Recent application of immunotherapy in clinical oncology revolutionized our management of advanced human cancers. Check point inhibitors targeting CTLA4 and PD-1/PD-L1 axis are immunotherapeutic agents currently available to treat a variety of cancers. However, a novel therapeutic approach is needed to further improve patient outcome with these agents. Indoleamine 2,3-dioxygenase 1 (IDO1) is a rate-limiting enzyme in the metabolism of essential amino acid tryptophan in the peripheral tissue. IDO1 is overexpressed in human cancer cells and suppresses effector T cell function and promotes regulatory T cells (Tregs). Overexpression of IDO1 is associated with poor patient survival in several types of human cancer. These findings indicate that IDO1 is a promising target that can improve the treatment outcome in the field of Immuno-oncology. Several orally available IDO1 inhibitors including Epacadostat have entered human clinical trials over the last few years without a major safety concern. Although there is no objective response in single-agent trials, combination regimens with PD-1 inhibitors appear to exceed the activity of PD-1 inhibitors alone. Recent phase III ECHO 301 trial testing the combination of Epacadostat with Pembrolizumab in melanoma did not show superior outcome compared to Pembrolizumab alone. This lead to halting of other phase III trials using IDO1 inhibitors. In this minireview, we will discuss the recent clinical development of Epacadostat and other IDO1 inhibitors.

Non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation eventually develop resistance to EGFR-targeted tyrosine kinase inhibitors (TKIs). Treatment resistance remains the primary obstacle to the successful treatment of NSCLC. Although drug resistance mechanisms have been studied extensively in NSCLC, the regulation of these mechanisms has not been completely understood. Recently, increasing numbers of microRNAs (miRNAs) are implicated in EGFR-TKI resistance, indicating that miRNAs may serve as novel targets and may hold promise as predictive biomarkers for anti-EGFR therapy. MicroRNA-506 (miR-506) has been identified as a tumor suppressor in many cancers, including lung cancer; however, the role of miR-506 in lung cancer chemoresistance has not yet been addressed. Here we report that miR-506-3p expression was markedly reduced in erlotinib-resistant (ER) cells. We identified Sonic Hedgehog (SHH) as a novel target of miR-506-3p, aberrantly activated in ER cells. The ectopic overexpression of miR-506-3p in ER cells downregulates SHH signaling, increases E-cadherin expression, and inhibits the expression of vimentin, thus counteracting the epithelial–mesenchymal transition (EMT)-mediated chemoresistance. Our results advanced our understanding of the molecular mechanisms underlying EGFR-TKI resistance and indicated that the miR-506/SHH axis might represent a novel therapeutic target for future EGFR mutated lung cancer treatment.

Background: SCLC, a variant of lung cancer marked by early metastases, accounts for 13% of all lung cancers diagnosed in US. Despite high response rates to treatment, it is an aggressive disease with a median survival of 9-11 months for patients with EX-SCLC. Detection of CTCs is a novel laboratory technique currently in use to determine response to therapy and to predict prognosis in breast, colorectal and prostate cancer. We initiated a study to study the role of CTC as a biomarker of response and relapse in patients with EX-SCLC. Methods: We collected blood sample from chemotherapy naïve patients with EX-SCLC prior to initiation of therapy, after completion of systemic therapy, and follow up every 6-8 weeks and at relapse. The CTC was determined using the Cell Search system in a central laboratory. The study was conducted in 4 different sites and it was reviewed and approved by respective Research Review Committee and IRBs. Results: We enrolled 27 patients with EX-SCLC, 1 was excluded due ineligibility, all patients were treated with platinum and etoposide. We observed partial response in 16 patients, stable disease in 3 patients, 1 with progression of disease and not assessed in 7 patients (5 deceased, 2 not available). The overall median number of CTCs in 24 patients measured at baseline and post-tx was 75 (range 0 to 3430) and 2 (range 0 to 526), respectively. A significant reduction in CTCs from baseline to post-treatment was identified—for the 15 subjects, the median reduction was 97.4% (range -100% to +100%, p < 0.001). Higher baseline CTC and percentage change in post treatment CTC were associated with decreased survival. Conclusions: We were able to demonstrate feasibility of using CTCs as a biomarker of response and prognosis in patients with EX-SCLC in clinical setting. CTC could be a useful biomarker in the management of EX-SCLC to predict response to therapy and predict outcome.

LCNEC of the lung comprises a small proportion of pulmonary malignancies. Traditionally, they have been classified based on histologic and immunohistochemistry characteristics with features of small cell and non-small cell lung cancer. The treatment outcome of advanced-stage LCNEC of the lung is poor with response rates ranging from 34 to 46% with platinum doublets, median progression-free survival (mPFS) ranging between 4.4 and 5.8 m, and median overall survival (mOS) ranging from 8 to 12.6 m. The optimal treatment strategy for LCNEC is debated given limited data and different outcomes based on chemotherapy type reported in the available literature. Recently, genomic profiling with Next Generation Sequencing (NGS) has been able to sub-classify LCNEC as SCLC-like or NSCLC-like. Treatment based on this sub-classification has improved outcomes by using SCLC and NSCLC regimens based on their genomic profile in retrospective analysis. Future studies in LCNEC of the lung should incorporate this new molecular sub-classification as stratification and possibly include SCLC-like LCNEC into SCLC studies and NSCLC-like into NSCLC studies.

The therapeutic landscape for patients with non-small cell lung cancer (NSCLC) has dramatically evolved with the development and adoption of immune checkpoint inhibitors (ICI) as front-line therapy. These novel antibodies target the interactions in immunoregulatory pathways, between programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1), or cytotoxic T-lymphocyte antigen 4 (CTLA-4) and B7, resulting in the activation of T cells and cytotoxic response to induce an immunologic response. ICIs have demonstrated significant survival benefits and sustained responses in the treatment of NSCLC leading to the long-term survival of up to 5 year. One unusual response to ICI is a phenomenon termed Hyperprogressive Disease (HYD), which occurs in a subset of patients for whom ICI therapy can induce rapid disease growth, which ultimately leads to poorer outcomes with an incidence rate ranging from 5 to 37% in NSCLC patients. Prior reviews demonstrated that HYD can be defined by rapid tumor progression, deterioration of patient’s symptoms or new onset of disease. The mechanism of HYD could be related to genomic and tumor microenvironment changes and altered immune response. It will be important to establish a common definition of HYD for future research and clinical care.