Genomic evolutional analysis of surgical resected specimen to assess osimertinib as a first-line therapy in two patients with lung cancer harboring EGFR mutation: Case series.

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) is crucial for patients with lung cancer harboring EGFR mutations. However, almost all patients experience disease progression, regardless of their response to the targeted therapy, necessitating the development of additional treatment options. Two patients with lung cancer harboring EGFR-L858R mutations in exon 21 were treated by surgical resection during successful osimertinib treatment. Because the pathological diagnosis was suspected to be pleural metastasis, osimertinib treatment was continued until disease progression. We analyzed the evolution of genomic alterations and the levels of AXL using tumor specimens obtained by repeated biopsies during the course of treatment: initial diagnosis, operation, and disease progression. Genetic alterations detected at the three time points were dramatically changed and showed reductions in numbers, while EGFR-L858R mutations were detected in all samples tested in both patients. Immunohistochemical expression of AXL remained positive from the beginning of analysis to disease progression. Clonal evolution under oncogenesis is related to gradual accumulation of genomic alterations during tumor growth. However, our case series revealed that volume reduction procedures may cause this phenomenon. Therefore, identification of intrinsic drug-resistant cells in tumors may be as important as detection of acquired genetic alterations.

Prognostic significance of initial tumor shrinkage in patients with stage III non-small cell lung cancer treated with durvalumab following chemoradiotherapy.

BACKGROUND: Baseline tumor size (BTS) is one of the prognostic factors of advanced non-small cell lung cancer (NSCLC) treated with immunotherapy. However, its prognostic value in patients with locally advanced NSCLC receiving durvalumab maintenance therapy remains unclear. METHODS: The present study retrospectively reviewed 136 patients with unresectable stage III NSCLC who underwent CRT and durvalumab at two institutions in Japan. The maximum diameter of the target lesion (max BTS) before CRT was measured, the best response to CRT before durvalumab was evaluated, and the impact of the response on durvalumab was explored. Progression-free survival (PFS) and overall survival (OS) were defined as the time from the day of starting durvalumab. RESULTS: Of the total cohort, 133 (97.8%) patients had at least one measurable lesion. The best response to CRT resulting in CR, PR, and SD was seen in 0 (0%), 69 (51.9%), and 64 (48.1%) patients, respectively. PFS was significantly longer in the patients with PR than in those with SD after CRT (median not reached vs. 20.0 months; HR: 0.51; P = 0.023). Moreover, the absence of a massive lesion (max BTS < 50 mm) was associated with a superior CRT response (P < 0.001). CONCLUSION: The best response to induction CRT was associated with better PFS in patients with stage III NSCLC receiving durvalumab following chemoradiotherapy. Although the absence of a massive lesion was associated with a better response to induction CRT in this cohort, this was not translated into PFS and OS benefit.

Predictive Impact of Diffuse Positivity for TTF-1 Expression in Patients Treated With Platinum-Doublet Chemotherapy Plus Immune Checkpoint Inhibitors for Advanced Nonsquamous NSCLC.

Introduction: Pervious studies reported the association of TTF-1 expression with the efficacy of platinum-doublet chemotherapy in combination with immune checkpoint inhibitors in advanced nonsquamous NSCLC. Nevertheless, the predictive value of extent of TTF-1 expression (diffuse or focal TTF-1 positivity) remains unclear. Methods: The present study retrospectively reviewed 74 patients with TTF-1-positive recurrent or advanced nonsquamous NSCLC receiving first-line chemoimmunotherapy in a single institution in Japan. TTF-1 expression score in pretreatment tumor specimens was evaluated using immunohistochemistry, and the impact of chemoimmunotherapy response was analyzed. Results: In the total cohort, ≥50% of the tumor cells were TTF-1 positive (i.e., diffusely TTF-1 positive) in specimens of 61 patients (82.4%), whereas 10% to 49% of the tumor cells were TTF-1 positive (i.e., focally TTF-1 positive) in specimens of the remaining 13 patients (17.6%). In multivariate analysis, the median progression-free survival and overall survival (OS) were significantly longer in patients with diffusely TTF-1-positive tumors than in those with focally TTF-1-positive tumors (14.2 versus 9.2 mo, p = 0.01 and 30.2 versus 17.3 mo, p = 0.01, respectively). Moreover, the median OS was significantly longer in patients receiving chemoimmunotherapy including pemetrexed than in those receiving chemoimmunotherapy not including pemetrexed among the patients with diffusely TTF-1-positive tumors (not attained versus 23.2 mo, p < 0.01). Conclusions: The positive extent of diffuse TTF-1 expression associated with patient outcome was an independent predictive factor for better progression-free survival and OS in patients with advanced nonsquamous NSCLC receiving chemoimmunotherapy.

Pulmonary manifestation of inflammatory bowel disease: Two case reports.

Pulmonary involvement associated with inflammatory bowel disease (IBD) are a rare extraintestinal manifestation (EIM) of inflammatory bowel disease (IBD), we herein presented two cases. Case 1: 53-year-old man with Crohn's disease treated with mesalazine and azathioprine. Pulmonary nodular shadows were incidentally detected on chest imaging, and revealed granulomas through transbronchial lung biopsy. Case 2: 68-year-old man with ulcerative colitis treated with mesalazine. He presented with fever and respiratory symptoms, and chest imaging showed multiple nodular infiltrates. He was diagnosed with organizing pneumonia by lung biopsy. Both cases were diagnosed to have pulmonary involvement associated with inflammatory bowel disease (IBD) according to multidisciplinary examination including positron emission tomography-computed tomography (FDG-PET) and pathological test. Pulmonary manifestations with IBD may not always require discontinuation of drugs or additional use of steroids or immunosuppressants.

Osimertinib early dose reduction as a risk to brain metastasis control in EGFR-mutant non-small cell lung cancer.

BACKGROUND: The epidermal growth factor receptor (EGFR) mutation is a risk factor associated with brain metastases (BMs) in patients with non-small cell lung cancer (NSCLC). This study aimed to evaluate the impact of osimertinib early dose reduction on BM worsening. METHODS: We retrospectively analyzed EGFR-mutant NSCLC patients treated with osimertinib as first-line treatment between August 2018 and October 2021. To evaluate the impact of osimertinib early dose reduction, we performed a landmark analysis of patients who achieved disease control at 4 months. Patients were divided into two groups according to whether the osimertinib dose was reduced or not, within 4 months after the start of treatment. We evaluated the time to BMs onset or progression, progression-free survival, and overall survival. RESULTS: In total, 62 NSCLC patients with EGFR mutations were analyzed. Thirteen patients experienced early dose reduction of osimertinib treatment. Seven patients received osimertinib 40 mg daily, and six received 80 mg every other day. The most common reason for dose reduction was gastrointestinal toxicity (n = 4), followed by skin rashes (n = 3). The time to BMs onset or progression was significantly shorter in patients who experienced early dose reduction than in those who continued regular treatment (Hazard ratio 4.47, 95% confidence interval, 1.52-13.11). The 1-year cumulative incidence of BM onset or progression was 23.1% in the reduced-dose group and 5.0% in the standard dose group. The risk of worsening BMs with early dose reduction of osimertinib treatment was higher in patients who had BMs before treatment and in younger patients. CONCLUSION: Early dose reduction of osimertinib was a risk factor for the worsening of BMs. A higher risk was associated with younger patients and those presenting BMs before treatment.

First-line nivolumab plus ipilimumab in metastatic non-small cell lung cancer: 5-year outcomes in Japanese patients from CheckMate 227 Part 1.

BACKGROUND: In CheckMate 227 Part 1 (NCT02477826), first-line nivolumab plus ipilimumab demonstrated long-term durable overall survival (OS) benefit versus chemotherapy in patients with metastatic non-small cell lung cancer (NSCLC), regardless of tumor programmed death ligand 1 (PD-L1) expression. We report results in Japanese patients with ≥ 5-year follow-up. METHODS: Adults with stage IV/recurrent NSCLC without EGFR/ALK aberrations were randomized 1:1:1 to nivolumab plus ipilimumab, nivolumab alone, or chemotherapy (patients with tumor PD-L1 ≥ 1%), or nivolumab plus ipilimumab, nivolumab plus chemotherapy, or chemotherapy (patients with tumor PD-L1 < 1%). Five-year efficacy and safety were assessed in Japanese patients. RESULTS: At 62.1 months' minimum follow-up, 143 Japanese patients with PD-L1 ≥ 1% or < 1% were randomized to nivolumab plus ipilimumab (n = 66) or chemotherapy (n = 77). Five-year OS rates were 46% with nivolumab plus ipilimumab versus 34% with chemotherapy (PD-L1 ≥ 1%) and 36% versus 19% (PD-L1 < 1%). Median duration of response was 59.1 versus 7.1 months (PD-L1 ≥ 1%) and 17.3 versus 3.0 months (PD-L1 < 1%). Among 5-year survivors treated with nivolumab plus ipilimumab (PD-L1 ≥ 1% and < 1%; n = 27), 59% (95% CI, 39%-75%) were off treatment for ≥ 3 years without receiving subsequent therapy. No new safety signals were observed. CONCLUSIONS: At 5-year follow-up, nivolumab plus ipilimumab continued to show long-term durable clinical benefit versus chemotherapy, regardless of tumor PD-L1 expression. Consistent with findings for the global population, these data support the use of nivolumab plus ipilimumab as first-line treatment in Japanese patients with metastatic NSCLC.

Bronchial Thermoplasty Attenuates Cough Reflex Sensitivity in Severe Asthma : A Single-Center Retrospective Study with 2-year Follow-up.

Despite the relatively short follow-up period in our previous study, we had reported that increased cough reflex sensitivity (CRS) may predict the efficacy of bronchial thermoplasty (BT) for treating asthma. Herein, we examined whether CRS predicts the efficacy of BT 2 years after the final BT treatment. We also investigated the influence of BT on CRS. We reviewed 10 patients 2 years after their final BT treatment. CRS, asthma-related symptoms, asthma exacerbations, and cough-related quality of life were assessed at baseline and 2 years after BT. Five patients responded positively to BT (BT responders) and their asthma control improved. No significant difference in CRS at baseline was detected between the BT responders and nonresponders. In contrast, BT responders exhibited significant improvements in CRS 2 years after BT. CRS at baseline could not predict the BT efficacy after 2 years. This is the first report demonstrating BT desensitized CRS in consecutive case series. J. Med. Invest. 70 : 271-275, February, 2023.

Pembrolizumab plus chemotherapy in Japanese patients with metastatic squamous non-small-cell lung cancer in KEYNOTE-407.

The global phase III KEYNOTE-407 (NCT02775435) trial showed that pembrolizumab plus chemotherapy prolonged overall and progression-free survival (OS/PFS) versus placebo plus chemotherapy in patients with metastatic squamous non-small-cell lung cancer (NSCLC). We present outcomes of patients from Japan enrolled in KEYNOTE-407. Patients were randomized 1:1 to receive pembrolizumab 200 mg or placebo with paclitaxel 200 mg/m2 every 3 weeks (Q3W) or nab-paclitaxel 100 mg/m2 (weekly) plus carboplatin area under the concentration-time curve of 6 mg/mL/min Q3W for four cycles, followed by pembrolizumab or placebo Q3W for a total of 35 cycles. Primary end-points were OS and PFS per RECIST version 1.1 by blinded independent central review. Fifty patients were randomized at Japanese sites (pembrolizumab plus chemotherapy, n = 22; placebo plus chemotherapy, n = 28). Median follow-up time at data cut-off (May 9, 2019) was 15.1 (range, 0.5-24.0) months. Median OS (95% confidence interval [CI]) was 17.3 (12.5-not reached) versus 11.0 (8.6-19.5) months in the pembrolizumab plus chemotherapy versus placebo plus chemotherapy group (hazard ratio [HR] 0.56; 95% CI, 0.27-1.15). Median PFS (95% CI) was 8.3 (6.1-13.0) versus 7.2 (3.9-8.8) months (HR 0.65; 95% CI, 0.35-1.23). Grade 3-5 adverse events (AEs) occurred in 86% and 75% of patients, respectively. There were three fatal AEs, two of which were treatment-related (one from each treatment group, pneumonitis and pulmonary hemorrhage). Efficacy and safety outcomes were consistent with the global study and support the use of pembrolizumab plus chemotherapy in Japanese patients with metastatic squamous NSCLC.

Evaluation of factors affecting epidermal growth factor receptor tyrosine kinase inhibitor-induced hepatotoxicity in Japanese patients with non-small cell lung cancer: a two-center retrospective study.

BACKGROUND: Gefitinib and erlotinib, are epidermal growth factor receptor tyrosine kinase inhibitors, and are currently recommended for non-small cell lung cancer stage IV in the elderly and in patients with decreased performance status in the Japanese Lung Cancer Society Guideline, but they occasionally caused severe hepatotoxicity requiring postponement or modification of treatment. However, little is known about the risk factors for hepatotoxicity in patients receiving gefitinib and erlotinib. In this study, we investigated the factors influencing hepatotoxicity in Japanese non-small cell lung cancer (NSCLC) patients treated with gefitinib or erlotinib monotherapy. METHODS: Japanese patients with NSCLC who started gefitinib or erlotinib monotherapy from January 2005 to December 2017 at Kanazawa University Hospital or Kanazawa Medical University Hospital were included in this study. Factors affecting hepatotoxicity were retrospectively investigated by multiple logistic regression analysis. RESULTS: A total of 102 patients who received gefitinib and 95 patients who received erlotinib were included in the analysis. In the gefitinib group, a body mass index (BMI) ≥ 25 was associated with an increased risk of hepatotoxicity (OR = 4.571, 95% CI = 1.486-14.056, P = 0.008). In the erlotinib group, concomitant use of acid-suppressing medications (AS), namely proton pump inhibitors or histamine-2 receptor antagonists, was associated with a reduced risk of hepatotoxicity (OR = 0.341, 95% CI = 0.129-0.900, P = 0.030). CONCLUSIONS: BMI ≥ 25 in patients treated with gefitinib increased the risk of hepatotoxicity. In contrast, AS combination with erlotinib reduced the risk of hepatotoxicity. Thus, because different factors influence the risk of hepatotoxicity, monitoring for adverse events should take into account patient background factors and concomitant medications.

An open-label, crossover study to compare different formulations and evaluate effect of food on pharmacokinetics of pimitespib in patients with advanced solid tumors.

This study compared the bioavailability of two pimitespib formulations (Formulations A and B), evaluated the food effect on Formulation A, and evaluated the safety and efficacy of multiple pimitespib doses in patients with solid tumors. This clinical, pharmacological multicenter study had two cohorts and periods. A single dose of Formulation A or B was administered in a crossover design to compare the pharmacokinetics in Cohort 1. In Cohort 2, the effects of fed vs fasting conditions were evaluated among those receiving Formulation A. Subsequently, multiple Formulation A doses were administered to all patients for safety and efficacy assessments. In Cohorts 1 and 2, 12 and 16 patients, respectively, were analyzed for pharmacokinetics. Thirty patients were analyzed for safety and efficacy. Maximum concentration (Cmax), area under the curve (AUC)last, and AUCinf geometric mean ratios for Formulations A and B (90% confidence interval [CI]) were 0.8078 (0.6569-0.9933), 0.7973 (0.6672-0.9529), and 0.8094 (0.6697-0.9782), respectively; 90% CIs were not within the bioequivalence range (0.80-1.25). In Cohort 2, mean Cmax, AUClast, and AUCinf were higher in fed vs fasting conditions. No safety concerns emerged with single or multiple administration. Overall response rate, disease control rate, and median progression-free survival were 0%, 33%, and 1.5 months, respectively. Four patients had stable disease ≥ 5 months. Bioequivalence of the two formulations was unconfirmed. Systemic exposure of Formulation A was approximately 20% less than Formulation B. A high-fat/calorie meal increased the relative pharmacokinetics and bioavailability of a single 160-mg dose. Trial Registration: JapicCTI-184191 (Japan Pharmaceutical Information Center) registered on November 5, 2018.

Primary ciliary dyskinesia with CCDC39 variants displaying specific ciliary ultrastructure and movement concordant with the genotype: A case report.

Primary ciliary dyskinesia (PCD) is a genetic disease with chronic airway infection and inflammation caused by ciliary ultrastructural defects and impairment in ciliary function. We present an adult case of PCD with compound heterozygous nonsense variants in CCDC39. The ciliary ultrastructure findings using electron microscopy and ciliary movement using high-speed video analysis matched the genotype. This is the first case report of PCD with CCDC39 variants in Japan demonstrating specific ciliary ultrastructure and movement related to the genotype.

Evaluation of Rhythmic Masseter Muscle Activity during Sleep and Awake in Patients with Dentofacial Deformity.

Objectives: Investigate the activity of rhythmic masseter muscles activity (RMMA) during sleep in patients with dentofacial deformities. Materials and methods: Fifty patients with dentofacial deformities (16 male, 34 female) who required orthognathic surgery. An electrode was attached to the masseter muscle bilaterally, and preoperative polysomnography was performed. The frequency of RMMA onset per hour was measured on the left and the right sides. Values were classified as phasic (grinding: P-RMMA) and tonic (clenching: T-RMMA) to examine the onset of RMMA. Correlation between the RMMA index and various morphological and physical factors were determined including sleep or awake, rapid eye movement (REM), non-rapid eye movement (NREM) phases (NR1-NR4) in the sleep stage, phasic and tonic, gender, and mandibular asymmetry. Results: The RMMA index values at the time of sleep were significantly small than during awake. The values were significantly higher during the NREM sleep than during the REM sleep and were the highest in the NR1 phase. P-RMMA index was significantly higher than the T-RMMA index. The P-RMMA index was also significantly higher than the T-RMMA index for men. In patients with greater asymmetry in the RMMA index values between the left and the right side (more than 30% difference), deviation between the midpoint of the maxillary and the mandibular incisal edges (U1-L1 deviation) was significantly higher. Conclusion: RMMA in patients with dentofacial deformity was statistically higher in awake than sleep, higher in NREM sleep than REM sleep, higher in male than female on grinding, and higher in upper and lower incisor high deviation.

Long-Term Survival of Patients With Non-Small Cell Lung Cancer Treated With Immune Checkpoint Inhibitor Monotherapy in Real-World Settings.

BACKGROUND: Immune checkpoint inhibitor (ICI) monotherapy is more effective than cytotoxic chemotherapy in improving overall survival (OS) among patients with advanced-stage non-small cell lung cancer (NSCLC). Recently, chemotherapy combined with ICI has been found to yield good outcomes. However, ICI monotherapy is still considered an important treatment option. Data on long-term progression-free survival (PFS) and OS in real-world settings are limited. PATIENTS AND METHODS: This was a multicenter retrospective observational study. A total of 435 consecutive patients histologically diagnosed with advanced, metastatic, or recurrent NSCLC treated with ICI monotherapy were enrolled in this study from December 2015 to December 2018. Clinical data were collected from electronic medical records and pharmacy databases. RESULTS: The PFS and OS of the patients were 3.4 and 13.0 months, respectively. The objective response and disease control rates were 22.8% and 54.9%, respectively, and the 4-year survival rate was 17.9%. Multivariate analyses revealed that elder patients (>70 years), good Eastern Cooperative Oncology Group Performance Status (ECOG PS) score, programmed death-ligand 1 tumor proportion score (PD-L1 TPS) of ≥ 50%, absence of bone metastasis, and presence of immune-related skin toxicity, which is an immune-related adverse event, were correlated with good PFS. Moreover, good ECOG PS score, PD-L1 TPS of ≥ 50%, absence of bone metastasis, and presence of skin toxicity were correlated with good OS. CONCLUSIONS: The 4-year survival rate was 17.9%. Good ECOG PS score, PD-L1 TPS of ≥ 50%, absence of bone metastasis, and presence of skin toxicity were correlated with good PFS and OS.

The Therapeutic Effect and Clinical Outcome of Immune Checkpoint Inhibitors on Bone Metastasis in Advanced Non-Small-Cell Lung Cancer.

Introduction: In advanced non-small-cell lung cancer (NSCLC), immune checkpoint inhibitors (ICIs) have been reported a better treatment outcome on primary lesions, however, the therapeutic effect on bone metastases has not been clarified. This study investigates the therapeutic effect of ICIs on bone metastases in advanced NSCLC. Methods: The data of patients with advanced NSCLC, treated with ICIs from 2016 to 2019 at our hospital, were analyzed. The therapeutic effects of ICIs on primary lung and metastatic bone lesions, concomitant use of bone modifying agents (BMA), treatment outcomes, and frequency of immune-related adverse events (irAEs) and skeletal-related events (SREs) were investigated. Results: A total of 29 patients were included (19 men and 10 women; mean age, 64.2 years). Among the ICIs, pembrolizumab was the most used (55.2%), and concomitant use of BMA was prevalent in 21 patients (zoledronic acid=1, denosumab=20). The therapeutic effect was partial response (PR) in 10.3% (n=3) on primary lung lesions by RECIST 1.1, complete response (CR) in 6.9% (n=2) and PR in 17.2% (n=5) on bone metastatic lesions by MDA criteria. ICIs suppressed the progression of bone metastasis in 21 cases (72.4%). All patients in CR and PR were treated with pembrolizumab and denosumab. SREs and irAEs were developed in 3.4% (n=1) and 20.7% (n=6), respectively. The median survival time after treatment with ICIs was 11.0 months. Concomitant therapy with ICIs and denosumab significantly prolonged the overall survival compared to ICI-only therapy (16.0 months vs. 2.5 months, p<0.01). Conclusions: This study showed that treatment with ICIs may successfully suppress the progression of bone metastasis in advanced NSCLC. Pembrolizumab with denosumab had the highest therapeutic effect on both primary lung lesions and bone metastases. Systemic treatment with this combination and conservative treatment of bone metastasis could be one of the options in the treatment of advanced NSCLC.

Methicillin-resistant Staphylococcus aureus Necrotizing Bronchitis after Radiotherapy in Combination with Axitinib.

A 38-year-old man with renal cell carcinoma was referred to our hospital because of a productive cough. He had received radiotherapy for lung metastasis and been treated with axitinib. Bronchoscopy revealed necrosis in the bronchi of the right middle and lower lobes. Culture of the necrotic bronchial specimen revealed methicillin-resistant Staphylococcus aureus (MRSA). Although radiotherapy in combination with axitinib carries a risk of causing airway toxicity, MRSA necrotizing bronchitis has not been reported. Physicians should consider the possibility of infectious necrotizing bronchitis if irradiated patients show prolonged respiratory symptoms.

First-line nivolumab plus ipilimumab combined with two cycles of chemotherapy in advanced non-small cell lung cancer: a subanalysis of Asian patients in CheckMate 9LA.

BACKGROUND: CheckMate 9LA, a phase 3, randomized, open-label study in first-line advanced non-small cell lung cancer (NSCLC), showed significantly improved overall survival (OS) with nivolumab plus ipilimumab combined with 2 cycles of chemotherapy versus chemotherapy alone (4 cycles). We present results for the Asian subpopulation enrolled in Japan and China. METHODS: Patients aged ≥ 18 years with treatment-naive, histologically confirmed stage IV or recurrent NSCLC, Eastern Cooperative Oncology Group performance status 0-1 and no sensitizing EGFR/ALK mutations were randomized 1:1 to nivolumab [360 mg every 3 weeks (Q3W)] plus ipilimumab (1 mg/kg Q6W) combined with chemotherapy (Q3W for 2 cycles), or chemotherapy alone (Q3W for 4 cycles). Primary endpoint was OS; secondary endpoints included progression-free survival (PFS) and objective response rate (ORR). RESULTS: Twenty-eight patients received nivolumab plus ipilimumab combined with chemotherapy and 30 received chemotherapy. At a minimum follow-up of 12.7 months, median OS was not reached with nivolumab plus ipilimumab combined with chemotherapy versus 13.3 months with chemotherapy [hazard ratio (HR) 0.33; 95% confidence interval (CI) 0.14-0.80]. Median PFS was 8.4 versus 5.4 months (HR 0.47; 95% CI 0.24-0.92) and ORR was 57% versus 23%, respectively. Grade 3-4 treatment-related adverse events were observed in 57% versus 60% of patients, respectively. CONCLUSION: Consistent with results in the all randomized population, nivolumab plus ipilimumab combined with chemotherapy improved efficacy in the Asian subpopulation versus chemotherapy alone and had a manageable safety profile, supporting its use as first-line treatment for advanced NSCLC in Asian patients.

Quantitative analysis of changes in lung density by dynamic chest radiography in association with CT values: a virtual imaging study and initial clinical corroboration.

Dynamic chest radiography (DCR) identifies pulmonary impairments as decreased changes in radiographic lung density during respiration (Δpixel values), but not as scaled/standardized computed tomography (CT) values. Quantitative analysis correlated with CT values is beneficial for a better understanding of Δpixel values in DCR-based assessment of pulmonary function. The present study aimed to correlate Δpixel values from DCR with changes in CT values during respiration (ΔCT values) through a computer-based phantom study. A total of 20 four-dimensional computational phantoms during forced breathing were created to simulate both CT and projection images of the same virtual patients. The Δpixel and ΔCT values of the lung fields were correlated on a regression line, and the inclination was statistically evaluated to determine whether there were significant differences among physical types, sex, and breathing methods. The resulting conversion expression was also assessed in the DCR images of 37 patients. The resulting Δpixel values for 30/37 (81%) real patients, 6/7 (86%) normal controls, and 24/30 (80%) chronic obstructive pulmonary disorder patients were within the range of ΔCT values ± standard deviation (SD) reported in a previous study. In addition, no significant differences were detected for each condition of thoracic breathing, suggesting that the same regression line inclination values measured across the entire lung can be used for the conversion of Δpixel values, providing a quantitative analysis that can be correlated with ΔCT values. The developed conversion expression may be helpful for improving the understanding of respiratory changes using radiographic lung densities from DCR-based assessments of pulmonary function.