Resistance mechanisms of EGFR tyrosine kinase inhibitors, in EGFR exon 20 insertion-mutant lung cancer.

BACKGROUND: Mobocertinib, an EGFR exon 20 insertion (Ex20ins)-specific tyrosine kinase inhibitor has been used for treatment of advanced/metastatic EGFR Ex20ins-mutant non-small cell lung cancer (NSCLC). However, resistance mechanisms to EGFR Ex20ins-specific inhibitors and the efficacy of subsequent amivantamab treatment is unknown. METHODS: To investigate resistance mechanisms, tissue and cfDNA samples were collected before treatment initiation and upon development of resistance from NSCLC patients with EGFR Ex20ins mutations received mobocertinib, poziotinib, and amivantamab treatments. Genetic alterations were analyzed using whole-genome and targeted sequencing, and in vitro resistant cell lines were generated for validation. RESULTS: EGFR amplification (n = 6, including 2 broad copy number gain) and EGFR secondary mutation (n = 3) were observed at the resistance of mobocertinib. One patient had both EGFR secondary mutation and high EGFR focal amplification. In vitro models harboring EGFR alterations were constructed to validate resistance mechanisms and identify overcoming strategies to resistance. Acquired EGFR-dependent alterations were found to mediate resistance to mobocertinib in patients and in vitro models. Furthermore, two of six patients who received sequential amivantamab followed by an EGFR tyrosine kinase inhibitor had MET amplification and showed partial response. CONCLUSIONS: Our study revealed EGFR-dependent and -independent mechanisms of mobocertinib resistance in patients with advanced EGFR Ex20ins-mutant NSCLC.

A phase II study of osimertinib in patients with NSCLC harboring EGFR exon 20 insertion: A multicenter trial of the Korean Cancer Study Group (LU17-19).

BACKGROUND: Epidermal growth factor receptor (EGFR) exon 20 insertions account for up to 10% of all EGFR mutations. Clinical outcomes in patients receiving approved EGFR exon 20 insertion-specific inhibitors have been variable. Although osimertinib has demonstrated antitumor activity in clinical trials, its clinical efficacy and translational potential remain to be determined in non-small cell lung carcinoma (NSCLC) with EGFR exon 20 insertion. METHODS: In this multicenter phase II study, patients with advanced NSCLC harboring EGFR exon 20 insertions for whom the standard chemotherapy failed received 80 mg osimertinib once daily. The primary endpoint was the investigator-assessed objective response rate (ORR) as defined by Response Evaluation Criteria in Solid Tumors version 1.1. The secondary endpoints were progression-free survival (PFS), overall survival (OS), and safety profile. RESULTS: Among 15 patients enrolled at stage 1, the best response was most commonly disease stabilization (73.3 %), which did not meet the stage 1 threshold (objective response ≥ 2/15). As of data cutoff, two patients remained on the treatment. The median PFS and OS were 3.8 (95 % confidence interval [CI] = 1.7-5.5) months and 6.5 (95 % CI = 3.9-not reached) months, respectively. Adverse events (≥grade 3) were anemia, hypercalcemia, and pneumonia (13.3 % each), and asthenia, femur fracture, increased alkaline phosphate, hyperkalemia, bone pain, and azotemia (6.7 % each). Pre-existing EGFR C797S mutation detected in plasma limited the efficacy of osimertinib. CONCLUSION: Osimertinib at 80 mg once daily had limited efficacy and mostly showed disease stabilization with an acceptable safety profile in advanced NSCLC harboring EGFR exon 20 insertions. CLINICALTRIALS: govIdentifier: NCT03414814.

The Survival and Financial Benefit of Investigator-Initiated Trials Conducted by Korean Cancer Study Group.

Purpose: The Korean Cancer Study Group (KCSG) is a nationwide cancer clinical trial group dedicated to advancing investigator-initiated trials (IITs) by conducting and supporting clinical trials. This study aims to review IITs conducted by KCSG and quantitatively evaluate the survival and financial benefits of IITs for patients. Materials and Methods: We reviewed IITs conducted by KCSG from 1998 to 2023, analyzing progression-free survival (PFS) and overall survival (OS) gains for participants. PFS and OS benefits were calculated as the difference in median survival times between the intervention and control groups, multiplied by the number of patients in the intervention group. Financial benefits were assessed based on the cost of investigational products provided. Results: From 1998 to 2023, KCSG conducted 310 IITs, with 133 completed and published. Of these, 21 were included in the survival analysis. The analysis revealed that 1,951 patients in the intervention groups gained a total of 2,558.4 months (213.2 years) of PFS and 2,501.6 months (208.5 years) of OS, with median gains of 1.31 months in PFS and 1.58 months in OS per patient. When analyzing only statistically significant results, PFS and OS gain per patients was 1.69 months and 3.02 months, respectively. Investigational drug cost analysis from 6 available IITs indicated that investigational products provided to 252 patients were valued at 10,400,077,294 won (approximately 8,046,481 US dollars), averaging about 41,270,148 won (approximately 31,930 US dollars) per patient. Conclusion: Our findings, based on analysis of published research, suggest that IITs conducted by KCSG led to survival benefits for participants and, in some studies, may have provided financial benefits by providing investment drugs.

Antibiotic prescription patterns during last days of hospitalized patients with advanced cancer: the role of palliative care consultation.

OBJECTIVES: Issues regarding antibiotic use in end-of-life patients with advanced cancer present a challenging ethical dilemma in academic referral centres. This study aimed to investigate the role of palliative care consultation on antibiotic prescription patterns among hospitalized patients with advanced cancer during their last days of life. METHODS: This retrospective cohort study included adult patients with metastatic solid cancer admitted to a tertiary referral hospital for at least 4 days and subsequently died and who were given antibiotics 4 days before death between January 2018 and December 2021. Patients were divided into palliative care consultation (PC) and non-consultation (non-PC) groups. The outcomes were the proportion of patients who received antibiotic combination treatment, antibiotic escalation and antibiotic de-escalation within 3 days of death. Propensity score analysis with the inverse probability of the treatment weighting method was used to compare the outcomes. RESULTS: Among the 1177 patients enrolled, 476 (40.4%) received palliative care consultation and 701 (59.6%) did not. The PC group received considerably less antibiotic combination treatment (49.0% versus 61.1%, adjusted OR: 0.69, 95% CI: 0.53-0.90, P = 0.006) and antibiotic escalation (15.8% versus 34.8%, adjusted OR: 0.41, 95% CI: 0.30-0.57, P < 0.001) than the non-PC group. Additionally, the PC group reported significantly higher antibiotic de-escalation (30.7% versus 17.4%, adjusted OR: 1.74, 95% CI: 1.28-2.36, P < 0.001). CONCLUSION: Receiving palliative care consultation may minimize aggressive antibiotic prescription patterns in the last days of patients with advanced cancer in an academic referral centre setting.

Targeting CD73 to Overcomes Resistance to First-Generation EGFR Tyrosine Kinase Inhibitors in Non-Small Cell Lung Cancer.

PURPOSE: In patients with epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC), EGFR tyrosine kinase inhibitors (TKIs) improve response rate and survival. However, most patients eventually develop resistance. This study aimed to identify the role of CD73 in EGFR-mutant NSCLC and explore whether CD73 inhibition may serve as a therapeutic strategy in NSCLC patients with acquired resistance to EGFR-TKIs. MATERIALS AND METHODS: We evaluated the prognostic role of CD73 expression in EGFR-mutant NSCLC using tumor samples from a single institution. We silenced CD73 in EGFR-TKI-resistant cell lines using short hairpin RNA (shRNA) targeting CD73 and also transfected a vector alone as a negative control. Using these cell lines, cell proliferation and viability assays, immunoblot assays, cell cycle analysis, colony-forming assays, flow cytometry, and apoptosis analysis were performed. RESULTS: High expression of CD73 was associated with shorter survival in patients with metastatic EGFR-mutant NSCLC treated with first-generation EGFR-TKI. CD73 inhibition synergistically inhibited cell viability with first-generation EGFR-TKI treatment compared with the negative control. When CD73 inhibition and EGFR-TKI treatment were combined, G0/G1 cell cycle arrest was induced through the regulation of p21 and cyclin D1. In addition, the apoptosis rate was increased in CD73 shRNA-transfected cells treated with EGFR-TKI. CONCLUSION: High expression of CD73 adversely affects the survival of patients with EGFR-mutant NSCLC. The study demonstrated that inhibiting CD73 in EGFR-TKI-resistant cell lines resulted in increased apoptosis and cell cycle arrest, which overcame the acquired resistance to first-generation EGFR-TKIs. Further research is needed to determine whether blocking CD73 plays a therapeutic role in EGFR-TKI-resistant patients with EGFR-mutant NSCLC.

Use of high-flow nasal cannula oxygen therapy for patients with terminal cancer at the end of life.

BACKGROUND: Few studies have focused on high-flow nasal cannula (HFNC) usage in the last few weeks of life. The aim of this study was to identify the status of HFNC use in patients with cancer at the end of life and the relevant clinical factors. METHODS: We performed a retrospective cohort study in a tertiary hospital in the Republic of Korea. Among patients with cancer who died between 2018 and 2020, those who initiated HFNC within 14 days before death were included. Patients were categorized based on the time from HFNC initiation to death as imminent (<4 days) and non-imminent (≥4 days). RESULTS: Among the 2191 deceased patients with terminal cancer, 329 (15.0%) were analyzed. The median age of the patients was 66 years, and 62.9% were male. The leading cause of respiratory failure was pneumonia (70.2%), followed by pleural effusion (30.7%) and aggravation of lung neoplasms (18.8%). Most patients were conscious (79.3%) and had resting dyspnea (76.3%) at HFNC initiation. Patients received HFNC therapy for a mean of 3.4 days in the last 2 weeks of life, and 62.6% initiated it within 4 days before death. Furthermore, female sex, no palliative care consultation, no advance statements in person on life-sustaining treatment, and no resting dyspnea were independently associated with the imminent use of HFNC. CONCLUSIONS: Many patients with cancer started HFNC therapy at the point of imminent death. However, efforts toward goal-directed use of HFNC at the end-of-life stage are required.

Clinical outcomes after incomplete cycles of R-CHOP for diffuse large B-cell lymphoma: 10 years' real-world experience in a single institute.

Although the current standard of care for diffuse large B-cell lymphoma (DLBCL) is six cycles of rituximab/cyclophosphamide/doxorubicin/vincristine/prednisolone combination chemotherapy (R-CHOP), a larger than expected number of patients cannot complete planned six cycles for various reasons in the real world. We aimed to evaluate the prognosis of patients with DLBCL after incomplete treatment by analyzing the chemotherapy response and survival according to the cause of discontinuation and the number of cycles. We analyzed a retrospective cohort of patients diagnosed with DLBCL who underwent incomplete cycles of R-CHOP at Seoul National University Hospital and Boramae Medical Center from January 2010 to April 2019. A total of 1183 patients were diagnosed with DLBCL, of which 260 (22%) did not complete six cycles of R-CHOP. The most common cause of discontinuation of chemotherapy was life-threatening infection, and the most common pathogen was Pneumocystis jirovecii. Overall survival (OS) and progression-free survival (PFS) were significantly better in patients who achieved complete response (CR) or partial response (PR) at the first response evaluation. Patients underwent three or more cycles of chemotherapy had a longer OS than those who did not. In patients with limited-stage disease, consolidative radiotherapy showed a significant improvement in OS and PFS. Advanced stage, high comorbidity score, and poor primary response to chemotherapy were poor prognostic factors in patients with unplanned treatment shortening. This study provides real-world outcomes for patients who could not complete the planned six cycles of R-CHOP.

The antitumor activity of a novel GCN2 inhibitor in head and neck squamous cell carcinoma cell lines.

BACKGROUND: General control nonderepressible 2 (GCN2) senses amino acid deprivation and activates activating transcription factor 4 (ATF4), which regulates many adaptive genes. We evaluated the impact of AST-0513, a novel GCN2 inhibitor, on the GCN2-ATF4 pathway. Additionally, we evaluated the antitumor effects of AST-0513 in amino acid deprivation in head and neck squamous cell carcinoma (HNSCC) cell lines. METHODS: GCN2 expression in HNSCC patient tissues was measured by immunohistochemistry. Five HNSCC cell lines (SNU-1041, SNU-1066, SNU-1076, Detroit-562, FaDu) grown under amino acid deprivation conditions, were treated with AST-0513. After AST-0513 treatment, cell proliferation was measured by CCK-8 assay. Flow cytometry was used to evaluate apoptosis and cell cycle phase. In addition, immunoblotting was performed to evaluate the effect of AST-0513 on the GCN2-ATF4 pathway, cell cycle arrest, and apoptosis. RESULTS: We demonstrated that GCN2 was highly expressed in HNSCC patient tissues. AST-0513 inhibited the GCN2-ATF4 pathway in all five HNSCC cell lines. Inhibiting the GCN2-ATF4 pathway during amino acid deprivation reduced HNSCC cell proliferation and prevented adaptation to nutrient stress. Moreover, AST-0513 treatment led to p21 and Cyclin B1 accumulation and G2/M phase cycle arrest. Also, apoptosis was increased, consistent with increased bax expression, increased bcl-xL phosphorylation, and decreased bcl-2 expression. CONCLUSION: A novel GCN2 inhibitor, AST-0513, inhibited the GCN2-ATF4 pathway and has antitumor activity that inhibits proliferation and promotes cell cycle arrest and apoptosis. Considering the high expression of GCN2 in HNSCC patients, these results suggest the potential role of GCN2 inhibitor for the treatment of HNSCC.

Monalizumab efficacy correlates with HLA-E surface expression and NK cell activity in head and neck squamous carcinoma cell lines.

PURPOSE: NKG2A, an inhibitory receptor expressed on NK cells and T cells, leads to immune evasion by binding to HLA-E expressed on cancer cells. Here, we investigated the relationship between HLA-E surface expression on head and neck squamous cell carcinoma (HNSCC) cell lines and the efficacy of monalizumab, an NKG2A inhibitor, in promoting NK cell activity. METHODS: Six HNSCC cell lines were used as target cells. After exposure to IFN- γ, HLA-E surface expression on HNSCC cell lines was measured by flow cytometry. Peripheral blood mononuclear cells (PBMCs) from healthy donors and isolated NK cells were used as effector cells. NK cells were stimulated by treatment with IL-2 and IL-15 for 5 days, and NK cell-induced cytotoxicity was analyzed by CD107a degranulation and 51Cr release assays. RESULTS: We confirmed that HLA-E expression was increased by IFN-γ secreted by NK cells and that HLA-E expression was different for each cell line upon exposure to IFN-γ. Cell lines with high HLA-E expression showed stronger inhibition of NK cell cytotoxicity, and efficacy of monalizumab was high. Combination with cetuximab increased the efficacy of monalizumab. In addition, stimulation of isolated NK cells with IL-2 and IL-15 increased the efficacy of monalizumab, even in the HLA-E low groups. CONCLUSION: Monalizumab efficacy was correlated with HLA-E surface expression and was enhanced when NK cell activity was increased by cetuximab or cytokines. These results suggest that monalizumab may be potent against HLA-E-positive tumors and that monalizumab efficacy could be improved by promoting NK cell activity.

The impact of palliative care consultation on reducing antibiotic overuse in hospitalized patients with terminal cancer at the end of life: a propensity score-weighting study.

OBJECTIVES: A substantial number of hospitalized patients with terminal cancer at the end-of-life phase receive antibiotics, even with imminent death. We evaluated the impact of palliative care consultation on antibiotic use in hospitalized patients with terminal cancer during the end-of-life phase. METHODS: We identified adult patients with metastatic solid cancer who died at a tertiary medical centre in Seoul, Republic of Korea, following at least 4 days of hospitalization (January 2018-December 2020). Patients were divided into palliative and non-palliative care consultation groups. Propensity score-weighted, multivariable logistic regression analysis was used to compare the proportion of patients receiving antibiotics within 3 days before death between the two groups. RESULTS: Among 1143 patients analysed, 940 (82.2%) received antibiotics within 3 days before death. The proportion of patients receiving antibiotics was significantly lower (propensity score-weighted P < 0.001) in the palliative care consultation group (344/468; 73.5%) than in the non-palliative care consultation group (596/675; 88.3%). The decrease in the proportion of patients receiving antibiotics in the palliative care consultation group was significant for a carbapenem (42.4% versus 22.4%; P < 0.001), a glycopeptide (23.3% versus 11.1%; P < 0.001) and a quinolone (30.5% versus 19.4%; P = 0.012). In the multivariable logistic regression analysis, receiving palliative care consultation (adjusted OR 0.46, 95% CI 0.33-0.65; P < 0.001) was independently associated with reduced antibiotic use during the end-of-life phase. CONCLUSIONS: Palliative care consultation may reduce aggressive antibiotic use in hospitalized patients with terminal cancer during the end-of-life phase.

Blockade of CD47 enhances the antitumor effect of macrophages in renal cell carcinoma through trogocytosis.

Immune checkpoint inhibitors and vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFR TKIs) are mainstream treatments for renal cell carcinoma (RCC). Both T cells and macrophages infiltrate the tumor microenvironment of RCC. CD47, an immune checkpoint of macrophages, transmits the "don't eat me" signal to macrophages. We propose a novel therapeutic strategy that activates the antitumor effect of macrophages. We found that CD47 was expressed in patients with RCC, and high CD47 expression was indicative of worse overall survival in datasets from The Cancer Genome Atlas. We observed that CD47-blocking antibodies enhanced the antitumor effect of macrophages against human RCC cell lines. Trogocytosis, rather than phagocytosis, occurred and was promoted by increased cell-to-cell contact between macrophages and RCC cells. Trogocytosis induced by CD47 blockade occurred in the presence of CD11b integrin signaling in macrophages and was augmented when RCC cells were exposed to VEGFR TKIs, except for sunitinib. In conclusion, this study presents evidence that anti-CD47 blocking antibodies improve the antitumor effect of macrophages in RCC. In combination with VEGFR TKIs, CD47 blockade is a potential therapeutic strategy for patients with RCC.

Aggressiveness of care in the last days of life in the emergency department of a tertiary hospital in Korea.

BACKGROUND: High-quality end-of-life (EOL) care requires both comfort care and the maintenance of dignity. However, delivering EOL in the emergency department (ED) is often challenging. Therefore, we aimed to investigate characteristics of EOL care for dying patients in the ED. METHODS: We conducted a retrospective cohort study of patients who died of disease in the ED at a tertiary hospital in Korea between January 2018 and December 2020. We examined medical care within the last 24 h of life and advance care planning (ACP) status. RESULTS: Of all 222 disease-related mortalities, 140 (63.1%) were men, while 141 (63.5%) had cancer. The median age was 74 years. As for critical care, 61 (27.5%) patients received cardiopulmonary resuscitation, while 80 (36.0%) received mechanical ventilation. The absence of serious illness (p = 0.011) and the lack of an advance statement (p < 0.001) were both independently associated with the receipt of more critical care. Only 70 (31.5%) patients received comfort care through opioids. Younger patients (< 75 years) (p = 0.002) and those who completed life-sustaining treatment legal forms (p = 0.001) received more comfort care. While EOL discussions were initiated in 150 (67.6%) cases, the palliative care team was involved only in 29 (13.1%). CONCLUSIONS: Patients in the ED underwent more aggressive care and less comfort care in a state of imminent death. To ensure better EOL care, physicians should minimize redundant evaluations and promptly introduce ACP.

Problems Related to the Act on Decisions on Life-Sustaining Treatment and Directions for Improvement.

The Act on Decisions on Life-Sustaining Treatment has been in effect since 2018 for end-of-life patients. However, only 20~25% of deaths of terminally ill patients comply with the law, while the remaining 75~80% do not. There is significant confusion in how the law distinguishes between those in the terminal stage and those in the dying process. These 2 stages can be hard to distinguish, and they should be understood as a single unified "terminal stage." The number of medical institutions eligible for life-sustaining treatment decisions should be legally expanded to properly reflect patients' wishes. To prevent unnecessary suffering resulting from futile life-sustaining treatment, life-sustaining treatment decisions for terminal patients without the needed familial relationships should be permitted and made by hospital ethics committees. Adult patients should be permitted to assign a legal representative appointed in advance to represent them. Medical records can be substituted for a patient's judgment letter (No. 9) and an implementation letter (No. 13) for the decision to suspend life-sustaining treatment. Forms 1, 10, 11, and 12 should be combined into a single form. The purpose of the Life-sustaining Medical Decisions Act is to respect patients' right to self-determination and protect their best interests. Issues related to the act that have emerged in the 3 years since its implementation must be analyzed, and a plan should be devised to improve upon its shortcomings.

Acquired Resistance Mechanism of EGFR Kinase Domain Duplication to EGFR TKIs in Non-Small Cell Lung Cancer.

PURPOSE: Epidermal growth factor receptor kinase domain duplication (EGFR-KDD) is a rare and poorly understood oncogenic mutation in non-small cell lung cancer (NSCLC). We aimed to investigate the acquired resistance mechanism of EGFR-KDD against EGFR-TKIs. MATERIALS AND METHODS: We identified EGFR-KDD in tumor tissue obtained from a patient with stage IV lung adenocarcinoma and established the patient-derived cell line SNU-4784. We also established several EGFR-KDD Ba/F3 cell lines: EGFR-KDD wild type (EGFR-KDDWT), EGFR-KDD domain 1 T790M (EGFR-KDDD1T), EGFR-KDD domain 2 T790M (EGFR-KDDD2T), and EGFR-KDD both domain T790M (EGFR-KDDBDT). We treated the cells with EGFR tyrosine kinase inhibitors (TKIs) and performed cell viability assays, immunoblot assays, and ENU (N-ethyl-N-nitrosourea) mutagenesis screening. RESULTS: In cell viability assays, SNU-4784 cells and EGFR-KDDWT Ba/F3 cells were sensitive to 2nd generation and 3rd generation EGFR TKIs. In contrast, the T790M-positive EGFR-KDD Ba/F3 cell lines (EGFR-KDDT790M) were only sensitive to 3rd generation EGFR TKIs. In ENU mutagenesis screening, we identified the C797S mutation in kinase domain 2 of EGFR-KDDBDT Ba/F3 cells. Based on this finding, we established an EGFR-KDD domain 1 T790M/domain 2 cis-T790M+C797S (EGFR-KDDT/T+C) Ba/F3 model, which was resistant to EGFR TKIs and anti-EGFR monoclonal antibody combined with EGFR TKIs. CONCLUSION: Our study reveals that the T790M mutation in EGFR-KDD confers resistance to 1st and 2nd generation EGFR TKIs, but is sensitive to 3rd generation EGFR TKIs. In addition, we identified that the C797S mutation in kinase domain 2 of EGFR-KDDT790M mediates a resistance mechanism against 3rd generation EGFR TKIs.

Analysis of Cancer Patient Decision-Making and Health Service Utilization after Enforcement of the Life-Sustaining Treatment Decision-Making Act in Korea.

PURPOSE: This study aimed to confirm the decision-making patterns for life-sustaining treatment (LST) and analyze medical service utilization changes after enforcement of the Life-Sustaining Treatment Decision-Making Act. MATERIALS AND METHODS: Of 1,237 patients who completed legal forms for life-sustaining treatment (hereafter called the LST form) at three academic hospitals and died at the same institutions, 1,018 cancer patients were included. Medical service utilization and costs were analyzed using claims data. RESULTS: The median time to death from completion of the LST form was three days (range, 0 to 248 days). Of these, 517 people died within two days of completing the document, and 36.1% of all patients prepared the LST form themselves. The frequency of use of the intensive care unit, continuous renal replacement therapy, and mechanical ventilation was significantly higher when the families filled out the form without knowing the patient's intention. In the top 10% of the medical expense groups, the decision-makers for LST were family members rather than patients (28% patients vs. 32% family members who knew and 40% family members who did not know the patient's intention). CONCLUSION: The cancer patient's own decision-making rather than the family's decision was associated with earlier decision-making, less use of some critical treatments (except chemotherapy) and expensive evaluations, and a trend toward lower medical costs.

Primary Prophylaxis for Pneumocystis jirovecii Pneumonia in Patients Receiving Rituximab.

BACKGROUND: Although previous studies suggested that rituximab increases the risk of Pneumocystis jirovecii pneumonia (PJP), it is uncertain whether its primary prophylaxis for PJP is justified. RESEARCH QUESTION: Does the benefit of primary prophylaxis for PJP in patients receiving rituximab treatment outweigh the potential risk of the prophylaxis? STUDY DESIGN AND METHODS: This retrospective study included 3,524 patients (hematologic diseases, 2,500; rheumatic diseases, 559; pre/post-solid organ transplantation, 465) first exposed to rituximab between 2002 and 2018 in a tertiary referral center in South Korea. Patients were classified into a control group (n = 2,523) and a prophylaxis group (n = 1,001) according to the administration of prophylactic trimethoprim-sulfamethoxazole (TMP-SMX) during the first 28 days after the start of rituximab (intention-to-treat analysis). In addition, exposure to TMP-SMX was examined as a time-varying variable (time-varying analysis). The primary outcome was the prophylactic effect of TMP-SMX on the 1-year incidence of PJP. Inverse probability of treatment weights was applied to minimize the baseline imbalance. The secondary outcome included the incidence of adverse drug reactions (ADRs) related to TMP-SMX. RESULTS: Over 2,759.9 person-years, 92 PJP infections occurred, with a mortality rate of 27.2%. The prophylaxis group showed a significantly lower incidence of PJP (adjusted subdistribution hazard ratio, 0.20 [95% CI, 0.10-0.42]) than the control group. This result was consistent with the results of time-varying analysis, in which only one PJP infection occurred during TMP-SMX administration (adjusted subdistribution hazard ratio, 0.01 [0.003-0.16]). The incidence of ADRs related to TMP-SMX was 18.1 (14.6-22.2)/100 person-years, and most were of mild to moderate severity. On the basis of 10 severe ADRs, the number needed to harm was 101 (61.9-261.1), whereas the number needed to prevent one PJP infection was 32 (24.8-39.4). INTERPRETATION: TMP-SMX prophylaxis significantly reduces PJP incidence with a tolerable safety profile in patients receiving rituximab treatment.

Soluble PD-L1 is a predictive and prognostic biomarker in advanced cancer patients who receive immune checkpoint blockade treatment.

Circulating soluble programmed death-1 ligand (sPD-L1) is measurable in the serum of cancer patients. This study aimed to investigate the significance of sPD-L1 in cancer patients receiving immune checkpoint inhibitor therapy. Blood samples were obtained before and after immune checkpoint inhibitor therapy (January 2015 to January 2019). The study cohort consisted of 128 patients who were diagnosed with non-small cell lung cancer (n = 50), melanoma (n = 31), small cell lung cancer (n = 14), urothelial carcinoma (n = 13), and other cancers (n = 20). Patients with a high level (> 11.0 pg/µL) of sPD-L1 were more likely to exhibit progressive disease compared with those with a low level (41.8% versus 20.7%, p = 0.013). High sPD-L1 was also associated with worse prognosis; the median PFS was 2.9 (95% confidence interval [CI] 2.1-3.7) months versus 6.3 (95% CI 3.0-9.6) months (p = 0.023), and the median OS was 7.4 (95% CI 6.3-8.5) months versus 13.3 (95% CI 9.2-17.4) months (p = 0.005). In the multivariate analyses, high sPD-L1 was an independent prognostic factor for both decreased PFS (HR 1.928, p = 0.038) and OS (HR 1.788, p = 0.004). sPD-L1 levels did not correlate with tissue PD-L1 expression. However, sPD-L1 levels were positively correlated with neutrophil to lymphocyte ratios and negatively correlated with both the proportion and the total number of lymphocytes. We found that high pretreatment sPD-L1 levels were associated with progressive disease and were an independent prognostic factor predicting lower PFS and OS in these patients.

Acquired Resistance to Third-Generation EGFR Tyrosine Kinase Inhibitors in Patients With De Novo EGFRT790M-Mutant NSCLC.

INTRODUCTION: EGFRT790M mostly exists subclonally and is acquired as the most common mechanism of resistance to EGFR tyrosine kinase inhibitors (TKIs). Nevertheless, because de novo EGFRT790M-mutant NSCLC is rare, little is known on acquired resistance mechanisms to third-generation EGFR TKIs. METHODS: Acquired resistance mechanisms were analyzed using tumor and plasma samples before and after third-generation EGFR TKI treatment in four patients with de novo EGFRT790M-mutant NSCLC. Genetic alterations were analyzed by whole-exome sequencing, targeted sequencing, fluorescence in situ hybridization, and droplet digital PCR. MTORL1433S, confirmed for oncogenicity using the Ba/F3 system, was reproduced in H1975 cell lines using CRISPR/Cas9-RNP. RESULTS: Of seven patients with NSCLC with de novo EGFRT790M/L858R mutation, four (LC1-4) who received third-generation EGFR TKIs acquired resistance after achieving a partial response (median = 27 mo, range: 17-48 mo). Novel MTORL1433S and EGFRC797S/L798I mutations in cis, MET amplification, and EGFRC797S mutation were identified as acquired resistance mechanisms to third-generation EGFR TKIs. The MTORL1433S mutation was oncogenic in Ba/F3 models and revealed resistance to osimertinib through AKT signaling activation in NCI-H1975 cells harboring the MTORL1433S mutation edited by CRISPR/Cas9 (half-maximal inhibitory concentration, 800 ± 67 nM). Osimertinib in combination with mTOR inhibitors abrogated acquired resistance to osimertinib. CONCLUSIONS: Activation of bypass pathways and the EGFRC797S or EGFRC797S/L798I mutation were identified as acquired resistance mechanisms to third-generation EGFR TKIs in patients with NSCLC with de novo EGFRT790M mutation. In addition, MTORL1433S- and EGFRL858R/T790M-mutant NSCLC cells were sensitive to osimertinib plus mTOR inhibitors.