Antibody-drug conjugates in lung and breast cancer: current evidence and future directions-a position statement from the ETOP IBCSG Partners Foundation.

Following the approval of the first antibody-drug conjugates (ADCs) in the early 2000s, development has increased dramatically, with 14 ADCs now approved and >100 in clinical development. In lung cancer, trastuzumab deruxtecan (T-DXd) is approved in human epidermal growth factor receptor 2 (HER2)-mutated, unresectable or metastatic non-small-cell lung cancer, with ADCs targeting HER3 (patritumab deruxtecan), trophoblast cell-surface antigen 2 [datopotamab deruxtecan and sacituzumab govitecan (SG)] and mesenchymal-epithelial transition factor (telisotuzumab vedotin) in late-stage clinical development. In breast cancer, several agents are already approved and widely used, including trastuzumab emtansine, T-DXd and SG, and multiple late-stage trials are ongoing. Thus, in the coming years, we are likely to see significant changes to treatment algorithms. As the number of available ADCs increases, biomarkers (of response and resistance) to better select patients are urgently needed. Biopsy sample collection at the time of treatment selection and incorporation of translational research into clinical trial designs are therefore critical. Biopsy samples taken peri- and post-ADC treatment combined with functional genomics screens could provide insights into response/resistance mechanisms as well as the impact of ADCs on tumour biology and the tumour microenvironment, which could improve understanding of the mechanisms underlying these complex molecules. Many ADCs are undergoing evaluation as combination therapy, but a high bar should be set to progress clinical evaluation of any ADC-based combination, particularly considering the high cost and potential toxicity implications. Efforts to optimise ADC dosing/duration, sequencing and the potential for ADC rechallenge are also important, especially considering sustainability aspects. The ETOP IBCSG Partners Foundation are driving strong collaborations in this field and promoting the generation/sharing of databases, repositories and registries to enable greater access to data. This will allow the most important research questions to be identified and prioritised, which will ultimately accelerate progress and help to improve patient outcomes.

Consolidation nivolumab and ipilimumab versus observation in limited-disease small-cell lung cancer after chemo-radiotherapy - results from the randomised phase II ETOP/IFCT 4-12 STIMULI trial.

BACKGROUND: Concurrent chemotherapy and thoracic radiotherapy followed by prophylactic cranial irradiation (PCI) is the standard treatment in limited-disease small-cell lung cancer (LD-SCLC), with 5-year overall survival (OS) of only 25% to 33%. PATIENTS AND METHODS: STIMULI is a 1:1 randomised phase II trial aiming to demonstrate superiority of consolidation combination immunotherapy versus observation after chemo-radiotherapy plus PCI (protocol amendment-1). Consolidation immunotherapy consisted of four cycles of nivolumab [1 mg/kg, every three weeks (Q3W)] plus ipilimumab (3 mg/kg, Q3W), followed by nivolumab monotherapy (240 mg, Q2W) for up to 12 months. Patient recruitment closed prematurely due to slow accrual and the statistical analyses plan was updated to address progression-free survival (PFS) as the only primary endpoint. RESULTS: Of the 222 patients enrolled, 153 were randomised (78: experimental; 75: observation). Among the randomised patients, median age was 62 years, 60% males, 34%/65% current/former smokers, 31%/66% performance status (PS) 0/1. Up to 25 May 2020 (median follow-up 22.4 months), 40 PFS events were observed in the experimental arm, with median PFS 10.7 months [95% confidence interval (CI) 7.0-not estimable (NE)] versus 42 events and median 14.5 months (8.2-NE) in the observation, hazard ratio (HR) = 1.02 (0.66-1.58), two-sided P = 0.93. With updated follow-up (03 June 2021; median: 35 months), median OS was not reached in the experimental arm, while it was 32.1 months (26.1-NE) in observation, with HR = 0.95 (0.59-1.52), P = 0.82. In the experimental arm, median time-to-treatment-discontinuation was only 1.7 months. CTCAE v4 grade ≥3 adverse events were experienced by 62% of patients in the experimental and 25% in the observation arm, with 4 and 1 fatal, respectively. CONCLUSIONS: The STIMULI trial did not meet its primary endpoint of improving PFS with nivolumab-ipilimumab consolidation after chemo-radiotherapy in LD-SCLC. A short period on active treatment related to toxicity and treatment discontinuation likely affected the efficacy results.

A randomised phase II study of osimertinib and bevacizumab versus osimertinib alone as second-line targeted treatment in advanced NSCLC with confirmed EGFR and acquired T790M mutations: the European Thoracic Oncology Platform (ETOP 10-16) BOOSTER trial.

BACKGROUND: While osimertinib, a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) is the standard treatment in patients with advanced non-small-cell lung cancer (NSCLC) with sensitising EGFR and acquired T790M mutations, progression inevitably occurs. The angiogenic pathway is implicated in EGFR TKI resistance. PATIENTS AND METHODS: BOOSTER is an open-label randomised phase II trial investigating the efficacy and safety of combined osimertinib 80 mg daily and bevacizumab 15 mg/kg every 3 weeks, versus osimertinib alone, in patients with EGFR-mutant advanced NSCLC and acquired T790M mutations after failure on previous EGFR TKI therapy. Primary endpoint was investigator-assessed progression-free survival (PFS). Secondary endpoints were overall survival (OS), objective response rate (ORR) and adverse events (AEs). RESULTS: Between May 2017 and February 2019, 155 patients were randomised (combination: 78; osimertinib: 77). At data cut-off of 22 February 2021, median follow-up was 33.8 months [interquartile range (IQR): 26.5-37.6 months] and 129 (83.2%) PFS events were reported in the intention-to-treat population. There was no difference in median PFS between the combination [15.4 months; 95% confidence interval (CI) 9.2-18.0 months] and osimertinib arm (12.3 months; 95% CI 6.2-17.2 months; stratified log-rank P = 0.83), [hazard ratio (HR) = 0.96; 95% CI 0.68-1.37]. Median OS was 24.0 months (95% CI 17.8-32.1 months) in the combination arm and 24.3 months (95% CI 16.9-37.0 months) in the osimertinib arm (stratified log-rank P = 0.91), (HR = 1.03; 95% CI 0.67-1.56). Exploratory analysis revealed a significant interaction of smoking history with treatment for PFS (adjusted P = 0.0052) with a HR of 0.52 (95% CI 0.30-0.90) for smokers, and 1.47 (95% CI 0.92-2.33) for never smokers. ORR was 55% in both arms and the median time to treatment failure was significantly shorter in the combination than in the osimertinib arm, 8.2 months versus 10.8 months, respectively (P = 0.0074). Safety of osimertinib and bevacizumab was consistent with previous reports with grade ≥3 treatment-related AEs (TRAEs) reported in 47% and 18% of patients on combination and osimertinib alone, respectively. CONCLUSIONS: No difference in PFS was observed between osimertinib plus bevacizumab and osimertinib alone. Grade ≥3 TRAEs were more common in patients on combination.

A multicentre randomised phase III trial comparing pembrolizumab versus single-agent chemotherapy for advanced pre-treated malignant pleural mesothelioma: the European Thoracic Oncology Platform (ETOP 9-15) PROMISE-meso trial.

BACKGROUND: Malignant pleural mesothelioma (MPM) is an aggressive malignancy characterised by limited treatment options and a poor prognosis. At relapse after platinum-based chemotherapy, single-agent chemotherapy is commonly used and single-arm trials of immune-checkpoint inhibitors have demonstrated encouraging activity. PATIENTS AND METHODS: PROMISE-meso is an open-label 1:1 randomised phase III trial investigating the efficacy of pembrolizumab (200 mg/Q3W) versus institutional choice single-agent chemotherapy (gemcitabine or vinorelbine) in relapsed MPM patients with progression after/on previous platinum-based chemotherapy. Patients were performance status 0-1 and unselected for programmed cell death ligand 1 (PD-L1) status. At progression, patients randomly assigned to receive chemotherapy were allowed to crossover to pembrolizumab. The primary end point was progression-free survival (PFS), assessed by blinded independent central review (BICR). Secondary end points were overall survival (OS), investigator-assessed PFS, objective response rate (ORR), and safety. Efficacy by PD-L1 status was investigated in exploratory analyses. RESULTS: Between September 2017 and August 2018, 144 patients were randomly allocated (pembrolizumab: 73; chemotherapy: 71). At data cut-off [20 February 2019, median follow-up of 11.8 months (interquartile range: 9.9-14.5)], 118 BICR-PFS events were observed. No difference in BICR-PFS was detected [hazard ratio = 1.06, 95% confidence interval (CI): 0.73-1.53; P = 0.76], and median BICR-PFS (95% CI) for pembrolizumab was 2.5 (2.1-4.2), compared with 3.4 (2.2-4.3) months for chemotherapy. A difference in ORR for pembrolizumab was identified (22%, 95% CI: 13% to 33%), over chemotherapy (6%, 95% CI: 2% to 14%; P = 0.004). Forty-five patients (63%) assigned to chemotherapy received pembrolizumab at progression. With follow-up to 21 August 2019 [17.5 months: (14.8-19.7)], no difference in OS was detected between groups (HR = 1.12, 95% CI: 0.74-1.69; P = 0.59), even after adjusting for crossover. Pembrolizumab safety was consistent with previous observations. Exploratory efficacy analyses by PD-L1 status demonstrated no improvements in ORR/PFS/OS. CONCLUSION: This is the first randomised trial evaluating the efficacy of pembrolizumab in MPM patients progressing after/on previous platinum-based chemotherapy. In biologically unselected patients, although associated with an improved ORR, pembrolizumab improves neither PFS nor OS over single-agent chemotherapy.

Prevalence and clinical association of gene mutations through multiplex mutation testing in patients with NSCLC: results from the ETOP Lungscape Project.

Background: Reported prevalence of driver gene mutations in non-small-cell lung cancer (NSCLC) is highly variable and clinical correlations are emerging. Using NSCLC biomaterial and clinical data from the European Thoracic Oncology Platform Lungscape iBiobank, we explore the epidemiology of mutations and association to clinicopathologic features and patient outcome (relapse-free survival, time-to-relapse, overall survival). Methods: Clinically annotated, resected stage I-III NSCLC FFPE tissue was assessed for gene mutation using a microfluidics-based multiplex PCR platform. Mutant-allele detection sensitivity is >1% for most of the ∼150 (13 genes) mutations covered in the multiplex test. Results: Multiplex testing has been carried out in 2063 (76.2%) of the 2709 Lungscape cases (median follow-up 4.8 years). FFPE samples mostly date from 2005 to 2008, yet recently extracted DNA quality and quantity was generally good. Average DNA yield/case was 2.63 µg; 38 cases (1.4%) failed QC and were excluded from study; 95.1% of included cases allowed the complete panel of mutations to be tested. Most common were KRAS, MET, EGFR and PIK3CA mutations with overall prevalence of 23.0%, 6.8%, 5.4% and 4.9%, respectively. KRAS and EGFR mutations were significantly more frequent in adenocarcinomas: PIK3CA in squamous cell carcinomas. MET mutation prevalence did not differ between histology groups. EGFR mutations were found predominantly in never smokers; KRAS in current/former smokers. For all the above mutations, there was no difference in outcome between mutated and non-mutated cases. Conclusion: Archival FFPE NSCLC material is adequate for multiplex mutation analysis. In this large, predominantly European, clinically annotated stage I-III NSCLC cohort, none of the mutations characterized showed prognostic significance.

Searching for targets for the systemic therapy of mesothelioma.

Malignant mesothelioma is an incurable disease associated with asbestos exposure arising in the pleural cavity and less frequently in the peritoneal cavity. Platinum-based combination chemotherapy with pemetrexed is the established standard of care. Multimodality approaches including surgery and radiotherapy are being investigated. Increasing knowledge about the molecular characteristics of mesothelioma had led to the identification of novel potential targets for systemic therapy. Current evidence suggests pathways activated in response to merlin deficiency, including Pi3K/mTOR and the focal adhesion kinase, as well as immunotherapeutic approaches to be most promising. This review elaborates on the rationale behind targeted approaches that have been and are undergoing exploration in mesothelioma and summarizes available clinical results and ongoing efforts to improve the systemic therapy of mesothelioma.

CD74: a new prognostic factor for patients with malignant pleural mesothelioma.

BACKGROUND: The pro-inflammatory cytokine migration inhibitory factor (MIF) and its receptor CD74 have been proposed as possible therapeutic targets in several cancers. We studied the expression of MIF and CD74 together with calretinin in specimens of malignant pleural mesothelioma (MPM), correlating their expression levels with clinico-pathologic parameters, in particular overall survival (OS). METHODS: Migration inhibitory factor, CD74, and calretinin immunoreactivity were investigated in a tissue microarray of 352 patients diagnosed with MPM. Protein expression intensities were semiquantitatively scored in the tumour cells and in the peritumoral stroma. Markers were matched with OS, age, gender, and histological subtype. RESULTS: Clinical data from 135 patients were available. Tumour cell expressions of MIF and CD74 were observed in 95% and 98% of MPM specimens, respectively, with a homogenous distribution between the different histotypes. CD74 (P<0.001) but not MIF overexpression (P=0.231) emerged as an independent prognostic factor for prolonged OS. High expression of tumour cell calretinin correlated with the epithelioid histotype and was also predictive of longer OS (P<0.001). When compared with previously characterised putative epithelial-to-mesenchymal transition markers, CD74 correlated positively with tumoral PTEN and podoplanin expressions, but was inversely related with periostin expression. CONCLUSIONS: High expression of CD74 is an independent prognostic factor for prolonged OS in mesothelioma patients.

The current and future role of the medical oncologist in the professional care for cancer patients: a position paper by the European Society for Medical Oncology (ESMO).

The number of cancer patients in Europe is rising and significant advances in basic and applied cancer research are making the provision of optimal care more challenging. The concept of cancer as a systemic, highly heterogeneous and complex disease has increased the awareness that quality cancer care should be provided by a multidisciplinary team (MDT) of highly qualified healthcare professionals. Cancer patients also have the right to benefit from medical progress by receiving optimal treatment from adequately trained and highly skilled medical professionals. Built on the highest standards of professional training and continuing medical education, medical oncology is recognised as an independent medical specialty in many European countries. Medical oncology is a core member of the MDT and offers cancer patients a comprehensive and systemic approach to treatment and care, while ensuring evidence-based, safe and cost-effective use of cancer drugs and preserving the quality of life of cancer patients through the entire 'cancer journey'. Medical oncologists are also engaged in clinical and translational research to promote innovation and new therapies and they contribute to cancer diagnosis, prevention and research, making a difference for patients in a dynamic, stimulating professional environment. Medical oncologists play an important role in shaping the future of healthcare through innovation and are also actively involved at the political level to ensure a maximum contribution of the profession to Society and to tackle future challenges. This position paper summarises the multifarious and vital contributions of medical oncology and medical oncologists to today's and tomorrow's professional cancer care.

Impact of smoking status on the relative efficacy of the EGFR TKI/angiogenesis inhibitor combination therapy in advanced NSCLC-a systematic review and meta-analysis.

BACKGROUND: The ETOP 10-16 BOOSTER trial failed to demonstrate a progression-free survival (PFS) benefit for adding bevacizumab to osimertinib in second line. An exploratory subgroup analysis, however, suggested a PFS benefit of the combination in patients with a smoking history and prompted us to do this study. METHODS: A systematic review and meta-analysis to evaluate the differential effect of smoking status on the benefit of adding an angiogenesis inhibitor to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor therapy was carried out. All relevant randomized controlled trials appearing in main oncology congresses or in PubMed as of 1 November 2021 were used according to the Preferred Reporting Items for Systematic Review and Meta-Analyses statement. Primarily PFS according to smoking status, and secondarily overall survival (OS) were of interest. Pooled and interaction hazard ratios (HRs) were estimated by fixed or random effects models, depending on the detected degree of heterogeneity. Bias was assessed using the revised Cochrane tool for randomized controlled trials (RoB 2). RESULTS: Information by smoking was available for 1291 patients for PFS (seven studies) and 678 patients for OS (four studies). The risk of bias was low for all studies. Combination treatment significantly prolonged PFS for smokers [n = 502, HR = 0.55, 95% confidence interval (CI): 0.44-0.69] but not for nonsmokers (n = 789, HR = 0.92, 95% CI: 0.66-1.27; treatment-by-smoking interaction P = 0.02). Similarly, a significant OS benefit was found for smokers (n = 271, HR = 0.66, 95% CI: 0.47-0.93) but not for nonsmokers (n = 407, HR = 1.07, 95% CI: 0.82-1.42; treatment-by-smoking interaction P = 0.03). CONCLUSION: In advanced EGFR-non-small-cell lung cancer patients, the addition of an angiogenesis inhibitor to EGFR-tyrosine kinase inhibitor therapy provides a statistically significant PFS and OS benefit in smokers, but not in non-smokers. The biological basis for this observation should be pursued and could determine whether this might be due to a specific co-mutational pattern produced by tobacco exposure.

Volumetry: an alternative to assess therapy response for malignant pleural mesothelioma?

The purpose of our study was to assess robustness of volumetric measurement of malignant pleural mesothelioma (MPM) before and after chemotherapy to modified RECIST (response evaluation criteria in solid tumours) criteria. 30 patients with digitally available chest computed tomography (CT) scans before and after three cycles of chemotherapy were included. Three readers independently assessed tumour response using two different methods: 1) the modified RECIST criteria; and 2) the tumour volumetric approach using dedicated software (Myrian; Intrasense, Paris, France). Inter-rater reliability of unidimensional and volumetric measurements was assessed using intraclass correlation. Tumour response classification for modified RECIST was compared to the volumetric approach applying unidimensional RECIST volumetric equivalent criteria. The determination of unidimensional tumour measurement (RECIST) revealed a low inter-rater reliability (0.55) and a low interobserver agreement for tumour response classification (general κ 0.33). Only 14 patients were classified equally. A high inter-rater reliability (0.99) and interobserver agreement (general κ 0.9) were found for absolute tumour volumes (volumetric measurements). 27 cases were classified equally. The number of cases classified as "stable disease" was higher for the volumetric approach using tumour-equivalent criteria compared to modified RECIST. Volumetric measurement of MPM on CT using Myrian software is a reliable, reproducible and sensitive method to measure tumour volume and, thus, therapy response after induction chemotherapy.

Survival outcome of non-small cell lung cancer patients: Comparing results between the database of the Comprehensive Cancer Center Zürich and the Epidemiological Cancer Registry Zurich and Zug.

BACKGROUND: Cancer cases among the population of the canton Zurich, are registered in the Cancer Registry of the cantons of Zurich and Zug (KKR). The Thoracic Oncology Center, founded in 2011 is one of 17 multidisciplinary centers within the Comprehensive Cancer Center Zurich (CCCZ). METHODS: The aim of the current study is to quantify the mortality risk of patients with NSCLC and identify differences on survival and other factors between patients receiving their primary treatment at the CCCZ and those treated elsewhere and registered by KKR. The differential effect between CCCZ and KKR cohorts on survival: overall, by stage, sex and age, is explored. Stratified log-rank and Wilcoxon tests, Cox models and restricted mean survival times (RMST) are estimated. Propensity score matching (PSM) is also used to adjust for confounding factors. RESULTS: Analysis included 848 NSCLC cases from the CCCZ and 1759 from the KKR, diagnosed between January 2011 and December 2015. At a median follow-up of 57 months, overall survival (OS) was significantly superior for patients treated at the CCCZ compared to KKR [Median OS: 36.0 months (95%CI: 31.0-45.0) and 12.0 months (95%CI: 11.0-13.0), respectively, stratified log-rank p < 0.001; adjusted HR = 1.31, (95% CI: 1.18-1.46), difference in RMST up to 72 months: 13.8 months (95%CI: 11.5-16.2), p < 0.001]. The effect of cohort was significant for stages III and IV (overall and also by sex and age). After PSM OS remained significantly superior for patients treated at the CCCZ compared to KKR. CONCLUSIONS: The survival probability for patients in the CCCZ cohort was superior to that of patients in the canton Zürich treated outside the center. This analysis provides further evidence of the importance of the volume of experience and the availability of a multidisciplinary organization and research environment, as delivered by a comprehensive cancer center, on the outcome of patients with NSCLC.

Safety evaluation of nivolumab added concurrently to radiotherapy in a standard first line chemo-radiotherapy regimen in stage III non-small cell lung cancer-The ETOP NICOLAS trial.

OBJECTIVES: Chemo-radiotherapy (CRT) and concurrent PD-1 inhibition has shown promising results in pre-clinical models. So far, the feasibility of delivering concurrent CRT and PD-1/PD-L1 inhibition has never been assessed in a clinical trial. MATERIAL AND METHODS: NICOLAS is a phase-II trial evaluating the safety and efficacy of nivolumab combined with CRT in stage III NSCLC. Patients received 3 cycles of platinum-based chemotherapy and concurrent RT (66 Gy/33fractions). Nivolumab started concurrently with RT. The primary endpoint was 6-month post-RT rate of grade-≥3-pneumonitis. A formal interim safety analysis (IA) was scheduled when the first 21 patients reached 3 months follow-up post-RT. An early positive safety conclusion would be reached at IA if there were no grade ≥3-pneumonitis in those patients. Efficacy evaluation was planned provided the safety conclusion was reached. RESULTS AND CONCLUSION: As of 13 December 2018, 82 patients were recruited with median follow-up of 13.4 months. The most frequent adverse events (AEs) were anaemia, fatigue and pneumonitis. No unexpected AEs or increased toxicities were observed. For the first 21 patients, no grade-≥3-pneumonitis was observed by the end of the 3-month post-RT follow-up period. The early safety IA provides evidence that the addition of nivolumab to concurrent CRT is safe and tolerable regarding the 6-month rate of pneumonitis grade ≥3 at the one-sided significance level of 5%. Following that, the 1-year progression-free survival will be evaluated in an expanded patient cohort. NICOLAS trial creates the opportunity for assessing the activity of the combination of checkpoint with concurrent CRT in larger prospective trials for locally advanced NSCLC.

Use of SM-1 monoclonal antibody and human complement in selective killing of small cell carcinoma of the lung.

SM-1 is a murine monoclonal antibody strongly reactive with a cell membrane antigen of small cell carcinoma (SCC) of the lung but unreactive with the membrane of most other carcinomas and normal tissues including normal bone marrow. We have found that in the presence of human complement, SM-1 antibody is highly cytotoxic to SCC cells. Using three treatments with antibody and complement, more than 99% of SCC cells in culture were lysed, as determined by the chromium release and clonogenic assays. Similar efficiency of SCC cell lysis was observed when one SM-1 antibody treatment was followed by three treatments with human complement. In contrast, there was little antibody-dependent lysis of non-small cell lung cancer cells, other carcinomas, and leukemia cell lines. The amount of chromium released from normal bone marrow cells treated with SM-1 antibody and complement was minimal and was mainly due to the effect of complement alone. Clonogenic assays, including colony-forming unit-granulocytic/monocytic, erythroid burst-forming unit, and colony-forming unit-granulocytic/erythroid/monocytic/megakaryocytic, also showed no significant SM-1 antibody-dependent cytotoxicity on normal bone marrow precursors. Since SM-1 antibody is selectively cytotoxic to SCC cells in the presence of human complement, it is a potentially useful agent for the selective eradication of tumor cell contamination in marrows of patients with metastatic small cell lung cancer and possibly for in vivo serotherapy.

Origin and prognostic value of circulating KRAS mutations in lung cancer patients.

Because of the current controversy on the origin and clinical value of circulating KRAS codon 12 mutations in lung cancer, we screened 180 patients using a combined restriction fragment-length polymorphism and polymerase chain reaction (RFLP-PCR) assay. We detected KRAS mutations in 9% plasma samples and 0% matched lymphocytes. Plasma KRAS mutations correlated significantly with poor prognosis. We validated the positive results in a second laboratory by DNA sequencing and found matching codon 12 sequences in blood and tumor in 78% evaluable cases. These results support the notion that circulating KRAS mutations originate from tumors and are prognostically relevant in lung cancer.

Induction of apoptosis in small-cell lung cancer cells by an antisense oligodeoxynucleotide targeting the Bcl-2 coding sequence.

BACKGROUND: The emergence of resistance to chemotherapy remains a major problem in the treatment of patients with small-cell lung cancer. Elevated expression of Bcl-2, a protein that inhibits programmed cell death or apoptosis, has been associated with radiation and drug resistance and has been observed in the majority of small-cell lung cancer specimens and cell lines. PURPOSE: To test the hypothesis that Bcl-2 expression levels are critical for inhibiting apoptosis in small-cell lung cancer cells, we used an antisense strategy to reduce Bcl-2 expression in these cells in an attempt to restore the natural occurrence of apoptosis. METHODS: Thirteen antisense oligodeoxynucleotides (ODNs) targeting various regions of the bcl-2 messenger RNA and a control scrambled-sequence ODN were tested to identify the most effective sequence(s) for reducing Bcl-2 protein levels. Northern and western blot analyses were used to examine basal bcl-2 messenger RNA and protein levels, respectively, in four human small-cell lung cancer cell lines (SW2, NCI-H69, NCI-H82, and NCI-N417). SW2 cells were treated with the antisense ODNs in the presence of cationic lipids (to facilitate uptake), and cytotoxic effects were measured by use of a cell viability assay. Flow cytometric analysis of DNA fragmentation and cell morphology was also performed. The cytotoxic effect of the most potent antisense ODN was also tested on the three other cell lines. RESULTS: The viability of SW2 cells was effectively reduced by ODNs that targeted the translation initiation and termination sites of the bcl-2 messenger RNA, but ODN 2009 that targeted the coding region was the most cytotoxic. Treatment of SW2 cells with 0.15 microM ODN 2009 for 96 hours reduced their viability by 91% (95% confidence interval [CI] = 88%-94%) and caused a dose-dependent reduction in Bcl-2 levels that became detectable 24 hours after treatment and persisted up to 96 hours; analysis of cellular morphology demonstrated that viability was reduced through apoptosis. Moreover, ODN 2009 at 0.15 microM was cytotoxic to NCI-H69, NCI-H82, and NCI-N417 cells, resulting in decreases in cell viability of 82% (95% CI = 78%-86%), 100%, and 100%, respectively, after 96 hours of treatment. The cytotoxic effects were inversely correlated with the basal Bcl-2 levels in the cell lines (r = -9964). A control scrambled-sequence oligodeoxynucleotide had no statistically significant effect on the cell lines (P values ranging from .38 to .89). CONCLUSION: We have identified a novel antisense ODN sequence (ODN 2009) that effectively reduces the viability of small-cell lung cancer cells by reducing Bcl-2 levels and facilitating apoptosis.

Activity of a novel bcl-2/bcl-xL-bispecific antisense oligonucleotide against tumors of diverse histologic origins.

BACKGROUND: Increased expression of the anti-apoptotic proteins Bcl-2 and Bcl-xL is involved in the development and progression of many tumors. We recently reported that the bcl-2/bcl-xL-bispecific antisense oligonucleotide 4625 induces apoptosis in lung carcinoma cells. To further assess the therapeutic potential of oligonucleotide 4625, we investigated its effect on a series of human tumor cell lines of diverse histologic origins in vitro and in vivo. METHODS: Oligonucleotide 4625-mediated inhibition of bcl-2 and bcl-xL expression in vitro was measured in breast carcinoma cells with the use of reverse transcription-polymerase chain reaction (PCR), real-time PCR, and western blotting. Cytotoxicity was assessed in several different cell lines by measurement of tumor cell growth, propidium iodide uptake, and nuclear apoptosis. The in vivo activity of oligonucleotide 4625 was determined by the inhibition of growth of established tumor xenografts in nude mice, immunohistochemical staining of Bcl-2 and Bcl-x proteins in the tumors, and western blotting of tumor lysates. Apoptosis in tumor xenografts was detected with the use of in situ TUNEL (i.e., terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick end labeling) staining. All statistical tests are two-sided. RESULTS: In breast carcinoma cells, oligonucleotide 4625 treatment reduced bcl-2 and bcl-xL messenger RNA levels in a dose-dependent manner. At 600 nM:, oligonucleotide 4625 reduced Bcl-2 and Bcl-xL protein levels to 25% (95% confidence interval [CI] = 16% to 34%) and 20% (95% CI = 14% to 26%), respectively, of the levels in untreated cells and it decreased viability in all cell lines mainly by inducing apoptosis. In vivo, oligonucleotide 4625 statistically significantly inhibited the growth of breast and colorectal carcinoma xenografts by 51% (95% CI = 28% to 74%) and 59% (95% CI = 44% to 74%), respectively, relative to those treated with control oligonucleotide 4626; it also reduced Bcl-2 and Bcl-xL protein levels and induced tumor cell apoptosis. CONCLUSION: The bcl-2/bcl-xL-bispecific antisense oligonucleotide 4625 merits further study as a novel compound for cancer therapy.

Characterization of an epithelial and a tumor-associated human small cell lung carcinoma glycoprotein antigen.

The small cell carcinoma (SCC) antigens recognized by LAM2 and LAM8 antibody were characterized by comparison of their tissue expression and analysis of their biochemical composition. LAM2, but not LAM8 antigen could be demonstrated in lipid extracts of SCC cells. By immunohistochemical staining the SCC antigen LAM2 was shown to be an epithelial type membrane antigen. Immunoblotting experiments and competition solid phase radioimmunoassays showed LAM2 antigen to be a native conformation of a glycoprotein with major bands at Mr 100,000-120,000 and a minor band at Mr 210,000. L-Fucose was a dominant part of the epitope which appeared to be closely related to the carbohydrate epitope of the blood group antigen H(O). The tumor-associated membrane antigen LAM8 was shown to be a glycoprotein with major bands at Mr 90,000-135,000 and a minor band at Mr 200,000. Neuraminic acid was the predominant part of the carbohydrate epitope. LAM8 antibody recognized a structure in the saliva of Lea positive probands, but untreated and neuraminidase-treated SCC extracts were unreactive with anti-Lea antibody. Anti CA 19-9 (sialo-Lea antigen) and LAM2 antibodies did not compete for LAM8 binding in direct radioimmunoassays. The sialo-GP90-135 antigen recognized by LAM8 antibody therefore is likely to represent a novel tumor antigen.

Imaging and therapy of small cell carcinoma xenografts using 131I-labeled monoclonal antibody SWA11.

The IgG2a monoclonal antibody SWA11 has been evaluated as a radioimmunotherapeutic agent for use in the treatment of small cell cancer of the lung. This antibody was initially selected for in vivo localization studies in a nude mouse model system because of its high affinity for the SW2 small cell cancer cell line in vitro. Following i.v. injection of 125I labeled antibody into nude mice bearing SW2 xenografts good selective accumulation was observed with 10.5% of injected material/g of tumor. The level remained constant from day 2 to day 4 following injection. At day 4 the tumor:blood ratio was 7:1 and tumor:liver, tumor:kidney, and tumor:lung ratios were 17:1, 24:1, and 12:1, respectively. Initial radioimmunotherapeutic studies performed on established small cell cancer of the lung xenografts have shown reduction in tumor burden following a single injection of 300 microCi of 131I labeled SWA11 with no evidence of regrowth up to day 34 postinjection. Histological evaluation of treated tumors revealed large areas of necrosis and extensive fibrosis. A few residual cells of tumor origin could be observed and these displayed atypical morphology. The clonogenic potential of such cells remains to be determined by long term observation.

CD24, a signal-transducing molecule expressed on human B cells, is a major surface antigen on small cell lung carcinomas.

Cell lines derived from human small cell carcinoma of the lung express high levels of a surface polypeptide termed the cluster-w4 antigen, which was previously identified as a potential target for toxin-based immunotherapy of lung cancer. We have cloned a complementary DNA encoding the cluster-w4 antigen from COS-1 fibroblasts transfected with a SW2 small cell carcinoma library, by panning with a mixture of the cluster-w4-specific monoclonal antibodies SWA11, SWA21, and SWA22. The sequence of the cluster-w4 complementary DNA encodes an unusually short (80-amino acid) protein identical to that recently reported for the leukocyte activation molecule CD24 except for a single valine-alanine substitution due to a single-base polymorphism within the region of the gene coding for the extracellular domain. Biochemical analyses of the cloned cluster-w4 antigen confirmed both the presence of the phosphatidylinositol tail and the extensive glycosylation reported for the CD24 molecule. Furthermore, the cloned cluster-w4 antigen expressed on COS cells was shown to react with a comprehensive panel of CD24-specific monoclonal antibodies, as assessed by indirect immunofluorescence staining. Northern blot hybridization indicated the presence of several transcript sizes for the cluster-w4 antigen that were greatly overexpressed in small cell carcinoma cell lines, compared with normal hemopoietic cells and CD24-positive cell lines. Southern blot hybridization of restriction digests of genomic DNA identified a complex pattern of bands consistent with either a complex gene structure containing many exons or the presence of a family of closely related genes.