Sensitive Small Cell Lung Cancer Research Articles

Abstract B025: ASCL1 and SOX2 expression levels predict sensitivity to LSD1 inhibition with iadademstat in small cell lung cancer

Abstract Lysine Specific Demethylase 1 (LSD1, also known as KDM1A) is a member of the FAD-containing family of lysine demethylases and is generally involved in repressing transcription by specifically removing methyl groups from mono- and di-methylated lysine 4 of histone 3 - epigenetic marks commonly associated with actively transcribed genes. LSD1 over-expression has been associated with disease progression and worse prognosis in several human cancers, and its inhibition has been shown to reduce cancer cell growth, migration and invasion. LSD1 has therefore been recognized as a target of interest for the development of new drugs to treat cancer. Iadademstat (aka ORY-1001), a highly potent and selective LSD1 inhibitor (LSD1i) in clinical development for malignant indications, and other LSD1is, have been reported to be effective for the treatment of small cell lung cancer (SCLC) in in vitro and in vivo models. However, the published data indicate that while certain SCLC are highly sensitive to LSD1 inhibition this sensitivity is not a universal feature of SCLC cells raising the need to develop methods for identifying sensitive SCLC tumors. Herein, we report the identification of the predictive biomarkers ASCL1 and SOX2 for the enrichment of the SCLC population more likely to respond to iadademstat and other LSD1is. Response to LSD1is was evaluated in a broad panel of SCLC cell lines (from viability assay data obtained internally at Oryzon Genomics with iadademstat and from data published elsewhere using other LSD1is). Additionally, analysis of gene expression was performed in this cell line panel using internal and publicly available datasets (Affymetrix, CCLE). This analysis revealed that the transcription factors ASCL1 and SOX2 are more likely to be highly expressed in SCLC cell lines that respond to LSD1 inhibition. Moreover, the mRNA levels of these biomarkers were highly correlated with their protein levels in both SCLC cell lines and in patient-derived xenografts. In particular, immunofluorescence staining of these patient-derived SCLC samples can discriminate different degrees of ASCL1 and SOX2 protein expression levels (none, low, medium, high), which correlate with their mRNA levels determined by RNAseq in the same samples. Moreover, analysis of ASCL1 and SOX2 protein levels analyzed internally by immunofluorescence in 40 SCLC biopsies showed that 58% samples concomitantly expressed medium to high levels of both biomarkers. Taken together, these data suggest that medium to high expression of both ASCL1 and SOX2 define a SCLC population more likely to respond to LSD1 inhibition, and that this population could account for nearly 60% of SCLC cases. Therefore, ASCL1 and SOX2 expression could be used as predictive biomarkers for personalized medicine with iadademstat in SCLC patients and clinical research to validate this hypothesis is warranted. Citation Format: Natalia Sacilotto, Serena Lunardi, Filippo Ciceri, Cristina Mascaro, Tamara Maes, Ana Limon, Douglas V. Faller. ASCL1 and SOX2 expression levels predict sensitivity to LSD1 inhibition with iadademstat in small cell lung cancer. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Epigenomics; 2022 Oct 6-8; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_2):Abstract nr B025.

Targeting the Ubiquitin-Proteasome System Using the UBA1 Inhibitor TAK-243 is a Potential Therapeutic Strategy for Small-Cell Lung Cancer.

Small cell lung cancer (SCLC) is an aggressive disease with an overall 5-year survival rate of less than 10%. Treatment for SCLC with cisplatin/etoposide chemotherapy (C/E) ± radiotherapy has changed modestly over several decades. The ubiquitin-proteasome system is an underexplored therapeutic target for SCLC. We preclinically evaluated TAK-243, a first-in-class small molecule E1 inhibitor against UBA1. We assessed TAK-243 in 26 SCLC cell-lines as monotherapy and combined with C/E, the PARP-inhibitor, olaparib, and with radiation using cell viability assays. We interrogated TAK-243 response with gene expression to identify candidate biomarkers. We evaluated TAK-243 alone and in combination with olaparib or radiotherapy with SCLC patient-derived xenografts (PDX). Most SCLC cell lines were sensitive to TAK-243 monotherapy (EC50 median 15.8 nmol/L; range 10.2 nmol/L-367.3 nmol/L). TAK-243 sensitivity was associated with gene-sets involving the cell cycle, DNA and chromatin organization, and DNA damage repair, while resistance associated with cellular respiration, translation, and neurodevelopment. These associations were also observed in SCLC PDXs. TAK-243 synergized with C/E and olaparib in vitro across sensitive and resistant SCLC cell lines. Considerable TAK-243-olaparib synergy was observed in an SCLC PDX resistant to both drugs individually. TAK-243 radiosensitization was also observed in an SCLC PDX. TAK-243 displays efficacy in SCLC preclinical models. Enrichment of gene sets is associated with TAK-243 sensitivity and resistance. TAK-243 exhibits synergy when combined with genotoxic therapies in cell lines and PDXs. TAK-243 is a potential therapeutic strategy to improve SCLC patient outcomes, both as a single agent and in combination with existing therapies.

Phase 2 study of NAB-paclitaxel in SensiTivE and refractory relapsed small cell lung cancer (SCLC) (NABSTER TRIAL)

BackgroundDespite sensitivity to first-line chemotherapy, most small-cell lung cancer (SCLC) patients relapse. In this setting, topotecan demonstrated modest activity with significant toxicity. Paclitaxel was also active. This study was designed to evaluate activity and safety of nab-paclitaxel in relapsed SCLC.MethodsIn this multicentre prospective Phase 2 trial, patients with refractory or sensitive SCLC progressed to first-line platinum-based chemotherapy received nab-paclitaxel 100 mg/smq on days 1, 8, 15 every 4 weeks up to six cycles, progressive disease or intolerable toxicity. Primary endpoint was investigator-assessed objective tumour response. Secondary endpoints were toxicity, progression-free survival (PFS) and overall survival (OS).ResultsOf the 68 patients treated, partial response was 8% in the refractory cohort and 14% in the sensitive cohort. Most common toxicities of any grade were fatigue (54%), anaemia (38%), neutropenia (29%), leukopenia (26%) and diarrhoea (21%). Median PFS was similar in both refractory (1.8 months) and sensitive cohorts (1.9 months), while median OS was longer in sensitive one (6.6 versus 3.6 months).ConclusionsAlthough nab-paclitaxel has shown some modest anti-tumour activity in relapsed SCLC, associated with a favourable toxicity profile, the primary end-point of the study was not met.Clinical Trial registrationClinical Trial registration number is ClinicalTrials.gov Identifier: NCT03219762.

Abstract 381: Combined inhibition of Bcl-2 and MCL-1 in small cell lung cancer (SCLC) is most effective in tumors with low Bcl-xL expression

Abstract Introduction: SCLC is an aggressive high-grade neuroendocrine malignancy in which targeting anti-apoptotic regulators such as Bcl-2 and Bcl-xL has shown efficacy in pre-clinical models but has not resulted in successful clinical trials (Rudin et al., Clin Cancer Res. 2012). Although SCLC cell-lines do not reflect the clinical impact of these inhibitors, patient-derived xenograft (PDX) models may more accurately recapitulate Bcl-2 family expression profiles and BH3 mimetic efficacy. One promising hypothesis is that the fellow anti-apoptotic protein MCL-1 rescues viability in the presence of Bcl-2/Bcl-xL antagonists. Here we evaluate the efficacy of the MCL-1 inhibitor S63845 in combination with a novel specific inhibitor of Bcl-2, BCL201/S55746, in SCLC patient-derived xenografts. Methods: BH3 mimetic compounds were tested for synergy in vitro in SCLC cell lines. A set of ten cell lines was chosen based on relative expression of BCL2, MCL1, and BCL2L1 (Bcl-xL) mRNA. Single agent and and pair-wise combinations of Bcl2 family inhibitors were compared in three-day growth inhibition assays. Loewe synergy scores were plotted versus Bcl2 family mRNA expression to identify the determinants of drug sensitivity. Based on the cell line synergy assays, a combination of BCL201/S55746 and S63845 was selected to test in PDX models of SCLC. Bcl-2 family expression was profiled across a panel of 37 SCLC PDX models generated at MGH by quantitative western blot, and standardized to the most sensitive SCLC cell line, NCI-H211. Ten models were selected based on absolute expression of Bcl-2, Bcl-xL and MCL-1. Mice were treated when subcutaneous tumors reached a volume of 400-800 cc, enabling precise measurement of tumor regression and time to tumor regrowth. Findings: Bcl-2 family dependency in SCLC cell lines was profiled with selective inhibitors as single agents or combinations. Maximum synergy was found between BCL201/S55746 and S63845 in cell lines with the highest Bcl-2:Bcl-xL expression ratio. Bcl-2 family expression was profiled across a panel of 37 PDX models of SCLC, and a representative set of 10 models was selected for in vivo testing. Consistent with cell line results, the two most sensitive models to BCL201/S55746+S63845 demonstrated the highest Bcl-2:Bcl-xL ratios, with moderate to high expression of MCL-1. In these models BCL201/S55746+S63845 resulted in a 44-70% tumor regression that was stable throughout 4 weeks of treatment. Efficacy was not dependent on MCL-1 expression, and was not strongly correlated with PDX sensitivity to platinum-etoposide. Conclusions: Combined inhibition of Bcl-2 with BCL201 and MCL-1 with S63845 is effective in SCLC tumors with relatively low Bcl-xL expression. This combination overcomes MCL-1 mediated resistance to Bcl-2 inhibitors, and represents a promising strategy to target anti-apoptotic dependency in SCLC. Citation Format: Benjamin J. Drapkin, Sneha Sanghavi, David T. Myers, Jun Zhong, Sarah Phat, Youzhen Wang, Ensar Halilovic, Javad Golji, Anna Farago, Erick Morris, Nicholas J. Dyson. Combined inhibition of Bcl-2 and MCL-1 in small cell lung cancer (SCLC) is most effective in tumors with low Bcl-xL expression [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 381.

P1.12-04 A Ph3 Study of Niraparib as Maintenance Therapy in 1L Platinum Responsive Extensive Disease Small Cell Lung Cancer Patients

Small cell lung cancer (SCLC) accounts for 15% of lung cancer, characterized by early dissemination and rapid development of chemo-resistant disease after platinum response (60-80%). Less than 2% of extensive disease SCLC (ED-SCLC) patients survive 5 years. The bi-allelic loss or inactivation of TP53 and RB1 is common in SCLC, the poly(ADP-ribose) polymerase-1 (PARP-1), a critical DNA damage repair enzyme, is highly expressed in SCLC, and SCLC is sensitive to platinum based chemotherapy, suggesting that the defect in DNA damage repair pathways plays an important role in SCLC. ZL2306/ Niraparib is a highly selective PARP-1/2 inhibitor which was exclusively licensed for development in China by Zai Laboratory from TESARO. In SCLC PDX model, niraparib demonstrated anti-tumor activities as monotherapy. In addition, niraparib demonstrated promising tumor growth inhibition in maintenance post platinum treatment in platinum sensitive SCLC PDX models. Clinically, in phase III NOVA study, niraparib demonstrated clear clinical benefit as maintenance treatment by significantly extending progression free survival in all platinum-sensitive recurrent ovarian cancer patients regardless gBRCA or HRD status which led to the approval by FDA and EMA in ovarian cancer. It is suggested that niraparib maintenance therapy could provide potential clinical benefit in platinum responsive SCLC. ZL-2306-005 is a randomized double-blind multi-center phase 3 study to evaluate the efficacy and safety of niraparib versus placebo as maintenance therapy in ED-SCLC patients who have had responses to platinum based chemotherapy. Approximately 590 Chinese patients with histologically or cytologically confirmed ED-SCLC who have achieved either complete response or partial response to their platinum based chemotherapy to their newly diagnosed disease will be randomized (2:1) to 2 groups, receiving either ZL-2306 or placebo in ZL-2306-005 study. Patients need to complete 4 cycles of etoposide + cisplatin/ carboplatin. All patients will be stratified by gender, LDH level and history of prophylactic cranial irradiation. ZL-2306 will be started with 300mg PO QD for patients with a baseline body weight ≥77 kg and a baseline platelet count ≥150,000/μL, or 200 mg PO QD for patients with a baseline body weight <77 kg or a baseline platelet count <150,000/μL based on RADAR analysis in NOVA study. Patients will remain on treatment until disease progression or intolerable toxicity. The co-primary endpoints are PFS assessed by independent central radiologic review and OS; the secondary endpoints are PFS assessed by investigator, CFI, QoL, safety and tolerability. Section not applicable Section not applicable

MA11.07 Improved Small Cell Lung Cancer (SCLC) Response Rates with Veliparib and Temozolomide: Results from a Phase II Trial

PARP1 is overexpressed in small cell lung cancer (SCLC) and represents a novel therapeutic target for this disease. Preclinical data indicates that combining veliparib (an oral PARP-1/2 inhibitor) and temozolomide (TMZ) results in synergistic tumor growth delay or regression. In this study, we investigated whether adding veliparib to TMZ would improve outcomes in patients with relapsed sensitive and refractory SCLCs. Candidate predictive biomarkers, including SLFN11, were then explored. SCLC patients previously treated with 1 or 2 prior regimens were enrolled in the trial and randomized 1:1 to receive oral TMZ 150-200mg/m2/day (D1-5) with either veliparib or placebo 40mg twice daily, orally (D1-7) (NCT01638546). Primary endpoint was 4-month progression free survival (PFS). Data were analyzed in patients with platinum sensitive (progression >60 days after 1st line therapy) or refractory disease (progression ≤60 days after 1st line therapy, or in need of 3rd line treatment). Archived tissue was available for 53 patients for biomarker analysis. 104 patients were enrolled and 100 patients were treated. Baseline characteristics were balanced between treatment arms: 52% female; median age 62.5 (range, 31-84); 59% refractory disease; 33% needing 3rd-line therapy. Progression free survival at 4-months was similar between the two arms, 36% vs. 27% (p=0.39). However, in 93 evaluable pts, response rate was significantly higher in pts treated with veliparib/TMZ compared to TMZ alone (39% vs 14%, p =0.016). Median overall survival: 8.2 mos (95% CI: 6.4-12.2) in veliparib arm and 7 mos (95% CI: 5.3-9.5) in placebo arm, p = 0.50. Grade 3/4 thrombocytopenia and neutropenia more commonly occurred in the veliparib/TMZ arm: 50% vs 9% and 31% vs 7%, respectively. Levels of SLFN11, a marker of SCLC response to PARP inhibition in preclinical models, were assessed by immunohistochemistry. High SLFN11 in patient tumors (obtained at original diagnosis) was associated with a trend towards better overall survival in the veliparib/TMZ arm, but no difference in outcome in the TMZ alone arm. Additional correlative studies are ongoing, including assessment of MGMT promoter methylation, and will be available at the time of presentation. The combination of veliparib/TMZ increased response rates significantly, compared to TMZ alone. Hematologic toxicities of the combination may have impacted PFS (which was not significantly different between the arms) by limiting dosing. Biomarkers such as SLFN11, ATM, or MGMT promoter methylation could potentially help guide patient selection in the SCLC population.

Abstract 4692: Targeting the BET bromodomain proteins and anti-apoptotic protein BCL2 in small cell lung cancer

Abstract 10% to 15% of all lung cancers are small cell lung cancer (SCLC), named for the size of the cancer cells when seen under a microscope. SCLC often starts in the bronchi near the center of the chest. It usually grows and spreads quickly to distant parts of the body before it is diagnosed. Unfortunately, no new treatment has been identified in the past 30 years for patients with SCLC. The BET (bromodomain and extra-terminal) proteins bind acetylated histones and recruit protein complexes to promote transcription initiation and elongation. In hematologic cancers, BET proteins have been shown to regulate expression of MYC and other oncogenic transcription factors that drive disease pathology. Pharmacologic inhibition of BET binding to acetylated proteins has been shown to inhibit tumor growth in MYC-dependent cancers, such as acute myeloid leukemia, multiple myeloma and neuroblastoma. Here, we demonstrate that ∼40% of SCLC cell lines are exquisitely sensitive to growth inhibition by the BET inhibitor ABBV-075. Whereas most SCLC cell lines undergo cell cycle arrest with ABBV-075 treatment, a few cell lines undergo apoptosis. Sensitivity does not correlate with MYC status (amplification/expression). However, downregulation of anti-apoptotic protein BCLxL and BCL2 by ABBV-075 was observed in sensitive SCLC cells. Synergy was observed when co-treating BET inhibitor and BCL2 inhibitors, venetoclax (ABT-199) or navitoclax (ABT-263), and it positively correlated with BCL2 expression. Thus, high BCL2 protein expression could potentially be a biomarker predictive of these therapeutic combinations. The potential higher synergy with venetoclax may be explained by downregulation of BCLxL with BET inhibition and potent activity of venetoclax against BCL2. Our studies have provided evidence for treating SCLC by BET inhibition and/or combination with BCL2 inhibitors and a rationale for the clinical development of BET inhibitors in this disease with high unmet medical need. Disclosures: All authors are employees of AbbVie. The design, study conduct, and financial support for this research were provided by AbbVie. AbbVie participated in the interpretation of data, review, and approval of the publication. Citation Format: Lloyd T. Lam, Xiaoyu Lin, Emily Faivre, Ziping Yang, Xiaoli Huang, Ricky Bellin, Xin Lu, Yu Shen, Tamar Uziel. Targeting the BET bromodomain proteins and anti-apoptotic protein BCL2 in small cell lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4692.

Abstract B169: A mouse avatar tumor maintenance study identified a subset of SCLC patient-derived tumor xenograft models sensitive to the PARP inhibitor niraparib

Abstract Introduction Small cell lung cancer (SCLC) is an aggressive form of disease that accounts for approximately 15% of all lung cancers. To date, targeted therapies have not impacted the treatment paradigm, which is dominated by platinum-based regimens. Here we evaluate the potential of niraparib, a clinical stage poly-ADP-ribose polymerase 1 inhibitor, in a cohort of 31 SCLC patient-derived xenograft (PDX) models in mice. Methods For the initial screening study forty-two SCLC PDX models were inoculated subcutaneously into the rear flank of NOD-SCID mice. Thirty-one models were placed on study. For each model, one animal was treated with a dose of chemotherapy to mimic front line standard of care (SOC, cisplatin day 1; etoposide day 1- 3), and one animal was dosed with the same representative SOC regimen followed by a niraparib maintenance regimen (starting day 8, QDx48). Confirmatory efficacy studies were performed on six responsive models with n = 5 per group. For all efficacy studies, tumor and body weight measurements were taken three times per week. Whole exome sequencing was carried out on untreated tumor samples from six highly sensitive and four resistant models to identify biomarkers predictive of response. Sequencing was performed on DNA from fresh frozen tissue to a depth of approximately 140x mean target coverage. Results Both the SOC, and SOC plus niraparib maintenance regimens were well-tolerated with no signs of treatment-related toxicity or significant body weight loss. Robust tumor growth inhibition (TGI) was observed in 6 of 31 (19%) models. Importantly, responses were confirmed in 6 of 6 models that were repeated with cohorts of 5 animals per treatment regimen. All tumor models that exhibited sensitivity to niraparib were considered platinum/etoposide responsive based on an anti-tumor response to the initial cisplatin/etoposide treatment. Robust TGI was observed in 6 of the 20 (30%) tumor models that exhibited sensitivity to cisplatin/etoposide treatment. Whole exome sequencing of sensitive vs. resistant tumors identified mutations in genes that may be used to further enrich for tumors that would be sensitive to maintenance niraparib treatment after first line cisplatin/etoposide treatment. Conclusions Niraparib exhibited robust anti-cancer activity in 30% of cisplatin/etoposide sensitive SCLC PDX models challenged with a dosing regimen that mimics SOC followed by niraparib maintenance. These data provide support for the clinical development of niraparib in platinum-sensitive patients and suggest biomarkers that may be useful for additional patient enrichment strategies. Citation Format: Keith Mikule, Yan Wang, Yonhong Xiao, Jill Rocono, Thomas Broudy, Keith Wilcoxen. A mouse avatar tumor maintenance study identified a subset of SCLC patient-derived tumor xenograft models sensitive to the PARP inhibitor niraparib. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B169.

First-Line Platinum-Based Chemotherapy Re-challenge in Sensitive Small Cell Lung Cancer (SCLC): A Standard Treatment?

Small cell lung cancer (SCLC) has typically high sensitivity to chemotherapy and radiotherapy, although greater part of patients with limited disease (LD) and all patients with extended disease (ED) will develop disease relapse or progression, with an overall survival of 2-4 months in case of only best supportive care

Abstract 1374: Identification of a transcription factor driving BET dependency in SCLC

Abstract The regulation, and subsequent recognition, of covalent chromatin modifications by an array of cellular proteins are key determinants of gene expression. For instance, the binding of bromodomain and extra terminal domain (BET) proteins to acetylated histone tails has been shown to regulate c-MYC transcription in some cell types. Consequently, pharmacological inhibition of BET proteins leads to an anti-proliferative activity in cancers dependent on c-MYC activity such as multiple myeloma and acute myelogenous leukemia. Since c-MYC has been implicated as a driver of cell proliferation in many cancer types, we investigated if BET inhibitors may have anti-proliferative activity in solid tumor cancer cell lines as well. Strikingly, in a panel of over 100 mixed histology lung cancer cell lines we identified selective growth inhibition of lines derived from small cell lung cancer (SCLC) histology. To better understand the mechanism of this dependency we performed 12-point dose response microarray analyses using the BET inhibitor, JQ1, in order to identify genes that are regulated by BET proteins in SCLC. In contrast to what has been observed in myeloma and leukemia, BET inhibition is not always accompanied by inhibition of c-MYC expression in the SCLC cell lines. From this analysis a lineage-specific transcription factor was found to be highly regulated in a dose-dependent manner. Previous studies have reported this transcription factor to be essential in maintaining the differentiated neuroendocrine phenotype characteristic of human SCLC. It has also been shown that loss of this transcription factor results in growth inhibition in SCLC tumor models. We have confirmed the growth dependency of SCLC to BET via dysregulation of this transcription factor using RNAi and a small molecule inhibitor. Furthermore, chromatin immunoprecipitation followed by deep-sequencing confirmed binding of BRD4, a BET family member, and RNA polymerase II, a marker of active gene transcription, to the enhancer region of this target gene in two sensitive SCLC cell lines. This binding is disrupted in the presence of BET compound treatment. SCLC is a disease with high unmet medical need, and the results of our studies have identified BET inhibition as a potential novel therapeutic opportunity for this subtype of lung cancer. Our results have also provided a mechanistic basis for the sensitivity of SCLC to BET inhibition, and a rationale for the clinical development of BET inhibitors beyond hematologic cancers. Citation Format: Susan Wee, Tai Wong, BMS. Identification of a transcription factor driving BET dependency in SCLC. [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 1374. doi:10.1158/1538-7445.AM2014-1374

Efficacy results of first-line chemotherapy re-challenge in sensitive small cell lung cancer (SCLC): A retrospective multicenter analysis.

e18561 Background: Response and duration to initial chemotherapy are important factors used to classify SCLC patients into two groups. The first group comprises sensitive disease that responds to initial chemotherapy and relapses after more than 3 months and for which disease control could be obtained by re-challenging with first-line chemotherapy. The second group comprises refractory disease that progresses at the end or within 3 months of finishing first-line chemotherapy and for whom second-line chemotherapy represents the gold-standard. Methods: We reviewed clinical data from 4 Oncology Departments on sensitive SCLC treated with a first-line chemotherapy re-challenge in order to evaluate its activity and efficacy. Results: Of 211 SCLC patients diagnosed from January 2007 to December 2011, 25 (12%; 20 males, 5 females) had sensitive disease of whom 13 (52%) limited disease (LD) and 12 (48%) extended disease (ED). Median interval between the last day of chemotherapy and the onset of disease progression was 205 days (95% CI 169 – 279; range: 90 – 665). Chemotherapy consisted of etoposide + carboplatin in 15 (60%) patients or cisplatin in 10 (40%). On average 3-4 (range: 1-6) chemotherapy courses were administered, producing 8 (32%) partial responses, 3 (12%) stable disease, 10 (40%) progressive disease and 4 (16%) non evaluable disease. Further-line chemotherapy, mainly topotecan, was administered in 13 (52%) patients. Median overall survival produced by all treatments was 19.6 months (95% CI 16.5 – 27.6). Conclusions: In our experience, sensitive SCLC treated with first-line platinum/etoposide re-challenge produced interesting results in terms of activity and efficacy. Prospective randomized trials are warranted to investigate whether this strategy produces better results than standard second-line chemotherapy.

Influence of Delta-Like 1 on chemotherapeutic sensitivity of small cell lung cancer

Our study investigated the role of Delta-Like 1 (DLL1) in multi-drug resistance of small cell lung cancer. Differentially expressed genes were detected in resistant small cell lung cancer H69AR cells and sensitive small cell lung cancer H69 cells by microarray. DLL1 expression in H69 cells and H69AR cells was further confirmed by RT-PCR and Western blot assay. eGFP-RNA was employed to up-regulate DDL1 expressing in H69AR cells (H69AR-eGFP-DLL1) by transfection. These cells were treated with different chemothera-peutics (ADM, DDP, and VP-16). Cell viability was detected. Cell cycle and apoptosis rate were determined. The DLL1 expression was significantly decreased in H69AR cells when compared with H69 cells. Over-expression of DLL1 increased the sensitivity of H69AR cells to chemotherapy, which was characterized by increase in apoptosis and arrest in G0/G1 phase. Our results demonstrate that up-regulation of DLL1 expression in small cell lung cancer cells may increase their sensitivity to chemotherapeutic agents.

A Systematic Analysis of Efficacy of Second-Line Chemotherapy in Sensitive and Refractory Small-Cell Lung Cancer

Small-cell lung cancer (SCLC) patients unresponsive or relapsing within 90 days after frontline chemotherapy have poor prognosis and are treated with regimens different from the first-line regimen. Potential differences in the efficacy of second-line therapy for refractory and sensitive SCLC have not been well studied. Studies that enrolled sensitive and refractory (relapse < 90 days or > 90 days) SCLC patients for second-line therapy were identified using electronic databases (MEDLINE, EMBASE, and Cochrane library), and meeting abstracts databases. A systematic analysis was conducted using Comprehensive Meta Analysis (version 2.2.048) software to calculate the odds ratio of response and 95% confidence interval. Median overall survival time for sensitive and resistant SCLC patients was compared by two-sided Student's t test. We tested for significant heterogeneity by Cochran's chi-square test and I-square index. Twenty-one studies published between 1984 and 2011 were eligible for this analysis with a total of 1692 patients enrolled; 912 with sensitive and 780 with refractory SCLC. The overall response rate was 17.9% with a higher response rate of 27.7% (range, 0%-77%) for sensitive SCLC versus 14.8% (range, 0%-70%) for refractory patients; p=0.0001. Pooled overall odds ratio of response was 2.235 (95% confidence interval: 1.518-3.291; p=0.001) favoring patients with sensitive disease. Median overall survival time was 6.7 months with a weighted survival of 7.7 and 5.4 months for sensitive and refractory SCLC, respectively (p = 0.0035). Refractory SCLC patients derive modest clinical benefit from second-line chemotherapy. However, response and survival outcomes are superior with chemosensitive disease.

Abstract 832: Suicide gene therapy is effective for treating chemo-resistant small cell lung cancer cells

Abstract Background: Resistance arises in patients with small cell lung cancer (SCLC) following treatment with chemotherapeutic agents. Suicide gene (SG) therapy is a novel treatment strategy for cancer in which the introduced therapeutic gene encodes an enzyme capable of transforming a non-toxic prodrug into a cell poison. By coupling the SCLC specific promoter Insulinoma-associated 1 (INSM1) to the SG, it is possible to target SG expression and resulting cytotoxicity exclusive to SCLC cells. The aim of this project was to investigate the influence of chemo-resistance on transcriptional targeted SG therapy. Results: As an in vitro model of chemo-resistance we used a number of SCLC cell lines resistant to different chemotherapeutic agents used in first-line treatment of SCLC patients. Protein expression analysis showed the cells lines to vary in expression of a several proteins correlated to development of resistance. Despite of this the INSM1 promoter activity was found to be equally or increased in chemo-resistant compared to chemo-sensitive cells as measured by luciferase reporter assays and determination of INSM1 mRNA levels by RT-PCR. Additionally, in tumor xenografts stably expressing EGFP from the INSM1 promoter it was apparent that the INSM1 promoter activity is very strong and stable in vivo. Cytotoxic effects of two different SG systems driven by the INSM1 promoter were tested in the chemo-resistant cell lines by MTT assays. One consisted of the fusion SG of yeast-cytosine-deaminase (YCD) and yeast-uracil-phosphoribosyl-transferase (YUPRT) and the prodrug 5-fluorocytosin (5-FC). The other system consisted of the Nitroreductase (NTR) gene and SN27686 prodrug. While equal sensitivity was found in chemo-sensitive and -resistant cells towards YCD-YUPRT/5-FC therapy, the NTR/SN276868 system showed reduced cytotoxicity in cells resistant to alkylating agents. Importantly, equal cytotoxicity could be obtained in these chemo-resistant cells upon NTR/SN27686 therapy by exposing cells to higher prodrug doses, still not inducing off-target toxicity in NTR-negative cells. Finally, the combination of YCD-YUPRT/5-FC SG therapy with standard chemotherapy and with NTR/SN27686 SG therapy, respectively, were tested and evaluated by MTT assay. In contrast to chemo-sensitive cells, where the combination therapy had no additive effect, significantly additive cytotoxicity was achieved in chemo-resistant SCLC cells exposed to combination therapy compared to single agent therapy. Conclusion: The results demonstrate that targeted SG therapy is equally effective in chemo-resistant and -sensitive SCLC cells and that additional effect can be achieved in chemo-resistant SCLC cells when SG therapy is given in combination with chemotherapy or another SG therapy system. INSM1-driven SG therapy therefore seems potent to be effective in the treatment of SCLC patients with chemo-resistant tumors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 832. doi:1538-7445.AM2012-832

Phase-II Trial of Rebeccamycin Analog, a Dual Topoisomerase-I and -II Inhibitor, in Relapsed “Sensitive” Small Cell Lung Cancer

Relapsed small cell lung cancer (SCLC) carries a poor prognosis. Topoisomerase I and II inhibitors and DNA-damaging agents are considered among the most active agents against SCLC. Rebeccamycin analog (RA, Becatecarin) is an antitumor antibiotic with inhibitory activity against both topoisomerase I and II, and DNA-intercalating properties. We performed a phase-II trial of RA in relapsed, sensitive SCLC with the primary end point of response rate. Patients with previously treated SCLC who relapsed more than 60 days after the completion of first-line chemotherapy were treated with RA-administered intravenously at a dose of 140 mg/m on days 1 to 5 of 21-day cycles for a maximum of six cycles. Eligibility included Eastern Cooperative Oncology Group performance status 0 to 2 and adequate organ function. A two-stage design was employed. Twenty evaluable patients were enrolled. Median age was 61 years. Two patients (10%) had a partial response and six had stable disease. The clinical benefit rate was 40% (95% confidence interval [CI], 23-64%). The median progression-free survival was 2 months (95% CI, 1.2-5.2 months). The median survival was 6.7 months (95% CI, 3.3-8.0 months). No treatment-related deaths occurred. Grade-4 neutropenia and thrombocytopenia occurred in 23% and 14% of the patients, respectively. In conclusion, RA has single-agent activity in relapsed, sensitive SCLC with manageable toxicities but is unlikely to provide any superiority compared to existing agents for this disease.

Therapeutic uses of topotecan for thoracic malignancies

Topotecan, a topoisomerase 1 inhibitor (topo1-i), is a semi-synthetic derivative of camptothecan with wellestablished cytotoxic properties. It is licensed for the treatment of relapsed, sensitive small cell lung cancer (SCLC) and for second line treatment in ovarian cancer. Studies have also shown this drug to be an effective first line treatment for SCLC with either cisplatin or in combination with a topoisomerase 2 inhibitor (topo2-i), etoposide; both combinations have shown similar efficacy. Oral and parenteral formulations of topotecan have proven to be equivocal in relapsed SCLC patients. The parenteral form showed reduced rates of severe haematological toxicities and better symptom control than an anthracycline combination (CAV). In relapsed SCLC, a randomised phase III trial of oral topotecan versus best supportive care showed a statistically significant increase in overall survival. In the second line treatment of non-small cell lung cancer (NSCLC), oral topotecan was not inferior to the current standard iv docetaxel for 1 year survival rates. Worthwhile potential investigations include combining oral topotecan with other oral agents to design treatments for different lines of therapy. The new oral formulation of topotecan also lends itself to testing with small molecule tyrosine kinase inhibitors. The myelosuppressive toxicity profile needs to be vigorously monitored and managed. The trials with oral topotecan have also highlighted the need to reassess the utility of the terms ‘sensitive’ and ‘resistant’ in the selection of patients with relapsed small cell lung cancer.

Phase II Multicenter Trial of Voreloxin as Second-Line Therapy in Chemotherapy-Sensitive or Refractory Small Cell Lung Cancer

Voreloxin is an anticancer quinolone derivative that intercalates DNA and inhibits topoisomerase II, causing double-strand breaks in DNA, irreversible G2 arrest, and rapid onset of apoptosis. Based on preclinical activity of voreloxin in chemoresistant tumors, early phase I clinical activity, and a mechanism of action similar to other topoisomerase II inhibitors such as the anthracyclines and etoposide, this phase II trial was undertaken as second-line treatment of small cell lung cancer (SCLC). Patients with extensive stage SCLC previously treated with one prior chemotherapy regimen were eligible. Patients with chemotherapy-sensitive or chemotherapy-refractory disease were considered as separate cohorts. Voreloxin (48 mg/m) was administered on the first day of each 21-day cycle for up to six cycles. The primary end point was objective response rate. Fifty-five patients were enrolled including 28 with refractory SCLC and 27 with sensitive SCLC; 47 were evaluable for response. Three patients with sensitive SCLC had an objective response, including one complete response and two partial responses (11% response rate based on intent to treat). No patients in the refractory cohort had a response. The primary grade 3 toxicity was neutropenia. Voreloxin has minimal activity in relapsed SCLC when administered at 48 mg/m in a 3-week schedule.

Combinations of DNA Methyltransferase and Histone Deacetylase Inhibitors Induce DNA Damage in Small Cell Lung Cancer Cells: Correlation of Resistance with IFN-Stimulated Gene Expression

Because epigenetic inhibitors can reduce cancer cell proliferation, we tested the hypothesis that concurrent inhibition of histone acetylation and DNA methylation could synergistically reduce the viability of small cell lung cancer (SCLC) cells. Sub-IC(50) concentrations of the DNA methyltransferase (DNMT) inhibitor decitabine (5-AZA-dC) and the histone deacetylase (HDAC) inhibitors (LBH589 or MGCD0103) synergistically reduced the proliferation of five of nine SCLC cell lines. Loss of viability of sensitive SCLC cells did not correlate with the inhibition of either DNMT1 or HDACs, suggesting nonepigenetic mechanisms for synergy between these two classes of epigenetic modulators. Because combinations of 5-AZA-dC and HDAC inhibitors had marginal effects on the apoptosis index, Comet assay was undertaken to assess DNA damage. MGCD0103 and 5AZA-dC cotreatment augmented DNA damage in SCLC cells, resulting in increased tail length and moment in Comet assays by 24 hours in sensitive cell lines (P < 0.01). Consistent with augmented DNA damage, combination of a DNMT and HDAC inhibitor markedly increased the levels of phospho-H2A.X in sensitive cells but not in resistant ones. Comparison of basal gene expression between resistant and sensitive cells identified markedly higher basal expression of IFN-stimulated genes in the resistant cell lines, suggesting that IFN-stimulated gene expression may determine SCLC cell sensitivity to epigenetic modulators or other DNA damaging agents.

Amrubicin (AMR) and cardiotoxicity in second-line treatment of small cell lung cancer (SCLC): A pooled analysis of left ventricular ejection fraction (LVEF) in two phase II trials

e19019 Background: Amrubicin (AMR) is a third-generation synthetic anthracycline and a potent topoisomerase II inhibitor approved in Japan for the treatment of lung cancer. In Japanese pre and postmarking studies, AMR treatment was not associated with cardiotoxicity. The purpose of this analysis was to determine if AMR treatment of Western patients (pts) is associated with anthracycline-induced cardiomyopathy. Methods: To evaluate risk of cardiomyopathy, LVEF was measured by echocardiogram or by multiple gated acquisition (MUGA) scan and pooled from pts enrolled in 2 trials of IV AMR, 40 mg/m2/day x 3 days q 21 days for second-line treatment of sensitive or refractory SCLC. Pts with measurable disease, ECOG PS 0–2, LVEF ≥50%, and prior platinum-based treatment were assessed at baseline (BL), cycles 3, 6, then every 2 cycles, and end of treatment. Pts were to be assessed by the same method (ECHO or MUGA) throughout the study. Pts with a persistent ≥20% decrease in LVEF during treatment were to be removed from the study. Results: 112 patients were treated (sensitive n=43, median 6 cycles; refractory, n=69, median 5 cycles) and had at least 1 LVEF assessment. Median age was 63 years and median BL LVEF was 60%. Changes in LVEF from baseline were minimal ( Table ) and similar across cumulative dosing groups including 15 pts who received a cumulative dose of &gt;1,000 mg/m2 AMR. Two refractory pts (1.8%) experienced drops in LVEF &gt;20%. One had BL LVEF of 85%, then 60% at cycle 3, and 70% subsequently with ongoing therapy. The second, with a history of cardiomegaly, had LVEF of 55% at BL, cycle 3, and 5 by ECHO, and 29% at the time of progression after cycle 9 (cumulative AMR dose 840 mg/m2) by MUGA. The patient died due to progressive disease with no evidence of CHF. Conclusions: In this pooled analysis of SCLC pts, LVEF remained stable even in pts with cumulative AMR dosing &gt;1,000 mg/m2. AMR for second-line treatment of SCLC does not appear to cause anthracycline-related cardiomyopathy. [Table: see text] [Table: see text]

Therapeutic uses of topotecan for thoracic malignancies

Topotecan, a topoisomerase 1 inhibitor (topo1-i), is a semi-synthetic derivative of camptothecan with well-established cytotoxic properties. It is licensed for the treatment of relapsed, sensitive small cell lung cancer (SCLC) and for second line treatment in ovarian cancer. Studies have also shown this drug to be an effective first line treatment for SCLC with either cisplatin or in combination with a topoisomerase 2 inhibitor (topo2-i), etoposide; both combinations have shown similar efficacy. Oral and parenteral formulations of topotecan have proven to be equivocal in relapsed SCLC patients. The parenteral form showed reduced rates of severe haematological toxicities and better symptom control than an anthracycline combination (CAV). In relapsed SCLC, a randomised phase III trial of oral topotecan versus best supportive care showed a statistically significant increase in overall survival. In the second line treatment of non-small cell lung cancer (NSCLC), oral topotecan was not inferior to the current standard iv docetaxel for 1 year survival rates. Worthwhile potential investigations include combining oral topotecan with other oral agents to design treatments for different lines of therapy. The new oral formulation of topotecan also lends itself to testing with small molecule tyrosine kinase inhibitors. The myelosuppressive toxicity profile needs to be vigorously monitored and managed. The trials with oral topotecan have also highlighted the need to reassess the utility of the terms ‘sensitive’ and ‘resistant’ in the selection of patients with relapsed small cell lung cancer.