Osimertinib plus local treatment for brain metastases versus osimertinib alone in patients with EGFR-Mutant Non-Small Cell Lung Cancer

OBJECTIVES

Osimertinib is a standard treatment for patients with EGFR-mutant non-small cell lung cancer (NSCLC) and is highly effective for brain metastases (BMs). However, it is unclear whether local treatment (LT) for BMs prior to osimertinib administration improves survival in EGFR-mutant NSCLC. We aimed to reveal the survival benefit of upfront local treatment (LT) for BMs in patients treated with osimertinib.

MATERIALS AND METHODS

This multicenter retrospective study included consecutive patients with EGFR mutation (19del or L858R)-positive NSCLC who had BMs before osimertinib initiation between August 2018 and October 2021. We compared overall survival (OS) and central nervous system progression-free survival (CNS-PFS) between patients who received upfront LT for BMs (the upfront LT group), and patients who received osimertinib only (the osimertinib-alone group). Inverse-probability treatment weighting (IPTW) analysis was performed to adjust for potential confounding factors.

RESULTS

Of the 121 patients analyzed, 57 and 64 patients had 19del and L858R, respectively. Forty-five and 76 patients were included in the upfront LT group and the osimertinib-alone groups, respectively. IPTW-adjusted Kaplan-Meier curves showed that the OS of the upfront LT group was significantly longer than that of the osimertinib-alone group (median, 95 % confidence intervals [95 %CI]: Not reached [NR], NR-NR vs. 31.2, 21.7-33.2; p = 0.021). The hazard ratio (HR) for OS and CNS-PFS was 0.37 (95 %CI, 0.16-0.87) and 0.36 (95 %CI, 0.15-0.87), respectively.

CONCLUSIONS

The OS and CNS-PFS of patients who received upfront LT for BMs followed by osimertinib were significantly longer than those of patients who received osimertinib alone. Upfront LT for BMs may be beneficial in patients with EGFR-mutant NSCLC treated with osimertinib.

Phosphoproteomic Analysis Identified Mutual Phosphorylation of FAK and Src as a Mechanism of Osimertinib Resistance in EGFR-Mutant Lung Cancer

Introduction

Osimertinib is a standard treatment for patients with EGFR-mutant NSCLC. Although some osimertinib resistance mechanisms have been identified, nearly 50% of the mechanisms remain to be elucidated. This study was aimed at identifying non-genetic mechanisms underlying osimertinib resistance.

Methods

We established two osimertinib-resistant cell lines from EGFR mutation-positive PC-9 and HCC827 NSCLC cell lines (PC-9OR and HCC827OR, respectively) using a stepwise method. We compared the phosphoproteomic profiles of the osimertinib-resistant and parental cells using mass spectrometry. Upstream kinases were identified using the application Kinase Enrichment Analysis version 3.

Results

Phosphoproteomic analysis revealed 80 phosphorylation sites that were mutually up-regulated in PC-9OR and HCC827OR cells. The Kinase Enrichment Analysis version 3 analysis identified focal adhesion kinase (FAK) and proto-oncogene tyrosine-protein kinase Src (Src) as upstream kinases of these up-regulated phosphoproteins. The small-interfering RNA-mediated knockdown of FAK reduced Src phosphorylation and that of Src reduced FAK phosphorylation in both cell lines. Furthermore, FAK- or Src-specific small-interfering RNA treatments restored EGFR phosphorylation in PC-9OR and HCC827OR cells. The combination of FAK and Src inhibitors inhibited PC-9OR and HCC827OR cell proliferation in vitro and suppressed tumor growth in a xenograft mouse model. Immunohistochemistry of tumors from patients with EGFR-mutant NSCLC suggested that phosphorylated FAK and Src are involved in initial and acquired resistance to osimertinib.

Conclusions

Phosphoproteomic analysis may help elucidate the mechanisms of resistance to molecular-targeted therapies in lung cancer. Mutual phosphorylation of FAK and Src is involved in osimertinib resistance. Thus, FAK and Src inhibition may be novel treatment strategies for osimertinib-resistant NSCLC.

Immunotherapy With Radiotherapy for Brain Metastases in Patients With NSCLC: NEJ060

Introduction

Immune checkpoint inhibitor (ICI)-based treatment has become standard treatment for patients with advanced NSCLC. We aimed to determine the survival benefit of upfront radiotherapy for brain metastases (BMs) in patients with NSCLC who received ICI alone (ICI-alone) or with chemotherapy (ICI-chemo).

Methods

This study included consecutive patients with NSCLC having BMs who received ICI alone or ICI-chemo at 50 institutes between February 2017 and September 2021. The presence of BMs was confirmed by imaging before treatment. Treatment outcomes were compared between patients who did and did not receive upfront radiotherapy for BMs. Potential confounding factors were adjusted between the groups through inverse probability treatment weighting (IPTW) analysis and overlap weighting (OW) analysis with propensity scores.

Results

Patients were grouped as ICI-alone cohort, 224 patients (upfront-radiotherapy group, 135 patients; no-radiotherapy group, 89 patients) and ICI-chemo cohort, 367 patients (upfront-radiotherapy group, 212 patients; no-radiotherapy group, 155 patients). In the ICI-alone cohort, the overall survival of the upfront-radiotherapy group was significantly longer than that of the no-radiotherapy group (IPTW-adjusted hazards ratio [HR] = 0.45 [95% confidence interval [CI]: 0.29-0.72], OW-adjusted HR = 0.52 [95% CI: 0.35-0.77]). In contrast, in the ICI-chemo cohort, the OS of the upfront-radiotherapy group was not significantly different from that of the no-radiotherapy group (IPTW-adjusted HR = 1.02 [95% CI: 0.70-1.48], OW-adjusted HR = 0.93 [95% CI: 0.65-1.33]).

Conclusions

Upfront radiotherapy for BMs was associated with longer overall survival in patients with NSCLC who received ICI alone; however, it did not exhibit survival benefits in the patients who received ICI-chemo.

Immunotherapy or Chemoimmunotherapy in Older Adults With Advanced Non-Small Cell Lung Cancer

Importance

Immune checkpoint inhibitor (ICI) plus chemotherapy combination treatment (ICI-chemotherapy) is now a standard treatment for non-small cell lung cancer (NSCLC) without targetable oncogene alterations, but there are few data on ICI-chemotherapy for patients 75 years and older.

Objective

To inform the choice of first-line drugs in clinical practice and assess the safety and efficacy of ICI-chemotherapy combination treatment in older adult patients with previously untreated advanced NSCLC.

Design, Setting, and Participants

This retrospective cohort study included 58 centers in Japan. The cohort consisted of patients 75 years and older with clinical stage IIIB, IIIC, IV, postoperative or radiotherapy recurrent NSCLC. Patients started first-line systemic therapy between December 2018 and March 2021. Those receiving first-line molecular targeted drugs were excluded. The data were analyzed from February 2022 to October 2022.

Exposures

Systemic therapy.

Main Outcomes and Measures

The main outcomes were overall survival (OS), progression-free survival (PFS), and safety.

Results

A total of 1245 patients (median [range] age, 78 [75-95] years; 967 [78%] male) with NSCLC were included in the cohort. Programmed death ligand-1 (PD-L1) expression of less than 1% occurred in 268 tumors (22%); 1% to 49% in 387 tumors (31%); 50% and higher in 410 tumors (33%), and unknown expression in 180 tumors (14%). Median OS was 20.0 (95% CI, 17.1-23.6) months for the 354 patients receiving ICI-chemotherapy (28%); 19.8 (95% CI, 16.5-23.8) months for the 425 patients receiving ICI alone (34%); 12.8 (95% CI, 10.7-15.6) months for the 311 patients receiving platinum-doublet chemotherapy (25%); and 9.5 (95% CI, 7.4-13.4) months for the 155 patients receiving single-agent chemotherapy (12%). After propensity score matching, no differences in OS and PFS were found between the patients receiving ICI-chemotherapy vs ICI alone. Each group consisted of 118 patients. For PD-L1 expression of 1% and higher the OS hazard ratio (HR) was 0.98 (95% CI, 0.67-1.42; P = .90), and the PFS HR was 0.92 (95% CI, 0.67-1.25; P = .59). Significance was also not reached when separately analyzed for lower or higher PD-L1 expression (1%-49% or ≥50%). However, grade 3 or higher immune-related adverse events occurred in 86 patients (24.3%) treated with ICI-chemotherapy and 76 (17.9%) with ICI alone (P = .03).

Conclusions and Relevance

In this study, ICI-chemotherapy combination treatment did not improve survival and increased the incidence of grade 3 and higher immune-related adverse events compared with ICI alone in patients 75 years and older. Based on these results, ICI alone may be recommended for older adult patients with PD-L1-positive NSCLC.

Second-line immunosuppressant administration for steroid-refractory immune-related adverse events in patients with lung cancer

BACKGROUND

Evidence for use of second-line immunosuppressants for immune-related adverse events (irAEs) is inadequate. Therefore, a multicenter analysis should assess the efficacy of second-line immunosuppressants for severe irAEs associated with different malignant diseases.

METHODS

This descriptive study aims to investigate the effects of second-line immunosuppressants on corticosteroid-refractory irAEs in patients with lung cancer. We analyzed the effects of second-line immunosuppressants on underlying lung cancer and associated adverse effects.

RESULTS

Our study included 4589 patients who had received immune checkpoint inhibitor treatment, with 73 patients (1.6%) developing irAEs requiring second-line immunosuppressants. The most commonly observed irAE was pneumonitis (26 patients), followed by hepatobiliary disorders (15 patients) and enteritis (14 patients). We found a confirmed response rate of 42.3% for pneumonitis, which was lower than the response rates of 86.7% for hepatobiliary disorders and 92.9% for enteritis. The time from the start of corticosteroid therapy to the addition of a second-line immunosuppressant correlated significantly with the resolution of irAE to Grade 1 (correlation coefficients of r = 0.701, p < 0.005). The median progression-free survival and duration of response of underlying lung cancer from second-line immunosuppressant administration were 2.1 and 3.0 months, respectively. Of the patients with irAE, 27.4% developed infections and 5.5% might die due to infection.

CONCLUSION

Second-line immunosuppressant response was confirmed in 72.2% of irAEs in patients with lung cancer, with lower response rates observed in irAE pneumonitis compared to other irAEs.

Successful Treatment with Definitive Concurrent Chemoradiotherapy Followed by Durvalumab Maintenance Therapy in a Patient with Tracheal Adenoid Cystic Carcinoma

Adenoid cystic carcinoma (ACC) is a rare type of malignant tracheal tumor originating from the secretory glands. Complete surgical resection is the current standard of care for tracheal ACC. However, there have been few case reports of chemoradiotherapy for unresectable tracheal ACC. We herein report a 28-year-old man with unresectable tracheal ACC who received concurrent chemoradiotherapy (CCRT) followed by maintenance therapy with durvalumab. CCRT was completed with a good response and safety, and the patient is currently receiving durvalumab as maintenance therapy. Durvalumab after CCRT can be a treatment option for patients with unresectable tracheal ACC.

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.

Subsequent treatment for locally advanced non-small-cell lung cancer that progressed after definitive chemoradiotherapy and consolidation therapy with durvalumab: a multicenter retrospective analysis (TOPGAN 2021-02)

PURPOSE

For patients with locally advanced non-small-cell lung cancer (LA-NSCLC) that progressed after definitive chemoradiotherapy (CRT) and durvalumab consolidation therapy, no subsequent standard treatment exists. The type of treatment selected for each timing of disease progression and its efficacy have not been investigated.

METHODS

We retrospectively enrolled patients with LA-NSCLC or inoperable NSCLC that progressed after definitive CRT and durvalumab consolidation therapy at 15 Japanese institutions. Patients were classified into the following: Early Discontinuation group (disease progression within 6 months after durvalumab initiation), Late Discontinuation group (disease progression from 7 to 12 months after durvalumab initiation), and Accomplishment group (disease progression from 12 months after durvalumab initiation).

RESULTS

Altogether, 127 patients were analyzed, including 50 (39.4%), 42 (33.1%) and 35 (27.5%) patients from the Early Discontinuation, Late Discontinuation, and Accomplishment groups, respectively. Subsequent treatments were Platinum plus immune checkpoint inhibitors (ICI) in 18 (14.2%), ICI in 7 (5.5%), Platinum in 59 (46.4%), Non-Platinum in 35 (27.6%), and tyrosine kinase inhibitor in 8 (6.3%) patients. In the Early Discontinuation, Late Discontinuation, and Accomplishment groups, 4 (8.0%), 7 (16.7%), and 7 (20.0%) patients were receiving Platinum plus ICI; 21 (42.0%), 22 (52.4%), and 16 (45.7%) were receiving Platinum, and 20 (40.0%), 8 (19.0%), and 7 (20.0%) were receiving Non-Platinum, respectively. No significant difference in progression-free survival was observed in the timing of disease progression.

CONCLUSION

In patients with LA-NSCLC hat progressed after definitive CRT and durvalumab consolidation therapy, subsequent treatment may change depending on the timing of disease progression.

Remarkable Clinical Response of ALK-Rearranged/TP53-Mutant Lung Adenocarcinoma with Liver Metastasis to Atezolizumab-Bevacizumab-Carboplatin-Paclitaxel After ALK Inhibitors: A Case Report

Anaplastic lymphoma kinase-positive (ALK-positive) lung adenocarcinoma with multiple liver metastases accounts for a relatively small number of cases of non-small cell lung cancer. Several ALK-tyrosine kinase inhibitors (ALK-TKIs) are available for the treatment of lung cancer. However, there is limited evidence on the treatment of multiple liver metastases in patients with lung cancer that are refractory to ALK-TKIs. We report the case of a 42-year-old male patient with ALK-positive lung adenocarcinoma who experienced rapid progression to multiple liver metastases while receiving treatment with alectinib. Biopsy of the liver metastases revealed echinoderm microtubule-associated protein-like 4-ALK (EML4-ALK) fusion and tumor protein p53 (TP53) mutation; notably, ALK secondary mutations were not detected. Despite the sequential administration of third-generation ALK-TKIs, the liver metastases did not respond, the serum levels of total bilirubin and biliary enzymes continued to increase, and the patient's general appearance worsened. Finally, the patient exhibited a remarkable clinical response to treatment with a combination of atezolizumab, bevacizumab, carboplatin, and paclitaxel (ABCP). ABCP is one of the optimal options for ALK-positive lung cancer with liver metastasis that is refractory to ALK-TKIs therapy.

Platinum-combination chemotherapy with or without immune-checkpoint inhibitor in patients with postoperative recurrent non-small cell lung cancer previously treated with adjuvant platinum-doublet chemotherapy: A multicenter retrospective study

BACKGROUND

Rechallenge with platinum-combination chemotherapy in patients with advanced non-small cell lung cancer (NSCLC) after disease progression on platinum-combination chemotherapy occasionally leads to a favorable response. The efficacy and safety of platinum-combination chemotherapy with or without immune-checkpoint inhibitor (ICI) for patients with recurrent NSCLC after surgery followed by adjuvant platinum-doublet chemotherapy remains uncertain.

METHODS

Patients who relapsed after surgery plus adjuvant platinum-doublet chemotherapy and received platinum-combination chemotherapy with or without ICI between April 2011 and March 2021 at four Nippon Medical School hospitals were retrospectively analyzed.

RESULTS

Among 177 patients who received adjuvant platinum-doublet chemotherapy after surgery, a total of 30 patients who received platinum-combination rechemotherapy with or without ICI after relapse were included in this study. Seven patients received ICI-combined chemotherapy. The median disease-free survival (DFS) after surgery was 13.6 months. The objective response rate and disease-control rate were 46.7% and 80.0%, respectively. The median progression-free survival and overall survival were 10.2 and 37.5 months, respectively. Patients with longer DFS (≥12 months) had a better prognosis than others. The most common grade ≥3 toxicity associated with this treatment was neutropenia (33%). Grade ≥3 immune-related adverse events were pneumonitis (14%) and colitis (14%). Treatment-related deaths did not occur in this study.

CONCLUSION

Platinum-combination chemotherapy with or without ICI for patients with postoperative recurrent NSCLC who previously received adjuvant platinum-doublet chemotherapy was effective and safe. In particular, this therapy may be promising for patients with longer DFS.

Soluble interleukin-2 receptor as a predictive biomarker for poor efficacy of combination treatment with anti-PD-1/PD-L1 antibodies and chemotherapy in non-small cell lung cancer patients

Soluble interleukin-2 receptor (sIL-2R) suppresses effector T-cells. Few studies have assessed serum sIL-2R in patients receiving immunotherapy. We evaluated the association between serum sIL-2R levels and the efficacy of anti-programmed cell death 1/ programmed death-ligand 1 (anti-PD-1/PD-L1) antibody combined with chemotherapy in non-small cell lung cancer (NSCLC) patients. We prospectively enrolled NSCLC patients who received anti-PD-1/PD-L1 antibody combined with platinum-based chemotherapy between 8/2019 and 8/2020 and measured their serum sIL-2R. The patients were divided into high and low sIL-2R groups based on the median of sIL-2R levels at pretreatment. Progression-free survival (PFS) and overall survival (OS) of patients in the high and low sIL-2R groups were compared. The Kaplan-Meier curves of PFS and OS were evaluated using the log-rank test. The multivariate analysis of PFS and OS was performed using the Cox proportional hazard models. Among 54 patients (median age 65, range 34-84), 39 were male and 43 had non-squamous cell carcinoma. The sIL-2R cut-off value was 533 U/mL. Median PFS was 5.1 months (95% CI, 1.8-7.5 months) and 10.1 months (95% CI, 8.3-not reached [NR] months) in the high and low sIL-2R groups (P = 0.007), respectively. Median OS was 10.3 months (95% CI, 4.0-NR months) and NR (95% CI, 10.3-NR months) in the high and low sIL-2R groups (P = 0.005), respectively. Multivariate Cox regression analysis showed that high sIL-2R was significantly associated with shorter PFS and OS. SIL-2R may be a biomarker for the poor efficacy of anti-PD-1/PD-L1 antibody combined with chemotherapy.

Alectinib-Induced Severe Hemolytic Anemia in a Patient with ALK-Positive Non-Small Cell Lung Cancer: A Case Report

Alectinib is a selective anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor as standard therapy for ALK-rearranged non-small cell lung cancer (NSCLC). Hemolytic anemia is considered as a rare but significant adverse event with alectinib. Here, we report a case of a 73-year-old female with lung adenocarcinoma, harbouring an ALK fusion gene, who received alectinib as second-line therapy and developed gradually progressive grade 4 (6.4 g/dL) drug-induced hemolytic anemia (DIHA) after complete response. We discontinued alectinib and performed a blood transfusion for the severe anemia. The anemia improved with no recurrence of lung adenocarcinoma over 10 months. Regular hematologic monitoring and the possibility of DIHA should be considered in case of progressive hemolytic anemia during alectinib treatment.

Clinical efficacy of amrubicin in patients with small cell lung cancer relapse after first-line treatment including immune checkpoint inhibitors: A retrospective multicenter study (TOPGAN 2021-01)

BACKGROUND

The therapeutic efficacy of cytotoxic anticancer drugs has been reported to be enhanced after immune checkpoint inhibitors (ICI) in non-small cell lung cancer; however, it is unclear whether the same is applicable for small cell lung cancer (SCLC). We evaluated the efficacy of second-line amrubicin (AMR) following first-line platinum-based chemotherapy and ICI combination therapy (chemo-ICI) in SCLC.

PATIENTS AND METHODS

We retrospectively enrolled consecutive patients with SCLC treated with AMR as a second-line following chemo-ICI as first-line between July 2019 and April 2021 from 16 institutions throughout Japan. We investigated the therapeutic effectiveness, safety, and efficacy-enhancing variables of AMR.

RESULTS

Overall, 89 patients treated with AMR after first-line chemo-ICI were analyzed. The overall response rate (ORR) was 29.2% (95% confidence intervals [CI], 20.1-39.8) and median PFS (m PFS) was 2.99 months (95% CI, 2.27-3.65). Patients who relapsed more than 90 days after receiving first-line platinum combination therapy (sensitive relapse) exhibited greater ORR (58.3% vs. 24.7%, p = 0.035) and m PFS (5.03 vs. 2.56 months, p = 0.019) than patients who relapsed in <90 days (refractory relapse). Grade 3 or higher adverse events were mainly hematological toxicity.

CONCLUSIONS

Our study suggested that the therapeutic effect of AMR was not enhanced after ICI on SCLC. However, AMR may be effective in cases of sensitive relapse after chemo-ICI. There was no increase in severe toxicity associated with AMR after ICI.

Successful Treatment with Short-Term Steroid Against Severe Hepatitis Confirmed by Liver Biopsy in a Patient with Advanced Squamous-Cell Lung Cancer Receiving a Combination of Pembrolizumab, Carboplatin, and Nab-Paclitaxel: A Case Report

Pembrolizumab is an immune checkpoint inhibitor (ICI) that targets programmed death-1. Although ICIs have shown efficacy in the treatment of lung cancer, they have also been reported to cause a variety of immune-related adverse events (irAEs). Hepatotoxicity is a known irAEs, but currently, there is not enough information on its pathological characteristics and treatment. We report the case of a 70-year-old man with advanced squamous-cell lung cancer who developed severe grade 4 hepatitis on day 8 after receiving carboplatin, nab-paclitaxel, and pembrolizumab as fourth-line therapy. We treated him with steroid therapy the day after a liver biopsy was performed to investigate his pathological features, which led to a rapid and remarkable improvement. Confirmation of immune-related hepatotoxicity by pathological findings allowed the early tapering and discontinuation of steroid therapy. Performing a liver biopsy and verifying histological characteristics are needed for successful treatment with short-term steroids when drug-induced hepatitis caused by anti-cancer therapy including pembrolizumab is considered.

Acute respiratory failure due to Aspergillus niger infection with acute fibrinous and organazing pneumonia: A case report

A 59-year-old woman complaining of wet cough, hemoptysis, slight fever, anorexia, and malaise was admitted to hospital with suspected lobar pneumonia. She received treatment for myocardial infarction and deep venous thrombosis caused by familial protein C deficiency. Rapid deterioration due to respiratory failure occurred despite intensive care with broad-spectrum antibiotics. At a later date, sputum examination revealed the presence of Aspergillus niger. Based on clinical and autopsy findings, she was diagnosed with acute respiratory failure due to pulmonary aspergillosis with acute fibrinous and organizing pneumonia. This is the first reported case of pulmonary aspergillosis with acute fibrinous and organizing pneumonia complicated by calcium oxalate resulting from Aspergillus niger infection, leading to severe inflammation and tissue injury in the lungs.

Association Between the Efficacy of Pembrolizumab and Low STK11/LKB1 Expression in High-PD-L1-expressing Non-small-cell Lung Cancer

BACKGROUND/AIM

STK11/LKB1 mutation has been suggested as a poorly responding candidate biomarker of the anti-programmed cell death-1 (PD-1) antibody; however, the association between STK11/LKB1 expression and the effects of anti-PD-1 antibodies is uncertain. The aim of the study was to correlate the efficacy of pembrolizumab monotherapy and STK11/LKB1 expression in untreated patients with non-small-cell lung carcinoma (NSCLC) and high PD-ligand 1 expression.

PATIENTS AND METHODS

From February 2017 to January 2020, we retrospectively analyzed 30 previously untreated patients with NSCLC and a tumor proportion score (TPS) ≥50% treated with pembrolizumab monotherapy. STK11/LKB1 expression in tumor tissue was evaluated by immunohistochemistry.

RESULTS

Twenty-three (76.7%) of the 30 patients were classified with low-STK11/LKB1 expression. The median progression-free survival and overall survival of patients with low-STK11/LKB1 expression was shorter than those with high-STK11/LKB1 expression, although the results were not statistically significant. The disease progression rate for the low-STK11/LKB1 group was higher than that of the high-STK11/LKB1 group.

CONCLUSION

STK11/LKB1 expression, as measured by immunohistochemistry, could be a useful biomarker associated with the efficacy of pembrolizumab monotherapy for patients with NSCLC and a TPS ≥50%.

Characteristics of central nervous system progression in non-small cell lung cancer treated with crizotinib or alectinib

Background

Most patients treated with anaplastic lymphoma kinase (ALK)‐tyrosine kinase inhibitors for ALK‐positive non‐small cell lung cancer (NSCLC) develop resistance, leading to metastasis, with progression to the central nervous system (CNS) being a primary concern. Although alectinib has better CNS penetration than crizotinib, patients treated with alectinib also develop CNS progression. CNS metastases more likely occurs during crizotinib treatment due to less blood‐brain barrier (BBB) penetration capability than alectinib. CNS progression pattern may be different during crizotinib and alecitinib treatment. Understanding the characteristics of CNS progression is important for developing treatment strategies.

Aims

We compared the clinical‐radiographic characteristics of CNS metastases among patients undergoing crizotinib and alectinib treatment for ALK‐positive NSCLCs.

Methods and results

We retrospectively analyzed the radiographic and clinical characteristics of CNS progression in ALK‐positive NSCLC patients treated with crizotinib or alectinib at our hospital between July 2011 and May 2020. CNS and systemic tumor progression were evaluated using computed tomography or magnetic resonance imaging. Fifty‐three and 65 patients were treated with crizotinib and alectinib, respectively. Baseline CNS metastasis was observed in 18 and 27 patients in the crizotinib and alectinib groups, respectively. Among the patients in the crizotinib and alectinib groups who developed disease progression, 15/49 (30.6%) and 9/44 (20.5%) had CNS progression, respectively (P = .344). Intra‐CNS progression‐free survival was significantly longer in the alectinib group than in the crizotinib group (median: 14.0 vs 5.6 months, P = .042). The number of CNS metastases sized ≥3 cm, rate of peritumoral brain edema, and the second progression pattern after treatment continuation was not significantly different between the groups.

Conclusion

We observed no significant difference in the clinical‐radiographic characteristics of CNS progression between patients undergoing crizotinib and alectinib treatments. Local therapy, including stereotactic radiosurgery, for CNS progression may be suitable and important following alectinib and crizotinib treatment.

Impact of Renin-angiotensin System Inhibitors on the Efficacy of Anti-PD-1/PD-L1 Antibodies in NSCLC Patients

BACKGROUND/AIM

The Renin-Angiotensin system (RAS) induces immunosuppression in the tumor microenvironment, and RAS inhibitors (RASi) improve the tumor immune microenvironment. We evaluated the impact of RASi on the efficacy anti-programmed cell death-1/Ligand-1 (anti-PD-1/PD-L1) antibodies.

PATIENTS AND METHODS

This retrospective study analyzed non-small cell lung cancer (NSCLC) patients who received anti-PD-1/PD-L1 antibodies monotherapy as second- or later-line treatment. We classified patients into those with or without use of RASi.

RESULTS

A total of 256 NSCLC patients were included and 37 patients used RASi. The median PFS of patients treated with RASi was significantly longer than that of patients treated without (HR=0.59, 95%CI=0.40-0.88). The median OS of patients treated with RASi tended to be longer than that of patients treated without (HR=0.71, 95%CI=0.45-1.11).

CONCLUSION

The use of RASi was associated with a significantly longer PFS in NSCLC patients treated with anti-PD-1/PD-L1 antibodies. RASi use may enhance the efficacy of anti-PD-1/PD-L1 antibodies.

Clinical influence of switching companion diagnostic tests for EGFR-TKs from Therascreen to Cobas v2

Background

Several companion diagnostic (CDx) tests for epidermal growth factor receptor tyrosine kinase inhibitors (EGFR‐TKIs) have been approved. In our institute, the CDx test for EGFR‐TKIs was changed from the Therascreen test (Therascreen) to the Cobas EGFR v2 test (Cobas) because only Cobas was approved for the use of osimertinib in patients with EGFR‐mutated non‐small cell lung cancer (NSCLC) with T790M mutations. The clinical influence of switching the CDx test has not yet been examined comprehensively.

Methods

All serial patients with lung cancer tested for EGFR mutations with CDx tests between February 2014 and February 2016 at the Cancer Institute Hospital of the Japanese Foundation for Cancer Research (JFCR) were enrolled in this analysis.

Results

Therascreen was used as a CDx test for EGFR‐TKI therapy in 607 patients between February 2014 and January 2015, and Cobas was used in 621 patients between February 2015 and February 2016. EGFR mutations were detected in 218 patients (35.9%) and 244 patients (39.3%) tested with Therascreen and Cobas, respectively. At the initial diagnosis, 400 and 459 patients were tested with Therascreen and Cobas, respectively. EGFR mutation subtypes, including del19, L858R, and others, were detected in 13.0%, 17.0%, and 2.5% of patients using Therascreen and 17.4%, 14.4%, and 1.5% of patients using Cobas, respectively.

Conclusions

No significant impact of switching from Therascreen to Cobas as the CDx test for EGFR mutations in clinical practice was observed. However, the detection pattern of the EGFR mutation subtypes between the two CDx tests was slightly different.

Key points

Significant findings of the study

We examined the influence of changing the EGFR test in 1228 patients in total. The detection rate of EGFR mutations was similar. However, the detection pattern for EGFR subtype mutations was slightly different between the two tests.

What this study adds

Switching CDx tests from target polymerase chain reaction (PCR)‐ to next‐generation sequencing (NGS)‐based methods may lead to obvious changes in clinical practice. When the CDx test is required to change, the investigation of this influence is warranted in future studies.

Feasibility of next-generation sequencing test for patients with advanced NSCLC in clinical practice

Background

The usefulness of the Oncomine Dx Target test (Oncomine Dx), a next‐generation sequencing (NGS) test, has already been proven in clinical trials. However, NGS requires high‐quality tumor samples and takes a long time to generate results. The feasibility of NGS for use in advanced non‐small cell lung cancer (NSCLC) patients in clinical practice has not yet been determined.

Methods

Patients serially diagnosed with advanced NSCLC were evaluated in our hospital. The Oncomine Dx, Cobas EGFR mutation test (Cobas EGFR), and ALK‐IHC were performed. The patients were divided into four sets: the full analysis set (FAS) that referred to patients diagnosed with NSCLC, the intent to perform companion diagnostics (CDx) set (IPS) that referred to patients in which CDx had been ordered regardless of sample quality, the per‐performed CDx set (PPS) that referred to patients who could undergo CDx regardless of the results, and the per‐completed CDx set (CCS) that referred to patients in which informative results were received from the CDx.

Results

The total number of patients analyzed in the study was 167. The IPS/FAS of Oncomine Dx (80.2%) was lower than that of the ALK‐IHC (85.0%) and Cobas EGFR (92.8%). The CCS/FAS of Oncomine Dx (65.9%) was lower than that of the ALK‐IHC (82.0%) and Cobas EGFR (92.2%). PPS/IPS and CCS/PPS of the Oncomine Dx with nonsurgical biopsy ranged between 78.6% and 90.9%, which was lower than those patients who underwent surgical resection (95.0% and 100%).

Conclusions

The feasibility of Oncomine Dx in clinical practice was lower than the other CDx. The feasibility of Oncomine Dx will increase by improving the biopsy procedure.

Key points

Significant study findings

The usefulness of a next‐generation sequencing (NGS) test has been proven in clinical trials.

The feasibility of NGS is lower than other diagnostics in clinical practice especially with regard to nonsurgical biopsy.

What this study adds

It is necessary to improve the feasibility of NGS in clinical practice.

To improve NGS feasibility, turnaround time must be shortened, and larger samples must be obtained during surgical procedures.

Association between continuous decrease of plasma VEGF-A levels and the efficacy of chemotherapy in combination with anti-programmed cell death 1 antibody in non-small cell lung cancer patients

OBJECTIVES

Vascular endothelial growth factor-A (VEGF-A) plays important roles in tumor immune suppression and thus correlates with the efficacy of anti-programmed cell death-1/ligand 1 (anti-PD-1/PD-L1) antibodies. We aimed to determine the association between change in plasma VEGF-A levels and the efficacy of chemotherapy combined with anti-PD-1/PD-L1 antibodies (chemo-PD1) in non-small cell lung cancer (NSCLC) patients.

METHODS

We included NSCLC patients treated with chemo-PD1. Plasma VEGF-A levels were measured at baseline (Pre) and days 7 (D7) and 14 (D14) after the initiation of chemo-PD1. Continuous VEGF-A decrease was determined by comparing Pre with the median value of maximum change rate of posttreatment VEGF-A as cutoff. Patients whose change rates of VEGF-A at both D7 and D14 were consistently lower than the cutoff value were classified into the VEGF-A decrease group, whereas those whose VEGF-A at D7 or D14 were higher than the cutoff level were classified into the VEGF-A no-decrease group. The primary outcome was progression-free survival (PFS).

RESULTS

A total of 32 patients were evaluated. The median Pre VEGF-A levels was 49 (range, 13-257). The median change rate of VEGF-A at D7 and D14 was -25.6% (range, -77.5-376.9) and -42.3% (range, -100-138.5) respectively. The cutoff value of posttreatment VEGF-A change rate was -9.3%. The PFS was significantly longer in the VEGF-A decrease group than that in the VEGF-A no-decrease group (median, not reached vs 2.4 months; p = 0.017).

CONCLUSIONS

Continuous decrease of plasma VEGF-A levels during treatment may be associated with the efficacy of chemo-PD1.

Poor efficacy of anti-programmed cell death-1/ligand 1 monotherapy for non-small cell lung cancer patients with active brain metastases

BACKGROUND

The efficacy of anti-programmed cell death-1/ligand 1 antibody monotherapy (anti-PD-1/PD-L1 monotherapy) in patients with active brain metastases (BMs) is not established. Here, we aimed to evaluate the efficacy of anti-PD-1/PD-L1 monotherapy in non-small cell lung cancer (NSCLC) patients with active BMs.

METHODS

This retrospective study included NSCLC patients treated with second-line or later-line anti-PD-1/PD-L1 monotherapy between December 2015 and August 2019. Patients were classified into those with or without active BMs, including symptomatic BMs requiring systemic steroids and untreated BMs. The progression-free survival (PFS) and overall survival (OS) of the patients with and without active BMs were compared. Intracranial and extracranial tumor responses were evaluated in patients with active BMs.

RESULTS

We analyzed 197 patients who had received anti-PD-1/PD-L1 monotherapy. Among them, 24 had active BMs. Among those without active BMs, 145 had no BMs and 28 had treated asymptomatic BMs. The PFS and OS of patients with active BMs were significantly shorter than those of patients without active BMs (1.3 vs. 2.7 months; P < 0.001, and 4.5 vs. 16.3 months; P = 0.001 respectively). For patients with active BMs, the intracranial and extracranial response rates were 13.3% and 26.7%, respectively. On multivariate analysis, active BMs, poor performance status (PS), and EGFR/ALK positivity were significant factors associated with shorter PFS. Active BMs and poor PS were significant factors associated with shorter OS.

CONCLUSIONS

This study suggested that anti-PD-1/PD-L1 monotherapy was not effective for NSCLC patients with active BMs. Further studies on immunotherapy are needed for patients with active BMs.

KEY POINTS

Significant findings of the study: The present study showed that anti-PD-1/PD-L1 antibody monotherapy was not effective for non-small cell lung cancer patients with active brain metastases. Intracranial and extracranial response rates were 13.3% and 26.7%, respectively.

WHAT THIS STUDY ADDS

Further studies on immunotherapy are needed for patients with active BMs.

Addition of ramucirumab enhances docetaxel efficacy in patients who had received anti-PD-1/PD-L1 treatment

OBJECTIVES

Docetaxel (DTX) efficacy increases in patients with non-small cell lung cancer (NSCLC) who had received anti-programmed cell death-1/ligand 1 (anti-PD-1/L1) therapy. However, the effect of ramucirumab (Ram) on DTX efficacy following anti-PD-1/L1 therapy is unknown. Here, we aimed to evaluate the effect of Ram on DTX efficacy following anti-PD-1/L1 therapy.

MATERIALS AND METHODS

This retrospective study included 99 patients with NSCLC, who were divided into those who had (pre-ICI group) or had not (no-ICI group) received anti-PD-1/L1 antibody before DTX. Both groups were then treated with DTX or DTX plus Ram (DTX/Ram). Patient characteristics were compared between the DTX and DTX/Ram groups and adjusted with inverse probability of treatment weighting using propensity scores and the following confounding variables: age, sex, performance status, smoking status, histology, driver mutation, and line of treatment. We compared DTX/Ram and DTX in terms of efficacy in both the pre-ICI and no-ICI groups.

RESULTS

In the pre-ICI group, 18 and 21 patients received DTX and DTX/Ram, respectively. In the no-ICI group, 35 and 25 patients received DTX and DTX/Ram. In the no-ICI group, progression-free survival (PFS) and overall survival (OS) were not significantly different between DTX/Ram- and DTX-treated patients (median PFS, 2.6 versus 1.6 months; p = 0.30, median OS; 8.2 versus 8.0 months; p = 0.30). In the pre-ICI group, PFS was significantly longer in DTX/Ram-treated than in DTX-treated patients (median, 5.9 versus 2.8 months; p = 0.03). Hazard ratio for disease progression or death was 0.75 (95% confidence interval, 0.20-0.96). The OS of DTX/Ram-treated patients tended to be longer than that of DTX-treated patients (median, 19.8 versus 8.6 months; p = 0.10).

CONCLUSIONS

DTX efficacy following anti-PD-1/L1 therapy may be enhanced by Ram. Further studies are needed to validate the efficacy of inhibiting the vascular endothelial growth factor pathway following anti-PD-1/L1 therapy.

Efficacy of anti-programmed cell death-1/ligand 1 monotherapy for non-small cell lung cancer patients with active brain metastases

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Background: The efficacy of anti-programmed cell death-1/ligand 1 (anti-PD-(L)1) for active brain metastases (BMs) is not established, because most clinical trials excluded patients (pts) with active BMs such as untreated, symptomatic, or unstable BMs. The aim of this study was to evaluate the efficacy of anti-PD-(L)1 monotherapy in non-small cell lung cancer (NSCLC) pts with active BMs. Methods: This retrospective study included NSCLC pts who had received anti-PD-(L)1 monotherapy in 2nd or later line between December 2015 and August 2019. Pts who had not evaluated BMs by CT/MRI before anti-PD-(L)1 were excluded. Pts were classified into those with or without active BMs which were defined as untreated or symptomatic BMs or BMs requiring systemic steroids. Progression free survival (PFS) and overall survival (OS) of pts with or without active BMs were compared. Intra-cranial and extra-cranial tumor responses were evaluated in pts with active BMs. Results: In this study, 242 pts who had received anti-PD-(L)1 monotherapy were identified and 197 pts were analyzed. Twenty-four pts were classified to pts with active BMs. Among pts without active BMs, 145 pts had no BMs and 28 pts had treated asymptomatic BMs. PFS of pts with active BMs was significantly shorter than that of pts without active BMs (1.3 versus 2.7 months; p < 0.001). OS of pts with active BMs was significantly shorter than that of pts without active BMs (4.5 vs 16.3 months; p = 0.001). Intracranial response rate (RR) was 13.3% (2/15) and extracranial RR was 26.7% (4/15) in pts with active BMs. In multivariate Cox regression analysis, active BM, poor PS and EGFR/ALK(+) were selected as significant factors associated with poor PFS. Active BM and poor PS were selected as significant factors associated with poor OS. Conclusions: Anti-PD-(L)1 monotherapy is not recommend for pts with active BMs.

Dissociated responses at initial computed tomography evaluation is a good prognostic factor in non-small cell lung cancer patients treated with anti-programmed cell death-1/ligand 1 inhibitors

Background

Dissociated responses (DR) are phenomena in which some tumors shrink, whereas others progress during treatment of patients with cancer. The purpose of the present study was to evaluate the frequency and prognosis of DR in non-small cell lung cancer (NSCLC) patients treated with anti-programmed cell death-1/ligand 1 (anti-PD-1/L1) inhibitors.

Methods

This retrospective study included NSCLC patients who received anti-PD-1/L1 inhibitor as second- or later-line treatment. We excluded patients without radiological evaluation.

In patients who showed progressive disease (PD) according to the RECIST 1.1 at the initial CT evaluation, we evaluated all measurable lesions in each organ to identify DR independently of RECIST 1.1. We defined DR as a disease with some shrinking lesions as well as growing or emerging new lesions. Cases not classified as DR were defined as ‘true PD’. Overall survival was compared between patients with DR and those with true PD using Cox proportional hazards models.

Results

The present study included 62 NSCLC patients aged 27–82 years (median: 65 years). DR and true PD were observed in 11 and 51 patients, respectively. The frequency of DR in NSCLC patients who showed PD to anti-PD-1/L1 was 17.7%. Median overall survival was significantly longer in patients with DR versus true PD (14.0 vs. 6.6 months, respectively; hazard ratio for death: 0.40; 95% confidence interval: 0.17–0.94).

Conclusions

Patients with DR exhibited a relatively favorable prognosis.

Association of High Neutrophil-to-Lymphocyte Ratio With Poor Outcomes of Pembrolizumab Therapy in High-PD-L1-expressing Non-small Cell Lung Cancer

BACKGROUND

This study aimed to determine whether the neutrophil-to-lymphocyte ratio (NLR) reflected poor treatment benefits in patients with tumor proportion score (TPS) ≥50% and who under went first-line pembrolizumab monotherapy.

PATIENTS AND METHODS

This study retrospectively analyzed patients with untreated stage III/IV or recurrent non-small cell lung cancer (NSCLC) with TPS ≥50% and who received pembrolizumab monotherapy at two hospitals between February 2017 and April 2019. The NLR was calculated from pre-treatment complete blood counts.

RESULTS

A total of 51 previously untreated patients with NSCLC who had TPS ≥50% and who underwent pembrolizumab monotherapy were evaluated. Multivariate analysis revealed that high NLR, Eastern Cooperative Oncology Group performance status (PS) ≥2, stage IV or recurrent cancer, and TPS=50-74% were significantly and independently associated with poor progression-free survival. Moreover, high NLR and PS ≥2 were significantly associated with short overall survival.

CONCLUSION

A high pre-treatment NLR was associated with significantly short progression-free and overall survival in previously untreated patients with NSCLC with high expression of programmed cell-death ligand 1 treated with pembrolizumab monotherapy.

Pembrolizumab-induced agranulocytosis in a pulmonary pleomorphic carcinoma patient who developed interstitial lung disease and ocular myasthenia gravis

An 82-year-old man with a recurrence of pulmonary pleomorphic carcinoma was treated with pembrolizumab. He achieved partial response after three cycles of pembrolizumab. However, he developed febrile neutropenia. A bone marrow aspiration sample revealed a decrease of mature neutrophils, and anti-neutrophil antibody was detected in blood. Computed tomography scans revealed consolidation in the right lung. Pathological findings in lung biopsy tissue revealed organizing pneumonia. Pembrolizumab-induced agranulocytosis and interstitial lung disease (ILD) were diagnosed. We initiated antibacterial therapy and granulocyte colony-stimulating factor (G-CSF). The neutrophil count immediately increased, and the fever decreased. The improvement of ILD was achieved without using systemic steroids. Moreover, the patient developed ocular myasthenia gravis induced by pembrolizumab. This is the first case report of pembrolizumab-induced agranulocytosis. Agranulocytosis was improved by administration of G-CSF without using systemic steroids. However, further studies are needed to determine the optimal treatment for patients with anti-neutrophil antibody whose tumor has progressed.

A case of interstitial lung disease with alveolar hemorrhage induced by pembrolizumab

We herein describe the case of a 67-year-old woman with advanced lung adenocarcinoma who developed interstitial lung disease (ILD) with alveolar hemorrhage induced by pembrolizumab. She received four courses of pembrolizumab therapy and achieved a partial response. She had no respiratory symptoms; however, chest radiography and computed tomography (CT) revealed ground-glass opacities (GGOs) and crazy-paving pattern. Based on findings of bloody bronchoalveolar lavage fluid and transbronchial lung biopsy samples, pembrolizumab-induced ILD with alveolar hemorrhage was diagnosed. Corticosteroid therapy rapidly improved alveolar hemorrhage and regressed GGOs on CT scan. This is the first report on ILD with alveolar hemorrhage induced by pembrolizumab.

Pembrolizumab and salvage chemotherapy in EGFR T790M-positive non-small-cell lung cancer with high PD-L1 expression

Immuno-checkpoint inhibitors (ICI) have become an effective treatment option for non-small-cell lung cancer patients. However, ICI therapy was reported to be less effective in patients with epidermal growth factor receptor (EGFR) mutations than in those with wild-type EGFR. We report here that an non-small-cell lung cancer patient with the EGFR mutant T790M showed a programmed cell death ligand 1 (PD-L1) expression level that increased from <25% to >90% after eighth-line osimertinib therapy. He was treated with pembrolizumab as a ninth-line treatment, and attained stable disease. After the pembrolizumab therapy, he was treated with gemcitabine, which produced a good response despite being the 10th-line treatment. We should consider administering ICI and chemotherapy even to EGFR mutant patients after failure of EGFR tyrosine kinase inhibitor, especially in cases with high PD-LI expression.

Systemic and cutaneous plasmacytosis with multiple skin lesions and polyclonal hypergammaglobulinaemia: significant serum interleukin-6 levels

We report two patients who developed benign plasmacytosis with multiple skin lesions. The cases were characterized by hyperplasia of mature plasma cells, and polyclonal hypergammaglobulinaemia. One patient had hyperplasia of mature plasma cells not only in the skin, but also extensively in lymph nodes and the retroperitoneal areas around the ureters. The other had plasma cell hyperplasia limited to the skin. Extensive investigations failed to reveal any clinical or laboratory evidence suggesting the presence of any underlying disease accompanying the hypergammaglobulinaemia and/or plasma cell proliferation, such as chronic infectious disease, collagen disease or other chronic inflammatory disorder. Clinically and histologically, the first patient showed features compatible with a diagnosis of systemic plasmacytosis and the second with a diagnosis of cutaneous plasmacytosis. Significant serum interleukin-6 (IL-6) levels were detected in both patients, suggesting that IL-6 may be involved in the pathogenesis of these conditions.

[Antihypertensive action of elcatonin]

Subcutaneous injections of elcatonin, a synthetic analogue of eel calcitonin, lowered the blood pressure in DOCA/saline-hypertensive and spontaneously hypertensive rats (SHR), but not in normotensive Wistar rats. The hypotensive effect was more prominent in the DOCA hypertensive rats. Daily injections of elcatonin (10-30 U/kg/day for 21 days) resulted in maximum hypotension on the 4th day in DOCA hypertensive rats and on the 14th day in SHR, and the reduced level of blood pressure was maintained. After the cessation of elcatonin injections, the pressure started to elevate gradually towards the control level. In normotensive rats, elcatonin did not significantly alter the blood pressure for 6 weeks. Daily injections of elcatonin significantly prevented the development of DOCA-induced hypertension and spontaneously-occurring hypertension. Elcatonin-induced hypotension did not differ in the control and parathyroidectomized DOCA hypertensive rats. Elcatonin did not alter the pressor response to noradrenaline, vasopressin and angiotensin II nor the depressor response to isoproterenol, acetylcholine and histamine in DOCA hypertensive rats. It is concluded that the antihypertensive effect of elcatonin is not associated with the release of parathyroid hormone nor with the blockade of alpha, beta, angiotensin II and vasopressin receptors.

[Pharmacological effects of [(octahydro-2-azocinyl)methyl] guanidine(guanazodine): its action mechanism and hypotensive effect]

Cardiovascular effects of guanazodine, a new antihypertensive drug, in anesthetized dogs, rabbits and rats and also isolated atria and arteries were compared with those of guanethidine and bethanidine. Guanazodine caused a sustained decrease in the systemic blood pressure of spontaneously hypertensive rats, renal hypertensive dogs and normal cats. No tachyphylaxis developed when the drug was administered orally to the rats once a day for 10 days. The heart rate decreased. Guanazodine relaxed the cat nictitating membrane, attenuated the positive chronotropic response to sympathetic nerve stimulation in anesthetized dogs and in isolated rabbit aorta to transmural electrical stimulation. Guazazodine potentiated the pressor response to noradrenaline but attenuated the response to tyramine in anesthetized cats. The noradrenaline content of rat hearts was significantly reduced 4 hr or later after the injection of guanazodine, while the content in brains and adrenal glands was unaffected. The LD50 of guanazodine injected intravenously to male rats was 136 +/- 11 mg/kg which was approximately 4 times the value of guanethidine and 7 times the value of bethanidine. It may be concluded that the hypotensive effect of guanazodine is related to adrenergic neuron blocking action, the noradrenaline-depleting action in peripheral tissues is similar to the effect of guanethidine and bethanidine, and that the extent and the duration of the hypotension induced by guanazodine are approximately the same as those with guanethidine but appreciably greater than those with bethanidine. Toxicity and side effects appear to be less with guanazodine than with guanethidine and bethanidine.