Angiogenesis is a complex biological process that plays a relevant role in sustaining the microenvironment, growth, and metastatic potential of several tumors, including non-small cell lung cancer (NSCLC). Bevacizumab was the first angiogenesis inhibitor approved for the treatment of patients with advanced NSCLC in combination with chemotherapy; however, it was limited to patients with non-squamous histology and first-line setting. Approval was based on the results of two phase III trials (ECOG4599 and AVAIL) that demonstrated an improvement of about two months in progression-free survival (PFS) in both trials, and in the ECOG4599 trial, an improvement in overall survival (OS) also. Afterwards, other antiangiogenic agents, including sunitinib, sorafenib, and vandetanib have been unsuccessfully tested in first and successive lines. Recently, two new antiangiogenic agents (ramucirumab and nintedanib) produced a significant survival benefit in second-line setting. In the REVEL study, ramucirumab plus docetaxel prolonged the median OS of patients with any histology NSCLC when compared with docetaxel alone (10.4 versus 9.1 months, hazard ratio (HR) 0.857, p = 0.0235). In the LUME-Lung 1 study, nintedanib plus docetaxel prolonged the median PFS of patients with any tumor histology (p = 0.0019), and improved OS (12.6 versus 10.3 months) in patients with adenocarcinoma. As a result, it became a new option for the second-line treatment of patients with advanced NSCLC and adenocarcinoma histology. Identifying predictive biomarkers to optimize the benefit of antiangiogenic drugs remains an ongoing challenge.
Small-cell lung cancer (SCLC) is an aggressive tumor type with limited therapeutic options and poor prognosis. Chemotherapy regimens containing platinum represent the cornerstone of treatment for patients with extensive disease, but there has been no real progress for 30 years. The evidence that SCLC is characterized by a high mutational burden led to the development of immune-checkpoint inhibitors as single agents or in combination with chemotherapy. Randomized phase III trials demonstrated that the combination of atezolizumab (IMpower-133) or durvalumab (CASPIAN) with platinum-etoposide chemotherapy improved overall survival of patients with extensive disease. Instead, the KEYNOTE-604 study demonstrated that the addition of pembrolizumab to chemotherapy failed to significantly improve overall survival, but it prolonged progression-free survival. The safety profile of these combinations was similar with the known safety profiles of all single agents and no new adverse events were observed. Nivolumab and pembrolizumab single agents showed anti-tumor activity and acceptable safety profile in Checkmate 032 and KEYNOTE 028/158 trials, respectively, in patients with SCLC after platinum-based therapy and at least one prior line of therapy. Future challenges are the identification predictive biomarkers of response to immunotherapy in SCLC and the definition of the role of immunotherapy in patients with limited stage SCLC, in combination with radiotherapy or with other biological agents.
The teratocarcinoma-derived growth factor-1 (TDGF-1) gene codes for a 188-aminoacid glycoprotein that shares structural homology with the epidermal growth factor (EGF) family of growth factors. TDGF-1 is highly expressed in the undierentiated embryonal carcinoma stem cell line NTERA2 clone D1 (NT2/D1) and its expression is downregulated in response to dierentiating agents such as retinoic acid (RA) and hexamethylenbisacetamide (HMBA). To assess the role of TDGF-1 in the onset and/or progression of human germ cell tumors, we analysed TDGF-1 expression by Northern blot and immunostaining in a panel of 59 human germ cell tumors of dierent histological origins. We show that TDGF-1 expression is markedly elevated in a subset of human testicular germ cell tumors as compared to normal testes. TDGF-1 overexpression occurs in about 100% of tumors with non-seminomatous phenotype, such as embryonal carcinomas and malignant undierentiated teratocarcinomas. To address the questions of how TDGF-1 (previously called CRIPTO) may aect the growth and/or the dierentiation of embryonal carcinoma cells, we have characterized the eects of exogenous recombinant TDGF-1 protein on the proliferation rate and dierentiation potential of NT2/D1. Exogenous TDGF-1 protein stimulated DNA synthesis and cell proliferation in both undierentiated and dierentiated NT2/D1 cells. However, TDGF-1 protein treatment was unable to block dierentiation induced by both RA and HMBA. These results suggest that TDGF-1 growth factor may represent an autocrine growth factor that may be involved in the process of development of testicular neoplasms.
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