Neoadjuvant Chemoimmunotherapy for NSCLC: A Systematic Review and Meta-Analysis.

Importance: To date, no meta-analyses have comprehensively assessed the association of neoadjuvant chemoimmunotherapy with clinical outcomes in non-small cell lung cancer (NSCLC) in randomized and nonrandomized settings. In addition, there exists controversy concerning the efficacy of neoadjuvant chemoimmunotherapy for patients with NSCLC with programmed cell death 1 ligand 1 (PD-L1) levels less than 1%. Objective: To compare neoadjuvant chemoimmunotherapy with chemotherapy by adverse events and surgical, pathological, and efficacy outcomes using recently published randomized clinical trials and nonrandomized trials. Data Sources: MEDLINE and Embase were systematically searched from January 1, 2013, to October 25, 2023, for all clinical trials of neoadjuvant chemoimmunotherapy and chemotherapy that included at least 10 patients. Study Selection: Observational studies and trials reporting the use of neoadjuvant radiotherapy, including chemoradiotherapy, molecular targeted therapy, or immunotherapy monotherapy, were excluded. Main Outcomes and Measures: Surgical, pathological, and efficacy end points and adverse events were pooled using a random-effects meta-analysis. Results: Among 43 eligible trials comprising 5431 patients (4020 males [74.0%]; median age range, 55-70 years), there were 8 randomized clinical trials with 3387 patients. For randomized clinical trials, pooled overall survival (hazard ratio, 0.65; 95% CI, 0.54-0.79; I2 = 0%), event-free survival (hazard ratio, 0.59; 95% CI, 0.52-0.67; I2 = 14.9%), major pathological response (risk ratio, 3.42; 95% CI, 2.83-4.15; I2 = 31.2%), and complete pathological response (risk ratio, 5.52; 95% CI, 4.25-7.15; I2 = 27.4%) favored neoadjuvant chemoimmunotherapy over neoadjuvant chemotherapy. For patients with baseline tumor PD-L1 levels less than 1%, there was a significant benefit in event-free survival for neoadjuvant chemoimmunotherapy compared with chemotherapy (hazard ratio, 0.74; 95% CI, 0.62-0.89; I2 = 0%). Conclusion and Relevance: This study found that neoadjuvant chemoimmunotherapy was superior to neoadjuvant chemotherapy across surgical, pathological, and efficacy outcomes. These findings suggest that patients with resectable NSCLC with tumor PD-L1 levels less than 1% may have an event-free survival benefit with neoadjuvant chemoimmunotherapy.

Obesity alters monocyte developmental trajectories to enhance metastasis.

Obesity is characterized by chronic systemic inflammation and enhances cancer metastasis and mortality. Obesity promotes breast cancer metastasis to lung in a neutrophil-dependent manner; however, the upstream regulatory mechanisms of this process remain unknown. Here, we show that obesity-induced monocytes underlie neutrophil activation and breast cancer lung metastasis. Using mass cytometry, obesity favors the expansion of myeloid lineages while restricting lymphoid cells within the peripheral blood. RNA sequencing and flow cytometry revealed that obesity-associated monocytes resemble professional antigen-presenting cells due to a shift in their development and exhibit enhanced MHCII expression and CXCL2 production. Monocyte induction of the CXCL2-CXCR2 axis underlies neutrophil activation and release of neutrophil extracellular traps to promote metastasis, and enhancement of this signaling axis is observed in lung metastases from obese cancer patients. Our findings provide mechanistic insight into the relationship between obesity and cancer by broadening our understanding of the interactive role that myeloid cells play in this process.

Stereotactic ablative radiotherapy before resection to avoid delay for early-stage lung cancer or oligometastases during the COVID-19 pandemic: Pathologic outcomes from the SABR-BRIDGE protocol.

BACKGROUND: During coronavirus disease 2019 (COVID-19)-related operating room closures, some multidisciplinary thoracic oncology teams adopted a paradigm of stereotactic ablative radiotherapy (SABR) as a bridge to surgery, an approach called SABR-BRIDGE. This study presents the preliminary surgical and pathological results. METHODS: Eligible participants from four institutions (three in Canada and one in the United States) had early-stage presumed or biopsy-proven lung malignancy that would normally be surgically resected. SABR was delivered using standard institutional guidelines, with surgery >3 months following SABR with standardized pathologic assessment. Pathological complete response (pCR) was defined as absence of viable cancer. Major pathologic response (MPR) was defined as ≤10% viable tissue. RESULTS: Seventy-two patients underwent SABR. Most common SABR regimens were 34 Gy/1 (29%, n = 21), 48 Gy/3-4 (26%, n = 19), and 50/55 Gy/5 (22%, n = 16). SABR was well-tolerated, with one grade 5 toxicity (death 10 days after SABR with COVID-19) and five grade 2-3 toxicities. Following SABR, 26 patients underwent resection thus far (13 pending surgery). Median time-to-surgery was 4.5 months post-SABR (range, 2-17.5 months). Surgery was reported as being more difficult because of SABR in 38% (n = 10) of cases. Thirteen patients (50%) had pCR and 19 (73%) had MPR. Rates of pCR trended higher in patients operated on at earlier time points (75% if within 3 months, 50% if 3-6 months, and 33% if ≥6 months; p = .069). In the exploratory best-case scenario analysis, pCR rate does not exceed 82%. CONCLUSIONS: The SABR-BRIDGE approach allowed for delivery of treatment during a period of operating room closure and was well-tolerated. Even in the best-case scenario, pCR rate does not exceed 82%.

A Simplified Version of the IASLC Grading System for Invasive Pulmonary Adenocarcinomas With Improved Prognosis Discrimination.

Tumor grading enables better management of patients and treatment options. The International Association for the Study of Lung Cancer (IASLC) Pathology Committee has recently released a 3-tier grading system for invasive pulmonary adenocarcinoma consisting of predominant histologic patterns plus a cutoff of 20% of high-grade components including solid, micropapillary, and complex glandular patterns. The goal of this study was to validate the prognostic value of the new IASLC grading system and to compare its discriminatory performance to the predominant pattern-based grading system and a simplified version of the IASLC grading system without complex glandular patterns. This was a single-site retrospective study based on a 20-year data collection of patients that underwent lung cancer surgery. All invasive pulmonary adenocarcinomas confirmed by the histologic review were evaluated in a discovery cohort (n=676) and a validation cohort (n=717). The median duration of follow-up in the combined dataset (n=1393) was 7.5 years. The primary outcome was overall survival after surgery. The 3 grading systems had strong and relatively similar predictive performance, but the best parsimonious model was the simplified IASLC grading system (log-rank P =1.39E-13). The latter was strongly associated with survival in the validation set ( P =1.1E-18) and the combined set ( P =5.01E-35). We observed a large proportion of patients upgraded to the poor prognosis group using the IASLC grading system, which was attenuated when using the simplified IASLC grading system. In conclusion, we identified a histologic simpler classification for invasive pulmonary adenocarcinomas that outperformed the recently proposed IASLC grading system. A simplified grading system is clinically convenient and will facilitate widespread implementation.

Relation between mismatch repair status, chemoresponse, survival and anatomic location in gastroesophageal adenocarcinoma.

BACKGROUND: It has recently been reported that mismatch repair (MMR) status and microsatellite instability (MSI) status in gastroesophageal carcinomas predict surgical, chemotherapeutic and immunotherapeutic outcomes; however, there is extensive variability in the reported incidence and clinical implications of MMR/MSI status in gastroesophaegal adenocarcinomas. We characterized a Canadian surgical patient cohort with respect to MMR status, clinicopathologic correlates and anatomic tumour location. METHODS: We investigated MMR and BRAF V600E status of gastroesophaegal adenocarcinomas in patients who underwent gastrectomy or esophagectomy with extended (D2) lymphadenectomy at a single centre between 2011 and 2019. We correlated patterns of MMR expression in the overall cohort and in anatomic location-defined subgroups with treatment response and overall survival using multivariate analysis. RESULTS: In all, 226 cases of gastroesophaegal adenocarcinoma (63 esophageal, 98 gastroesophageal junctional and 65 gastric) were included. The MMR-deficient (dMMR) immunophenotype was found in 28 tumours (12.3%) (15 junctional [15.3%], 13 gastric [20.0%] and none of the esophageal). The majority (25 [89%]) of dMMR cases showed MLH1/PMS2 loss without concurrent BRAF V600E mutation. Two MSH2/ MSH6-deficient gastric tumours and 1 MSH6-deficient junctional tumour were detected. The pathologic response to preoperative chemotherapy was comparable in the dMMR and MMR-proficient (pMMR) cohorts. However, dMMR status was associated with significantly longer median overall survival than pMMR status (5.8 yr v. 2.4 yr, hazard ratio [HR] 1.91, 95% confidence interval [CI] 1.06-3.46), particularly in junctional tumours (4.6 yr v. 1.9 yr, HR 2.97, 95% CI 1.27-6.94). CONCLUSION: Our study shows that MMR status has at least prognostic value, which supports the need for biomarker testing in gastroesophageal adenocarcinomas, including junctional adenocarcinomas. This highlights the clinical significance of determining the MMR status in all adenocarcinomas of the upper gastrointestinal tract. Response to induction chemotherapy, however, was not influenced by MMR status.

Neutrophil oxidative stress mediates obesity-associated vascular dysfunction and metastatic transmigration.

Metastasis is the leading cause of cancer-related deaths, and obesity is associated with increased breast cancer (BC) metastasis. Preclinical studies have shown that obese adipose tissue induces lung neutrophilia associated with enhanced BC metastasis to this site. Here we show that obesity leads to neutrophil-dependent impairment of vascular integrity through loss of endothelial adhesions, enabling cancer cell extravasation into the lung. Mechanistically, neutrophil-produced reactive oxygen species in obese mice increase neutrophil extracellular DNA traps (NETs) and weaken endothelial junctions, facilitating the influx of tumor cells from the peripheral circulation. In vivo treatment with catalase, NET inhibitors or genetic deletion of Nos2 reversed this effect in preclinical models of obesity. Imaging mass cytometry of lung metastasis samples from patients with cancer revealed an enrichment in neutrophils with low catalase levels correlating with elevated body mass index. Our data provide insights into potentially targetable mechanisms that underlie the progression of BC in the obese population.

Canadian Multicenter Project on Standardization of Programmed Death-Ligand 1 Immunohistochemistry 22C3 Laboratory-Developed Tests for Pembrolizumab Therapy in NSCLC.

INTRODUCTION: The programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) assay is used to select patients for first or second-line pembrolizumab monotherapy in NSCLC. The PD-L1 IHC 22C3 pharmDx assay requires an Autostainer Link 48 instrument. Laboratories without this stainer have the option to develop a highly accurate 22C3 IHC laboratory-developed test (LDT) on other instruments. The Canadian 22C3 IHC LDT validation project was initiated to harmonize the quality of PD-L1 22C3 IHC LDT protocols across 20 Canadian pathology laboratories. METHODS: Centrally optimized 22C3 LDT protocols were distributed to participating laboratories. The LDT results were assessed against results using reference PD-L1 IHC 22C3 pharmDx. Analytical sensitivity and specificity were assessed using cell lines with varying PD-L1 expression levels (phase 1) and IHC critical assay performance controls (phase 2B). Diagnostic sensitivity and specificity were assessed using whole sections of 50 NSCLC cases (phase 2A) and tissue microarrays with an additional 50 NSCLC cases (phase 2C). RESULTS: In phase 1, 80% of participants reached acceptance criteria for analytical performance in the first attempt with disseminated protocols. However, in phase 2A, only 40% of participants reached the desired diagnostic accuracy for both 1% and 50% tumor proportion score cutoff. In phase 2B, further protocol modifications were conducted, which increased the number of successful laboratories to 75% in phase 2C. CONCLUSIONS: It is possible to harmonize highly accurate 22C3 LDTs for both 1% and 50% tumor proportion score in NSCLC across many laboratories with different platforms. However, despite a centralized approach, diagnostic validation of predictive IHC LDTs can be challenging and not always successful.

"Interchangeability" of PD-L1 immunohistochemistry assays: a meta-analysis of diagnostic accuracy.

Different clones, protocol conditions, instruments, and scoring/readout methods may pose challenges in introducing different PD-L1 assays for immunotherapy. The diagnostic accuracy of using different PD-L1 assays interchangeably for various purposes is unknown. The primary objective of this meta-analysis was to address PD-L1 assay interchangeability based on assay diagnostic accuracy for established clinical uses/purposes. A systematic search of the MEDLINE database using PubMed platform was conducted using "PD-L1" as a search term for 01/01/2015 to 31/08/2018, with limitations "English" and "human". 2,515 abstracts were reviewed to select for original contributions only. 57 studies on comparison of two or more PD-L1 assays were fully reviewed. 22 publications were selected for meta-analysis. Additional data were requested from authors of 20/22 studies in order to enable the meta-analysis. Modified GRADE and QUADAS-2 criteria were used for grading published evidence and designing data abstraction templates for extraction by reviewers. PRISMA was used to guide reporting of systematic review and meta-analysis and STARD 2015 for reporting diagnostic accuracy study. CLSI EP12-A2 was used to guide test comparisons. Data were pooled using random-effects model. The main outcome measure was diagnostic accuracy of various PD-L1 assays. The 22 included studies provided 376 2×2 contingency tables for analyses. Results of our study suggest that, when the testing laboratory is not able to use an Food and Drug Administration-approved companion diagnostic(s) for PD-L1 assessment for its specific clinical purpose(s), it is better to develop a properly validated laboratory developed test for the same purpose(s) as the original PD-L1 Food and Drug Administration-approved immunohistochemistry companion diagnostic, than to replace the original PD-L1 Food and Drug Administration-approved immunohistochemistry companion diagnostic with a another PD-L1 Food and Drug Administration-approved companion diagnostic that was developed for a different purpose.

The impact of first untreated subclinical minimal acute rejection on risk for chronic lung allograft dysfunction or death after lung transplantation.

Acute cellular rejection (ACR) is a significant risk factor for chronic lung allograft dysfunction (CLAD). Although clinically manifest and higher grade (≥A2) ACR is generally treated with augmented immunosuppression, management of minimal (grade A1) ACR remains controversial. In our program, patients with subclinical and spirometrically stable A1 rejection (StA1R) are routinely not treated with augmented immunosuppression. We hypothesized that an untreated first StA1R does not increase the risk of CLAD or death compared to episodes of spirometrically stable no ACR (StNAR). The cohort was drawn from all consecutive adult, first, bilateral lung transplantations performed between 1999 and 2017. Biopsies obtained in the first-year posttransplant were paired with (forced expiratory volume in 1 second FEV1 ). The first occurrence of StA1R was compared to a time-matched StNAR. The risk of CLAD or death was assessed using univariable and multivariable Cox proportional hazards models. The analyses demonstrated no significant difference in risk of CLAD or death in patients with a first StA1R compared to StNAR. This largest study to date shows that, in clinically stable patients, an untreated first A1 ACR in the first-year posttransplant is not significantly associated with an increased risk for CLAD or death. Watchful-waiting approach may be an acceptable tactic for stable A1 episodes in lung transplant recipients.

A case report on lipofuscin deposition in a graft biopsy two years after kidney transplantation: an insignificant bystander or a pathogenic benefactor?

BACKGROUND: Lipofuscin deposition is a characteristic manifestation of aging. There is very limited literature in humans and in animals describing these deposits in native kidneys. Overall, it is thought to be non-pathogenic and successful transplants from a donor with lipofuscin deposits have been reported. We present the case of a patient who underwent a kidney transplant and a for-cause biopsy post-transplantation incidentally revealed lipofuscin deposition. CASE PRESENTATION: A 48-year old gentleman with a past medical history of diabetes, hypertension, coronary artery disease, and ischemic and then hemorrhagic cardiovascular accident underwent a successful kidney transplant. His donor was an expanded criteria donor with no major past medical history. Post-transplant course was complicated by delayed graft function requiring one dialysis treatment for hyperkalemia. After that he had an uneventful course and achieved a baseline creatinine of 1.2 mg/dL, with no proteinuria. On a routine 19-month follow-up he was noted to have proteinuria and an antibody against the major-histocompatibility-complex class I-related chain A. A graft biopsy revealed acute antibody-mediated rejection and impressive lipofuscin deposition. He was subsequently treated with an antibody-mediated rejection protocol that included high dose steroids, Rituximab, plasmapheresis, and intravenous immunoglobulin, but responded poorly to this regimen. A 6-month follow up biopsy continued to show lipofuscin deposition, with similar microvascular injury scores and 12-months later his creatinine remained stable but his proteinuria worsened. Patient was struggling with recurrent infectious episodes requiring hospitalizations and thus no further diagnostic or therapeutic treatments were pursued. CONCLUSIONS: Lipofuscin deposition has been reported in solid organ transplants but the significance and cause are not well understood. Several physiologic and some pathologic causes to these deposits have been reported including age, diabetes, medications and a genetic syndrome. We propose that immunologic causes such as rejection in the presence of other risk factors could potentiate the oxidative stress leading to excessive lipofuscin deposition in kidney transplants. In the case of our patient, we conclude that these deposits were likely recipient-derived, and postulate that the cumulative burden of inflammation from rejection, and underlying medical conditions led to increased lipofuscin deposition. We speculate them to be an innocent bystander.

Fit-For-Purpose PD-L1 Biomarker Testing For Patient Selection in Immuno-Oncology: Guidelines For Clinical Laboratories From the Canadian Association of Pathologists-Association Canadienne Des Pathologistes (CAP-ACP).

Since 2014, programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) checkpoint inhibitors have been approved by various regulatory agencies for the treatment of multiple cancers including melanoma, lung cancer, urothelial carcinoma, renal cell carcinoma, head and neck cancer, classical Hodgkin lymphoma, colorectal cancer, gastroesophageal cancer, hepatocellular cancer, and other solid tumors. Of these approved drug/disease combinations, a subset also has regulatory agency-approved, commercially available companion/complementary diagnostic assays that were clinically validated using data from their corresponding clinical trials. The objective of this document is to provide evidence-based guidance to assist clinical laboratories in establishing fit-for-purpose PD-L1 biomarker assays that can accurately identify patients with specific tumor types who may respond to specific approved immuno-oncology therapies targeting the PD-1/PD-L1 checkpoint. These recommendations are issued as 38 Guideline Statements that address (i) assay development for surgical pathology and cytopathology specimens, (ii) reporting elements, and (iii) quality assurance (including validation/verification, internal quality assurance, and external quality assurance). The intent of this work is to provide recommendations that are relevant to any tumor type, are universally applicable and can be implemented by any clinical immunohistochemistry laboratory performing predictive PD-L1 immunohistochemistry testing.

Anaplastic lymphoma kinase 5A4 immunohistochemistry as a diagnostic assay in lung cancer: A Canadian reference testing center's results in population-based reflex testing.

BACKGROUND: The presence of anaplastic lymphoma kinase (ALK) rearrangement predicts response to ALK tyrosine kinase inhibitor (TKI) therapy. Fluorescence in situ hybridization (FISH) was the initial reference standard to detect ALK rearrangement, but immunohistochemistry (IHC) using D5F3 has gained acceptance as an alternative diagnostic method. ALK IHC assays using other ALK antibodies have also been used as screening methods, but data supporting their utility as diagnostic tests have not been widely reported. METHODS: Data from reflexive clinical ALK IHC test using the 5A4 clone concurrent with epidermal growth factor receptor (EGFR) mutation testing were analyzed. ALK IHC results were reported as negative (-), equivocal, or positive (+), with equivocal or positive staining validated by FISH break-apart probe testing. Treatment outcomes were reviewed for ALK IHC+ patients. RESULTS: Between 2012 and 2015, 146 (2.5%) cases were reported as ALK IHC+, 188 (3.2%) were reported as equivocal, and 5624 (94.4%) were reported as ALK IHC-. Of the ALK IHC+ cases, 131/143(91.6%) were ALK FISH+. Excluding 6 cases in which FISH was inconclusive or not performed, the positive predictive value was 95.6%, and the negative predictive value was 100%. Most specimens (n = 5352 [89.6%]) were also successfully tested for EGFR. Clinical responses to ALK TKIs were noted in 49 ALK IHC+ patients, with a median progression-free survival of 9.9 months. CONCLUSIONS: ALK 5A4 IHC can serve as a robust diagnostic test for ALK-rearranged lung cancer and is associated with treatment response and survival. Optimized tissue allocation resulted in high success rates of combined reflex EGFR and ALK testing.

The innate immune architecture of lung tumors and its implication in disease progression.

Lung malignancies are the leading cause of cancer-related mortality. By virtue of its unique physiological function, the lung microenvironment is highly dynamic and constantly subjected to mechanical, chemical and pathogenic stimuli. Thus, the airways rely on highly organized innate defense mechanisms to rapidly protect against pathogens and maintain pulmonary homeostasis. However, in the context of lung malignancy, these defenses often provide collateral inflammatory insults that can foster tumor progression. This review summarizes the interactions between cancer cells, recruited immune cells and tissue-resident cell subpopulations, such as airway epithelial cells and alveolar macrophages, during homeostasis and disease. Furthermore, we examine the role of the lung immune landscape in response to current therapeutic interventions for cancer. Given the prevalence of lung malignancies, we propose that consideration of lung physiology as a whole is necessary to understand and treat these lethal diseases. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

A practical guide for ancillary studies in pulmonary cytologic specimens.

Although most pulmonary cytologic specimens obtained by either exfoliation or fine needle aspirates can be reliably and accurately diagnosed based on pure morphologic criteria alone, a small proportion of cases require ancillary studies for either refining a diagnosis, for resolving a differential diagnosis or increasingly, for predictive purposes in primary lung carcinomas. This article aims to provide practical guidance on the use of common ancillary studies in pulmonary cytologic specimens. Cancer Cytopathol 2018;000:000-000. © 2018 American Cancer Society.

Longitudinal mutational analysis of a cerebellar pilocytic astrocytoma recurring as a ganglioglioma.

A cerebellar pilocytic astrocytoma (PA) in a child recurred first with a PA histology and then with features of a ganglioglioma (GG). Molecular genetic analyses of the tumors confirmed a BRAF V600E mutation in all. They also all harbored a T202M mutation in ERK1, a kinase downstream of BRAF that is implicated in glial versus neuronal differentiation. The GG sample contained several variants that were not present in the PA samples; in particular, it had a truncating mutation in MAP2. These findings not only underscore the role of BRAF as oncogenic driver but also suggest that other genes may influence tumor morphology.

Cul3 overexpression depletes Nrf2 in breast cancer and is associated with sensitivity to carcinogens, to oxidative stress, and to chemotherapy.

Nrf2 is the key transcription factor for cytoprotective gene programs. Nrf2 is normally maintained at very low concentrations by proteasomal degradation, through its interaction with the adapter protein Keap1 and the Cul3 E3 ligase. Increased Nrf2 concentration resulting from loss of function Keap1 mutations has been described in chemoresistant non-small cell lung cancer. Previous studies in breast cancer showed low levels of some Nrf2-regulated detoxification genes, but the mechanism has not been systematically examined. We found that half of the breast cancer cell lines examined have decreased concentration of Nrf2 compared with normal mammary epithelial cell lines, associated with variable but detectable levels in Keap1 levels, and consistently increased Cul3 mRNA and protein. Immunochemistry showed that 7 of 10 breast cancer specimens examined also have low Nrf2 levels and increased Cul3. Keap1 protein levels are variable. We found no C23Y mutation in Keap1 of any of the cell lines. Using siRNA, we silenced Cul3 in MCF-7 breast cancer cells, and microarray analysis reveals the induction of GCL, NQO1, AKR1C1, UGDH, and TXN by at least 2-fold. The Nrf2-regulated ABCC1 drug transporter was also found to be increased. These Cul3-silenced MCF7 cells are highly resistant to oxidative stress induced by H(2)O(2,) to the carcinogen benzo(a)pyrene, and to both Doxorubicin and Paclitaxel. This high Cul3/low Nrf2 signature may be key to cellular sensitivity to both chemical carcinogeneic stimuli as well as to cytotoxicity of commonly used chemotherapeutic drugs in established breast cancers.

Increased expression of ADAM33 and ADAM8 with disease progression in asthma.

BACKGROUND: ADAM33, a disintegrin and metalloproteinase 33 gene, has been identified as a risk factor for asthma and bronchial hyperresponsiveness and has been postulated as a gene for airway remodeling. ADAM8 is strongly induced by allergens and T(H)2 cytokines in the lung in experimental asthma. OBJECTIVES: To assess the importance of these genes in asthma pathogenesis and to investigate whether expression relates to disease severity or deterioration in lung function, we measured the mRNA and protein expression of both genes in bronchial biopsies of subjects with asthma and control subjects. METHODS: RNA was extracted from frozen endobronchial biopsies of mild, moderate, and severe adults with asthma and controls. Subjects with moderate and severe asthma were taking corticosteroids. The mRNA transcript of both genes was measured by real time RT-PCR using specific primers. Protein expression was examined by immunohistochemistry on paraffin sections. RESULTS: ADAM33 mRNA expression was significantly higher in both moderate and severe asthma compared with mild asthma (P < .05) and controls. Immunostaining for ADAM33 was increased in the epithelium, submucosal cells, and smooth muscle in severe asthma compared with mild disease and controls. ADAM8 mRNA expression was significantly increased in all asthma groups compared with controls. Increased inflammatory cells stained positive for ADAM8 in both moderate (P < .05) and severe asthma (P < .005) compared with mild disease. CONCLUSIONS: These results demonstrate increased expression of both ADAM genes as asthma severity increases. CLINICAL IMPLICATIONS: These genes may contribute to the remodeling process that occurs with asthma progression and may have implications for future treatment in severe disease.