLC patients.

Trial Registration

ClinicalTrials.

gov NCT02008227

References

Kowanetz M, Leng N, Roder J, et al. Evaluation of immune-related markers in the circulating proteomic and their association with atezolizumab efficacy in patients with 2L+ NSCLC. J Immunother Cancer 2018;6(Suppl1):114.

Rittmeyer A, Barlesi F, Waterkamp D, et al. Atezolizumab versus docetaxel in patients with previously treated non-small-cell lung cancer (OAK): a phase 3, open-label, multicenter randomized controlled trial. Lancet 2017;389(10066):255–265.

Herbst R, Giaccone G, de Marinis F, et al. Atezolizumab for first-line treatment of PD-L1-selected patients with NSCLC. N Engl J Med 2020;383:1328–1339.

Ethics Approval

The OAK study (NCT02008227) was done in 194 academic medical centres and community oncology practices across 31 countries worldwide. The study was done in full accordance with the guidelines for Good Clinical Practice and the Declaration of Helsinki. All patients gave written informed consent.

Oncogene-specific differences in tumor mutational burden, PD-L1 expression, and outcomes from immunotherapy in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) patients bearing targetable oncogene alterations typically derive limited benefit from immune checkpoint blockade (ICB), which has been attributed to low tumor mutation burden (TMB) and/or PD-L1 levels. We investigated oncogene-specific differences in these markers and clinical outcome.

METHODS

Three cohorts of NSCLC patients with oncogene alterations (n=4189 total) were analyzed. Two clinical cohorts of advanced NSCLC patients treated with ICB monotherapy [MD Anderson (MDACC; n=172) and Flatiron Health-Foundation Medicine Clinico-Genomic Database (CGDB; n=894 patients)] were analyzed for clinical outcome. The FMI biomarker cohort (n=4017) was used to assess the association of oncogene alterations with TMB and PD-L1 expression.

RESULTS

High PD-L1 expression (PD-L1 ≥50%) rate was 19%-20% in classic EGFR, EGFR exon 20 and HER2-mutant tumors, and 34%-55% in tumors with ALK, BRAF V600E, ROS1, RET, or MET alterations. Compared with KRAS-mutant tumors, BRAF non-V600E group had higher TMB (9.6 vs KRAS 7.8 mutations/Mb, p=0.003), while all other oncogene groups had lower TMB (p<0.001). In the two clinical cohorts treated with ICB, molecular groups with EGFR, HER2, ALK, ROS1, RET, or MET alterations had short progression-free survival (PFS; 1.8-3.7 months), while BRAF V600E group was associated with greater clinical benefit from ICB (CGDB cohort: PFS 9.8 months vs KRAS 3.7 months, HR 0.66, p=0.099; MDACC cohort: response rate 62% vs KRAS 24%; PFS 7.4 vs KRAS 2.8 months, HR 0.36, p=0.026). KRAS G12C and non-G12C subgroups had similar clinical benefit from ICB in both cohorts. In a multivariable analysis, BRAF V600E mutation (HR 0.58, p=0.041), PD-L1 expression (HR 0.57, p=0.022), and high TMB (HR 0.66, p<0.001) were associated with longer PFS.

CONCLUSIONS

High TMB and PD-L1 expression are predictive for benefit from ICB treatment in oncogene-driven NSCLCs. NSCLC harboring BRAF mutations demonstrated superior benefit from ICB that may be attributed to higher TMB and higher PD-L1 expression in these tumors. Meanwhile EGFR and HER2 mutations and ALK, ROS1, RET, and MET fusions define NSCLC subsets with minimal benefit from ICB despite high PD-L1 expression in NSCLC harboring oncogene fusions. These findings indicate a TMB/PD-L1-independent impact on sensitivity to ICB for certain oncogene alterations.

Molecular determinants of response to PD-L1 blockade across tumor types

Immune checkpoint inhibitors targeting the PD-1/PD-L1 axis lead to durable clinical responses in subsets of cancer patients across multiple indications, including non-small cell lung cancer (NSCLC), urothelial carcinoma (UC) and renal cell carcinoma (RCC). Herein, we complement PD-L1 immunohistochemistry (IHC) and tumor mutation burden (TMB) with RNA-seq in 366 patients to identify unifying and indication-specific molecular profiles that can predict response to checkpoint blockade across these tumor types. Multiple machine learning approaches failed to identify a baseline transcriptional signature highly predictive of response across these indications. Signatures described previously for immune checkpoint inhibitors also failed to validate. At the pathway level, significant heterogeneity is observed between indications, in particular within the PD-L1⁺ tumors. mUC and NSCLC are molecularly aligned, with cell cycle and DNA damage repair genes associated with response in PD-L1- tumors. At the gene level, the CDK4/6 inhibitor CDKN2A is identified as a significant transcriptional correlate of response, highlighting the association of non-immune pathways to the outcome of checkpoint blockade. This cross-indication analysis reveals molecular heterogeneity between mUC, NSCLC and RCC tumors, suggesting that indication-specific molecular approaches should be prioritized to formulate treatment strategies.

Comparison of SP142 and 22C3 Immunohistochemistry PD-L1 Assays for Clinical Efficacy of Atezolizumab in Non-Small Cell Lung Cancer: Results From the Randomized OAK Trial

BACKGROUND

This phase III OAK trial (NCT02008227) subgroup analysis (data cutoff, January 9, 2019) evaluated the predictive value of 2 PD-L1 IHC tests (VENTANA SP142 and Dako 22C3) for benefit from atezolizumab versus docetaxel by programmed death ligand 1 (PD-L1) status in patients with previously treated metastatic non-small cell lung cancer.

METHODS

PD-L1 expression was assessed prospectively with SP142 on tumor cells (TC) and tumor-infiltrating immune cells (IC) and retrospectively with 22C3 using a tumor proportion score (TPS) based on TC membrane staining. Efficacy was assessed in the 22C3 biomarker-evaluable population (22C3-BEP) (n = 577; 47.1% of SP142-intention-to-treat population) and non-22C3-BEP (n = 648) in PD-L1 subgroups (high, low, and negative) and according to selection by 1 or both assays.

RESULTS

In the 22C3-BEP, overall survival benefits with atezolizumab versus docetaxel were observed across PD-L1 subgroups; benefits were greatest in SP142-defined PD-L1-high (TC3 or IC3: hazard ratio [HR], 0.39 [95% confidence interval (CI), 0.25-0.63]) and 22C3-defined PD-L1-high (TPS ≥ 50%: HR, 0.56 [95% CI, 0.38-0.82]) and low (TPS, 1% to < 50%: HR, 0.55 [95% CI, 0.37-0.82]) groups. Progression-free survival improved with increasing PD-L1 expression for both assays. SP142 and 22C3 assays identified overlapping and unique patient populations in PD-L1-high, positive, and negative subgroups. Overall survival and progression-free survival benefits favored atezolizumab over docetaxel in double PD-L1-positive and negative groups; patients with both SP142- and 22C3-positive tumors derived the greatest benefit.

CONCLUSIONS

Despite different scoring algorithms and differing sensitivity levels, the SP142 and 22C3 assays similarly predicted atezolizumab benefit at validated PD-L1 thresholds in patients with non-small cell lung cancer.

Abstract 4055: Late-differentiated effector neoantigen-specific CD8+ T cells are enriched in non-small cell lung cancer patients responding to atezolizumab treatment

There is strong evidence that immunotherapy-mediated tumor rejection can be driven by the reinvigoration of tumor-specific CD8+ T cells recognizing neoantigens derived from tumor somatic mutations (citations). Thus, it is possible that the relative abundance and/or characteristics of these tumor-reactive, mutation-specific CD8+ T cells can be used as predictive biomarkers of response to immunotherapy. However, only a fraction of these potential neoantigens are usually immunogenic and in addition, these tumor-reactive, mutation-specific CD8+ cells are present only at low frequencies in blood, making it difficult to reliably identify these effector cells.

Here, mass cytometry and highly-multiplexed combinatorial tetramer staining together with cellular barcoding was used to profile immune cells in longitudinally collected PBMCs from 14

non-small cell lung cancer (NSCLC) patients treated with anti-PD-L1 (atezolizumab) antibody to compare patients with objective response (n=8) and progressive disease (n=6). Although no significant phenotypic differences were detected in bulk CD8+ T cells, greater insight was gained from a parallel analysis using highly multiplexed peptide-MHC multimer staining to screen and profile antigen-specific T cells.

A longitudinal analysis was performed using peripheral blood CD8+ T cells for 800 candidate tumor neoantigens and 73 known viral-derived control peptides across all patient samples. In addition to virus antigen-specific T cells, a total of 20 different neoantigen-specific T cell populations were detected and their high dimensional profiles were compared. We found that neoantigen-specific T cells were more frequently detected in responding patients and their phenotypes were almost entirely distinct from non-responding patients. Neoantigen-specific T cells from responding patients showed a differentiated effector phenotype with high expression of KLRG1, 2B4 (CD244) and CD57, similar to CD8+ T cells associated with CMV and some types of EBV infection. In contrast, more memory-like phenotypic profiles, with high CD27 and CD127 expression, were observed for neoantigen-specific CD8+ T cells from patients with progressive disease.

In addition to the utility of this approach for the ex vivo identification, characterization, and longitudinal tracking of rare tumor-specific T cells, this study supports further research into assessing whether the presence of late-differentiated neoantigen-specific T cells could be used as a predictor of response to checkpoint blockade.

Citation Format: Mahesh Yadav, Michael Fehlings, Suchit Jhunjhunwala, Bill O'Gorman, Priti Hegde, Leesun Kim, Alessandra Nardin, Susan Flynn, Hermi Sumatoh, Marcus Ballinger, David Shames, Boon Heng Lee, Evan Newell. Late-differentiated effector neoantigen-specific CD8+ T cells are enriched in non-small cell lung cancer patients responding to atezolizumab treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4055.

Characterization of PD-L1 expression in Chinese non-small cell lung cancer patients with PTEN expression as a means for tissue quality screening

The goal of this study is to evaluate PD-L1 prevalence and its association with major clinical characteristics in Chinese non-small cell lung cancer (NSCLC) patients to inform the clinical development of anti-PD1/PD-L1 agents in this population. We used phosphatase and tensin homolog (PTEN) expression through IHC as a surrogate tissue quality marker to screen surgical NSCLC samples in tissue microarray (TMA; 172 cases) or whole-section (268 cases) format. The samples were then analyzed with a clinically validated PD-L1 IHC assay. The results were correlated with baseline characteristics and clinical outcomes. PTEN IHC showed that 108 TMA samples and 105 whole-section samples qualified for PD-L1 IHC. With a clinically relevant cutoff, 41.7% of the TMA samples were PD-L1 positive. PD-L1 level was much lower in EGFR-mutant patients and seemed to be a favorable prognostic factor for both overall survival (OS) and recurrence-free survival (RFS). These findings were confirmed in the whole-section samples except that their survival data were not mature enough for correlation analysis. In summary, PD-L1 expression was detected in approximately 40% of PTEN-qualified Chinese NSCLC samples, negatively correlated with EGFR mutation and seemed to be a favorable prognostic factor for both OS and RFS. Notably, the different results from PTEN-qualified and PTEN-disqualified samples underscore the importance of tissue quality control prior to biomarker testing.

Abstract 490: High-throughput mutational analysis in cell-free DNA by targeted next-generation sequencing

Circulating cell-free DNA (cfDNA) in plasma offers a non-invasive approach to monitor tumor molecular profiling in real-time at multiple time-points, detection of emerging genomic alterations associated with drug resistance and clarifying cancer prognosis and diagnosis of cancer recurrence or progression. We developed a robust, multiplexed and PCR-based targeted next-generation sequencing approach to detect actionable mutations in cfDNA with low DNA input (1-5 ng). We employed the latest Ion TorrentTM S5/XL bench-top sequencer with Ion ChefTM Automation System and successfully automated the entire 2-day workflow from libraries preparation to semi-conducting chip sequencing. The hands-on time has been reduced to only 30 min.

We will present data showing validation of this NGS platform using commercially available DNA control, archival FFPE tissue and cfDNA matched samples and demonstrate robust sensitivity and specificity by using the off-the-shelf Ion AmpliSeq Cancer Hotspot Panel v2 that covers 50 oncogenes. We also compared this approach to other orthogonal technologies, including quantitative PCR (qPCR) and droplet digital PCR (ddPCR) and achieved 100% concordance across these platforms. NGS can detect mutations down to 1% allelic frequency with 100% sensitivity and specificity.

This robust and automated NGS platform is being routinely used in our lab to analyze cell-free DNA samples from multiple clinical trials. These efforts enable the development of a non-invasive method to overcome existing challenges to provide molecular understanding of patient's tumor evolution in real time, and aid in the development of personalized therapies for cancer patients.

Citation Format: Nga wan Rachel Tam, David Shames, Walter Darbonne. High-throughput mutational analysis in cell-free DNA by targeted next-generation sequencing. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 490.

Abstract POSTER-THER-1441: Biomarker evaluation of phase 1 clinical trials of antibody-drug conjugates (ADCs) in platinum resistant ovarian cancer

Purpose: DNIB0600A and DMUC5754A are two ADCs that conjugate the anti-mitotic agent MMAE with anti-NaPi2b and anti-MUC16 monoclonal antibodies, respectively. Both ADCs have shown promising anti-tumor activity in patients with platinum resistant ovarian cancer. Here we report biomarker analysis in patient samples collected from these phase 1 studies. The main goal of this study is to evaluate tissue-based biomarkers that can predict response or resistance to these ADCs. We also explored the utility of serum protein biomarkers and circulating tumor cells (CTCs) as potential surrogates for monitoring treatment response to ADCs and disease progression.

Methods: Biomarker analysis was done on 55 ovarian cancer patients treated with clinically relevant doses (1.8-3.2mg/kg) from DNIB0600A and DMUC5754A Phase 1 studies. Protein and mRNA expression levels of NaPi2b and MUC16 targets were assessed in archival tumor specimen by immunohistochemistry (IHC) and qRT-PCR respectively. Serum collected at baseline and post-treatment were analyzed by CA125 and HE4 ELISA assays as well as by the OLINK 96-plex PEA protein biomarker panel. CTCs at baseline and post-treatment were analyzed using the Veridex CellSearch System.

Results: Target expression in tumor tissues for both NaPi2b and MUC16 measured by IHC and qRT-PCR are concordant. High NaPi2b or MUC16 expression (IHC 2+/3+) was identified in all responders by RECIST criteria (11 from DNIB0600A and 5 from DMUC5754A) for respective target, while no patient from either study with IHC 0 showed RECIST response. In patients treated with DNIB0600A, longitudinal changes in serum CA125 level correlated with RECIST response. Additionally, CTC was detected in 60% of patients at baseline in the DNIB0600A trial, and decreased CTC counts was observed after 1-2 cycles of treatment for two-third of patients. In patients treated with DMUC5754A, circulating CA125 (i.e. extra-cellular domain of MUC16 shed in circulation) is cleared after initial dosing; therefore other ovarian cancer biomarkers including HE4 were assessed. Baseline serum HE4 level correlates well with the tumor burden at pre-treatment in DMUC5754A trial, and showed excellent correlation with RECIST response post-treatment.

Conclusions: Target expression in archival tumor tissues is predictive to clinical response to ADCs. CTC enumeration as well as serum HE4 could be used as potential surrogate biomarkers for monitoring treatment response in ovarian cancer. Further validation of these findings is required.

Citation Format: Yulei Wang, Ron Firestein, Lisa Ryner, Walter Darbonne, Yinghui Guan, Shan Lu, YJ Choi, Yuanyuan Xiao, Paul Polakis, Becky Suttmann, Rupal Desai, Ling Fu, Ola Saad, Kirsten Achilles Poon, Mitch Denker, Vincent Leveque, Teiko Sumiyoshi, Mark Lackner, David Shames, Eric Humke, Daniel Mayslar. Biomarker evaluation of phase 1 clinical trials of antibody-drug conjugates (ADCs) in platinum resistant ovarian cancer [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-THER-1441.

Abstract 4978: Lung cancers regulate the immune suppressor PD-L1 by multiple mechanisms, altering its role in tumor survival

The immune system has multiple mechanisms by which it can eliminate cancer and yet, tumors are able to adapt resistance to host immune surveillance and continue to survive and grow. One critical resistance mechanism involves Programmed cell death 1 ligand 1 (PD-L1, CD274, B7-H1), the predominant ligand for PD-1, an inhibitory receptor expressed on T cells following activation. PD-L1 also binds to B7.1 (CD80), inhibiting its ability to provide an immune stimulatory signal. PD-L1 is expressed broadly on multiple peripheral blood mononuclear cell subtypes, placenta, and numerous cancers, including NSCLC. Tumor-specific T cells infiltrate tumors and recognize tumor cells, releasing Interferon-gamma (IFNγ), initiating signaling of the Janus kinase/Signal Transducer and Activator of Transcription (JAK/STAT) pathway in the tumor cells. IFNγ induces and/or greatly enhances the expression of PD-L1 in the tumor, among other cell types, allowing the tumor to become resistant to the host T cell response. Blockade of PD-L1 binding to PD-1 and B7.1 can reinvigorate the host immune response against the tumor and overcome tumor adaptive resistance. The regulation of PD-L1 expression is complex and likely involves multiple types of pre- and post-translational events. We show that basal PD-L1 expression levels can vary greatly in cancer cells, as can PD-L1 induction by IFNγ. Here we describe the different categories of PD-L1 basal expression and IFNγ–dependent regulation across multiple lung cell lines and human tumor samples. Reverse Phase Protein Array and RNA microarray data show that the JAK/STAT canonical pathways are still intact among all of these distinct categories, so alternative mechanisms of expression regulation must be active in these cell lines and tumor samples. We provide evidence that a combination of mechanisms regulate both the basal and stimulated expression levels of PD-L1 across these distinct categories. This data regarding PD-L1 expression regulation provides valuable information to better understand the PD-1/PD-L1 pathway as a therapeutic target.

Citation Format: Edward (Ward) E. Kadel, Kimberly Walter, Rupal Desai, Juliet Carbon, Marigold Boe, David Shames, Marcin Kowanetz. Lung cancers regulate the immune suppressor PD-L1 by multiple mechanisms, altering its role in tumor survival. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4978. doi:10.1158/1538-7445.AM2013-4978

Lactate dehydrogenase B is required for the growth of KRAS-dependent lung adenocarcinomas

PURPOSE

This study is aimed to identify genes within the KRAS genomic amplicon that are both coupregulated and essential for cell proliferation when KRAS is amplified in lung cancer.

EXPERIMENTAL DESIGN

We used an integrated genomic approach to identify genes that are coamplified with KRAS in lung adenocarcinomas and subsequently preformed an RNA interference (RNAi) screen to uncover functionally relevant genes. The role of lactate dehydrogenase B (LDHB) was subsequently investigated both in vitro and in vivo by siRNA and short hairpin RNA (shRNA)-mediated knockdown in a panel of lung adenocarcinoma cells lines. LDHB expression was also investigated in patient tumors using microarray and immunohistochemistry analyses.

RESULTS

RNAi-mediated depletion of LDHB abrogated cell proliferation both in vitro and in xenografted tumors in vivo. We find that LDHB expression correlates to both KRAS genomic copy number gain and KRAS mutation in lung cancer cell lines and adenocarcinomas. This correlation between LDHB expression and KRAS status is specific for lung cancers and not other tumor types that harbor KRAS mutations. Consistent with a role for LDHB in glycolysis and tumor metabolism, KRAS-mutant lung tumors exhibit elevated expression of a glycolysis gene signature and are more dependent on glycolysis for proliferation compared with KRAS wild-type lung tumors. Finally, high LDHB expression was a significant predictor of shorter survival in patients with lung adenocarcinomas.

CONCLUSION

This study identifies LDHB as a regulator of cell proliferation in a subset of lung adenocarcinoma and may provide a novel therapeutic approach for treating lung cancer.

Abstract LB-130: Abnormal expression of SWI/SNF chromatin remodeling complex genes in lung cancer

Objective: To study deregulation of the SWI/SNF chromatin remodeling complex in lung cancer tumors and cell lines with the emphasis on SMARCA2, SMARCA4 and ARID1A.

Background: The DNA in each mammalian cell is compacted about 5000 fold into chromatin, and in the compacted state is unavailable for transcription. This compaction is controlled by three mechanisms: including the ATP-dependent chromatin remodeling complex SWI/SNF, consisting of 20 genes that code for about 12 protein subunits (some of which can substitute for each other). There are over 280 possible subunit permutations, influencing transcription, chromatin binding and remodeling, and tissue and gene specificity. Several subunit genes function as tumor suppressor genes (TSGs) including the interchangeable ATP catalytic components SMARCA2 (protein = BRM) and SMARCA4 (protein = BRG1) and the ARID1A (protein = BAF250a) accessory gene. The catalytic components are known to be inactivated in several cancers including lung, and ARID1A in ovarian cancer.

Materials and Methods: Up to 58 cell lines and 60 non small cell lung cancer tumors arising in smokers and never smokers were studied. NextGen and Sanger sequencing of the SWI/SNF complex genes were performed on the cell lines. Western blots of nuclear extracts, methylation and qPCR were also performed on cell lines. Genome wide gene copy number (by SNP analyses) and microarray expression studies were performed on the tumors and cell lines. Immunostaining (for BRG1 and BAF250a) were performed on lung cancer microarrays. Results: Mutations rates in NSCLC lines were: SMARCA4 28% (mainly homozygous deletions), SMARCA2 0%, ARID1A 11% (mainly heterozygous point mutations). However, a marked decrease in nuclear protein expression was frequently present in NSCLC lines: BRG1 28%, BRM 28%, BAF250a 31%. Loss of BRG1, BRM, or BAF250a was present in 41% of the NSCLC lines, and 16% had loss of two or three. Combined analyses with microarray expression, immunostaining and qPCR studies of these three genes indicated frequent low expression in both NSCLC tumors and cell lines. In addition, DNA copy number by SNP analyses of NSCLC tumors indicated widespread loss of alleles of multiple members of the SWI/SNF complex. Evidence for epigenetic inactivation of one or more complex genes was present.

Conclusions: Our data indicate frequent inactivation of one or more members of the SWI/SNF complex by a variety of mechanisms including deletions, mutations, epigenetic, transcriptional and translational control. The predicted downstream effects on transcription and histone regulation are likely to be widespread and possibly demonstrating cell type and gene specific effects. Although highly complicated, elucidation of the precise chromatin complex abnormalities, mechanisms and downstream effects indicate the possibility of multiple new therapeutic targets for lung cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-130. doi:10.1158/1538-7445.AM2011-LB-130

Abstract LB-126: A pooled shRNA screen for erlotinib sensitizers in Kras-mutant non-small cell lung cancer

Erlotinib is a small-molecule inhibitor of the epithelial growth factor receptor (EGFR) that provides a survival benefit in patients with chemoresistant non-small cell lung cancer (NSCLC). In the second and third line setting, patients whose tumors harbor activating mutations in Kras showed less benefit than patients with tumors harboring wild type Kras.

To identify genes whose inhibition sensitizes Kras-mutant NSCLC cells to erlotinib, we performed a whole-genome pooled-shRNA screen and identified 337 shRNAs that were selectively depleted in erlotinib-treated cells. We subsequently validated 148 of the top 200 hits in an siRNA-based viability assay and selected 37 hits for further analysis. We are currently characterizing these hits in a panel of ∼10 additional NSCLC lines to identify targets with broad cell line activity that synergize with erlotinib to induce apoptosis. Our current understanding of the relationships between our top hits and erlotinib sensitivity will be discussed.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-126.

Abstract 303: Developing predictive biomarkers of PI3K/AKT pathway activation

The PI3K/AKT pathway is frequently up-regulated in cancer. This occurs through activation of growth factor receptors, PI3K (p110α) mutations and amplifications, PTEN loss, and more rarely mutations and amplifications of the AKT genes. These pathway alterations could be useful as predictive biomarkers to identify the tumors that are dependent on the PI3K/AKT pathway and therefore, most likely to respond to PI3K/AKT targeted agents. PTEN is frequently inactivated in tumors from various tissues especially brain, endometrium, prostate, ovary, and breast. Developing a predictive biomarker assay PTEN status is challenging because PTEN is lost in cancer by multiple mechanisms including gene deletion, mutations, and DNA methylation. Here we evaluate multiple assays to detect PTEN loss in breast, ovarian, and prostate cancer cell lines as well as tumors to assess the prevalence by which loss occurs by these different mechanisms.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 303.

Regulatory perspective on clinical trials and end points for female sexual dysfunction, in particular, hypoactive sexual desire disorder: formulating recommendations in an environment of evolving clinical science

This article examines the history, current status, and potential future challenges in the development of drugs for female sexual dysfunction (FSD) from the perspective of the United States Food and Drug Administration. In particular, the article focuses on testosterone therapy for hypoactive sexual desire disorder (a component of FSD), and the role of the Division of Reproductive and Urologic Products in facilitating the development of safe and effective therapies for this indication.

Quantification of breast tumor microvascular permeability with feruglose-enhanced MR imaging: initial phase II multicenter trial

PURPOSE

To investigate use of the macromolecular contrast agent feruglose for differentiating and grading of human benign and malignant breast tumors on the basis of their microvascular characteristics.

MATERIALS AND METHODS

Sixty-three women with 63 primary breast lesions were examined with dynamic T1-weighted gradient-echo magnetic resonance (MR) imaging after intravenous injection of feruglose. A two-compartment unidirectional kinetic model applied to the dynamic data yielded estimates of the endothelial transfer coefficient, KPS, and the fractional plasma volume of the tumors. These MR imaging-derived parameters were correlated with the histologic tumor grade and quantified according to the Scarff-Bloom-Richardson (SBR) score by means of Pearson product moment correlation analyses. Differences between malignant and nonmalignant breast lesions with respect to KPS for feruglose were evaluated by means of the chi2 test and by calculating the sensitivity, specificity, and positive and negative predictive values.

RESULTS

Histologic analysis revealed 26 benign and 37 malignant tumors. A moderate yet statistically significant correlation between KPS and SBR score was found (R = 0.496, P <.001). No significant correlation was observed between fractional plasma volume and SBR score (R = 0.085, P =.507). The KPS values were zero for 19 (73%) of the 26 benign tumors and were greater than zero for 27 (73%) of the 37 carcinomas. This distribution was significantly different (chi2 = 13.035, P =.001). With the criterion KPS > 0 in carcinomas, sensitivity was 0.73, specificity was 0.73, and the positive predictive value was 0.79.

CONCLUSION

Quantitative measures of tumor microvascular permeability can be used for breast tumor characterization. The probability of breast tumor microvascular hyperpermeability to be associated with malignancy is 79%.

Antisense RNA down-regulation of bcl-xL Expression in prostate cancer cells leads to diminished rates of cellular proliferation and resistance to cytotoxic chemotherapeutic agents

bcl-xL is a M(r) 26,000 bcl-2 homologue that is highly expressed in prostate cancer cells. In previous studies, the down-regulation of its expression by antisense oligonucleotides led to resistance. In this work, the 445-bp 5' terminus of the bcl-xL cDNA was cloned in the antisense orientation and stably transfected into DU145 and LNCaP prostate cancer cells. In the DU145 (and to a lesser extent the LNCaP) transfectants, phenotypic changes (versus mock-transfected cells) included an increase in doubling time (from 36 to 175 h) in the clone in which bcl-xL protein expression was 25% of control. The transfectants did not demonstrate characteristic apoptotic changes, as demonstrated by 4',6-diamidino-2-phenylindole staining, lack of either DNA laddering, caspase-3 activation, or poly(ADP)ribose and lamin cleavage, and the absence of a significant sub-G(0) population. Cell cycle analysis demonstrated an increase in a tetraploid population (from 28% to 66%), as well as the appearance of a hypertetraploid population. Levels of cIAP-1 protein were almost undetectable in the mock cells but increased at least 25-fold in the DU145 transfectants. The down-regulation of bcl-xL in both DU145 (and to a much lesser extent in LNCaP) cells led to their resistance to cytotoxic agents, including docetaxel, mitoxantrone, etoposide, vinblastine, and carboplatin. Reversion of bcl-xL expression in stable DU145 transfectants to nearly the levels found in the mock-transfected cells was accomplished by retroviral infection of the cells with a bcl-xL sense cDNA under control of a prolific promoter. This led to a dramatic increase in the growth rate and in BrdUrd incorporation, as well as a sharp decrease in the expression of cIAP-1 protein. Overall, these findings highlight the adaptability of prostate cancer cells to loss of bcl-xL and suggest that in addition to its prosurvival role, bcl-xL protein may also be involved in the regulation of the rate of cellular proliferation.

MR imaging of the arthritic rabbit knee joint using albumin-(Gd-DTPA)30 with correlation to histopathology

The purpose of this study was to demonstrate a technique, in a pilot study, for measuring abnormal capillary permeability in synovial tissue of rabbit arthritic knees using dynamic MRI with a gadolinium-based blood pool agent. Arthritis, simulating rheumatoid arthritis, was induced in knees of 8 rabbits by intra-articular injection of carrageenan (n = 4) or ovalbumin (n = 4). Sequential fat presaturated T1-weighted Spoiled Grass images were obtained before and up to 30 min after intravenous administration of albumin-(Gd-DTPA)30. Estimates of synovial tissue plasma-volume (PV), fractional-leak-rate (FLR), and permeability-surface-area-product (PS) were computed. Histologic correlation was obtained in the corresponding regions. Dynamic MRI showed extravasation of albumin-(Gd-DTPA)30 into hypertrophic synovium in six of the eight arthritic knees. Histologic examination of these six knees showed markedly inflamed synovium. The two knees that did not show abnormal vascular permeability contained non-hypertrophic synovium. None of the rabbits showed abnormal permeability in muscle. MRI derived microvascular characteristics (PV, FLR and PS) correlated positively (r2 = 0.51, 0.97 and 0.86) with the histology. Factors involving the structural and functional microvascular characteristics of synovial tissue can be estimated non-invasively using albumin-(Gd-DTPA)30. This technique may be useful for monitoring disease progression and treatment response in rheumatoid arthritis.

Neuromuscular oropharyngeal dysphagia secondary to bone metastases

Oropharyngeal dysphagia in adults is secondary to either a structural lesion or neuromuscular disorder of the upper esophageal sphincter. In cricopharyngeal achalasia (incomplete relaxation of the upper esophageal sphincter), the etiology is usually either related to neck surgery or other neuromuscular disorders. We report on a rare case of neuromuscular oropharyngeal dysphagia secondary to bone metastases to the base of the skull. The patient is an 81-year old man with prostate cancer with metastases to the sacrum. A gastroscopy was attempted to discern the etiology of his dysphagia, but the endoscope could not be advanced. A barium swollow showed cricopharyngeal achalasia, and an magnetic resonance image of the brain demonstrated bone destruction to the floor of the left posterior fossa in the region of the jugular foramen and foramen magnum. The bone destruction caused disruption of the glosso-pharyngeal and vagus nerves. Selective radiotherapy resulted in rapid improvement in his symptoms. The primary treatment of cricopharyngeal achalasia is to correct the underlying process, if possible. This case illustrates an unusual presentation of secondary cricopharyngeal achalasia caused by cranial nerve involvement secondary to bone metastases.

Assessing tumor angiogenesis using macromolecular MR imaging contrast media

MRI enhanced with a macromolecular contrast medium (MMCM) has previously been shown to estimate tumor microvascular characteristics that correlate closely with histologic microvascular density, an established surrogate of tumor angiogenesis. A similar MMCM-enhanced MRI technique has now been used to investigate the acute tumor microvascular effects of antibody-mediated inhibition of vascular endothelial growth factor (VEGF), a well-studied and potent angiogenesis stimulator. Athymic rats xenografted with a human breast carcinoma (MDA-MB-435) were imaged after administration of albumin-gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA30) using a heavily T1-weighted three dimensional-spoiled gradient-refocused acquisition in a steady-state pulse sequence before and 24 hours after treatment with anti-VEGF antibody (single dose of 1 mg). Changes in longitudinal relaxivity (delta R1) were analyzed using a bidirectional two-compartment kinetic model to estimate tumor fractional blood volume (fBV) and permeability surface area product (PS). Data showed a significant decrease (P < 0.05) of tumor PS with respect to macromolecular contrast medium at 24 hours after treatment with anti-VEGF antibody. No significant change was observed in fBV. Suppression of tumor microvascular permeability induced by anti-VEGF antibody can be detected and quantified by MMCM-enhanced MRI. MRI grading of tumor angiogenesis and monitoring of anti-angiogenesis interventions could find wide clinical application.

A Re-Examination of the Proximity Effect in Man

A recent report indicated that the mere proximity to refined sugar could reduce human grip strength. A reexamination of this hypothesis yielded no significant effect.

Contrast enhancement of thallium-201 myocardial scintigrams: improved sensitivity with diminished specificity in coronary disease detection

Thallium-201 myocardial scintigraphy (TMS) has become an increasingly popular noninvasive technique with a high diagnostic specificity, but a somewhat lower sensitivity for coronary disease (CAD) detection. Many centers now routinely employ computer techniques to contrast enhance scintigrams, but the resulting changes in sensitivity and specificity have not been carefully evaluated. In the present study, three observers with different levels of experience blindly interpreted both unprocessed and enhanced exercise TMS from 40 patients with CAD and from 15 without significant obstructions. The sensitivity for CAD achieved by each observer was higher with the enhanced scintigrams (increase from an average of 80% to 93%), but there was concomitant loss of specificity (from 93% to 73%). Similarly, significant changes were present in the sensitivity and specificity with which ischemic regions were diagnosed. In addition, contrast enhancement facilitated interpretation of TMS studies, particularly in making comparisons between exercise scintigrams and subsequent rest or redistribution images. Contrast enhancement affected the interpretations of the inexperienced observer most significantly. We conclude that contrast enhancement improves TMS sensitivity but results in some loss of specificity. The variable effect of enhancement on observers with different levels of experience suggests that laboratories should critically evaluate their own results before routinely employing computer processing.

Relationship of regional myocardial perfusion to segmental wall motion: a physiologic basis for understanding the presence and reversibility of asynergy

Experimental work has shown that even small reductions in myocardial perfusion impair contractile performance. We, therefore, studied the relationship between regional perfusion, assessed by thallium-201 scintigraphy and segmental wall motion, quantitated on biplane contrast ventriculograms, in patients with coronary artery disease. We evaluated 270 segments in 54 patients, including 27 without evidence of myocardial infarction. Most normally perfused regions (125 of 140) contracted normally, whereas those with scintigraphic defects at rest were usually asynergic (42 of 46). Surprisingly, 57% (48 of 84) of regions with exercise-induced perfusion defects were also asynergic, including 48% (25 of 52) of those in patients without myocardial infarction. In 22 patients who had intervention ventriculograms, improvement of perfusion abnormalities at rest correlated closely with reversibility of asynergy. Although there was an association between the location and severity of coronary artery stenosis and segmental wall motion, myocardial perfusion during exercise was a significantly better predictor of asynergy. These findings suggest that resting asynergy may occur even in patients without previous infarction, predominantly in regions with jeopardized perfusion. Asynergy in regions with exercise-induced perfusion abnormalities may, therefore, be an indicator of resting ischemia and may be reversible by coronary artery revascularization.

Applications and limitations of quantitative sacroiliac joint scintigraphy

Evaluation of sacroiliac joint pathology by quantitative analysis of radionuclide bone scanning has been advocated as a useful technique. We have examined this technique in 61 patients and controls. The procedure was useful in detecting early sacroiliitis but was of limited value in patients with advanced sacroiliac joint findings radiographically. False positive values were found in patients with metabolic bone disease or structural abnormalities in the low back. Normative data must be determined for each laboratory.