Association of PD-L1 overexpression with activating EGFR mutations in surgically resected nonsmall-cell lung cancer

Tyrosine kinase inhibitors for epidermal growth factor receptor gene mutation-positive non-small cell lung cancers: an update for recent advances in therapeutics

The presence of activating gene mutations in the epidermal growth factor receptor of non-small cell lung cancer patients is predictive (improved progression-free survival and improved response rate) when treated with small molecule tyrosine kinase inhibitors such as gefitinib, erlotinib and afatinib. The two most common mutations that account for greater than 85% of all EGFR gene mutations are in-frame deletions in exon 19 (LREA deletions) and substitution in exon 21 (L858R). Exon 18 mutations occur much less frequently at about 4% of all EGFR gene mutations. Together, exon 19 deletion and exon 21 L858R gene substitution are present in about 10% of Caucasian patients and 20-40% of Asian patients with non-small cell lung cancer. T790M gene mutation at exon 20 is associated with acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors. Early studies showed that activating EGFR gene mutations are most common in patients with adenocarcinoma histology, women, never smokers and those of Asian ethnicity. A recent multi-center phase III trial suggested that frontline epidermal growth factor receptor tyrosine kinase inhibitor therapy with afatinib is associated with improved progression-free survival compared to chemotherapy regardless of race. Moreover, guidelines now suggest EGFR gene mutation testing should be conducted in all patients with lung adenocarcinoma or mixed lung cancers with an adenocarcinoma component, regardless of characteristics such as smoking status, gender or race. The success of targeted therapies in non-small cell lung cancer patients has changed the treatment paradigm in metastatic non-small cell lung cancer. However, despite a durable response of greater than a year, resistance to epidermal growth factor receptor tyrosine kinase inhibitors inevitably occurs. This mini-review describes the clinically relevant EGFR gene mutations and the efficacy/toxicity of small molecule epidermal growth factor receptor tyrosine kinase inhibitors as targeted therapies for these gene mutations. Therapeutic strategies to overcome resistance, including emerging and novel therapies, are discussed.

Inducible but not constitutive expression of PD-L1 in human melanoma cells is dependent on activation of NF-κB

Monoclonal antibodies against immune checkpoint blockade have proven to be a major success in the treatment of melanoma. The programmed death receptor-1 ligand-1 (PD-L1) expression on melanoma cells is believed to have an inhibitory effect on T cell responses and to be an important escape mechanism from immune attack. Previous studies have shown that PD-L1 can be expressed constitutively or can be induced by IFN-γ secreted by infiltrating lymphocytes. In the present study we have investigated the mechanism underlying these two modes of PD-L1 expression in melanoma cells including cells that had acquired resistance to the BRAF inhibitor vemurafenib. PD-L1 expression was examined by flow cytometry and immunoblotting. Specific inhibitors and siRNA knockdown approaches were used to examine the roles of the RAF/ MEK, PI3K, NF-κB, STAT3 and AP1/ c-Jun pathways. IFN-γ inducible expression of PD-L1 was dependent on NF-κB as shown by inhibition with BMS-345541, an inhibitor of IκB and the BET protein inhibitor I-BET151, as well as by siRNA knockdown of NF-κB subunits. We were unable to implicate the BRAF/MEK pathway as major regulators in PD-L1 expression on vemurafenib resistant cells. Similarly the PI3K/AKT pathway and the transcription factors STAT3 and c-Jun had only minor roles in IFN-γ induced expression of PD-L1. The mechanism underlying constitutive expression remains unresolved. We suggest these results have significance in selection of treatments that can be used in combination with monoclonal antibodies against PD1, to enhance their effectiveness and to reduce inhibitory effects melanoma cells have against cytotoxic T cell activity.

A multi-institutional study of clinicopathological features and molecular epidemiology of epidermal growth factor receptor mutations in lung cancer patients living with human immunodeficiency virus infection

PURPOSE

Lung cancer has become a crucial problem among individuals living with the human immunodeficiency virus (HIV) and causes high mortality in Western countries. Japan has an increasing number of newly infected HIV patients, and lung cancer is becoming a theme in this population. However, clinical factors of this particular population in East Asian are unclear given the identification of ethnic differences in lung cancer in the general population.

METHODS

From 1986 to 2013, a retrospective nationwide study involving Japanese patients living with HIV and diagnosed with lung cancer was undertaken.

RESULTS

Forty-three lung cancer patients with HIV were identified (median age, 60.0 years; males, 97.7%; early-stage cancer, 37.2%; metastatic cancer, 34.9%), 41 (95.3%) of whom developed lung cancer in the antiretroviral era. The median CD4-positive T-cell count was 326 cells/µL. Adenocarcinoma was the most frequent histology (55.8%), followed by squamous cell carcinoma (27.9%). Epidermal growth factor receptor (EGFR) status was examined in 14 patients; five (35.7%) had EGFR mutations. The median overall survival time was 25.1 months for all stages and 7.9 months for advanced-stage cancer. Using univariate analysis, the only favorable prognostic factor for overall survival was cancer stage (p = 0.02).

CONCLUSIONS

The incidence of lung cancer among HIV patients in Japan has been increasing in the past decade. The present Japanese cohort showed similar EGFR mutation status similar to that of general population. The ethnic differences known in the general population were seen even in the population living with HIV, implying distinct clinical characteristics and outcomes from those reported in Western countries.

Circulating PD-L1 in NSCLC patients and the correlation between the level of PD-L1 expression and the clinical characteristics

Background

The programmed cell death-1/programmed cell death-1 ligand (PD-1/PD-L1) pathway plays a crucial role in tumor evasion. This study evaluated the association between circulating PD-L1 expression and clinical characteristics in patients with advanced non-small cell lung cancer (NSCLC).

Methods

A total of 109 advanced NSCLC and 65 healthy patients from the Beijng Cancer Hospital were enrolled in the study. Circulating PD-L1 expression was tested by enzyme-linked immunosorbent assay. The associations between the level of PD-L1 expression and clinicopathologic features and prognosis were statistically analyzed.

Results

The expression of PD-L1 in advanced NSCLC patients was significantly upregulated compared with the healthy control (P < 0.001). The expression of PD-L1 was significantly correlated with abdominal organ metastasis (P = 0.004). A high PD-L1 expression had a worse prognosis than a low expression in patients (18.7 vs. 26.8 month, P < 0.001).

Conclusions

PD-L1 was elevated in advanced NSCLC patients and may play an important role in tumor immune evasion and patient prognosis.

Nivolumab in NSCLC: latest evidence and clinical potential

New insight on the interaction between the immune system and tumor has identified the programmed death-1/programmed death-1 ligand pathway to be a key player in evading host immune response. The immune checkpoint modulator, nivolumab (BMS-936558/ONO-4538), is the first PD-1 inhibitor to gain regulatory approval, for the treatment of patients with unresectable melanoma. This review will discuss results from early phase studies of nivolumab in solid tumors including non-small cell lung cancer (NSCLC) as well as studies of nivolumab in combination with chemotherapy, other immune modulators and molecular targeted therapy in patients with NSCLC.

Prognostic significance of programmed cell death 1 (PD-1) or PD-1 ligand 1 (PD-L1) Expression in epithelial-originated cancer: a meta-analysis

The expression of programmed cell death 1 (PD-1) and its ligand (PD-L1) has been observed in various epithelial-originated malignancies. However, whether the expression of PD-L1 on tumor cells or the expression of PD-1 on tumor-infiltrating lymphocytes (TILs) is associated with patients' survival remains controversial.Electronic databases were searched for eligible literatures. Data of hazard ratio (HR) for overall survival (OS) with 95% confidence interval (CI) according to the expression status of PD-L1 or PD-1 evaluated by immunohistochemistry were extracted. The outcomes were synthesized based on random-effects model. Subgroup analyses were proposed.Twenty-nine studies covering 12 types of epithelial-originated malignancies involving 7319 patients (2030/3641 cases for PD-L1 positive/negative, 505/1143 cases for PD-1 positive/negative) with available data of the outcome stratified by PD-L1/PD-1 status were enrolled. Epithelial-originated cancer patients with positive expression of PD-L1 on tumor tissues were associated with significantly poorer OS when compared to those with negative expression of PD-L1 (HR 1.81, 95% CI 1.33-2.46, P < 0.001). Similarly, patients with PD-1 positive expression on TILs had significantly shorter OS than the PD-1 negative group (HR 2.53, 95% CI 1.22-5.21, P = 0.012). In analyses of PD-L1, all subgroups showed consistent trends toward unfavorable prognoses of patients with positive PD-L1 expression, regardless of antibodies and evaluation cutoffs. Subgroup analyses on PD-1 were not available due to limited data.PD-L1 or PD-1 expression status is a significant prognostic factor in epithelial-originated malignancies.

The prognostic value of PD-L1 expression for non-small cell lung cancer patients: a meta-analysis

BACKGROUND

A meta-analysis was conducted to investigate the much-debated relationship between the gene expression of programmed cell death-ligand 1 (PD-L1) and cancer patient prognosis. The prognostic value of measuring PD-L1 expression in non-small cell lung cancer (NSCLC) patients was analyzed.

METHODS

We searched PubMed for studies about the relationship between PD-L1 expression and NSCLC patient prognosis. Only studies with patient survival data related to PD-L1 expression in NSCLC patients with different characteristics were included. The effect size (ES) for this analysis was the hazard ratio (HR) with 95% confidence intervals (CI) for overall survival (OS).

RESULTS

Six studies with 1157 patients were included with the defined including and excluding criteria. There is no significant heterogeneity among the studies (I(2) = 0%, p = 0.683). PD-L1 expression was significantly associated with the differentiation of tumor (poor vs. well: OR = 1.91, 95% CI: 1.33-2.75, p = 0.001). High PD-L1 expression was also correlated with poor prognosis in terms of the OS of patients with NSCLC (pooled HR = 1.75, 95% CI: 140-2.20, p < 0.001; heterogeneity test: I(2) = 0%, p = 0.643).

CONCLUSIONS

NSCLC patients with positive PD-L1 expression exhibited poor OS. The PD-L1 expression was higher in tumors with poor differentiation.

Current and Future Approaches in the Management of Non-Small-Cell Lung Cancer Patients With Resistance to EGFR TKIs

Metastatic non-small-cell lung cancer carries a dismal prognosis. However, the recognition of the predictive value of activating epidermal growth factor receptor (EGFR) mutations and the availability of tyrosine kinase inhibitors has markedly improved the prognosis of these patients, because treatment with these inhibitors induces rapid and robust responses. Unfortunately, the responses are not durable and resistance inevitably occurs after a median of 9 to 14 months. Although the management of resistant patients who harbor EGFR mutations is rapidly evolving, there are no conclusive guidelines regarding this issue. However, palliative cytotoxic chemotherapy is considered the standard of care for these patients. The elucidation of the mechanisms of acquired resistance has led to efforts to personalize the treatment approach. Promising results from early clinical trials using the third-generation inhibitors that specifically target the most common mechanism of resistance, the gatekeeper T790M mutation, provide the basis to look to the future with cautious optimism. Moreover, it has been shown that in some cases of oligoprogressive disease, aggressively treating all metastatic sites while continuing the targeted treatment could improve outcomes. Herein, we review the treatment strategies being evaluated that will shape the future management of these patients.

Human cancer immunotherapy with antibodies to the PD-1 and PD-L1 pathway

The programmed death 1 (PD-1) receptor and its ligands programmed death ligand 1 (PD-L1) and PD-L2, members of the CD28 and B7 families, play critical roles in T cell coinhibition and exhaustion. Overexpression of PD-L1 and PD-1 on tumor cells and tumor-infiltrating lymphocytes, respectively, correlates with poor disease outcome in some human cancers. Monoclonal antibodies (mAbs) blockading the PD-1/PD-L1 pathway have been developed for cancer immunotherapy via enhancing T cell functions. Clinical trials with mAbs to PD-1 and PD-L1 have shown impressive response rates in patients, particularly for melanoma, non-small-cell lung cancer (NSCLC), renal cell carcinoma (RCC), and bladder cancer. Further studies are needed to dissect the mechanisms of variable response rate, to identify biomarkers for clinical response, to develop small-molecule inhibitors, and to combine these treatments with other therapies.

Intrinsic and extrinsic control of expression of the immunoregulatory molecule PD-L1 in epithelial cells and squamous cell carcinoma

Recent clinical results for PD-1 blockade therapy have demonstrated durable tumor control with minimal immune-related adverse effects. PD-L1 is induced in non-lymphoid tissue cells and tumor cells, in addition to tissue-recruiting immune cells, under inflammatory conditions triggered by several cytokines, especially IFN-γ, and exogenous stimuli delivered by pathogen-associated molecular patterns. Receptor-mediated signaling molecules that affect the cell cycle, proliferation, apoptosis, and survival (including NF-κB, MAPK, PI3K, mTOR, and JAK/STAT) are involved in PD-L1 induction. PD-L1 expression in tumor cells is also triggered by the signals described above, but in some instances, intrinsic cell alteration associated with carcinogenesis contributes to PD-L1 induction. The tumor suppressor genes PTEN and Lkb1 and epithelial-mesenchymal transition-related molecules are also involved in the regulation of PD-L1 expression. Notably, squamous cell carcinoma of the head and neck (SCCHN) often exhibits both host immunosuppression and cytogenetic alternations of tumor cells. Precise understanding of how PD-L1 expression is controlled will allow the development of effective approaches to PD-1 blockade therapy for patients with SCCHN.