Phase I study of G3139, a bcl-2 antisense oligonucleotide, combined with carboplatin and etoposide in patients with small-cell lung cancer

[Small cell lung cancer--state of the art and future perspectives]

Lung cancer is the leading cause of cancer-related death in Portugal. Almost 3500 Portuguese are expected to be diagnosed with lung cancer in 2006; approximately 20% will have small cell lung cancer (SCLC). At presentation, 25% to 30% of patients will have local or regional disease, classified as limited stage disease. The concurrent chemovalidation therapy is the best choice. Once daily thoracic radiation therapy to doses in the range of 50 Gy to 60 Gy would reflect an accepted standard of care in daily practice. Because of the increase toxicity associated with hyper fractionated radiation, this approach is often limited to select patients. Etoposide plus cisplatin are synergistic, well tolerated and result in equal or superior survival compared with other regimens. This is the standard regimen for concomitant therapy in limited stage and for extensive disease SCLC. Despite good chemo sensitivity and radio sensitivity, the prognosis of SCLC is very poor because of the early development of resistance and the associated high tendency to recurrence, making second line treatment of SCLC a problem of real medical relevance. Topotecan now offers an effective and well tolerated monosubstance for second line therapy of recurrent SCLC. There has been a significant increase in median survival for patients with SCLC receiving topotecan plus symptomatic therapy versus symptomatic therapy. The efficacy of this drug is comparable to the efficacy of the three-drug combination CAV. The tolerability can be improved by means of toxicity-adapted dosing. In elderly and in patients with performance status 2, topotecan is also well tolerated and has good efficacy. Initial studies into weekly administration also demonstrate good efficacy. The combination of topotecan with cranial radiotherapy is well tolerated and effective in the treatment of cerebral metastases of SCLC. New classes of agents, such as antiangiogenic agents including bevacizumab, small molecule tyrosine kinase inhibitors and thalidomide are being evaluated with chemotherapy for patients with extensive stage SCLC.

A phase I safety and dose escalation trial of docetaxel combined with GEM231, a second generation antisense oligonucleotide targeting protein kinase A R1alpha in patients with advanced solid cancers

PURPOSE

GEM231 is a second-generation antisense oligonucleotide targeting the mRNA of the R1alpha regulatory subunit of cAMP dependent protein kinase A. Preclinical studies have demonstrated synergistic antitumor activity when GEM231 is combined with docetaxel. This trial assesses the safety of this combination.

EXPERIMENTAL DESIGN

Docetaxel was administered once every three weeks (one-cycle) at doses between 50-75 mg/m2. GEM231 was administered twice weekly at 220 mg/m2 for 3 (schedule-A), or 2 (schedule-B) weeks.

RESULTS

Twenty patients with chemotherapy-refractory advanced cancer received a total of 39 cycles of therapy. Six patients in schedule-A received docetaxel 50 mg/m2, and 14 patients in schedule-B received docetaxel 50-75 mg/m2. In schedule-A, 2 of 6 patients developed cycle-1 dose limiting toxicity (DLT)-grade-3 fatigue or grade-3 serum transaminase elevation. In schedule-B, 1 of 4 patients developed cycle-1 DLT at the highest dose of docetaxel tested (75 mg/m2)--grade-3 febrile neutropenia. Subsequent dose escalations were not pursued since the overall incidence of grade-3 toxicities (including those that occurred after cycle 1) was 75%, and this dose was close to the single agent MTD of docetaxel. Grade-3 toxicities included fatigue (2 patients), transaminase elevation (4 patients), and altered mentation (1 patient). The mean post-infusion aPTT was significantly higher than the pre-infusion value [14.8 seconds; p<0.001]; however, there were no hemorrhagic episodes.

CONCLUSIONS

The recommended dose for further development of the combination of docetaxel and GEM231 is 75 mg/m2 and 220 mg/m2, respectively. It is important to administer GEM231 twice weekly for 2 consecutive weeks followed by a one-week break.

Current status of second-line treatment and novel therapies for small cell lung cancer

Despite high response rates to first-line standard treatment, the great majority of patients with small cell lung cancer (SCLC) will relapse and succumb to their disease rather quickly. In the context of salvage therapy, symptom palliation and quality-of-life improvements, besides survival prolongation, are primary treatment endpoints. A variety of single-agent and multi-agent chemotherapy regimens have been tested with limited success in patients with recurrent SCLC. A number of combination regimens have demonstrated high response rates in second-line settings, but these can be considered only for patients with good performance status. Treatment outcome depends on many factors, including type of response to first-line therapy, treatment-free interval, and performance status. Currently, topotecan represents an effective, tolerable therapeutic option and is the only agent approved for this indication. The management of patients with recurrent disease remains an area of active research. This review provides an update of clinical research on second-line chemotherapy of SCLC and of recent results obtained with novel molecular targeted approaches in both first- and second-line therapy.

Up-regulation of Bcl-2 through ERK phosphorylation is associated with human macrophage survival in an estrogen microenvironment

Estrogen is a known immunomodulator with pleiotropic effects on macrophage function that partly accounts for the gender bias observed in numerous autoimmune, cardiovascular, and neurodegenerative disorders. The effect of estrogen on the survival of human macrophages is largely unknown, and in this study we demonstrate that 17beta-estradiol (E2) provokes a death response in human THP-1 macrophages by initiating Bax translocation from cytosol to the mitochondria; however, a concomitant up-regulation of Bcl-2 creates a Bax to Bcl-2 ratio favorable for Bcl-2, thus ensuring cell survival. Both Bcl-2 up-regulation and Bax translocation are estrogen receptor-dependent events; however, Bcl-2 augmentation but not Bax translocation is dependent on Ca(2+) increase, activation of protein kinase C, and ERK phosphorylation. This estrogen-induced Bcl-2 increase is crucial for the survival of THP-1 macrophages as well as that of human peripheral blood monocyte-derived macrophages, which is evident from E2-induced cell death under small interfering RNA-mediated Bcl-2 knockdown conditions. Hence, this study demonstrates that E2-induced Bcl-2 up-regulation is a homeostatic survival mechanism necessary for the manifestation of immunomodulatory effect of estrogen on human macrophages.

Molecular-targeted therapies: lessons from years of clinical development

Over the past decade, molecular-targeted therapies have been added to cytotoxic and anti-endocrine drugs in the treatment of cancer, with the aim to target the molecular pathways that underlie the carcinogenic process and maintain the cancer phenotype. Success with some of these agents has suggested that identification and validation of the drug target is the starting point for the route of development of active, safe and effective drugs. Main molecular targets used to the development of anticancer drugs are cell surface receptors, signal transduction pathways, gene transcription targets, ubiquitin-proteasome/heat shock proteins and tumour microenvironment components (especially antiangiogenic agents). Here, we review the development of the main molecular targeted non-cytotoxic agents studied in cancer, highlighting lessons derived from the development of these novel drugs and proposing new horizons for the clinical development of molecular-targeted therapies.

Targeted therapies in small-cell lung cancer

Small-cell lung cancer is an aggressive form of lung cancer that, overall, remains the most common cause of cancer death in the US. Some advances have been made in the treatment of small-cell lung cancer using cytotoxic chemotherapeutic agents but no truly targeted therapies are available as of yet. At present, research is focused on finding therapies that can target the specific molecular mechanisms responsible for the survival, growth and metastasis of the tumor thereby improving responses to chemotherapy and minimizing toxicity. Several new agents, such as angiogenesis inhibitors and regulators of apoptosis, have reached clinical testing and multiple others are in preclinical trials. Some of these will be discussed in this review.

DNA-damage sensitizers: Potential new therapeutical tools to improve chemotherapy

Agents that induce DNA damage in cells--the so-called genotoxins--have successfully been used for decades to treat patients with tumors. Genotoxins alter the DNA of cells, which is detected by DNA damage sensors and which leads to the activation of p53. Activation of p53 can lead to the death of cancer cells. The efficacy of genotoxins in humans is however limited by their toxicity to normal tissues. Specific sensitization of tumor cells to the action of genotoxins would reduce the efficacious doses of genotoxins to be used in patients, diminishing the detrimental side-effects of the drugs on normal tissues. A series of compounds able to sensitize cancer cells to DNA-damaging drugs have recently been identified that have the potential to increase the efficacy of currently used anti-cancer treatments.

Downstream signalling and specific inhibition of c-MET/HGF pathway in small cell lung cancer: implications for tumour invasion

The c-MET receptor can be overexpressed, amplified, or mutated in solid tumours including small cell lung cancer (SCLC). In c-MET-overexpressing SCLC cell line NCI-H69, hepatocyte growth factor (HGF) dramatically induced c-MET phosphorylation at phosphoepitopes pY1230/1234/1235 (catalytic tyrosine kinase), pY1003 (juxtamembrane), and also of paxillin at pY31 (CRKL-binding site). We utilised a global proteomics phosphoantibody array approach to identify further c-MET/HGF signal transduction intermediates in SCLC. Strong HGF induction of specific phosphorylation sites in phosphoproteins involved in c-MET/HGF signal transduction was detected, namely adducin-alpha [S724], adducin-gamma [S662], CREB [S133], ERK1 [T185/Y187], ERK1/2 [T202/Y204], ERK2 [T185/Y187], MAPKK (MEK) 1/2 [S221/S225], MAPKK (MEK) 3/6 [S189/S207], RB [S612], RB1 [S780], JNK [T183/Y185], STAT3 [S727], focal adhesion kinase (FAK) [Y576/S722/S910], p38alpha-MAPK [T180/Y182], and AKT1[S473] and [T308]. Conversely, inhibition of phosphorylation by HGF in protein kinase C (PKC), protein kinase R (PKR), and also CDK1 was identified. Phosphoantibody-based immunohistochemical analysis of SCLC tumour tissue and microarray established the role of c-MET in SCLC biology. This supports a role of c-MET activation in tumour invasive front in the tumour progression and invasion involving FAK and AKT downstream. The c-MET serves as an attractive therapeutic target in SCLC, as shown through small interfering RNA (siRNA) and selective prototype c-MET inhibitor SU11274, inhibiting the phosphorylation of c-MET itself and its downstream molecules such as AKT, S6 kinase, and ERK1/2. Investigation of mechanisms of invasion and, ultimately, metastasis in SCLC would be very useful with these signal transduction molecules.

Phase II trial of thalidomide as maintenance therapy for extensive stage small cell lung cancer after response to chemotherapy

BACKGROUND

Extensive-stage small cell lung cancer (SCLC) is a highly aggressive malignancy for which little therapeutic progress has been made over the past 20 years. SCLC is a highly angiogenic tumor and targeting angiogenesis is being investigated. The putative mechanism of action of thalidomide is through inhibition of new blood vessel formation. This trial was designed to evaluate thalidomide in ES-SCLC.

PATIENTS AND METHODS

Patients who had received first-line chemotherapy without disease progression were eligible. Patients received thalidomide 200 mg daily as maintenance therapy starting 3-6 weeks after completion of chemotherapy.

RESULTS

Thirty patients were enrolled. Toxicity was minimal with grade 1 neuropathy in 27% of patients and only one case of grade 3 neuropathy. Median survival from time of initiation of induction chemotherapy was 12.8 months (95% CI: 10.1-15.8 months) and 1-year survival of 51.7% (95% CI: 32.5-67.9%). Median duration on thalidomide was 79 days.

CONCLUSION

Thalidomide 200mg daily is well tolerated when given as maintenance therapy for ES-SCLC after induction chemotherapy. Further evaluation of anti-angiogenic agents in SCLC is warranted.

Oblimersen and alpha-interferon in metastatic renal cancer: a phase II study of the California Cancer Consortium

PURPOSE

Oblimersen is an 18-base oligodeoxynucleotide encoding antisense to the gene for bcl-2, an anti-apoptotic protein that is upregulated in renal and other cancers. This study was designed to evaluate the combination of oblimersen with alpha-Interferon in advanced renal cancer. Trial endpoints were antitumor efficacy and toxicity, pharmacokinetics, and evidence of apoptosis in peripheral blood mononuclear cells.

METHODS

Patients with measurable advanced renal cancer and 0-1 prior therapy were eligible. Treatment consisted of oblimersen, 7 mg/kg/day, as a continuous intravenous infusion 7 days of every 14 day cycle, plus alpha-IFN, 5 million units/m(2) subcutaneously, days 4 and 6 of the first oblimersen infusion, then thrice weekly. Blood for laboratory correlates was collected before treatment, during oblimersen, and during therapy with both agents.

RESULTS

Twenty-three patients were enrolled, five of whom had prior systemic therapy (three with prior high-dose interleukin-2). The median number of treatment cycles was 4 (range 1-12). One patient had a partial response lasting 2.5 months. The Grade 3-4 toxicities were fatigue, fever, myelosuppression, hepatic enzyme and metabolic abnormalities. Laboratory analyses of CD3+ lymphocyte apoptotic markers demonstrated no change between pre-treatment and on-treatment levels of bcl-2 or Annexin/PI positivity by flow cytometry. Mean oblimersen steady-state plasma concentration and clearance was 2.3 +/- 0.9 microg/ml and 0.15 +/- 0.07 l/h/kg, respectively.

CONCLUSIONS

Oblimersen given in this dose and schedule with alpha-IFN does not appear sufficiently active to warrant further study in advanced renal cancer. Combinations with newer targeted agents may show greater promise.

A small molecule pan-Bcl-2 family inhibitor, GX15-070, induces apoptosis and enhances cisplatin-induced apoptosis in non-small cell lung cancer cells

PURPOSE

Overexpression of Bcl-2 family members as well as deregulated apoptosis pathways are known hallmarks of lung cancer. Non-small cell lung cancer (NSCLC) cells are typically resistant to cytotoxic chemotherapy and approaches that alter the balance between pro-survival and pro-death Bcl-2 family members have shown promise in preclinical models of NSCLC.

METHODS

Here we evaluated the effects of a novel pan-Bcl-2 inhibitor GX15-070 on NSCLC survival and when combined with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors as well as traditional cytotoxic agents. GX15-070 is a small molecule agent that binds anti-apoptotic Bcl-2 proteins and interferes with their ability to interact with pro-apoptotic proteins. We evaluated the effect of GX15-070 and correlated the effect on EGFR status as well as Bcl-2 family protein expression.

RESULTS

We show that GX15-070 can disrupt Mcl-1:Bak interactions in lung cancer cells. We identified differential sensitivity of a panel of lung cancer cells to GX15-070 and no clear relationship existed between EGFR status or Bcl-2 family protein expression and sensitivity to GX15-070. GX15-070 could induce apoptosis in a subset of lung cancer cell lines and this correlated with the effects on cell viability. GX15-070 combined with gefitinib was synergistic in a cell line dependent on EGFR for survival but GX15-070 could not reverse resistance to gefitinib in cell lines not dependent on EGFR for survival. Finally, we observed synergy between GX15-070 and cisplatin in NSCLC cells.

CONCLUSIONS

Based on these results, GX15-070 can trigger apoptosis in NSCLC cells and can enhance chemotherapy-induced death. These data suggest that clinical trials with GX15-070 in combination with cytotoxic chemotherapy are indicated.

Phase I Trial of G3139, a bcl-2 antisense oligonucleotide, combined with doxorubicin and cyclophosphamide in children with relapsed solid tumors: a Children's Oncology Group Study

PURPOSE

To determine the maximum-tolerated dose, toxicity, pharmacokinetics, and biologic effects of G3139 when administered with doxorubicin and cyclophosphamide to children with relapsed solid tumors.

PATIENTS AND METHODS

Patients received a 7-day continuous infusion of 3, 5, or 7 mg/kg/d of G3139 every 21 days. Doxorubicin, cyclophosphamide, and dexrazoxane were administered on days 5 and 6 of the infusion. Pharmacokinetics and biology studies were performed during the first course.

RESULTS

Thirty-seven patients, median age 14 years (range, 1 to 19 years), were enrolled, of whom 29 were fully assessable for toxicity. Because of dose-limiting neutropenia, doses of doxorubicin 30 mg/m2/d for 2 days, dexrazoxane 300 mg/m2/d for 2 days, and cyclophosphamide 500 mg/m2/d for 2 days were reduced initially, but with the addition of granulocyte colony-stimulating factor (GCSF), could be re-escalated to starting doses. At the 7 mg/kg/d dose level, only one of six patients experienced DLT (neutropenia > 7 days). At this dose, the average (+/- standard deviation) steady-state G3139 concentration was 2.04 +/- 1 microg/mL, a concentration associated with biologic activity. Eleven of 15 patients had reduced bcl-2 expression in peripheral-blood mononuclear cells at the first assessable time point of G3139 exposure, and in eight of 14 patients with serial specimens this reduction persisted through day 6.

CONCLUSION

The recommended phase II dose of G3139 is 7 mg/kg/d as a 7-day continuous infusion, with cyclophosphamide 500 mg/m2/d and doxorubicin 30 mg/m2/d on days 5 and 6, followed by GCSF. G3139 may accentuate the myelosuppressive effects of doxorubicin and cyclophosphamide. Evidence for biologic effects of G3139 was demonstrated.

Fast, hungry and unstable: finding the Achilles' heel of small-cell lung cancer

Over 95% of patients with small-cell lung cancer (SCLC) die within five years of diagnosis. The standard of care and the dismal prognosis for this disease have not changed significantly over the past 25 years. Some of the characteristics of SCLC that have defined it as a particularly virulent form of cancer -- rapid proliferation, excessive metabolic and angiogenic dependence, apoptotic imbalance and genetic instability -- are now being pursued as tumor-specific targets for intervention both in preclinical and early phase clinical studies. Here, we summarize areas of ongoing anti-cancer drug development, including classes of agents that target essential pathways regulating proliferation, angiogenesis, apoptotic resistance, chromosomal and protein stability, and cell-cell and cell-matrix interaction.

Targeting receptor tyrosine kinase signalling in small cell lung cancer (SCLC): what have we learned so far?

Small cell lung cancer (SCLC) is an aggressive form of lung cancer, which represents 13% of all cases and is strongly associated with cigarette smoking. The survival of SCLC patients is dismal and has not greatly improved in the last 20 years, despite advances in chemotherapy regimens and a better understanding of SCLC biology. The development of resistance to chemotherapy and metastasis are commonly recognized as important causes of poor clinical outcome in SCLC. Targeting receptor tyrosine kinase (RTK) signalling represents an attractive approach to develop new drugs for SCLC, in view of the accumulating data demonstrating that polypeptide growth factors play a key role in driving SCLC cell proliferation, chemoresistance and metastasis. The insulin-like growth factor-I receptor (IGF-IR), c-Kit, vascular endothelial growth factor receptor (VEGFR) and epidermal growth factor receptor (EGFR) have been identified as potential drug targets in SCLC. Moreover, downstream signalling mediators of RTKs, such as phosphoinositide 3-kinase (PI3K)/Akt and the mammalian target of rapamycin (mTOR) may also represent attractive candidate molecules for anti-cancer therapies in SCLC. Here we will review the available data concerning results with RTK inhibitors in SCLC and the clinical trials undertaken to investigate the potential of these compounds as anti-tumour agents in SCLC.

Treatment options for relapsed small-cell lung cancer

Small-cell lung cancer is a chemo-sensitive disease with a response rate ranging from 70 to 90% for first-line treatment; however, relapses are very common and as a result long-term survival is poor. Chemotherapy has demonstrated a benefit over the best supportive care, even in patients who have relapsed after initial treatment with a platinum-based regimen. Agents currently being used in salvage therapy include topotecan, cyclophosphamide, doxorubicin and vincristine regimen. In the last 5 years, several drugs have shown promise in initial evaluation; however, randomized phase III trials would be needed to answer this question. Our understanding of the biology of small-cell lung cancer has improved dramatically over the past few years and this has translated into the developments of new therapeutic targets for this disease. Agents affecting several targets, including bcl-2, matrix metalloproteinases, epidermal growth factors and angiogenesis, are being studied currently and have the potential to change the treatment paradigms of this otherwise fatal malignancy. This review focuses on the various current and future options, including cytoxic and targeted agents, for salvage therapy in patients with this disease.

Small cell lung cancer and targeted therapies

PURPOSE OF REVIEW

Small cell lung cancer is a chemosensitive malignancy, yet long-term survival remains elusive for the majority of patients. Here, we report on progress in evaluating novel targeted therapies for the treatment of this disease.

RECENT FINDINGS

Interferons, matrix metalloproteinase inhibitors, thalidomide, bevacizumab, ZD6474, imatinib, gefitinib, oblimersen and aplidine have all entered clinical trial in patients with small cell lung cancer. Immunotherapy approaches targeting cell surface antigens such as CD-56 (BB10901) and GD3 ganglioside are also being evaluated. Interferons, matrix metalloproteinase inhibitors, imatinib and gefitinib have failed to demonstrate efficacy for this disease. Preliminary data for thalidomide are promising and so results from trials of other antiangiogenics such as bevacizumab and ZD6474 are awaited with interest.

SUMMARY

Although the promise of targeted therapy has yet to be realized in patients with small cell lung cancer, the number of agents available for evaluation provides new optimism that progress will be made over the next decades.

Influence of Bcl-2 Family Members on the Cellular Response of Small-Cell Lung Cancer Cell Lines to ABT-737

ABT-737 is a novel and potent Bcl-2 antagonist with single-agent activity against small-cell lung cancer (SCLC) cell lines. Here, we evaluated the contribution of Bcl-2 family members to the in vitro cellular response of several SCLC cell lines to ABT-737. Relatively higher levels of Bcl-2, Bcl-X(L), Bim and Noxa, and lower levels of Mcl-1 characterized naïve SCLC cell lines that were sensitive to ABT-737. Conversely, a progressive decrease in the relative levels of Bcl-2 and Noxa and a progressive increase in Mcl-1 levels characterized the increased resistance of H146 cells following chronic exposure to ABT-737. Knockdown of Mcl-1 with small interfering RNA sensitized two resistant SCLC cell lines H196 and DMS114 to ABT-737 by enhancing the induction of apoptosis. Likewise, up-regulation of Noxa sensitized H196 cells to ABT-737. Combination treatment with DNA-damaging agents was extremely synergistic with ABT-737 and was associated with the down-regulation of Mcl-1 and the up-regulation of Noxa, Puma, and Bim in H196 cells. Thus, SCLC cells sensitive to ABT-737 expressed the target proteins Bcl-2 and Bcl-X(L), whereas Mcl-1 and factors regulating Mcl-1 function seem to contribute to the overall resistance of SCLC cells to ABT-737. Overall, these observations provide further insight as to the mechanistic bases for ABT-737 efficacy in SCLC and will be helpful for profiling patients and aiding in the rational design of combination therapies.

Novel therapies for the treatment of small-cell lung cancer: a time for cautious optimism?

Small-cell lung cancer accounts for up to one-fifth of all lung cancers diagnosed. While the response rates to chemotherapy are high, ultimately the majority of patients will relapse and die from their disease. Long-term outcomes are poor. A number of new agents and novel strategies for the treatment of small-cell lung cancer are under evaluation, and this review outlines the current most promising agents and pivotal trials. Oblimersen, an antisense oligonuclide to the oncogene bcl-2, has been safely combined with chemotherapy. The proteosome inhibitor bortezomib has not demonstrated single-agent activity in phase II trials but is now being evaluated with proapoptotic triggers. A number of anti-angiogenic strategies have been evaluated in small-cell lung cancer. The vascular endothelial growth factor (VEGF) antibody bevacizumab and a number of VEGF receptor tyrosine kinase inhibitors are in the early phases of clinical trials. Results from trials have not demonstrated any survival advantage with the addition of matrix metalloproteinase inhibitors. A phase III trial has reported improvements in median survival with the addition of thalidomide to chemotherapy, but toxicity has been problematic. Immunotherapy with p53 vaccines and BEC2 antibodies have shown some promise and require further evaluation to determine whether humoral responses can predict for response. Trials with the immunoconjugate BB-10901 and temirolimus are ongoing.

Antisense and nonantisense effects of antisense Bcl-2 on multiple roles of Bcl-2 as a chemosensitizer in cancer therapy

Bcl-2 is an oncoprotein that plays a critical role in inhibiting apoptotic cell death in the mitochondria-dependent pathway in cancer chemotherapy. As a strategy for blocking Bcl-2 for enhancement of the chemotherapeutic effect, antisense Bcl-2 (AS Bcl-2; G3139, oblimersen sodium, Genasense) has shown promise, and there are several ongoing clinical studies with hematological malignancies as well as solid tumors. Although several preclinical and clinical studies have shown the therapeutic efficacy of Bcl-2 in combination with an anticancer drug as a chemosensitizer, in clinical trials the downregulation of Bcl-2 has not been observed with a high frequency in tumor cells. Nevertheless, previous studies showed nonantisense effects such as production of reactive oxygen species and immunostimulatory action through cytosine-phosphate-guanosine-motif in the antisense oligodeoxynucleotides. Further, Bcl-2 is able to inhibit Beclin 1-dependent autophagic cell death, which is a nonapoptotic cell death. The current status and future directions of AS Bcl-2 and the potential mechanisms for multiple roles that Bcl-2 has in cancer therapy are reviewed.

Mitochondria in hematopoiesis and hematological diseases

Mitochondria are involved in hematopoietic cell homeostasis through multiple ways such as oxidative phosphorylation, various metabolic processes and the release of cytochrome c in the cytosol to trigger caspase activation and cell death. In erythroid cells, the mitochondrial steps in heme synthesis, iron (Fe) metabolism and Fe-sulfur (Fe-S) cluster biogenesis are of particular importance. Mutations in the specific delta-aminolevulinic acid synthase (ALAS) 2 isoform that catalyses the first and rate-limiting step in heme synthesis pathway in the mitochondrial matrix, lead to ineffective erythropoiesis that characterizes X-linked sideroblastic anemia (XLSA), the most common inherited sideroblastic anemia. Mutations in the adenosine triphosphate-binding cassette protein ABCB7, identified in XLSA with ataxia (XLSA-A), disrupt the maturation of cytosolic (Fe-S) clusters, leading to mitochondrial Fe accumulation. In addition, large deletions in mitochondrial DNA, whose integrity depends on a specific DNA polymerase, are the hallmark of Pearson's syndrome, a rare congenital disorder with sideroblastic anemia. In acquired myelodysplastic syndromes at early stage, exacerbation of physiological pathways involving caspases and the mitochondria in erythroid differentiation leads to abnormal activation of a mitochondria-mediated apoptotic cell death pathway. In contrast, oncogenesis-associated changes at the mitochondrial level can alter the apoptotic response of transformed hematopoietic cells to chemotherapeutic agents. Recent findings in mitochondria metabolism and functions open new perspectives in treating hematopoietic cell diseases, for example various compounds currently developed to trigger tumor cell death by directly targeting the mitochondria could prove efficient as either cytotoxic drugs or chemosensitizing agents in treating hematological malignancies.

Thymidine-phosphorothioate oligonucleotides induce activation and apoptosis of CLL cells independently of CpG motifs or BCL-2 gene interference

We compared antisense phosphorothioate oligonucleotides (PS-ODN) that target BCL-2 such as Genasense (G3139-PS), with other PS-ODN or phosphodiester-ODN (PO-ODN) in their relative capacity to induce apoptosis of chronic lymphocytic leukemia (CLL) B cells in vitro. Surprisingly, we found that thymidine-containing PS-ODN, but not PO-ODN, induced activation and apoptosis of CLL cells independent of BCL-2 antisense sequence or CpG motifs. All tested thimidine-containing PS-ODN, irrespective of their primary sequences, reduced the expression of Bcl-2 protein and increased the levels of the proapoptotic molecules p53, Bid, Bax in CLL cells. Apoptosis induced by thymidine-containing PS-ODN was preceded by cellular activation, could be blocked by the tyrosine-kinase inhibitor imatinib mesylate (Gleevec), and was dependent on ABL kinase. We conclude that thymidine-containing PS-ODN can activate CLL cells and induce apoptosis via a mechanism that is independent of BCL-2 gene interference or CpG motifs.

Antisense therapy in malignant diseases: status quo and quo vadis?

Preclinical and clinical studies indicate a role for AS ODNs (antisense oligonucleotides) as therapeutics for malignant diseases. The principle of antisense technology is the sequence-specific binding of an AS ODN to the target mRNA, resulting in a translational arrest. The specificity of hybridization makes antisense strategy attractive to selectively modulate the expression of genes involved in the pathogenesis of malignant diseases. One antisense drug has been approved for local therapy of CMV (cytomegalovirus) retinitis, and a number of AS ODNs are currently being tested in clinical trials, including AS ODN targeting Bcl-2, XIAP (X-linked inhibitor of apoptosis protein) and TGF-beta-2 (transforming growth factor beta-2). AS ODNs are well tolerated and may have therapeutic activity. In particular, an AS ODN to Bcl-2 has been tested in phase III clinical trials in chronic lymphocytic leukaemia, multiple myeloma and malignant melanoma. In this review, therapeutic concepts, clinical studies and new promising molecular targets to treat malignancies with AS ODNs are summarized.

Specific lipoplex-mediated antisense against Bcl-2 in breast cancer cells: a comparison between different formulations

G3139 is an antisense oligonucleotide (ODN) that can down-regulate bcl-2, thus potentially acting as a potent anticancer drug. However, effective therapy requires efficient ODN delivery, which may be achieved by employing G3139 lipoplexes. Yet, lipofection is a complex, multifactorial process that is still poorly understood. In order to shed more light on this issue, we prepared 18 different G3139 lipoplex formulations and compared them in terms of their capability to transfect MCF-7 breast cancer cells. Each formulation was composed of a cationic lipid and sometimes a helper lipid. The cationic lipid was either DOTAP (N-(1-(2,3-dioleoyloxy)propyl)-N,N,N-trimethylammonium chloride), DC-CHOL (3ss[N-(N',N'-dimethylaminoethane)carbamoyl]-cholesterol), or CCS (ceramide carbomoyl spermine). The helper lipid was either DOPC, DOPE, or cholesterol. Each lipid combination existed in two different structural forms--either large unilamellar vesicles (approximately 100 nm LUV) or unsized heterolamellar vesicles (UHV). Cell proliferation assays were used to evaluate the cytotoxicity of G3139 lipoplexes, control cationic lipid assemblies, and free G3139. Western blots were used to confirm the specific activity of G3139 as an anti-bcl-2 antisense agent. We determined that treatment of MCF-7 cells with G3139:CCS lipoplexes (UHV-derived) produced a maximal 50-fold improvement in antisense efficacy compared to treatment with free G3139. The other G3139 lipoplexes were not superior to free G3139. Thus, successful lipofection requires precise optimization of lipoplex lipid composition, structure, and concentration.

Strategies and methodologies for identifying molecular targets in sarcomas and other tumors

Sarcomas are a heterogeneous group of tumors that respond poorly to conventional cytotoxic chemotherapy. Sarcomas possess specific molecular characteristics that exist because of unique somatic mutations, vital growth factor or growth factor receptor overexpression, or are critically dependent on host pathways. Currently these tumors are classified on the basis of their tissue of origin and histologic appearance. Gene expression and proteomic analysis of sarcomas may enable reclassification of these tumors and help predict their biologic behavior and devise common therapeutic strategies within a class. It may not be long before cDNA/protein expression profiling and karyotyping complement the current standard pathological evaluation of a newly diagnosed sarcoma, thereby helping the clinician pick targeted agent(s) relevant to the expression profile. The spectacular success of imatinib in patients with gastrointestinal stromal tumor demonstrates how molecular targeting can fulfill the promise of low toxicity and high response rates. Finding new targets, and learning how to use the current generation of targeting drugs in sarcoma, are urgent challenges. Therapeutic clinical trials with a host of new molecular-targeting agents are underway that will drive new paradigms in sarcoma therapeutics. Patients with refractory disease who currently have no viable therapeutic options may have options that open up with the advent of newer targeted approaches, converting their disease from an acute short-lived one to a chronic process with preservation of quality of life while receiving therapy.

Management of small cell lung cancer

Small cell lung cancer (SCLC) is an aggressive type of lung cancer characterized by rapid growth and early metastasis. It is chemosensitive and radiosensitive, yet decades of research investigating multimodality treatments have failed to control or cure this disease in most patients. First-line treatment of limited-stage disease consists of chemotherapy (often etoposide/cisplatin or etoposide/carboplatin) combined with thoracic radiation therapy (TRT), followed by prophylactic cranial irradiation to decrease brain metastases as a site of disease progression for those who experience complete remission or a very good partial response to multimodality treatment. In a Japanese trial, the combination of irinotecan and cisplatin had initially shown promise in treating patients with extensive-stage SCLC, but a confirmatory trial in the United States did not find a difference in overall survival with irinotecan/cisplatin versus etoposide/cisplatin. Adding a third drug to the etoposide/cisplatin combination, as well as other triplet therapies, has mostly been ineffective in improving outcomes. Variables in chemotherapy administration, including maintenance therapy, alternating non-cross-resistance regimens, and dose intensification, have not been shown to increase survival at large. In terms of radiation therapy, early administration of TRT concurrent with chemotherapy, and hyperfractionation, have been beneficial in treatment of limited-stage disease. In patients who relapse, second-line therapy options consist of reinduction of previous chemotherapy or administration of a single agent. Targeted biological therapies for SCLC are now being investigated, and although a great deal of research remains to be done, these agents and their derivatives may provide the most hope for future treatment of SCLC.

Inhibition of Bcl-2 expression by a novel tumor-specific RNA interference system increases chemosensitivity to 5-fluorouracil in Hela cells

AIM

RNA interference (RNAi) has been proposed as a potential treatment for cancer, but the lack of cellular targets limits its use in cancer gene therapy. No current technology has achieved direct tumor-specific gene silencing using RNAi. In the present study we attempt to develop a tumor-specific RNAi system using the human telomerase reverse transcriptase (hTERT) promoter; furthermore, we analyzed its inhibitive effect on Bcl-2 expression.

METHODS

The vectors containing a small hairpin RNA (shRNA) to target exogenous reporters [firefly luciferase and enhanced green fluorescent protein (EGFP)] and endogenous gene (Bcl-2) were constructed. Luciferase expression was determined by dual luciferase assay. Reverse transcription-polymerase chain reaction (RT-PCR), fluorescence microscopy and fluorescence-activated cell sorting (FACS) were used to measure EGFP expression. Inhibition of Bcl-2 was evaluated by RT-PCR and Western blotting. Cell proliferation and viability were measured by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. FACS was used to analyze the cell cycle distribution profile.

RESULTS

We showed that with the hTERT promoter directly driving shRNA transcription, expression of the exogenous reporters (LUC and EGFP) in tumor cells, but not normal cells, was specifically inhibited in vitro. The hTERT promoter-driven shRNA also depressed the expression of Bcl-2. Inhibition of Bcl-2 did not affect cell proliferation, but increased the chemosensitivity of HeLa cells to 5-fluorouracil.

CONCLUSION

The present study describes an efficient RNAi system for gene silencing that is specific to tumor cells using the hTERT promoter. Suppression of Bcl-2 by using this system sensitized HeLa cells to 5-fluorouracil. This system may be useful for RNAi therapy.

A phase I, pharmacokinetic and biologic correlative study of oblimersen sodium (Genasense, G3139) and irinotecan in patients with metastatic colorectal cancer

PURPOSE

To assess the feasibility and antitumor activity of oblimersen sodium, an antisense oligonucleotide directed to the Bcl-2 mRNA, combined with irinotecan in patients with advanced colorectal carcinoma, characterize the pharmacokinetic behavior of both oblimersen sodium and irinotecan, and examine Bcl-2 protein inhibition in peripheral blood mononuclear cells (PBMC).

PATIENTS AND METHODS

Patients were treated with escalating doses of oblimersen sodium administered by continuous intravenous infusion (CIVI) days 1-8, and irinotecan administered intravenously on day 6 once every 3 weeks.

RESULTS

Twenty patients received a total of 84 courses at doses ranging from 3 to 7 mg/kg/day for oblimersen sodium and from 280 to 350 mg/m2 for irinotecan. Febrile neutropenia and diarrhea limited escalation of oblimersen sodium and irinotecan to 5 mg/kg/day and 350 mg/m2, respectively. Other toxicities included nausea, vomiting, fever and fatigue. Steady-state plasma concentrations were achieved within 48 h of beginning oblimersen sodium treatment and the agent was undetectable 24 h after the discontinuation of the infusion. Reduction in levels of Bcl-2 protein in PBMC was documented following treatment with oblimersen sodium. One patient experienced a partial response and 10 additional patients had stable disease lasting 2.5-10 months.

CONCLUSIONS

The combination is well tolerated at the recommended phase II oblimersen sodium dose of 7 mg/kg/day CIVI days 1-8 with irinotecan 280 mg/m2 intravenously on day 6 every 3 weeks.

Bcl-2 antisense oligonucleotide overcomes resistance to E1A gene therapy in a low HER2-expressing ovarian cancer xenograft model

We are currently conducting clinical trials of E1A gene therapy for patients with ovarian cancer. The adenovirus type 5 E1A gene suppresses growth of ovarian cancer cells that overexpress HER-2/neu (HER2) and growth of some--but not all--that express low HER2. In HER2-overexpressing cells, suppression by E1A is predominantly by down-regulation of HER2, but the mechanism in low HER2-expressing cells is not fully understood. The adenoviral E1B protein has sequential and functional homology to Bcl-2 and prolongs the viability of adenovirus host cells by inhibiting E1A-induced apoptosis. Bcl-2 is overexpressed in ovarian cancer and participates in chemoresistance; we hypothesized that Bcl-2 inhibits E1A-induced apoptosis leading to resistance to E1A gene therapy. E1A suppressed colony formation of ovarian cancer cells that express low levels of Bcl-2 and HER2 (OVCAR-3 and OVCA 433), but enhanced colony formation in low HER2-, high Bcl-2-expressing ovarian cancer cells (2774 and HEY). Treating 2774 or HEY cells with antisense oligonucleotide Bcl-2 (Bcl-2-ASO) did not reduce cell viability. E1A combined with Bcl-2-ASO led to significant decreases in cell viability resulting from increased apoptosis relative to cells treated with E1A alone (P < 0.05). The increase in apoptosis was partly due to cytochrome c release and subsequently caspase-9 activation by Bcl-2-ASO. Finally, in an ovarian cancer xenograft model, treatment with Bcl-2-ASO did not prolong survival, but E1A plus Bcl-2-ASO did (P < 0.001). In conclusion, ovarian tumors overexpressing Bcl-2 may not respond well to E1A gene therapy, but treatment with a combination of E1A and Bcl-2-ASO may overcome this resistance.

Antisense-induced Fas mRNA degradation produces site-specific stable 3'-mRNA fragment by exonuclease cleavage at the complementary sequence

Antisense-mediated degradation of target mRNA is achieved by the enzymatic action of nuclease RNase H. The enzyme recognizes hybrid RNA-DNA duplexes and hydrolyzes the RNA strand. Here, we compared six different phosphorothioate oligonucleotides for their ability to induce target-specific mRNA degradation in cultured mouse AML12 cells. We targeted transcripts of the cell surface receptor Fas and analyzed the levels of mRNA by Northern blotting and ribonuclease protection assay (RPA). Four of the tested antisense oligonucleotides reduced the mRNA levels significantly. Cultures treated with one of the antisense molecules resulted in a shifted band on Northern blots. This band of lower molecular weight was not detected after 6 hours of transfection but appeared at 24 hours. By RPA, the product was shown to be a 3'-cleavage fragment of the full-length Fas mRNA. The RPA also mapped the stable fragment to start within the antisense complementary sequence.

Recent studies in novel therapy for metastatic sarcomas

Many new chemotherapeutic agents and targeted therapies are being studied in the treatment of metastatic soft tissue sarcomas (STSs). This article reviews results of recent clinical studies of gemcitabine, docetaxel, paclitaxel, ecteinascidin, 9-nitrocamptothecin, and pegylated liposomal doxorubicin, in patients who have STSs. The use of targeted therapy in STSs is an exciting, constantly changing field. The activity of imatinib mesylate, SU11248, everolimus, and bortezomib are summarized.

Reduction in BCL-2 levels by 26S proteasome inhibition with bortezomib is associated with induction of apoptosis in small cell lung cancer

Overexpression of the anti-apoptotic protein BCL-2 is frequently observed in small cell lung cancers (SCLC) and is associated with chemoresistance. We examined the signaling pathways involved in upregulation of BCL-2 in SCLC, and whether inhibition of NF-kappaB using the 26S proteasome inhibitor bortezomib had any effect on BCL-2 levels or apoptosis. Mutation of a NF-kappaB site in the BCL-2 promoter reduced promoter activity to less than 20% of the wild-type promoter. Treatment with bortezomib resulted in decreased transcription of the BCL-2 promoter, decreased BCL-2 levels, and induced apoptosis. These data provide the necessary laboratory background for further investigation of bortezomib in the treatment of SCLC.

Apoptosis: mechanisms and relevance in cancer

Apoptosis or programmed cell death is a process with typical morphological characteristics including plasma membrane blebbing, cell shrinkage, chromatin condensation and fragmentation. A family of cystein-dependent aspartate-directed proteases, called caspases, is responsible for the proteolytic cleavage of cellular proteins leading to the characteristic apoptotic features, e.g. cleavage of caspase-activated DNase resulting in internucleosomal DNA fragmentation. Currently, two pathways for activating caspases have been studied in detail. One starts with ligation of a death ligand to its transmembrane death receptor, followed by recruitment and activation of caspases in the death-inducing signalling complex. The second pathway involves the participation of mitochondria, which release caspase-activating proteins into the cytosol, thereby forming the apoptosome where caspases will bind and become activated. In addition, two other apoptotic pathways are emerging: endoplasmic reticulum stress-induced apoptosis and caspase-independent apoptosis. Naturally occurring cell death plays a critical role in many normal processes like foetal development and tissue homeostasis. Dysregulation of apoptosis contributes to many diseases, including cancer. On the other hand, apoptosis-regulating proteins also provide targets for drug discovery and new approaches to the treatment of cancer.

Targeting and regulation of the HER-2/neu oncogene promoter with bis-peptide nucleic acids

Antigene oligonucleotides have the potential to regulate gene expression through site-specific DNA binding. However, in vivo applications have been hindered by inefficient cellular uptake, degradation, and strand displacement. Peptide nucleic acids (PNAs) address several of these problems, as they are resistant to degradation and bind DNA with high affinity. We designed two cationic pyrimidine bis-PNAs (cpy-PNAs) to target the polypurine tract of the HER-2/neu promoter and compared them to an unmodified phosphodiester triplex-forming oligonucleotide (TFO1) and a TFO-nitrogen mustard conjugate (TFO2). PNA1 contains a + 2 charge and bound two adjacent 9-bp target sequences with high affinity and specificity, but only at low pH. PNA2 contains a +5 charge and bound one 11-bp target with high affinity up to pH 7.4, but with lower specificity. The PNA:DNA:PNA triplex formed by these cpy-bis-PNAs presented a stable barrier to DNA polymerase extension. The cpy-bis-PNAs and the TFO-alkylator conjugate prevented HER-2/neu transcription in a reporter gene assay (TFO2 = PNA1 > PNA2 >> TFO1). Both PNAs and TFOs were effective at binding the target sequence in naked genomic DNA, but only the TFO-alkylator (TFO2) and the more cationic PNA (PNA2) were detected at the endogenous HER-2/neu promoter in permeabilized cells. This work demonstrates the potential for preventing HER-2/neu gene expression with cpy-bis-PNAs in tumor cells.

Antitumor effects of radioiodinated antisense oligonuclide mediated by VIP receptor

A 15-mer phosphorothioate antisense oligonuclide (ASON) complementary to the translation start region of the C-myc oncogene mRNA was radioiodinated to enhance its antitumor activity, and vasoactive intestinal peptide bound covalently polylysine (VIP-polylysine) was used as a carrier to deliver the oligonucleotide into VIP receptor-positive tumor cells. The antitumor activity of radioiodinated ASON conjugated to VIP-polylysine(VIP-131I-ASON) was investigated in athymic mice bearing HT29 tumor xenografts in comparison with unconjugated radioiodinated ASON(131I-ASON), unlabelled ASON (VIP-ASON) and scrambled oligonucleotide (VIP-131I-MON) conjugated to VIP-polylysine. Conjugation 125I-ASON to VIP-polylysine resulted in a 5.6-fold decrease in the plasma clearance and a 3.4-fold increase in tumor uptake of the radiopharmaceutical. Athymic mice bearing HT29 tumor xenografts were treated with 4 weekly doses of VIP-131I-ASON and the antitumor effects were assessed by use of the slope of the tumor growth curve. VIP-131I-ASON exhibited strong antitumor effects against HT29 xenografts, decreasing tumor growth rate 9.67-, 7.90-fold more effectively than 131I-ASON and VIP-ASON at equivalent doses of ASON. Conversely, 131I-ASON, VIP-ASON or VIP-131I-MON caused no significant effect compared with the normal saline. These data indicated that use of a VIP-polylysine carrier greatly increased HT29 tumor uptake of ASON and treatment with the VIP-131I-ASON complexes resulted in tumor growth delay in human colon cancer xenograft.

Perspectives on novel therapies for bronchial carcinoma

Improvements in conventional cytotoxic treatment have probably reached a plateau for the treatment of lung cancer; therefore, new treatment strategies that are based on a better understanding of tumour biology are required. Some progress has been made for non-small cell lung cancer, in which erlotinib (Tarceva, OSI-774; Genentech), an epidermal growth factor receptor antagonist, has demonstrated a significant clinical benefit in a Phase III randomised trial, and has been licensed for second- or third-line treatment. Other therapies under investigation include angiogenesis inhibitors, COX-2 inhibitors, retinoids, farnesyl transferase inhibitors, Bcl-2 inhibitors and c-Kit antagonists. In this article the recent and ongoing Phase II and III trials of these therapies in lung cancer are summarised, and the prospects for their further clinical development are discussed.

Novel therapies in lung cancer

This article reviews novel therapies that are under development for non-small cell lung cancer and small cell lung cancer.

Safety and pharmacokinetic study of RPI.4610 (ANGIOZYME), an anti-VEGFR-1 ribozyme, in combination with carboplatin and paclitaxel in patients with advanced solid tumors

PURPOSE

RPI.4610 (ANGIOZYME) is a chemically stabilized ribozyme targeting vascular endothelial growth factor receptor 1. The purpose of this study was to evaluate the safety and pharmacokinetics of RPI.4610 in combination with carboplatin and paclitaxel in patients with advanced solid tumors.

METHODS

The study used a sequential treatment design evaluating a single dose level for all three drugs: paclitaxel 175 mg m-2 and carboplatin AUC=6 on day 1 of a 21-day cycle, and RPI.4610 100 mg m-2 day-1 beginning on day 8 and continuing daily thereafter. Pharmacokinetic samples were drawn on day 1 of courses 1 (chemotherapy alone) and 2 (chemotherapy+RPI.4610), and on day 8 of course 1 (RPI.4610 alone). Ratios were generated by comparing the pharmacokinetic parameters for the combination of carboplatin with paclitaxel when administered alone or together with RPI.4610.

RESULTS

Twelve patients were enrolled in this trial and received two to six courses of treatment each. The most common grade 3-4 toxicities were neutropenia (three patients), thrombocytopenia (three patients), pain (three patients), anemia (two patients) and fatigue (two patients). The ratio of the mean maximum plasma concentration (Cmax) for carboplatin when administered with paclitaxel alone versus when administered with paclitaxel and RPI.4610 was 1.07 (90% confidence interval, 0.77-1.37). Similarly, the ratio of the mean AUC0-last for carboplatin was 1.04 (0.73-1.35). For paclitaxel the ratio of the mean Cmax when administered with carboplatin alone versus with carboplatin and RPI.4610 was 1.17 (1.03-1.31), and the ratio of the mean AUC0-last was 1.17 (1.04-1.30). Objective tumor responses were observed and included one patient with a complete response (bladder cancer) and one patient with a partial response (esophageal cancer).

CONCLUSIONS

These results indicate that RPI.4610, carboplatin, and paclitaxel can be administered safely in combination without substantial pharmacokinetic interactions.

Phase II study of G3139, a Bcl-2 antisense oligonucleotide, in combination with dexamethasone and thalidomide in relapsed multiple myeloma patients

PURPOSE

Bcl-2 regulates the mitochondrial apoptosis pathway that promotes chemotherapy resistance. Bcl-2 antisense oligonucleotide, G3139, targets Bcl-2 mRNA.

PATIENTS AND METHODS

G3139 was administered (3 to 7 mg/kg/d for 7 days) by continuous intravenous infusion. On day 4, patients started thalidomide (100 to 400 mg as tolerated) and dexamethasone (40 mg daily for 4 days) on 21-day cycles for three cycles. Stable and responding patients continued on 35-day cycles for 2 years.

RESULTS

Thirty-three patients (median age, 60 years; range, 28 to 76 years) received 220 cycles. Patients received a median of three prior regimens including thalidomide (n = 15) and stem-cell transplantation (n = 31). The regimen was well tolerated; the median number of cycles per patient was eight (range, one to 16+ cycles). Toxicities included reversible increase in creatinine, thrombocytopenia, neutropenia, fatigue, anorexia, constipation, fever, neuropathy, edema, electrolyte disturbances, and hyperglycemia. Fifty-five percent of patients had objective responses, including two complete responses (CRs), four near CRs (positive immunofixation), and 12 partial responses; six patients had minimal responses (MRs). Of patients who received prior thalidomide, seven had objective responses, and three had MRs. The median duration of response was 13 months, and estimated progression-free and overall survival times were 12 and 17.4 months, respectively. Responding patients had significant increase in polyclonal immunoglobulin M (P = .005), indicating innate immune system activation. Western blot analysis of Bcl-2 protein isolated from myeloma cells before and after G3139 demonstrated a decrease of Bcl-2 levels in three of seven patients compared with six of nine patients using reverse transcriptase polymerase chain reaction.

CONCLUSION

G3139, dexamethasone, and thalidomide are well tolerated and result in encouraging clinical responses in relapsed multiple myeloma patients.

Phase I study of oblimersen sodium, an antisense to Bcl-2, in untreated older patients with acute myeloid leukemia: pharmacokinetics, pharmacodynamics, and clinical activity

PURPOSES

Pharmacologic downregulation of Bcl-2, an antiapoptotic protein overexpressed in cancer, might increase chemosensitivity in acute myeloid leukemia (AML). Herein, we investigated the feasibility of this approach in untreated elderly AML patients by administering oblimersen sodium (G3139), an 18-mer phosphorothioate antisense to Bcl-2, during induction and consolidation treatments.

PATIENTS AND METHODS

Untreated patients with primary or secondary AML (stratified to cohort 1 or 2, respectively) who were > or = 60 years received induction with G3139, cytarabine, and daunorubicin at one of two different dose levels (45 and 60 mg/m2) and, on achievement of complete remission (CR), consolidation with G3139 and high-dose cytarabine. An enzyme-linked immunosorbent assay (ELISA)-based assay was used to measure plasma and intracellular concentrations (IC) of G3139. Bcl-2 mRNA and protein levels were quantified by real-time reverse transcriptase polymerase chain reaction and ELISA, respectively, in bone marrow samples collected before induction treatment and after 72 hours of G3139 infusion, prior to initiation of chemotherapy.

RESULTS

Of the 29 treated patients, 14 achieved CR. With a median follow-up of 12.6 months, seven patients had relapsed. Side effects of this combination were similar to those expected with chemotherapy alone and were not dose limiting at both dose levels. After 72-hour G3139 infusion, Bcl-2/ABL mRNA copies were decreased compared with baseline (P = .03) in CR patients and increased in nonresponders (NRs; P = .05). Changes in Bcl-2 protein showed a similar trend. Although plasma pharmacokinetics did not correlate with disease response, the median IC of the antisense was higher in the CR patients compared with NRs (17.0 v 4.4 pmol/mg protein, respectively; P = .05).

CONCLUSION

G3139 can be administered safely in combination with intensive chemotherapy, and the degree of Bcl-2 downmodulation may correlate with response to therapy.

Chemotherapy strategies in the treatment of small cell lung cancer

Lung cancer is the most prevalent, yet most preventable malignancy worldwide. Given the tendency of small cell lung cancer (SCLC) to early relapse and its subsequent resistance to treatment, there is an urgent need to optimize standard treatment strategies and develop new treatments. Over the last decade, several strategies have been adopted and advances in the molecular biology of lung cancer have identified a number of targets for future therapy. In this article, we review chemotherapy strategies that have been evaluated in the management of patients with SCLC.