Neoadjuvant Chemoradiotherapy Treatment for a Classic Biphasic Pulmonary Blastoma with High PD-L1 Expression

Pulmonary blastomas are rare malignant tumors, comprising only 0.25-0.5% of all malignant lung neoplasms. The prognosis of pulmonary blastoma is very poor, with an overall five-year survival of 16%. No standard treatment has been defined for unresectable disease. We present the case of a 25-year-old woman with unresectable locally advanced classic biphasic pulmonary blastoma (CBPB) successfully treated with neodjuvant chemoradiotherapy based on two chemotherapy induction cycles of cisplatin plus etoposide, followed by concurrent weekly cisplatin to 50.4 Gy radiotherapy treatment. The patient had a significant reduction in tumor size, allowing for complete resection by pneumonectomy. Molecular study for epidermal growth factor receptor (EGFR) mutations, anaplastic lymphoma kinase (ALK), proto-oncogene receptor tyrosine kinase (ROS1) and rearranged during transfection (RET) rearrangements, and programmed death ligand 1 (PD-L1) expression was performed in the pre-treatment tumor sample. Our patient presented a high expression (>90% of tumor cells) of PD-L1. To our knowledge, this is the first report of PD-L1 expression in CBPB. This could lead to new treatment options based on new immunotherapy agents blocking the PD-1/PD-L1 pathway for this rare disease with poor prognosis.

Targeting PD-1/PD-L1 in lung cancer: current perspectives

Increased understanding of tumor immunology has led to the development of effective immunotherapy treatments. One of the most important advances in this field has been due to pharmacological design of antibodies against immune checkpoint inhibitors. Anti-PD-1/PD-L1 antibodies are currently in advanced phases of clinical development for several tumors, including lung cancer. Results from Phase I-III trials with anti-PD-1/PD-L1 antibodies in non-small-cell lung cancer have demonstrated response rates of around 20% (range, 16%-50%). More importantly, responses are long-lasting (median duration of response, 18 months) and fast (50% of responses are detected at time of first tumor evaluation) with very low grade 3-4 toxicity (less than 5%). Recently, the anti-PD-1 antibody pembrolizumab received US Food and Drug Administration (FDA) breakthrough therapy designation for treatment of non-small-cell lung cancer, supported by data from a Phase Ib trial. Another anti-PD-1 antibody, nivolumab, has also been approved for lung cancer based on survival advantage demonstrated in recently released data from a Phase III trial in squamous cell lung cancer.

Understanding the function and dysfunction of the immune system in lung cancer: the role of immune checkpoints

Survival rates for metastatic lung cancer, including non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), are poor with 5-year survivals of less than 5%. The immune system has an intricate and complex relationship with tumorigenesis; a groundswell of research on the immune system is leading to greater understanding of how cancer progresses and presenting new ways to halt disease progress. Due to the extraordinary power of the immune system-with its capacity for memory, exquisite specificity and central and universal role in human biology-immunotherapy has the potential to achieve complete, long-lasting remissions and cures, with few side effects for any cancer patient, regardless of cancer type. As a result, a range of cancer therapies are under development that work by turning our own immune cells against tumors. However deeper understanding of the complexity of immunomodulation by tumors is key to the development of effective immunotherapies, especially in lung cancer.

Assays for predicting and monitoring responses to lung cancer immunotherapy

Immunotherapy has become a key strategy for cancer treatment, and two immune checkpoints, namely, programmed cell death 1 (PD-1) and its ligand (PD-L1), have recently emerged as important targets. The interaction blockade of PD-1 and PD-L1 demonstrated promising activity and antitumor efficacy in early phase clinical trials for advanced solid tumors such as non-small cell lung cancer (NSCLC). Many cell types in multiple tissues express PD-L1 as well as several tumor types, thereby suggesting that the ligand may play important roles in inhibiting immune responses throughout the body. Therefore, PD-L1 is a critical immunomodulating component within the lung microenvironment, but the correlation between PD-L1 expression and prognosis is controversial. More evidence is required to support the use of PD-L1 as a potential predictive biomarker. Clinical trials have measured PD-L1 in tumor tissues by immunohistochemistry (IHC) with different antibodies, but the assessment of PD-L1 is not yet standardized. Some commercial antibodies lack specificity and their reproducibility has not been fully evaluated. Further studies are required to clarify the optimal IHC assay as well as to predict and monitor the immune responses of the PD-1/PD-L1 pathway.

AXL mediates resistance to PI3Kα inhibition by activating the EGFR/PKC/mTOR axis in head and neck and esophageal squamous cell carcinomas

Phosphoinositide-3-kinase (PI3K)-α inhibitors have shown clinical activity in squamous cell carcinomas (SCCs) of head and neck (H&N) bearing PIK3CA mutations or amplification. Studying models of therapeutic resistance, we have observed that SCC cells that become refractory to PI3Kα inhibition maintain PI3K-independent activation of the mammalian target of rapamycin (mTOR). This persistent mTOR activation is mediated by the tyrosine kinase receptor AXL. AXL is overexpressed in resistant tumors from both laboratory models and patients treated with the PI3Kα inhibitor BYL719. AXL dimerizes with and phosphorylates epidermal growth factor receptor (EGFR), resulting in activation of phospholipase Cγ (PLCγ)-protein kinase C (PKC), which, in turn, activates mTOR. Combined treatment with PI3Kα and either EGFR, AXL, or PKC inhibitors reverts this resistance.

Concordance of IHC, FISH and RT-PCR for EML4-ALK rearrangements

The echinoderm microtubule-associated protein-like 4 anaplastic lymphoma kinase (EML4-ALK) has emerged as the second most important driver oncogene in lung cancer and the first targetable fusion oncokinase to be identified in 4-6% of lung adenocarcinomas. Crizotinib, along with a diagnostic test-the Vysis ALK Break Apart fluorescence in situ hybridization (FISH) Probe Kit-is approved for the treatment of ALK positive advanced non-small cell lung cancer (NSCLC). However, the success of a targeted drug is critically dependent on a sensitive and specific screening assay to detect the molecular drug target. In our experience, reverse transcription polymerase chain reaction (RT-PCR)-based detection of EML4-ALK is a more sensitive and reliable approach compared to FISH and immunohistochemistry (IHC). Although ALK FISH is clinically validated, the assay can be technically challenging and other diagnostic modalities, including IHC and RT-PCR should be further explored.

Abstract 4601: Astrocytic elevated gene 1 (AEG1) a target for pharmacological anticancer intervention

AEG1 is highly expressed in solid tumors; hyperexpression confers multidrug resistance, increased tumor proliferation, angiogenesis, metastatic potential and poor outcome in most solid tumors. AEG1 activates multiple protumorogenic signal transduction pathways like PIK3/ALT, NFKB, MAMPK, WNT and is a rational target for therapeutic intervention in solid tumors.Also AEG1 functionality is instrumental in the natural history of brain tumors. Our data in NSCLCs confirm AEG1 overexpression as the main parameter (uni and multivariate analysis) indicative of outcome to targeted and cytotoxic therapy. We designed an in silico model based on inhibition of AEG1-p65 crosstalk, identifying a possible interacting interface between the 2 proteins that could be modeled as a three-dimensional structure. This interface was further reduced and transformed into a 3-point pharmacophore for virtual screening comparing both molecular interaction fields and the pharmacophore. A total of 217.000 chemical entities (CEs) were tested in this model giving a Hercules® affinity ranking. Sixty CEs with the highest Hercules® ranking were identified for a second (16 CEs) and third (5 CEs) selection to implement the first round of in vitro studies in our human solid tumor panel. Twenty analogs were generated to seek for a lead according to prospective selection criteria. PB0412-3 (PB3), a small molecule polyheterocyclic compound, was selected for further development. PB3 displays antitumor activity in the human solid tumor panel (median IC50 1.3 uM) and PB3-induced growth inhibition appears independent of EGFR, KRAS & p53 mutational status, Her2 amplification, PIK3 mutations and BRCA1 expression;tumor cell lines bearing highest AEG1-mRNA expression levels were sensititive to PB3. Median IC50 in our glioblastoma (GBM) panel was 60 nM with no impact of MGMT methylation status on PB3's molar potency (MP). IC50s delta solid vs brain tumors were significant (p<.0001) representing a 25-fold increase in MP. Data from nitrosureas in the same GBM panel indicate PB3 is 250 times more potent than BCNU and temozolamide. Median IC50s in human non cancer lines is 2 uM. PB3 was re-screened in the in silico model; PB3 fully matches the AEG1 binder pharmacophore model and was screened in the Chemical Space web tool; results confirm PB3 as first-in-class CE. Functional studies are ongoing; preliminary data in PC9 NSCLC cell line demonstrate significant PB3-induced downregulation of AEG1 mRNA expression. Expansion of the CNS tumor panel, cell kinetics, drug-induced cell death & in vivo/PK-PD studies in SC orthotopic models is ongoing. To the best of our knowledge, this is the first successful attempt at the Pharmacological intervention against the AEG1 pathway. A dual developmental plan for PB3 as local brain drug delivery and systemic therapy is proposed.

Citation Format: Jose M. Jimeno, Gerardo Acosta, Miguel Ángel Molina, Nicky Karachaliou, Cristina Teixidó, Carlos Obiol, Oriol Villacañas, Jordi Bertran, María Sánchez Rouco, Ana Giménez Capitán, Santiago Ramón y Cajal, Miquel Taron, Rafael Rosell, Fernando Albericio. Astrocytic elevated gene 1 (AEG1) a target for pharmacological anticancer intervention. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4601. doi:10.1158/1538-7445.AM2014-4601

ErbBs inhibition by lapatinib blocks tumor growth in an orthotopic model of human testicular germ cell tumor

In this work, we have analyzed the expression of different members of the ErbB family in human samples of testicular germ cell tumors (GCTs). We observed expression of ErbB1 or ErbB2 in different tumor subtypes, but we also found high expression of ErbB3 in all GCTs tested. This pattern of expression was maintained when primary tumors were orthotopically implanted in nude mice. We have chosen a choriocarcinoma model characterized by high levels of ErbB1, but also of ErbB2 and ErbB3, to assay the in vivo effect of ErbB inhibitors on tumoral growth. Our results showed a complete lack of effect (refractoriness) to the pure ErbB1 receptor inhibitors cetuximab and gefitinib. While these inhibitors blocked ErbB1 phosphorylation, ErbB2 phosphorylation was not affected, suggesting an ErbB1-independent activation of this receptor. To confirm the importance of ErbB2 activation, animals were treated with lapatinib, a dual ErbB1 and ErbB2 inhibitor. Lapatinib treatment caused a 50% inhibition in tumor growth, an effect correlated with a blockade of both ErbB1 and ErbB2 phosphorylation levels, and of downstream signaling pathways (Akt, ERKs and Stat3). ErbB2 activation could still occur due to the formation of ErbB2/ErbB3 heterodimers, and ErbB3 activation was completely inhibited by lapatinib. Finally, combined inhibition of ErbB1 (gefitinib) and ErbB3 activities (knockdown expression by shRNA) inhibited tumoral testicular cells proliferation in a similar way to lapatinib. Our results explain why lapatinib but not anti-ErbB1 agents might be effective for treatment of testicular GCT patients.

Epithelial-mesenchymal transition markers and HER3 expression are predictors of elisidepsin treatment response in breast and pancreatic cancer cell lines

Elisidepsin (elisidepsin trifluoroacetate, Irvalec®, PM02734) is a new synthetic depsipeptide, a result of the PharmaMar Development Program that seeks synthetic products of marine origin-derived compounds. Elisidepsin is a drug with antiproliferative activity in a wide range of tumors. In the present work we studied and characterized the mechanisms associated with sensitivity and resistance to elisidepsin treatment in a broad panel of tumor cell lines from breast and pancreas carcinomas, focusing on different factors involved in epithelial-mesenchymal transition (EMT) and the use of HER family receptors in predicting the in vitro drug response. Interestingly, we observed that the basal protein expression levels of EMT markers show a significant correlation with cell viability in response to elisidepsin treatment in a panel of 12 different breast and pancreatic cancer cell lines. In addition, we generated three elisidepsin treatment-resistant cell lines (MCF-7, HPAC and AsPC-1) and analyzed the pattern of expression of different EMT markers in these cells, confirming that acquired resistance to elisidepsin is associated with a switch to the EMT state. Furthermore, a direct correlation between basal HER3 expression and sensitivity to elisidepsin was observed; moreover, modulation of HER3 expression levels in different cancer cell lines alter their sensitivities to the drug, making them more resistant when HER3 expression is downregulated by a HER3-specific short hairpin RNA and more sensitive when the receptor is overexpressed. These results show that HER3 expression is an important marker of sensitivity to elisidepsin treatment.

ErbB3 expression predicts sensitivity to elisidepsin treatment: in vitro synergism with cisplatin, paclitaxel and gemcitabine in lung, breast and colon cancer cell lines

Irvalec® (elisidepsin trifluoroacetate, PM02734) is a novel marine-derived cyclic peptide belonging to the Kahaladide family of compounds, currently in clinical trials with preliminary evidence of antitumor activity. Previous studies have shown a correlation between elisidepsin sensitivity and expression of the ErbB3 receptor in a panel of NSCLC cell lines. We have studied the effect of elisidepsin on the ErbB3 pathway, characterizing the expression of all members of the ErbB (HER) family of receptors and their main downstream signaling effectors, such as Akt and MAPK. Interestingly, we observed a downregulation of ErbB3 upon elisidepsin treatment that correlates with a reduction in the Akt phosphorylation levels in the most sensitive cell lines, whereas ErbB3 levels are not affected in the less sensitive ones. Also, we observed that the basal levels of ErbB3 protein expression show a significant correlation with cell viability response against elisidepsin treatment in 14 different cell lines. Furthermore, we analyzed the combination of elisidepsin with different chemotherapeutics agents, such as cisplatin, paclitaxel and gemcitabine, in a panel of different breast (MDA-MB-435, MDA-MB-231 and MCF7), lung (HOP62, DV90 and A549) and colorectal cancer cell lines (DLD1 and HT29). IC50 values for the different drugs were tested. We observed a synergistic effect in all cell lines tested with any chemotherapeutic agent. More importantly, the two in vitro elisidepsin-resistant cell lines (MDA-MB-231 and HOP62) presented a synergistic effect in combination with cisplatin and paclitaxel, respectively. These results provide a rationale for further development of these combinations in an ongoing clinical trial.

RSK4 inhibition results in bypass of stress-induced and oncogene-induced senescence

p90 Ribosomal S6 kinase (RSK) 4 is a serine-threonine kinase that belongs to the p90RSK family. RSK4 has been proposed as a tumor suppressor gene, related with anti-invasive activity, inhibition of the RAS-mitogen-activated protein kinase (MAPK) pathway and induction of senescence. Despite the related findings, little is known about RSK4 effectors. In human tumors, RSK4 is downregulated even in some benign lesions, such as colon adenomas and breast papillomas, indicating that RSK4 inhibition could be an early event in cellular transformation. For cells to achieve immortality and transformation, it is believed that they must override senescence. In the present study, we found that when RSK4 is inhibited in vitro using short hairpin RNA technology, cells can bypass stress-induced senescence and oncogene-induced senescence: normal human fibroblasts grew following oxidative stress, induction of DNA damage and KRAS(V12) or BRAF(E600) overexpression. To investigate the RSK4 effectors, we used short hairpin RNA or inhibitor molecules against major senescence mediators. We found that RSK4-induced senescence is mediated through p21, but is independent of p16, p38MAPKs and induction of reactive oxygen species, delimiting RSK4 signaling. These data support the importance of RSK4 for regulating senescence and indicate that downregulation of this kinase could be an important element in facilitating cell transformation.