Small Cell Lung Cancer Xenografts Research Articles

Targeting the Somatostatin Receptor 2 with the Miniaturized Drug Conjugate, PEN-221: A Potent and Novel Therapeutic for the Treatment of Small Cell Lung Cancer.

Small cell lung cancer (SCLC) is an aggressive neuroendocrine carcinoma with a 95% mortality rate with no improvement to treatment in decades, and new therapies are desperately needed. PEN-221 is a miniaturized peptide-drug conjugate (∼2 kDa) designed to target SCLC via a Somatostatin Receptor 2 (SSTR2)-targeting ligand and to overcome the high proliferation rate characteristic of this disease by using the potent cytotoxic payload, DM1. SSTR2 is an ideal target for a drug conjugate, as it is overexpressed in SCLC with limited normal tissue expression. In vitro, PEN-221 treatment of SSTR2-positive cells resulted in PEN-221 internalization and receptor-dependent inhibition of cellular proliferation. In vivo, PEN-221 exhibited rapid accumulation in SSTR2-positive SCLC xenograft tumors with quick clearance from plasma. Tumor accumulation was sustained, resulting in durable pharmacodynamic changes throughout the tumor, as evidenced by increases in the mitotic marker of G2-M arrest, phosphohistone H3, and increases in the apoptotic marker, cleaved caspase-3. PEN-221 treatment resulted in significant antitumor activity, including complete regressions in SSTR2-positive SCLC xenograft mouse models. Treatment was effective using a variety of dosing schedules and at doses below the MTD, suggesting flexibility of dosing schedule and potential for a large therapeutic window in the clinic. The unique attributes of the miniaturized drug conjugate allowed for deep tumor penetration and limited plasma exposure that may enable long-term dosing, resulting in durable tumor control. Collectively, these data suggest potential for antitumor activity of PEN-221 in patients with SSTR2-positive SCLC.

P1.12-05 Microenvironment Characterization of Small Cell Lung Cancer Xenografts Implanted in Hematopoietic Humanized Mice

With the high mutational burden seen in small cell lung cancer (SCLC) there is the theoretical potential to improve SCLC outcome through immunotherapy. Recent immunotherapeutic clinical trials in SCLC have demonstrated promising results. However, to better understand the immune response and the potential role of immunotherapy in SCLC, immunocompetent models are needed. To this end, we have applied a hematopoietic humanized mouse model, Hu-CB-BRGS to investigate the mechanisms underlying SCLC immunotherapy and develop novel strategies to improve therapeutic efficacy. BALB/c-Rag2nulllll2rynullSIRPαNOD (BRGS) pups were humanized through transplantation of cord blood (CB)-derived CD34+ cells. SCLC flank tumors were initiated in BRGS mice using two characterized SCLC cell lines (CDX) and 1 patient derived xenograft (PDX). Upon verification of human T-cell chimerism in the Hu-CB-BRGS mice, SCLC tumors grown in BRGS mice were engrafted into the flanks of Hu-CB-BRGS mice by trocar transfer. Tumor growth was quantified by twice weekly measurement and harvested on reaching 1200 mm3. At harvest, tumor tissue as well as host immune organs (lymph node, spleen) were collected for immunological assessment. Humanized immune system and tumor were evaluated by flow cytometry and immunohistochemistry (IHC). Flank tumors from two CDX tumors (H82 and H187) and one PDX tumor (LX-95) were successfully developed in the Hu-CB-BRGS mice with take rates averaging 82%. SCLC tumor growth rate in Hu-CB-BRGS mice was comparable to that seen in BRGS mice. Although human T cells were well represented in the lymph nodes and spleens of the Hu-CB-BRGS mice, we detected very few tumor infiltrating immune cells in the engrafted SCLC tumors by IHC and flow cytometry as defined by CD45 and CD3, which is consistent with the observations in SCLC patient tumor tissue. Tumor cells, identified by EpCAM expression, expressed low levels of MHC class I, II and PD-L1. PD-1 was expressed by human T cells found in the lymph nodes and spleen of Hu-CB-BRGS mice, while the SCLC xenografts expressed varying levels. We demonstrate that both SCLC PDX and CDX tumors can be grown in the context of a humanized immune system within mouse recipients. SCLC Hu-CB-BRGS mice demonstrate persistence of human immune cells, including T cells and B cells in the immune organs. The xenograft tumor microenvironment included variable human immune infiltrates. The SCLC Hu-CB-BRGS mouse model may be a valuable preclinical platform for testing human specific immune-oncology therapeutics for SCLC patients.

P1.12-01 CD81-HOTTIP Regulating Loop Enhances Myc-Mediated Chemoresistance in Small Cell Lung Cancer via ERK Signaling Pathway

The majority of small cell lung cancer (SCLC) patients who are treated with platinum-based chemotherapy will eventually develops into drug resistance. Currently, there are no effective durable therapies for patients with resistant recurrent SCLC. High expression of CD81 is associated with SCLC chemoresistance and poor clinical outcome. Here, our goal is to study the underlying mechanism and define a novel signaling pathway controlled by CD81 -modulating SCLC chemotherapy resistance. The expression of CD81, HOTTIP, and MYCBP were examined in human SCLC tissues, patient-derived xenograft (PDX) models, cell lines derived xenograft tumor model, and SCLC cell lines. The correlations between CD81 and HOTTIP were also confirmed by RNA immunoprecipitation and luciferase reporter assay. Functional analysis of HOTTIP, MYCBP, and ERK signaling was investigated in SCLC cell lines and xenografts. Knockdown CD81 enhanced cell responsiveness to chemotherapeutic drugs in SCLC and decreased the expression of HOTTIP, as well as inhibited the intra-nuclear translocation of MYCBP/MYC complex. Conversely, overexpression of CD81 decreased the chemotherapeutic reactivity and increased the expression of HOTTIP and promoting nuclear translocation of MYCBP/MYC complex. CD81 upregulation of HOTTIP requires the transcription factor TCF4. Further analysis demonstrated that CD81-mediated activation of ERK signaling pathway and inhibition of β-catenin degradation leads to promotion of β-catenin transfer to the nucleus. Nuclear β-catenin enhances transcriptional activity of TCF4 and then promotes the transcription of HOTTIP. Synergistically, HOTTIP could bind and increase the nucleus transduction of the MYCBP, form a HOTTIP/MYCBP/MYC complex in nucleus, resulting in increased MYC levels in nucleus. Nuclear MYC further mediates chemoresistance and promotes CD81 expression, forming a positive feedback regulatory pathway in SCLC. In addition, in vivo experiments showed that inhibitors that target the CD81-HOTTIP feedback regulatory loop combined with chemotherapeutic drugs can reverse the chemotherapeutic resistance of SCLC. Our findings suggest a novel feedback regulatory pathway dominated by CD81 and HOTTIP controlling SCLC chemotherapeutic resistance, which could serve as a new therapeutic targets for this devastating disease.

Contactin 1 modulates pegylated arginase resistance in small cell lung cancer through induction of epithelial\u2013mesenchymal transition

Drug resistance is a major hurdle in the treatment of small cell lung cancer (SCLC). Previously we demonstrated the potential anticancer effect of pegylated arginase BCT-100 in SCLC cell lines and xenograft models. To facilitate future clinical application of BCT-100 in SCLC treatment, we elucidated the potential mechanisms that underlie acquired drug resistance to BCT-100. H446 and H526 SCLC cells were serially cultured in stepwise increasing concentrations of BCT-100 until stable BCT-100-resistant cell lines emerged (H446-BR and H526-BR). Compared with parent cells, H446-BR and H526-BR displayed stronger migration ability, anoikis resistance and EMT progression. Gene chip assay was employed to select three potential targets (CDH17, CNTN-1 and IGF2BP1). Silencing CNTN-1 rather than CDH17 or IGF2BP1 in H446-BR and H526-BR cells re-sensitized resistant cells to BCT-100 treatment and attenuated the epithelial–mesenchymal transition (EMT) phenotype. The AKT signaling pathway was activated in H446-BR and H526-BR cells accompanied by EMT progression, and AKT inhibitor LY294002 reversed the EMT progression in resistant cells.

Tumor characteristics associated with engraftment of patient-derived non-small cell lung cancer xenografts in immunocompromised mice.

Patient-derived xenograft (PDX) models increasingly are used in translational research. However, the engraftment rates of patient tumor samples in immunodeficient mice to PDX models vary greatly. Tumor tissue samples from 308 patients with non-small cell lung cancer were implanted in immunodeficient mice. The patients were followed for 1.5 to approximately 6years. The authors performed histological analysis of PDXs and some residual tumor tissues in mice with failed PDX growth at 1year after implantation. Quantitative polymerase chain reaction and enzyme-linked immunoadsorbent assay were performed to measure the levels of Epstein-Barr virus genes and human immunoglobulin G in PDX samples. Patient characteristics were compared for PDX growth and overall survival as outcomes using Cox regression analyses. Disease staging was based on the 7th TNM staging system. The overall engraftment rate for PDXs from patients with non-small cell lung cancer was 34%. Squamous cell carcinomas had a higher engraftment rate (53%) compared with adenocarcinomas. Tumor samples from patients with stage II and stage III disease and from larger tumors were found to have relatively high engraftment rates. Patients whose tumors successfully engrafted had worse overall survival, particularly those individuals with adenocarcinoma, stage III or stage IV disease, and moderately differentiated tumors. Lymphoma formation was one of the factors associated with engraftment failure. Human CD8-positive and CD20-positive cells were detected in residual samples of tumor tissue that failed to generate a PDX at 1year after implantation. Human immunoglobulin G was detected in the plasma of mice that did not have PDX growth at 14months after implantation. The results of the current study indicate that the characteristics of cancer cells and the tumor immune microenvironment in primary tumors both can affect engraftment of a primary tumor sample.

Abstract CT019: Population pharmacokinetics of an aurora kinase A inhibitor, LY3295668 erbumine (AK-01), in patients with locally advanced or metastatic solid tumors

Abstract Background: The aurora kinase family plays a vital regulatory role in mitotic and meiotic events, with aurora kinase A (AurA) critical to centrosome maturation, mitotic spindle formation and checkpoint activation. LY3295668 erbumine (AK-01) is an inhibitor of AurA with 1000-fold selectivity for inhibition of AurA over aurora kinase B (AurB). Pharmacokinetic-pharmacodynamic (PK-PD) nonclinical models have shown that 90% inhibition of AurA phosphorylation (pAurA) over an extended period (≥ 16 hours per day) was required to yield efficacy in H446 (small cell lung cancer) xenograft models. Nonclinical plasma LY3295668 concentrations associated with 90% pAurA inhibition (IC90) were estimated previously using a direct sigmoidal relationship between PK and pAurA. In this first-in-man study, PK of LY3295668 in patients with advanced/metastatic cancer were evaluated. Human PK profiles were simulated subsequently and compared to pAurA IC90 to estimate a human efficacious dose range. Methods: LY3295668 erbumine was administered to 13 patients with locally advanced or metastatic solid tumors over a dose range of 25 to 75 mg given twice daily (BID). In the first cycle, serial plasma PK samples were collected up to 8 hours on Day 1 and Day 15. Additional trough samples were obtained prior to dosing on Day 2, on Day 8 and at discontinuation if applicable. PK parameter estimations were performed using non-linear mixed effects models in NONMEM v7.3. Results: The population PK model was developed using 146 plasma concentrations collected from 13 patients. A 2-compartment PK model with first order absorption best described the disposition of LY3295668. Following oral administration, LY3295668 was rapidly absorbed with peak concentrations occurring within 1 to 2 hours. The estimated elimination half-life was approximately 21 hours; therefore, steady state was attained within 4 to 5 days of dosing. Simulations of plasma concentration-time profiles showed that at the maximum tolerated dose (MTD) of 25 mg BID, 90% of patients are expected to achieve steady-state plasma concentrations greater than the pAurA IC90 for the entire day. Patients with dose limiting toxicities (DLTs) had the highest model-predicted exposures amongst the 13 patients. Conclusion: At the MTD of 25 mg BID, steady state LY3295668 plasma concentrations are maintained above the pAurA IC90 for the entire dosing interval, exceeding the minimum requirements for efficacy associated with non-clinical xenograft models. Trial Registration: NCT03092934 Citation Format: Eunice Yuen, Yu-Hua Hui, Amparo de la Peña, Sonya C. Tate, John R. Stille, Andrew Lithio, Patricia S. Smith, Quincy Chu, Gerald Batist, Nathaniel Bouganim, Caroline Fortier, Sara Zaknoen, Jill Kremer. Population pharmacokinetics of an aurora kinase A inhibitor, LY3295668 erbumine (AK-01), in patients with locally advanced or metastatic solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT019.

Abstract 3833: Antitumor activity of novel reversible LSD1 inhibitor in preclinical models of AML and SCLC

Abstract Introduction: Global changes in the epigenetic landscape are known as the hallmark in cancer and the histone demethylase Lysine-specific demethylase 1 (LSD1) is one of the novel targets for the therapy of various malignant diseases. Also LSD1 overexpression is associated with poor prognosis in various cancers. LSD1-mediated epigenetic modification is known to play a key role in the regulation of gene expression by removing the methyl groups from methylated lysine 4 and lysine 9 of histone H3. Alterations in histone methylation lead to aberrant silencing of expression of multiple genes involved in tumor survival and in cell cycle. Moreover, epigenetic dysregulation plays a critical role in pathogenesis of various types of cancers such as acute myeloid leukemia (AML) or small cell lung cancer (SCLC). In this study, we have characterized a novel LSD1 inhibitor and assessed its potential as a novel therapy for AML and SCLC patients. Materials and Methods: Novel LSD1 inhibitor, HM97211 and its derivatives were designed and synthesized as the active biologic inhibitory compound against the AML and SCLC cells. Biochemical enzyme assay was performed to identify enzyme selectivity of HM97211 derivatives. Standard proliferation assay, immunoblotting, and apoptosis analysis were carried out to validate the potency of HM97211 derivatives in AML and SCLC cell lines. In vivo anti-tumor activity was evaluated in AML and SCLC cell xenograft mice models. Tumor sizes were measured and tumor samples were analyzed to define the mechanisms of action. Results: HM97211 derivatives showed higher selectivity toward LSD1 compared to other FAD-utilizing enzyme as well as other epigenetic enzymes. HM97211 derivatives alter expression of various genes and induce differentiation and apoptosis, resulting in growth suppression in a panel of AML and SCLC cells. Moreover, HM97211 derivatives significantly induced programmed cell death in AML and SCLC cells. Oral administration of HM97211 derivatives inhibited tumor growth of human AML and SCLC xenograft models as a single agent at doses exhibiting significant. Efficacy of HM97211 derivatives was further evaluated in combination treatment with standard chemotherapies in human AML and SCLC xenograft model. Conclusion: Collectively, results of this study suggested that novel reversible LSD1 inhibitor, HM97211 derivatives, can be a strong therapeutic agent for AML and SCLC patients. Hanmi presents a new insight to epigenetics application in anticancer therapy. Citation Format: InHwan Bae, WonJeoun Kim, JiSook Kim, JiYoung Song, JungSoo Nam, Moonsub Lee, Jooyun Byun, Hyeongki Kim, TaeHun Song, Seokhyun Hong, KyuHang Lee, YoungGil Ahn, YoungHoon Kim, Kwee Hyun Suh. Antitumor activity of novel reversible LSD1 inhibitor in preclinical models of AML and SCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3833.

Phase 1 study of AMG 757, a half-life extended bispecific T cell engager (BiTE) antibody construct targeting DLL3, in patients with small cell lung cancer (SCLC).

TPS8577 Background: SCLC is an aggressive neuroendocrine tumor; response to initial chemotherapy and radiotherapy is often followed by recurrence, rapid progression, and resistance to current therapies. Delta-like ligand 3 (DLL3) is an inhibitory ligand of Notch receptors that is expressed in most SCLC tumors but minimally expressed in normal tissues. DLL3 may therefore be a promising target for T cell–redirecting immunotherapy. AMG 757 is a half-life extended BiTE antibody construct that is designed to transiently connect DLL3-positive cells to CD3-positive T cells and induce T cell–mediated cell lysis and concomitant T cell proliferation. AMG 757 induces potent killing of SCLC cell lines in vitro and inhibits tumor growth in the SHP-77 human SCLC xenograft model in vivo. AMG 757 was well tolerated in a preclinical multi-dose toxicology study in cynomolgus monkeys, with no evidence of tissue damage at weekly doses up to 4.5 mg/kg. Methods: NCT03319940 is an open-label, ascending, multiple dose, phase 1 study evaluating AMG 757. The study will initially enroll adult patients with relapsed/refractory SCLC who have progressed after at least 1 platinum-based chemotherapy regimen. Additional inclusion criteria include ECOG performance status 0–2, at least 2 measurable lesions per modified RECIST 1.1, no untreated or symptomatic brain metastases, and adequate organ function. Primary objectives are to evaluate safety and tolerability and to determine the maximum tolerated dose (MTD) or recommended phase 2 dose (RP2D). Secondary objectives are to characterize pharmacokinetics (PK) and evaluate preliminary antitumor activity. In the dose exploration phase, patients will be monitored for dose-limiting toxicities during the first 28 days. A Bayesian logistic regression model will be used to inform dose escalation/de-escalation decisions. The dose expansion phase will confirm the MTD or RP2D and collect further safety and efficacy data. AMG 757 will be administered as a short-term intravenous infusion once every 2 weeks. Alternative dosing schedules may be explored based on emerging PK and safety data. Clinical trial information: NCT03319940.

Phase 1 study of AMG 119, a chimeric antigen receptor (CAR) T cell therapy targeting DLL3, in patients with relapsed/refractory small cell lung cancer (SCLC).

TPS8576 Background: SCLC is an aggressive neuroendocrine tumor, with initial sensitivity to chemotherapy and radiotherapy often followed by chemoresistant disease progression. Notch signaling is a key regulator of neuroendocrine differentiation in SCLC, and delta-like ligand 3 (DLL3) is an inhibitory ligand of Notch receptors. DLL3 is expressed in most SCLC tumors but minimally expressed in normal tissues, suggesting that it may be a promising target for cancer immunotherapy. AMG 119 is an adoptive cellular therapy that consists of a patient’s autologous T cells that have been genetically modified ex vivo to express a transmembrane CAR that targets DLL3 and redirects cytotoxic T cell specificity to DLL3-positive cells. AMG 119 CAR T cells show potent killing of SCLC cells expressing DLL3 in vitro and inhibit tumor growth in an SCLC xenograft model in vivo. Methods: This phase 1 study will evaluate the safety and tolerability of AMG 119 administered as a single infusion in adult patients with relapsed/refractory SCLC who have progressed after at least 1 platinum-based chemotherapy regimen. The primary objectives are to evaluate safety and tolerability and determine the maximum tolerated cell dose (MTCD) or recommended phase 2 cell dose (RP2CD). Secondary objectives are to evaluate preliminary evidence of antitumor activity, expansion and persistence of AMG 119, and trafficking of AMG 119 to the tumor in post-treatment biopsy. Key inclusion criteria include histologically confirmed SCLC with radiographically documented disease progression or recurrence after at least 1 platinum-based regimen, ECOG performance status 0–1, at least 2 measurable lesions per modified RECIST 1.1, no untreated or symptomatic brain metastases, and adequate organ function. In the cell dose exploration phase, 3–4 patients will receive a single IV infusion of AMG 119 at each cell dose. Cell dose escalation/de-escalation decisions will be guided by a modified toxicity probability interval design. The dose expansion phase will seek to confirm the MTCD or RP2CD and obtain further safety and efficacy data. Clinical trial information: NCT03392064.

Adjudin synergizes with paclitaxel and inhibits cell growth and metastasis by regulating the sirtuin 3-Forkhead box O3a axis in human small-cell lung cancer.

BackgroundSmall‐cell lung cancer (SCLC), a malignant tumor, is usually widely metastatic when diagnosed. The lack of important therapeutic clinical advances makes it difficult to treat. Previous studies showed that Adjudin had anticancer effects in many other human cancers, and it was synergetic with cisplatin in non‐small cell lung cancer. However, the mechanism on SCLC was unclear.MethodsWe investigated the potential mechanism and effect of Adjudin on SCLC both in vitro and in vivo.ResultsAn SCLC xenograft model showed that Adjudin inhibited tumor growth and was significantly synergetic with paclitaxel (in vitro as well). Cell Counting Kit‐8 assays, flow cytometric analysis and western blotting showed that Adjudin effectively suppressed SCLC cell proliferation by inducing S phase arrest and caspase‐dependent apoptosis. Moreover, Transwell and scratch assays showed that Adjudin also effectively inhibited migration and invasion. Furthermore, Adjudin activated the sirtuin 3 (SIRT3)–Forkhead box O3a (FOXO3a) pathway. Downregulating SIRT3 or FOXO3a significantly attenuated Adjudin‐induced anticancer effects. Furthermore, higher expression of SIRT3 and FOXO3a were positively correlated, and both were associated with longer survival in lung cancer patients.ConclusionOverall, the present study is the first to show that Adjudin synergizes with paclitaxel and inhibits cell growth and metastasis by regulating the SIRT3–FOXO3a axis in SCLC; thus, Adjudin has great potential to be an anticancer agent.

Small-cell lung cancer growth inhibition: synergism between NMDA receptor blockade and chemotherapy.

BackgroundSmall-cell lung cancer (SCLC) has a poor prognosis since there is currently no effective therapy for commonly recurring disease. In our previous study, both primary and recurrent human tumors have been shown to express functional N-methyl-D-aspartate (NMDA) receptors, and blockade of these receptors with GluN1 and GluN2B antagonists decreased tumor cell viability in vitro, and growth of tumor xenografts in nu/nu mice.Materials and methodsIn this study, we examine the influence of the GluN2B antagonist ifenprodil and the channel-blocker antagonist memantine, on cell viability and growth of tumor xenografts of recurrent SCLC (rSCLC) in mice.ResultsBoth antagonists significantly reduced cell viability and levels of components of the ERK1/2 pathway, increased apoptosis, and at very safe levels significantly reduced the growth of tumors in mice. Each antagonist and topotecan had additive effects to reduce cell viability with significant synergy demonstrated for the case of memantine. More significantly, combination treatments of xenografts in mice with ifenprodil and the chemotherapeutic agent topotecan produced clear additive effects that completely stopped tumor growth. Moreover, the ifenprodil and topotecan combination showed excellent supra-addition or synergy of inhibition for tumors ≤300 mm in size (P=4.7E−4). Combination treatment of memantine with topotecan also showed clear addition but, unlike ifenprodil, no synergy for the doses chosen.ConclusionSince topotecan is a drug of choice for treatment of rSCLC, our findings suggest that combining this agent with NMDA receptor blockade using the GluN2B antagonist, ifenprodil, will significantly improve patient outcomes.

Gambogenic acid inhibits the proliferation of small‑cell lung cancer cells by arresting the cell cycle and inducing apoptosis.

Gambogenic acid (GNA), which is an important active compound present in gamboge, exerts anticancer activity in various types of tumor cells. However, the effect of GNA on small-cell lung cancer (SCLC) cell lines and the underlying mechanism involved still remain unclear. In the present study, GNA inhibited the proliferation and cell cycle progression of SCLC cells. GNA also promoted the apoptosis of SCLC cells in a dose-dependent manner, which is associated with modulating the levels of proteins involved in apoptosis pathways in NCI-H446 and NCI-H1688 cells. The results demonstrated that GNA increased the level of cleaved caspase-3, −8 and −9, and Bax but decreased the expression of anti-apoptotic protein, Bcl-2. Furthermore, similar results were obtained in a mouse tumor xenograft model. Additionally, GNA exhibit low toxicity in tissues when administered to mice in the SCLC xenograft models. Collectively, our findings demonstrated that GNA significantly inhibited the proliferation of SCLC cells and promoted cell apoptosis via cell cycle arrest and induction of apoptosis.

BIW-8962, an Anti GM2 Ganglioside Monoclonal Antibody, in Previously Treated Advanced/Recurrent Lung Cancer: a Phase I/II Study

BIW-8962 is a monoclonal antibody to GM2 ganglioside that shows pre-clinical activity towards lung cancer cell lines and in an animal model bearing small-cell lung cancer (SCLC) xenografts. In phase I, patients (N=16) with advanced, recurrent lung cancer received BIW-8962 (1-10 mg/kg) intravenously every 3 weeks. There were no dose-limiting toxicities and the maximum tolerated dose was not established. The highest dose (10 mg/kg) was administered to patients with advanced, recurrent SCLC (N=21) in phase II. The phase II study was prematurely terminated due to lack of efficacy. Objective response rate was 5% (95% CI: 0.1-24.9%) in the efficacy evaluable population (N=20). One patient showed a durable partial response and there were a few with stable disease, which was generally not durable. No pattern of consistent toxicity was observed across the phases: there were no treatment-related adverse events (AEs) grade ? 3, serious AEs, AEs leading to discontinuation of BIW-8962, or deaths. Exploratory analysis of circulating tumor cells and other potentially predictive orpharmacodynamic markers did not reveal any results consistent with an effect from BIW-8962. Given the complete lack of response in the study population, further development of BIW- 8962 has been discontinued. The reason for the lack of clinical activity with BIW-8962 is unknown. It is hoped that the negative findings of this study will contribute to other investigations of GM2 as a therapeutic target, possibly by combination therapy, and of alternative tumor markers in patients with SCLC.

Targeting Lactate Transport in Small-Cell Lung Cancer

Small cell lung cancer (SCLC) is the most aggressive lung cancer and though many patients respond well to frontline chemotherapy and radiation (RT), most recur quickly and have poor outcomes. Robust glucose uptake and glycolytic flux provides energy and metabolic intermediates needed to sustain rapid tumor growth; consequently, the production of excess lactic acid must be used as fuel or shuttled from the cytoplasm to the extracellular milieu. Monocarboxylate transporters (MCTs) are the primary transporters of lactate and require the co-chaperone protein CD147 for cell surface expression. CD147 aids in organizing diverse multiprotein complexes (e.g. MCTs, heterodimeric amino acid (AA) transporter heavy chain (CD98) and light chain AA transporters). We hypothesize that exploiting SCLC reliance on this multiprotein metabolic complex, particularly lactate transport, will perturb other interconnected metabolic pathways and will provide novel approaches to target SCLC. Human SCLC cell lines were assessed for expression, localization and interactions of metabolic complex proteins (e.g. CD147, MCT1, MCT4, CD98, and xCT) by western blot, confocal microscopy, gradient/subcellular fractionation and proximity ligation assays (PLA). Cells treated with SR-13800, a MCT1-specific inhibitor, were profiled for metabolic alterations using the Seahorse XF analyzer, radioactive lactate and AA transport assays and mass spectrometry. RT-induced DNA damage was quantified by γH2AX staining. Protein expression of MCT1 and MCT4 was assessed in SCLC xenografts in mice and intratumoral levels of SR-13800 was quantified after intraperitoneal (I.P) injection. Finally, tests for synergy of SR-13800 with other metabolic inhibitors were performed ex vivo. SCLCs express varying levels of metabolic complex proteins, with some expressing MCT1 or MCT4 exclusively. CD147, MCT1, CD98 and xCT localized in similar membrane fractions and CD147-MCT1 and CD98-xCT colocalized at the cell surface and were found to interact by PLA. Interestingly, CD147 and MCT1 also localized in mitochondria. SR-13800 treatment of MCT1- vs. MCT4-expressing cells decreased lactate transport and incited a shift to OXPHOS; electron transport chain analysis demonstrated this is primarily due to complex I/II activity. Differences in select metabolites were noted after SR-13800 treatment at 1 and 24 hr. SR-13800 when delivered with 2 Gy RT increased DNA damage. In vivo, MCT1 was highly expressed in the tumor whereas MCT4 was limited to necrotic regions. SR-13800 (30 mg/kg I.P) resulted in an intratumoral concentration of ∼600 nM after 24 hr. Lastly, synergism of SR-13800 with other metabolic inhibitors was observed ex vivo, especially those that disable central carbon metabolism. Disrupting lactate transport incites compensatory metabolic shifts that provide novel therapeutic opportunities when combined with other metabolic pathway inhibitors or standard of care therapies.

Modeling and antitumor studies of a modified L-penetratin peptide targeting E2F in lung cancer and prostate cancer.

E2F1-3a overexpression due to amplification or to mutation or loss of the retinoblastoma gene, induces genes involved in DNA synthesis and leads to abnormal cellular proliferation, tumor growth, and invasion. Therefore, inhibiting the overexpression of one or more of these activating E2Fs is a recognized target in cancer therapeutics. In previous studies we identified by phage display, a novel 7-mer peptide (PEP) that bound tightly to an immobilized consensus E2F1 promoter sequence, and when conjugated to penetratin to increase its uptake into cells, was cytotoxic to several malignant cell lines and human prostate and small cell lung cancer xenografts. Based on molecular simulation studies that showed that the D-Arg penetratin peptide (D-Arg PEP) secondary structure is more stable than the L-Arg PEP, the L-Arg in the peptide was substituted with D-Arg. In vitro studies confirmed that it was more stable than the L- form and was more cytotoxic as compared to the L-Arg PEP when tested against the human castrate resistant cell line, DU145 and the human lung cancer H196 cell line. When encapsulated in PEGylated liposomes, the D-Arg-PEP potently inhibited growth of the DU145 xenograft in mice. Our findings validate D- Arg PEP, an inhibitor of E2F1and 3a transcription, as an improved second generation drug candidate for targeted molecular therapy of cancers with elevated levels of activated E2F(s).

Preclinical Antitumor Activity of a Novel Anti-c-KIT Antibody-Drug Conjugate against Mutant and Wild-type c-KIT-Positive Solid Tumors.

Purpose: c-KIT overexpression is well recognized in cancers such as gastrointestinal stromal tumors (GIST), small cell lung cancer (SCLC), melanoma, non-small cell lung cancer (NSCLC), and acute myelogenous leukemia (AML). Treatment with the small-molecule inhibitors imatinib, sunitinib, and regorafenib resulted in resistance (c-KIT mutant tumors) or limited activity (c-KIT wild-type tumors). We selected an anti-c-KIT ADC approach to evaluate the anticancer activity in multiple disease models.Experimental Design: A humanized anti-c-KIT antibody LMJ729 was conjugated to the microtubule destabilizing maytansinoid, DM1, via a noncleavable linker (SMCC). The activity of the resulting ADC, LOP628, was evaluated in vitro against GIST, SCLC, and AML models and in vivo against GIST and SCLC models.Results: LOP628 exhibited potent antiproliferative activity on c-KIT-positive cell lines, whereas LMJ729 displayed little to no effect. At exposures predicted to be clinically achievable, LOP628 demonstrated single administration regressions or stasis in GIST and SCLC xenograft models in mice. LOP628 also displayed superior efficacy in an imatinib-resistant GIST model. Further, LOP628 was well tolerated in monkeys with an adequate therapeutic index several fold above efficacious exposures. Safety findings were consistent with the pharmacodynamic effect of neutropenia due to c-KIT-directed targeting. Additional toxicities were considered off-target and were consistent with DM1, such as effects in the liver and hematopoietic/lymphatic system.Conclusions: The preclinical findings suggest that the c-KIT-directed ADC may be a promising therapeutic for the treatment of mutant and wild-type c-KIT-positive cancers and supported the clinical evaluation of LOP628 in GIST, AML, and SCLC patients. Clin Cancer Res; 24(17); 4297-308. ©2018 AACR.

Abstract 1668: NHWD-870, a novel BET family bromodomain inhibitor targeting BRD4, proved to be effective and promising for treatment of small cell lung cancer

Abstract Background, Small molecule inhibitors targeting bromodomain and extraterminal domain (BET) protein is promising for cancer therapy. Previous study show that BRD4 was unregulated in different kind of cancer, with leukemia included, and BETi (BET inhibitors), such as JQ1(+) show evidence to inhibit the proliferation of cancer in vitro and vivo. However, there is no powerful data to evaluate the expression of BRD4, phosphorylation of BRD4 (p-BRD4) and the effectiveness of BETi in small cell lung cancer (SCLC). According to our previous study, BRD4 was highly expressed in 34 SCLC patients (70%) and correlated with poor prognosis in. Method, More than 120 tissue samples and survival data of SCLC patients in Hunan Cancer Hospital were collected. Immunohistochemistry was conducted to evaluate the expression of BRD4, p-BRD4 and the prognosis of these SCLC patients. Based on our previous finding, we design and modify series small molecular compound with carbocycles shape named NHWDs. We use the MTT in SCLC cell lines to evaluate the activity and selected the best. And then potential pathway was demonstrated with Array and Western blot. Finally, the activity of small compounds free base and HCL formation were conducted by xenograft and Patient Derived Xenograft (PDX) with or without double Platinum chemotherapy patients of etoposide and cisplatin resistant. Result, In 120 SCLC formalin-fixed specimens, BRD4 and p-BRD4 was highly expressed in SCLC and correlated with the poor prognosis of SCLC patients. All the compounds, free base and HCL formation which design and modify by ourselves were potent and selective BET family bromodomain inhibitor, not only binds bromodomains of BRD2/3/4/T, but the p-BRD4. Compare with JQ1(+) and other molecular compounds, NHWD-870 free base and NHWD-870-HCL have the best effectiveness and powerful anti-cancer in SCLC, and the IC50 was 1.579nM. NHWD-870 exhibited robust single agent activity in cell viability assay across cell lines in vitro and xenografts of SCLC in vivo by downregulating MYC. Consistent with its broad spectrum of activities in invo, NHWD-870 and NHWD-870-HCL have potent tumor suppressive efficacies in PDX model of SCLC. Monotherapy and combining with antiangiogenesis, such as bevacizumab and apatinib, NHWD-870 and NHWD-870-HCL proved to be more effective in SCLC cell lines and PDX in patients who show resistant to double Platinum chemotherapy with etoposide and cisplatin. Conclusion, NHWD-870 shows to be a powerful anti-cancer drug in SCLC. Further basic and clinical research should be conducted from bench to beside. Citation Format: Yongchang Zhang, Fang Wu, Nong Yang. NHWD-870, a novel BET family bromodomain inhibitor targeting BRD4, proved to be effective and promising for treatment of small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1668.

First in human phase 1/2a study of PEN-221 somatostatin analog (SSA)-DM1 conjugate for patients (PTS) with advanced neuroendocrine tumor (NET) or small cell lung cancer (SCLC): Phase 1 results.

4097Background: Somatostatin receptor 2 (SSTR2) is highly expressed in NET and SCLC. PEN-221, a SSA-DM1 conjugate that targets SSTR2, results in complete tumor regressions in SSTR2+ SCLC xenograft ...

Venetoclax Is Effective in Small-Cell Lung Cancers with High BCL-2 Expression.

Purpose: Small-cell lung cancer (SCLC) is an often-fatal neuroendocrine carcinoma usually presenting as extensive disease, carrying a 3% 5-year survival. Despite notable advances in SCLC genomics, new therapies remain elusive, largely due to a lack of druggable targets.Experimental Design: We used a high-throughput drug screen to identify a venetoclax-sensitive SCLC subpopulation and validated the findings with multiple patient-derived xenografts of SCLC.Results: Our drug screen consisting of a very large collection of cell lines demonstrated that venetoclax, an FDA-approved BCL-2 inhibitor, was found to be active in a substantial fraction of SCLC cell lines. Venetoclax induced BIM-dependent apoptosis in vitro and blocked tumor growth and induced tumor regressions in mice bearing high BCL-2-expressing SCLC tumors in vivo BCL-2 expression was a predictive biomarker for sensitivity in SCLC cell lines and was highly expressed in a subset of SCLC cell lines and tumors, suggesting that a substantial fraction of patients with SCLC could benefit from venetoclax. Mechanistically, we uncover a novel role for gene methylation that helped discriminate high BCL-2-expressing SCLCs.Conclusions: Altogether, our findings identify venetoclax as a promising new therapy for high BCL-2-expressing SCLCs. Clin Cancer Res; 24(2); 360-9. ©2017 AACR.

Promiximab-duocarmycin, a new CD56 antibody-drug conjugates, is highly efficacious in small cell lung cancer xenograft models.

Small cell lung cancer (SCLC) is of a highly invasive and metastatic lung cancer subtype and there had not been effective targeted therapies. CD56, a cell surface marker highly expressed on most SCLC, is a promising therapeutic target for treatment of this aggressive cancer. In this study, we generated a novel anti-CD56 antibody named promiximab, characterized by high affinity, internalization and tumor specificity. Then, the promiximab was conjugated with a potent DNA alkylating agent duocarmycin via reduced interchain disulfides to yield the promiximab-Duocarmycin (promiximab-DUBA) conjugates. Mass spectrometry analysis showed promiximab-DUBA had an average DAR (Drug-to-Antibody Ratio) of about 2.04. In vitro, promiximab-DUBA exerted strong inhibitory effects on SCLC cell lines NCI-H526, NCI-H524 and NCI-H69, with IC50 values of 0.07 nmol/L, 0.18 nmol/L and 0.29 nmol/L, respectively. In vivo antitumor activity, promiximab-DUBA at the dose of 5 mg/kg and 10 mg/kg every three days with a total of three times were sufficient to induce sustained regression of NCI-H526 tumors over control treatment with promiximab. Mostly, no recurrence was observed until 65 days post treatment with promiximab-DUBA. In the NCI-H69 subcutaneous xenograft model, significant inhibition of tumor growth was also observed following administration of promiximab-DUBA at the dose of 5 mg/kg or 10 mg/kg. Moreover, body weight and histopathology of major organs (liver, spleen, heart, lung and kidney) showed no significant changes after treatment of promiximab-DUBA. In conclusion, promiximab-DUBA is highly efficacious in small cell lung cancer xenograft models, and provides a new immunotherapy approach for SCLC.