Expression of the readthrough transcript CiDRE in alveolar macrophages boosts SARS-CoV-2 susceptibility and promotes COVID-19 severity.

Lung infection during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) via the angiotensin-I-converting enzyme 2 (ACE2) receptor induces a cytokine storm. However, the precise mechanisms involved in severe COVID-19 pneumonia are unknown. Here, we showed that interleukin-10 (IL-10) induced the expression of ACE2 in normal alveolar macrophages, causing them to become vectors for SARS-CoV-2. The inhibition of this system in hamster models attenuated SARS-CoV-2 pathogenicity. Genome-wide association and quantitative trait locus analyses identified a IFNAR2-IL10RB readthrough transcript, COVID-19 infectivity-enhancing dual receptor (CiDRE), which was highly expressed in patients harboring COVID-19 risk variants at the IFNAR2 locus. We showed that CiDRE exerted synergistic effects via the IL-10-ACE2 axis in alveolar macrophages and functioned as a decoy receptor for type I interferons. Collectively, our data show that high IL-10 and CiDRE expression are potential risk factors for severe COVID-19. Thus, IL-10R and CiDRE inhibitors might be useful COVID-19 therapies.

Galectin-10 in serum extracellular vesicles reflects asthma pathophysiology.

BACKGROUND: Novel biomarkers (BMs) are urgently needed for bronchial asthma (BA) with various phenotypes and endotypes. OBJECTIVE: We sought to identify novel BMs reflecting tissue pathology from serum extracellular vesicles (EVs). METHODS: We performed data-independent acquisition of serum EVs from 4 healthy controls, 4 noneosinophilic asthma (NEA) patients, and 4 eosinophilic asthma (EA) patients to identify novel BMs for BA. We confirmed EA-specific BMs via data-independent acquisition validation in 61 BA patients and 23 controls. To further validate these findings, we performed data-independent acquisition for 6 patients with chronic rhinosinusitis without nasal polyps and 7 patients with chronic rhinosinusitis with nasal polyps. RESULTS: We identified 3032 proteins, 23 of which exhibited differential expression in EA. Ingenuity pathway analysis revealed that protein signatures from each phenotype reflected disease characteristics. Validation revealed 5 EA-specific BMs, including galectin-10 (Gal10), eosinophil peroxidase, major basic protein, eosinophil-derived neurotoxin, and arachidonate 15-lipoxygenase. The potential of Gal10 in EVs was superior to that of eosinophils in terms of diagnostic capability and detection of airway obstruction. In rhinosinusitis patients, 1752 and 8413 proteins were identified from EVs and tissues, respectively. Among 11 BMs identified in EVs and tissues from patients with chronic rhinosinusitis with nasal polyps, 5 (including Gal10 and eosinophil peroxidase) showed significant correlations between EVs and tissues. Gal10 release from EVs was implicated in eosinophil extracellular trapped cell death in vitro and in vivo. CONCLUSION: Novel BMs such as Gal10 from serum EVs reflect disease pathophysiology in BA and may represent a new target for liquid biopsy approaches.

Cancer-associated SNRPD3 mutation confers resistance to hypoxia, which is attenuated by DRP1 inhibition.

RNA splicing is a fundamental cellular mechanism performed by spliceosomes that synthesise multiple mature RNA isoforms from a single gene. The association between spliceosome abnormality and solid cancers remains largely unknown. Here, we demonstrated that Sm proteins, which are common components of the spliceosomes and constitute the Sm ring, were overexpressed in multiple cancers and their expression levels were correlated with clinical prognosis. In a pan-cancer mutational hotspot in the Sm ring at SNRPD3 G96V, we found that the G96V substitution confers resistance to hypoxia. RNA-seq detected numerous differentially spliced events between the wild-type and mutation-carrying cells cultured under hypoxia, wherein skipping exons and mutually exclusive exons were frequently observed. This was observed in DNM1L mRNA, which encodes the DRP1 protein that regulates mitochondrial fission. The mitochondria of cells carrying this mutation were excessively fragmented compared with those of wild-type cells. Furthermore, treatment with a DRP1 inhibitor (Mdivi-1) recovered the over-fragmented mitochondria, leading to the attenuation of hypoxia resistance in the mutant cells. These results propose a novel correlation between the cancer-related spliceosome abnormality and mitochondrial fission. Thus, targeting SNRPD3 G96V with a DRP1 inhibitor is a potential treatment strategy for cancers with spliceosome abnormalities.

Balloon Dilatation for Bronchoscope Delivery in a Swine Model: A Novel Technique for Ultra-Peripheral Lung Field Access and Accurate Biopsy.

INTRODUCTION: In transbronchial biopsy of peripheral pulmonary lesions, the bronchoscope can reach only a limited depth due to the progressive narrowing of bronchi, which may reduce the diagnostic rate. This study examined the balloon dilatation for bronchoscope delivery (BDBD) technique, employing a novel balloon device to enhance bronchoscopy into the peripheral lung areas. METHODS: Anaesthetised swine served as our primary model. Using computed tomography (CT) scans, we positioned virtual targets characterised by a positive bronchus sign and a diameter of 20 mm beneath the pleura. The bronchoscope was navigated along the pathways determined from the CT images. We performed balloon dilatation when bronchial narrowing obstructed progress to assess whether balloon dilatation would enable the bronchoscope to enter further into the periphery. RESULTS: We established 21 virtual targets on the CT scans. An average of 12.1 branches were identified along the pathways on the CT scans; however, bronchoscopy without BDBD only allowed access to an average of 6.7 branches. Based on 72 balloon dilatations with 3.0-mm or 4.0-mm ultra-thin bronchoscopes, there was an average increased access of 3.43 and 5.14 branches per route, respectively, with no significant BDBD complications. The bronchoscope was able to reach the planned location along all pathways, and the mean final bronchoscopic endpoints were at an average distance of 14.7 mm from the pleura. Post-procedure CT confirmed biopsy accuracy. CONCLUSION: The BDBD technique can enhance access of a flexible bronchoscope into the peripheral lung fields, which could potentially allow more accurate transbronchial interventions for peripheral targets.

Comparison of timing and decision-makers of do-not-resuscitate orders between thoracic cancer and non-cancer respiratory disease patients dying in a Japanese acute care hospital.

PURPOSE: The aim of the study was to compare timing and decision-makers of do-not-resuscitate (DNR) orders between patients with end-stage thoracic cancer and non-cancer respiratory diseases in a Japanese acute care hospital. METHODS: This study retrospectively reviewed the medical records of patients who died between January 2008 and March 2013 in the Department of Respiratory Medicine of Osaka Police Hospital, a teaching and acute care hospital. We compared the decision-making process, especially timing and decision-maker, of DNR orders between patients with thoracic cancer and patients with non-cancer respiratory diseases. RESULTS: There were 300 cancer patients and 147 non-cancer patients. Cancer patients were significantly younger, were hospitalized more frequently and for longer, were more likely to have a DNR order placed earlier and decided in advance of last admission, and were more likely to have normal cognitive function at the time of the DNR order than non-cancer patients. Spouses of cancer patients were more likely to participate in DNR discussion. Only approximately 6 % of patients participated in DNR discussion in both groups. Cancer patients less frequently received aggressive treatment at the end of life (EOL) and were more likely to die in general wards than in intensive care units. CONCLUSIONS: Our study found that most Japanese patients, with or without cancer, who died in an acute care respiratory department, were not included in DNR discussions and that familial surrogates usually made the DNR decision at the EOL.

Sema6D forward signaling impairs T cell activation and proliferation in head and neck cancer.

Immune checkpoint inhibitors (ICIs) are indicated for a diverse range of cancer types, and characterizing the tumor immune microenvironment is critical for optimizing therapeutic strategies, including ICIs. T cell infiltration and activation status in the tumor microenvironment greatly affects the efficacy of ICIs. Here, we show that semaphorin 6D (Sema6D) forward signaling, which is reportedly involved in coordinating the orientation of cell development and migration as a guidance factor, impaired the infiltration and activation of tumor-specific CD8+ T cells in murine oral tumors. Sema6D expressed by nonhematopoietic cells was responsible for this phenotype. Plexin-A4, a receptor for Sema6D, inhibited T cell infiltration and partially suppressed CD8+ T cell activation and proliferation induced by Sema6D stimulation. Moreover, mouse oral tumors, which are resistant to PD-1-blocking treatment in wild-type mice, showed a response to the treatment in Sema6d-KO mice. Finally, analyses of public data sets of human head and neck squamous cell carcinoma, pan-cancer cohorts, and a retrospective cohort study showed that SEMA6D was mainly expressed by nonhematopoietic cells such as cancer cells, and SEMA6D expression was significantly negatively correlated with CD8A, PDCD1, IFNG, and GZMB expression. Thus, targeting Sema6D forward signaling is a promising option for increasing ICI efficacy.

SFTPB in serum extracellular vesicles as a biomarker of progressive pulmonary fibrosis.

Progressive pulmonary fibrosis (PPF), defined as the worsening of various interstitial lung diseases (ILDs), currently lacks useful biomarkers. To identify novel biomarkers for early detection of patients at risk of PPF, we performed a proteomic analysis of serum extracellular vesicles (EVs). Notably, the identified candidate biomarkers were enriched for lung-derived proteins participating in fibrosis-related pathways. Among them, pulmonary surfactant-associated protein B (SFTPB) in serum EVs could predict ILD progression better than the known biomarkers, serum KL-6 and SP-D, and it was identified as an independent prognostic factor from ILD-gender-age-physiology index. Subsequently, the utility of SFTPB for predicting ILD progression was evaluated further in 2 cohorts using serum EVs and serum, respectively, suggesting that SFTPB in serum EVs but not in serum was helpful. Among SFTPB forms, pro-SFTPB levels were increased in both serum EVs and lungs of patients with PPF compared with those of the control. Consistently, in a mouse model, the levels of pro-SFTPB, primarily originating from alveolar epithelial type 2 cells, were increased similarly in serum EVs and lungs, reflecting pro-fibrotic changes in the lungs, as supported by single-cell RNA sequencing. SFTPB, especially its pro-form, in serum EVs could serve as a biomarker for predicting ILD progression.

Tumor-derived semaphorin 4A improves PD-1-blocking antibody efficacy by enhancing CD8+ T cell cytotoxicity and proliferation.

Immune checkpoint inhibitors (ICIs) have caused revolutionary changes in cancer treatment, but low response rates remain a challenge. Semaphorin 4A (Sema4A) modulates the immune system through multiple mechanisms in mice, although the role of human Sema4A in the tumor microenvironment remains unclear. This study demonstrates that histologically Sema4A-positive non-small cell lung cancer (NSCLC) responded significantly better to anti-programmed cell death 1 (PD-1) antibody than Sema4A-negative NSCLC. Intriguingly, SEMA4A expression in human NSCLC was mainly derived from tumor cells and was associated with T cell activation. Sema4A promoted cytotoxicity and proliferation of tumor-specific CD8+ T cells without terminal exhaustion by enhancing mammalian target of rapamycin complex 1 and polyamine synthesis, which led to improved efficacy of PD-1 inhibitors in murine models. Improved T cell activation by recombinant Sema4A was also confirmed using isolated tumor-infiltrating T cells from patients with cancer. Thus, Sema4A might be a promising therapeutic target and biomarker for predicting and promoting ICI efficacy.

Cerebral Infarction Caused by Trousseau's Syndrome Associated With Lung Cancer.

Background: Lung cancer is one of the common cancers that can cause Trousseau's syndrome. However, there are few reports of cerebral infarction due to Trousseau's syndrome associated with lung cancer. The aim of this study is to investigate the clinical features of lung cancer-related cerebral infarction and effective management practice. Methods: Japanese patients diagnosed with Trousseau's syndrome-related cerebral infarction associated with lung cancer between August 2012 and November 2021 in our hospital were retrospectively enrolled. Clinical data, treatment, and outcomes of the patients were collected. Results: Ten patients were enrolled. The median age was 65 years (range: 43 - 84 years). All patients had advanced lung cancer. The histological types were adenocarcinoma (n = 8), pleomorphic carcinoma (n = 1), and small cell lung cancer (n = 1). Recurrent cerebral infarction occurred in six patients. Among four patients who had continued heparin since the initial infarction, recurrence occurred in one. D-dimer was high in all 10 patients at the initial cerebral infarction. D-dimer level at the time of recurrent cerebral infarctions was higher than that at the first cerebral infarctions. Since performance status declined in nine patients, one patient continued anticancer drugs after cerebral infarction. Four patients died within 100 days of the onset of cerebral infarction. Conclusions: Cerebral infarction of lung cancer-related Trousseau's syndrome has poor prognosis. Heparin may be effective in controlling the condition. In addition, D-dimer may serve as a marker of cancer-related thrombosis.

Leucine-rich a-2 glycoprotein as a potential biomarker of idiopathic multicentric Castleman disease with pulmonary involvement: a single-center case-control study from Japan.

Background: There are no known biomarkers for monitoring disease activity in idiopathic multicentric Castleman disease (MCD) with pulmonary involvement. We investigated the utility of serum leucine-rich α2-glycoprotein levels, which reflects interleukin 6 independent inflammatory change, for monitoring disease activity in patients with idiopathic MCD with pulmonary involvement. Methods: We retrospectively examined cases of idiopathic MCD diagnosed at Osaka University Hospital. The serum levels of leucine-rich α2-glycoprotein were compared between patients with idiopathic MCD and healthy controls. The difference in leucine-rich α2-glycoprotein levels before and after treatment (∆leucine-rich α2-glycoprotein) was evaluated with respect to the relationship with pulmonary function. In addition, the relationship between cytokine and chemokine profiles and the leucine-rich α2-glycoprotein concentration was investigated. The results were analyzed using pathway analysis. Results: The leucine-rich α2-glycoprotein concentrations were significantly higher in treatment-naïve patients (n=5) than in healthy controls (n=3) (P=0.035). Further, the ∆leucine-rich α2-glycoprotein concentration was significantly correlated with ∆ percent diffusing capacity of the lung for carbon monoxide (r=-0.88, P=0.049) and tended to correlate with ∆ percent vital capacity (r=-0.68, P=0.21) although the difference was not significant for the latter association. The concentrations of chemokines and cytokines, such as CXCL9, CXCL11, CXCL1, and a proliferation-inducing ligand, were higher in the patient group than in the healthy control group. Enrichment analysis indicated that leucine-rich α2-glycoprotein could be elevated via the upregulation of chemokines in patients with idiopathic MCD using these parameters. Conclusions: Leucine-rich a2-glycoprotein may be useful for monitoring disease activity in patients with idiopathic MCD with pulmonary involvement.

Quantitative evaluation of emphysema for predicting immunotherapy response in patients with advanced non-small-cell lung cancer.

The efficacy of immune checkpoint inhibitors (ICIs) in patients with advanced non-small-cell lung cancer (NSCLC) might depend on the presence of emphysema, but this association is not established. We aimed to investigate if quantitively and automatically measuring emphysema can predict the effect of ICIs. We retrospectively analyzed 56 patients with NSCLC who underwent immunotherapy at our hospital. We used the Goddard scoring system (GS) to evaluate the severity of emphysema on baseline CT scans using three-dimensional image analysis software. The emphysema group (GS ≥ 1) showed better progression-free survival (PFS) than the non-emphysema group (GS = 0) (6.5 vs. 2.3 months, respectively, p < 0.01). Multivariate analyses revealed that good performance status, GS of ≥ 1, and high expression of PD-L1 were independently associated with better PFS, while smoking status was not. In conclusion, quantitative evaluation of emphysema can be an objective parameter for predicting the therapeutic effects of ICIs in patients with NSCLC. Our findings can be used to generate hypotheses for future studies.

Proposal of a novel pipeline involving precise bronchoscopy of distal peripheral pulmonary lesions for genetic testing.

Next-generation sequencing (NGS) has become increasingly more important for lung cancer management. We now expect biopsies to be sensitive, safe, and yielding sufficient samples for NGS. In this study, we propose ultraselective biopsy (USB) with sample volume adjustment (SVA) as a novel method that integrates an ultrathin bronchoscope, radial probe endobronchial ultrasound, and the direct oblique method for ultraselective navigation, and adjustment of sample volume for NGS. Our purpose was to estimate the diagnostic potential and the applicability of USB-SVA for amplicon-based NGS analysis. The diagnostic yield of bronchoscopy in forty-nine patients with malignant peripheral pulmonary lesions (PPLs) was retrospectively analyzed, and amplicon-based NGS analysis was performed on samples from some patients using USB. The diagnostic yields of distal PPLs in the USB group were significantly higher than those in the non-USB group (90.5% vs. 50%, respectively, p = 0.015). The extracted amounts of nucleic acids were at least five times the minimum requirement and the sequence quality met the criteria for the Oncomine™ Target Test. Only the tumor cell content of some samples was insufficient. The feasibility of the pipeline for USB, SVA, and amplicon-based NGS in distal PPLs was demonstrated.

Bronchoalveolar lavage fluid reveals factors contributing to the efficacy of PD-1 blockade in lung cancer.

Bronchoalveolar lavage is commonly performed to assess inflammation and identify responsible pathogens in lung diseases. Findings from bronchoalveolar lavage might be used to evaluate the immune profile of the lung tumor microenvironment (TME). To investigate whether bronchoalveolar lavage fluid (BALF) analysis can help identify patients with non-small cell lung cancer (NSCLC) who respond to immune checkpoint inhibitors (ICIs), BALF and blood were prospectively collected before initiating nivolumab. The secreted molecules, microbiome, and cellular profiles based on BALF and blood analysis of 12 patients were compared with regard to therapeutic effect. Compared with ICI nonresponders, responders showed significantly higher CXCL9 levels and a greater diversity of the lung microbiome profile in BALF, along with a greater frequency of the CD56+ subset in blood T cells, whereas no significant difference in PD-L1 expression was found in tumor cells. Antibiotic treatment in a preclinical lung cancer model significantly decreased CXCL9 in the lung TME, resulting in reduced sensitivity to anti-PD-1 antibody, which was reversed by CXCL9 induction in tumor cells. Thus, CXCL9 might be associated with the lung TME microbiome, and the balance of CXCL9 and lung TME microbiome could contribute to nivolumab sensitivity in patients with NSCLC. BALF analysis can help predict the efficacy of ICIs when performed along with currently approved examinations.

Monitoring PD-1-Blocking Antibodies Bound to T Cells Derived from a Drop of Peripheral Blood.

Immune checkpoint inhibitors, including PD-1-blocking antibodies, have significantly improved treatment outcomes in various types of cancer. The pharmacological efficacy of these immunotherapies is long lasting, extending even beyond the discontinuation of their injections, due to persistent blood concentrations. Here we developed a simple flow cytometry assay to evaluate the T cell binding status of the PD-1-blocking antibodies nivolumab and pembrolizumab. Like a glucose test, this assay requires just a single drop of peripheral blood. Visualizing antibody binding on T cells is more reliable than measuring antibody blood concentrations. In addition, if necessary, we can potentially analyze many distinctive immune-related markers on T cells bound to PD-1-blocking antibodies. Thus, this is a simple and minimally invasive strategy to analyze the pharmacological effect of PD-1-blocking antibodies in cancer patients.

A case of successful concurrent anti-cancer treatment in a patient who developed follicular lymphoma during treatment with afatinib for advanced lung adenocarcinoma.

The present report describes the case of a 64-year-old woman with advanced lung adenocarcinoma expressing mutant epidermal growth factor receptor (EGFR). The patient developed follicular lymphoma during treatment with the EGFR-tyrosine kinase inhibitor afatinib. Standard immunochemotherapy for follicular lymphoma was introduced in addition to continuing treatment with afatinib for lung cancer. Immunochemotherapy was effective and improved the patient's performance status while afatinib controlled the progression of lung cancer. Our case study suggests that it is safe to introduce standard immunochemotherapy for patients who develop malignant lymphoma while continuing treatment with tyrosine kinase inhibitors for lung adenocarcinoma expressing mutant EGFR.

Impact of sarcopenia in patients with advanced non-small cell lung cancer treated with PD-1 inhibitors: A preliminary retrospective study.

The aim of this study was to investigate the clinical impact of sarcopenia on the efficacy of programmed death (PD)-1 inhibitors. We retrospectively reviewed the medical records of all patients treated with nivolumab or pembrolizumab between January 2016 and September 2018 for previously treated advanced non-small cell lung cancer (NSCLC). The cross-sectional area of the psoas muscle at the level of the third lumbar vertebra on baseline computed tomography was assessed to calculate the psoas muscle index (PMI). Sarcopenia was defined based on PMI cut-off values for Asian adults (6.36 cm2/m2 for males and 3.92 cm2/m2 for females). A total of 42 patients were analysed. The prevalence of sarcopenia was 52.4%. Sarcopenia was significantly associated with poorer progression-free survival (PFS) (median, 2.1 vs. 6.8 months, p = 0.004). Compared to patients with sarcopenia, those without sarcopenia had a higher overall response rate (40.0% vs. 9.1%, p = 0.025) and 1-year PFS rate (38.1% vs. 10.1%). In conclusion, sarcopenia at baseline as determined using computed tomography is a significant predictor of worse outcome in patients with advanced NSCLC receiving PD-1 blockade. Screening for sarcopenia may help identify patients more likely to achieve a long-term response in routine clinical practice.

Skin Rash Can Be a Useful Marker for Afatinib Efficacy.

BACKGROUND/AIM: Although afatinib has a strong efficacy, it can be toxic; hence, we aimed to determine markers of response to afatinib in order to assess prognosis. PATIENTS AND METHODS: Information on clinical background, therapeutic effects, and adverse events was collected retrospectively at one Institution from patients treated with afatinib as initial epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI). We examined the relationship between different adverse events and their effects on prognosis. RESULTS: Afatinib was used in 32 patients as the initial EGFR-TKI. Adverse events of grade 3 or higher including diarrhoea (12.5%), paronychia (6.3%), and stomatitis (3.1%) were experienced by patients. The median progression-free survival (PFS) was 15.4 months. A relationship between skin rash severity and PFS was observed. CONCLUSION: Grade 2 or higher skin rash might be a marker for long-term efficacy of afatinib when administered as a first-line treatment.

Osimertinib Treatment Was Unsuccessful for Lung Adenocarcinoma with G719S, S768I, and T790M Mutations.

Epidermal growth factor receptor (EGFR) T790M mutations are the most frequent mechanism of resistance to first- and second-generation tyrosine kinase inhibitors, and osimertinib is an effective treatment for patients with both EGFR-activating mutations and T790M resistance mutations. We describe the case of a 68-year-old woman with lung adenocarcinoma with G719S, S768I, and T790M mutations in which osimertinib treatment was unsuccessful. The patient died of disease progression one month after discontinuing osimertinib treatment. This case suggests that osimertinib may be ineffective for treating patients with uncommon mutations such as G719S when the patient has also acquired a T790M resistance mutation.

Impact of Pleural Effusion on Outcomes of Patients Receiving Osimertinib for NSCLC Harboring EGFR T790M.

BACKGROUND/AIM: Osimertinib has demonstrated promising efficacy in patients with epidermal growth factor receptor (EGFR) T790M-positive non-small cell lung cancer (NSCLC). We investigated the efficacy of osimertinib in such patients presenting with pleural effusion, which has been unclear to date. PATIENTS AND METHODS: The medical records of all patients treated with osimertinib for advanced NSCLC with EGFR T790M between April 2016 and July 2017 at our Institution were retrospectively reviewed. Time to treatment failure (TTF) and overall survival (OS) were determined as endpoints. RESULTS: Twenty-three patients (seven with pleural effusions) were treated with osimertinib. Patients with pleural effusion had significantly shorter median TTF than those without (3.7 vs. 12.8 months, respectively, p=0.021), as well as shorter median OS (7.8 months vs. not attained, respectively, p=0.002). Metastasis to the brain, bone, and liver did not significantly influence our endpoints. CONCLUSION: Osimertinib monotherapy is less effective in patients with NSCLC with pleural effusions.

Transformation to small cell lung cancer after first-line afatinib treatment.

Acquiring resistance to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) is inevitable. Transformation to small cell lung cancer (SCLC) is reported as a possible mechanism of this acquired resistance. We describe the case of a 35-year-old man with lung adenocarcinoma harboring EGFR exon 19 deletion. After 7 months of successful treatment with afatinib, he experienced relapse and rebiopsy revealed SCLC with EGFR exon 19 deletion. Tumor marker tests at this point showed normal levels of serum neuron-specific enolase and pro-gastrin releasing peptide. Our case highlights the importance of rebiopsy for revealing SCLC transformation, a potential mechanism of acquired resistance to afatinib as with other EGFR-TKIs, and normal-range values of tumor markers for SCLC cannot exclude the possibility of SCLC transformation.