Modulating immune inhibitory pathways has been a major recent breakthrough in cancer treatment. Checkpoint blockade antibodies targeting cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programed cell-death protein 1 (PD-1) have demonstrated acceptable toxicity, promising clinical responses, durable disease control, and improved survival in some patients with advanced melanoma, non-small cell lung cancer (NSCLC), and other tumor types. About 20 % of advanced NSCLC patients and 30 % of advanced melanoma patients experience tumor responses from checkpoint blockade monotherapy, with better clinical responses seen with the combination of anti-PD-1 and anti-CTLA-4 antibodies. Given the power of these new therapies, it is important to understand the complex and dynamic nature of host immune responses and the regulation of additional molecules in the tumor microenvironment and normal organs in response to the checkpoint blockade therapies. In this era of precision oncology, there remains a largely unmet need to identify the patients who are most likely to benefit from immunotherapy, to optimize the monitoring assays for tumor-specific immune responses, to develop strategies to improve clinical efficacy, and to identify biomarkers so that immune-related adverse events can be avoided. At this time, PD-L1 immunohistochemistry (IHC) staining using 22C3 antibody is the only FDA-approved companion diagnostic for patients with NSCLC-treated pembrolizumab, but more are expected to come to market. We here summarize the current knowledge, clinical efficacy, potential immune biomarkers, and associated assays for immune checkpoint blockade therapies in advanced solid tumors.

BackgroundProgrammed cell death 1 (PD-1) and its ligand 1 (PD-L1) inhibitors have quickly become standard of care for patients with advanced non-small cell lung cancer and increasing numbers of other cancer types. In this report, we discuss the clinical history, pathological evaluation, and genomic findings in a patient with metastatic lung squamous cell cancer (SCC) who developed severe nivolumab-induced pneumonitis preceding durable clinical remission after three doses of nivolumab.Case presentationA patient with chemotherapy-refractory, metastatic lung SCC developed symptomatic pneumonitis by week 4 after nivolumab treatment, concurrently with onset of a potent antitumor response. Despite discontinuation of nivolumab after three doses and the use of high dose oral corticosteroids for grade 3 pneumonitis, continued tumor response to a complete remission by 3 months was evident by radiographic assessment. At the time of this submission, the patient has remained in clinical remission for 14 months. High PD-L1 expression by immunohistochemistry staining was seen in intra-alveolar macrophages and viable tumor cells in the pneumonitis and recurrent tumor specimens, respectively. Tumor genomic profiling by FoundationOne targeted exome sequencing revealed a very high tumor mutation burden (TMB) corresponding to 95–96 percentile in lung SCC, i.e., 87.4–91.0 and 82.9 mut/Mb, respectively, in pre- and post-nivolumab tumor specimens. Except for one, the 13 functional genomic alterations remained the same in the diagnostic, recurrent, and post-treatment, relapsed tumor specimens, suggesting that nivolumab reset the patient’s immune system against one or more preexisting tumor-associated antigens (TAAs). One potential TAA candidate is telomerase reverse transcriptase (TERT) in which an oncogenic promoter -146C>T mutation was detected. Human leukocyte antigen (HLA) typing revealed HLA-A*0201 homozygosity, which is the prevalent HLA class I allele that has been used to develop universal cancer vaccine targeting TERT-derived peptides.ConclusionsNivolumab could quickly reset and sustain host immunity against preexisting TAA(s) in this chemotherapy-refractory lung SCC patient. Further mechanistic studies are needed to characterize the effective immune cells and define the HLA-restricted TAA(s) and the specific T cell receptor clones responsible for the potent antitumor effect, with the aim of developing precision immunotherapy with improved effectiveness and safety.

BackgroundThis retrospective study was undertaken to determine if the plasma circulating tumor DNA (ctDNA) level and tumor biological features in patients with advanced solid tumors affected the detection of genomic alterations (GAs) by a plasma ctDNA assay.MethodCell-free DNA (cfDNA) extracted from frozen plasma (N = 35) or fresh whole blood (N = 90) samples were subjected to a 62-gene hybrid capture-based next-generation sequencing assay FoundationACT. Concordance was analyzed for 51 matched FoundationACT and FoundationOne (tissue) cases. The maximum somatic allele frequency (MSAF) was used to estimate the amount of tumor fraction of cfDNA in each sample. The detection of GAs was correlated with the amount of cfDNA, MSAF, total tumor anatomic burden (dimensional sum), and total tumor metabolic burden (SUVmax sum) of the largest ten tumor lesions on PET/CT scans.ResultsFoundationACT detected GAs in 69 of 81 (85%) cases with MSAF > 0. Forty-two of 51 (82%) cases had ≥ 1 concordance GAs matched with FoundationOne, and 22 (52%) matched to the National Comprehensive Cancer Network (NCCN)-recommended molecular targets. FoundationACT also detected 8 unique molecular targets, which changed the therapy in 7 (88%) patients who did not have tumor rebiopsy or sufficient tumor DNA for genomic profiling assay. In all samples (N = 81), GAs were detected in plasma cfDNA from cancer patients with high MSAF quantity (P = 0.0006) or high tumor metabolic burden (P = 0.0006) regardless of cfDNA quantity (P = 0.2362).ConclusionThis study supports the utility of using plasma-based genomic assays in cancer patients with high plasma MSAF level or high tumor metabolic burden.

Background α3β1 integrin is a promising cancer biomarker and drug target. We previously identified a 9-amino-acid cyclic peptide LXY30 for detecting α3β1 integrin on the surface of live tumor cells. This study was undertaken to characterize LXY30 in the detection, cellular function, imaging, and targeted delivery of in vitro and in vivo non-small cell lung cancer (NSCLC) models. Methods The whole-cell binding assay was performed by incubating NSCLC cells, extracellular vesicles (EVs), and peripheral blood mononuclear cells (PBMCs) with TentaGel resin beads coated with LXY30. In this study, we defined the nanosize EVs as exosomes, which were characterized by flow cytometry, transmission electron microscopy, dynamic light scattering, and Western blots. The function of LXY30 was determined by modulating the epidermal growth factor receptor (EGFR) signaling pathway by growth inhibition and Western blots. For in vivo biodistribution, mice bearing subcutaneous and intracranial NSCLC xenograft tumors were administrated intraveneously with LXY30-biotin/streptavidin-Cy5.5 complex and then analyzed for in vivo and ex vivo optical imaging and histopathology. Results We showed that LXY30 specifically and sensitively detected α3β1 integrin-expressing NSCLC cells and tumor-derived exosomes. Tumor DNA isolated from LXY30-enriched plasma exosomes might be used to detect driver oncogenic mutations in patients with metastatic NSCLC. LXY30 only enriches tumor cells but not neutrophils, macrophages, or monocytes in the malignant pleural effusion of NSCLC patients for detecting genomic alterations by next-generation sequencing. LXY30 detected increased α3β1 integrin expression on the EGFR -mutant NSCLC cells with acquired resistance to erlotinib compared to parental erlotinib-sensitive EGFR -mutant NSCLC cells. We further showed that LXY30 modulated the EGFR signaling pathway independently from another peptide ligand LXW64 targeting αvβ3 integrin in erlotinib-resistant, EGFR -mutant H1975 cells. Analysis of The Cancer Genome Atlas (TCGA) revealed high α3 integrin expression was associated with poor prognosis in lung squamous cell carcinoma. LXY30-biotin/streptavidin-Cy5.5 complex had higher uptakes in the subcutaneous and intracranial xenografts of various α3β1 integrin-expressing lung adenocarcinoma and patient-derived lung squamous cell carcinoma xenografts while sparing the surrounding normal tissues. Conclusion LXY30 is a promising peptide for the cancer diagnosis and in vivo targeted delivery of imaging agents and cancer drugs in NSCLC, independent of histology and tumor genotype. Electronic supplementary material The online version of this article (10.1186/s13045-019-0740-7) contains supplementary material, which is available to authorized users.