Among the cellular responses observed following treatment with DNA-damaging agents is the activation of Short Interspersed Elements (SINEs; retrotransposable genetic elements that comprise over 10% of the human genome). By placing a human SINE (the Alu element) into murine cells, we have previously shown that DNA-damaging agents such as etoposide can induce both upregulation of SINE transcript levels and SINE retrotransposition. A similarly cytotoxic (but not genotoxic) exposure to vincristine was not associated with SINE activation. Here we demonstrate that multiple other genotoxic exposures are associated with upregulation of SINE transcript levels. By comparing the effects of similarly cytotoxic doses of the topoisomerase II inhibitors etoposide and merbarone, we confirm that DNA strand breakage is specifically associated with SINE induction. By evaluating transcription rate and RNA stability, we demonstrate that SINE induction by genotoxic exposure is associated with transcriptional induction and not with transcript stabilization. Finally we demonstrate that SINE induction by genotoxic stress is mediated by a Trp53-independent pathway, and in fact that Trp53 plays an inhibitory role in attenuating the transcriptional induction of SINE elements following exposure to a genotoxic agent. Together these data support a model in which initial DNA damage can trigger genomic instability due to SINE activation, a response which may be amplified in cancer cells lacking functional TP53.
Vismodegib (GDC-0449), an orally bioavailable small-molecule inhibitor of Hedgehog signaling, was recently approved by the U.S. Food and Drug Administration for the treatment of basal cell carcinoma that is either metastatic or locally advanced in patients who are not candidates for surgical resection or radiation. Given the absence of previously defined effective drug therapy for this disease, approval was granted primarily on the basis of outcome of a nonrandomized parallel cohort phase II study of 99 patients with advanced basal cell carcinoma, with a primary endpoint of objective response rate. Response rates of 30.3% and 42.9% were observed in metastatic and locally advanced cohorts in this study, respectively, associated with median progression-free survival in both cohorts of 9.5 months. Ongoing clinical investigations include evaluation of the potential efficacy of vismodegib in a variety of diseases and in combination with other agents. The mechanism of action, preclinical and clinical data, and potential utility in other disease contexts are reviewed here.
The causative association between tobacco use and lung cancer is a well-established fact. However, lung cancer also occurs, at surprisingly high rates, in lifelong never smokers. In fact, lung cancer in never smokers is among the leading causes of cancer-related mortality. This CCR Focus summarizes recent data, identifies knowledge deficits, and suggests future research directions with regard to this critically important subset of lung cancer patients.
Vismodegib (GDC-0449), an orally bioavailable small molecule inhibitor of Hedgehog signaling, was recently approved by the U.S. Food and Drug Administration for the treatment of basal cell carcinoma that is either metastatic or locally advanced in patients who are not candidates for surgical resection or radiation. Given the absence of previously defined effective drug therapy for this disease, approval was granted based primarily on outcome of a non-randomized parallel cohort phase II study of 99 patients with advanced basal cell carcinoma, with a primary endpoint of objective response rate. Response rates of 30.3 and 42.9 percent were observed in metastatic and locally advanced cohorts in this study, respectively, associated with median progression-free survival in both cohorts of 9.5 months. Ongoing clinical investigations include evaluation of the potential efficacy of vismodegib in a variety of disease contexts, and in combination with other agents. The mechanism of action, preclinical and clinical data, and potential utility in other disease contexts are reviewed.
The aim of this study was to determine the maximum tolerated dose (MTD), dose limiting toxicities (DLTs), and determine the phase II dose for the combination of irinotecan-carboplatin-paclitaxel given as induction chemotherapy and with concomitant chest radiotherapy for patients with Stage III non-small cell lung cancer.
Patients with Cancer and Leukemia Group B performance status of 0 to 2, stage IIIA and IIIB NSCLC patients with resectable or unresectable disease were treated with induction chemotherapy (irinotecan 100 mg/m2, carboplatin AUC 5, and paclitaxel 175 mg/m2 days 1 and 22) followed by concomitant chemotherapy (irinotecan, carboplatin, and paclitaxel) and chest radiotherapy (66 Gy for unresectable and 50 Gy for resectable disease) beginning on week 7. The primary objective was to escalate the dose of irinotecan during chemoradiation in sequential cohorts to determine the DLT and MTD of the regimen.
Thirty-eight patients were enrolled (median age 63 years, 57% male, 41% performance status 0, 30% resectable). Induction chemotherapy was tolerable and active (response rate 26%; stable disease 60%). Eight patients did not receive concurrent chemoradiotherapy because of progressive disease (5), death (1), hypersensitivity reaction to paclitaxel (1), and withdrawal of consent (1). Twenty-nine patients received concurrent chemoradiotherapy. The concomitant administration of chest radiotherapy with weekly irinotecan, carboplatin, and paclitaxel was not feasible at the first, second, and third dose levels. DLT was failure to achieve recovery to ≤ grade 1 absolute neutrophil count by the day of scheduled chemotherapy administration. Dose de-escalation to irinotecan 30 mg/m2, paclitaxel 40 mg/m2 (with omission of carboplatin) delivered on weeks 2, 3, 5, and 6 of radiotherapy was the MTD. After induction chemotherapy, partial responses, stable disease, and progressive disease was observed in 26%, 60%, and 14% of patients, respectively. After chemoradiotherapy, partial responses were attained in 16 (55%) patients, whereas 12 patients (41%) attained disease stabilization. Median overall survival was 21 months for the entire cohort. Resectable patients had a median survival of 24 months, whereas unresectable patients had a median survival of 19 months. Differences in overall and progression-free survival rates between resectable and unresectable patients was not statistically significant (p = 0.52 and p = 0.90, respectively).
Carboplatin, paclitaxel, and irinotecan with concurrent chemoradiotherapy was poorly tolerated as a result of neutropenia. Although dose de-escalation was required for delivery of the regimen, the response rates and survival outcomes were comparable to other similar regimens.
Non-small cell lung cancer; Irinotecan; Radiation therapy; Multimodality therapy
SCLC; tyrosine receptor kinases; developmental pathways; immunology; oncolytic replication-selective viruses
The promise of targeting epigenetic abnormalities for cancer therapy has not been realized for solid tumours, although increasing evidence is demonstrating its worth in haematological malignancies. In fact, true clinical efficacy in haematopoietic-related neoplasms has only become evident at low doses of epigenetic-targeting drugs (namely, inhibitors of histone deacetylase and DNA methyltransferases). Describing data from preclinical studies and early clinical trial results, we hypothesize that in using low-dose epigenetic-modulating agents, tumour cells can be reprogrammed, which overrides any immediate cytotoxic and off-target effect observed at high dose. We suggest that such optimization of drug dosing and scheduling of currently available agents could give these agents a prominent place in cancer management—when used alone or in combination with other therapies. If so, optimal use of these known agents might also pave the way for the introduction of other agents that target the epigenome.
The Notch signaling pathway is a critical embryonic developmental regulatory pathway that has been implicated in oncogenesis. In non-small cell lung cancer (NSCLC), recent evidence suggests that Notch signaling may contribute to maintenance of a cancer stem or progenitor cell compartment required for tumorigenesis. We explored whether intact Notch signaling is required for NSCLC clonogenic and tumorigenic potential in vitro and in vivo using a series of genetically modified model systems. In keeping with previous observations, we find that Notch3 in particular is upregulated in human lung cancer lines, and that down regulation of Notch signaling using a selective γ-secretase inhibitor (MRK-003) is associated with decreased proliferation and clonogenic capacity in vitro. We demonstrate that this phenotype is rescued with the expression of NICD3, a constitutively active cleaved form of Notch3 not affected by γ-secretase inhibition. Using an inducible LSL-KRASG12D model of lung cancer in vivo, we demonstrate a transient upregulation of Notch pathway activity in early tumor precursor lesions. However, a more rigorous test of the requirement for Notch signaling in lung oncogenesis, crossing the LSL-KRASG12D mouse model with a transgenic with a similarly inducible global dominant negative suppressor of Notch activity, LSL-DNMAML (dominant negative mastermind-like), reveals no evidence of Notch pathway requirement for lung tumor initiation or growth in vivo. Distinct Notch family members may have different, and potentially opposing, activities in oncogenesis, and targeted inhibition of individual Notch family members may be a more effective anti-cancer strategy than global pathway suppression.
Bcl-2 is a critical regulator of apoptosis that is overexpressed in the majority of small cell lung cancers (SCLC). Nativoclax (ABT-263) is a potent and selective inhibitor of Bcl-2 and Bcl-xL. The primary objectives of this phase IIa study included safety at the recommended phase II dose and preliminary, exploratory efficacy assessment in patients with recurrent and progressive SCLC after at least one prior therapy.
Thirty-nine patients received navitoclax 325 mg daily, following an initial lead-in of 150 mg daily for 7 days. Study endpoints included safety and toxicity assessment, response rate, progression-free and overall survival (PFS and OS), as well as exploratory pharmacodynamic correlates.
The most common toxicity associated with navitoclax was thrombocytopenia, which reached grade III–IV in 41% of patients. Partial response was observed in one (2.6%) patient and stable disease in 9 (23%) patients. Median PFS was 1.5 months and median OS was 3.2 months. A strong association between plasma pro–gastrin-releasing peptide (pro-GRP) level and tumor Bcl-2 copy number (R = 0.93) was confirmed. Exploratory analyses revealed baseline levels of cytokeratin 19 fragment antigen 21-1, neuron-specific enolase, pro-GRP, and circulating tumor cell number as correlates of clinical benefit.
Bcl-2 targeting by navitoclax shows limited single-agent activity against advanced and recurrent SCLC. Correlative analyses suggest several putative biomarkers of clinical benefit. Preclinical models support that navitoclax may enhance sensitivity of SCLC and other solid tumors to standard cytotoxics. Future studies will focus on combination therapies.
We previously reported data on the safety, tolerability, and recommended phase II dose of obatoclax mesylate in conjunction with topotecan in patients with advanced solid tumor malignancies. Preliminary efficacy data suggested activity in patients with recurrent small cell lung cancer (SCLC). Based on these data, we performed a phase II study of obatoclax mesylate plus topotecan in patients with relapsed SCLC to assess efficacy.
This was an open-label, single-arm, phase II extension of obatoclax mesylate plus topotecan in patients with relapsed SCLC. Obatoclax mesylate was given intravenously (IV) at a dose of 14 mg/m2 on days 1 and 3 with IV topotecan at 1.25 mg/m2 on days 1–5 of an every 3-week cycle. The primary end-point of this study was overall response rate.
Nine patients with recurrent SCLC were enrolled into the first stage of the study. Patients received a median of 2 cycles of treatment. All patients were evaluable for the primary end-point of overall response. There were no partial or complete responses. Five patients (56%) had stable disease. The remaining four patients (44%) developed progressive disease. The most common grade 3 or 4 adverse events included thrombocytopenia (22%), anemia (11%), neutropenia (11%), and ataxia (11%).
Obatoclax mesylate added to topotecan does not exceed the historic response rate seen with topotecan alone in patients with relapsed SCLC following the first-line platinum-based therapy.
Obatoclax mesylate; Topotecan; Small cell lung cancer (SCLC); Apoptosis
To assess the efficacy and toxicity of carboplatin, etoposide, and the bcl-2 antisense oligonucleotide oblimersen as initial therapy for extensive-stage small-cell lung cancer (ES-SCLC). bcl-2 has been implicated as a key factor in SCLC oncogenesis and chemotherapeutic resistance.
Patients and Methods
A 3:1 randomized phase II study was performed to evaluate carboplatin and etoposide with (arm A) or without oblimersen (arm B) in 56 assessable patients with chemotherapy-naïve ES-SCLC. Outcome measures including toxicity, objective response rate, complete response rate, failure-free survival, overall survival, and 1-year survival rate.
Oblimersen was associated with slightly more grade 3 to 4 hematologic toxicity (88% v 60%; P = .05). Response rates were 61% (95% CI, 45% to 76%) for arm A and 60% (95% CI, 32% to 84%) for arm B. The percentage of patients alive at 1 year was 24% (95% CI, 12% to 40%) with oblimersen, and 47% (95% CI, 21% to 73%) without oblimersen. Hazard ratios for failure-free survival (1.79; P = .07) and overall survival (2.13; P = .02) suggested worse outcome for patients receiving oblimersen. These results hold when adjusted for other prognostic factors, such as weight loss, in multivariate regression analysis.
Despite extensive data supporting a critical role for Bcl-2 in chemoresistance in SCLC, addition of oblimersen to a standard regimen for this disease did not improve any clinical outcome measure. Emerging data from several groups suggest that this lack of efficacy may be due to insufficient suppression of Bcl-2 in vivo. Additional evaluation of this agent in SCLC is not warranted.
Cancer patients at Johns Hopkins undergo insurance clearance to verify coverage for enrollment to interventional clinical trials. We sought to explore the impact of insurance clearance on disparities in access to cancer clinical trials at this urban comprehensive cancer center.
We evaluated the frequency of insurance-based denial of access to cancer clinical trials over a 5-year period after initiation of a formal insurance clearance process. We used a case-control design to compare demographic and clinical parameters of patients denied or approved for clinical trials participation by their insurance company in a 3-year interval.
From July 2003 to July 2008, insurance requests for clinical trial participation were submitted on 4,617 consented cancer patients at Johns Hopkins. A total of 628 patients (13.6%) with health insurance were denied therapeutic trial enrollment owing to lack of insurance coverage for participation. A total of 254 patients denied enrollment from 2005 to 2007 were selected for further analysis. Two-hundred sixty randomly selected patients approved for clinical trial participation served as controls. Patients approved were on average older (59.2 versus 54.9 years) than patients denied (P = 0.0001). Residents of Pennsylvania, which lacks a state law mandating cancer clinical trial coverage for residents, were overrepresented among the denied patients (P = 0.0009). No statistically significant variance in the likelihood of insurance denial was found on the basis of sex, race, stage of disease, or presence of comorbidities.
Denial of access to therapeutic clinical trials, even among insured patients, is a significant barrier to clinical cancer research. This barrier spans racial, ethnic, and gender categories.
In a phase I trial for patients with refractory solid tumors, hedgehog pathway inhibitor vismodegib (GDC-0449) showed little decline in plasma concentrations over 7 days after a single oral dose and nonlinearity with respect to dose and time after single and multiple dosing. We studied the role of GDC-0449 binding to plasma protein alpha-1-acid glycoprotein (AAG) to better understand these unusual pharmacokinetics.
Sixty-eight patients received GDC-0449 at 150 (n = 41), 270 (n = 23), or 540 (n = 4) mg/d, with pharmacokinetic (PK) sampling at multiple time points. Total and unbound (dialyzed) GDC-0449 plasma concentrations were assessed by liquid chromatography/tandem mass spectrometry, binding kinetics by surface plasmon resonance–based microsensor, and AAG levels by ELISA.
A linear relationship between total GDC-0449 and AAG plasma concentrations was observed across dose groups (R2 = 0.73). In several patients, GDC-0449 levels varied with fluctuations in AAG levels over time. Steady-state, unbound GDC-0449 levels were less than 1% of total, independent of dose or total plasma concentration. In vitro, GDC-0449 binds AAG strongly and reversibly (KD = 13 μmol/L) and human serum albumin less strongly (KD = 120 μmol/L). Simulations from a derived mechanistic PK model suggest that GDC-0449 pharmacokinetics are mediated by AAG binding, solubility-limited absorption, and slow metabolic elimination.
GDC-0449 levels strongly correlated with AAG levels, showing parallel fluctuations of AAG and total drug over time and consistently low, unbound drug levels, different from previously reported AAG-binding drugs. This PK profile is due to high-affinity, reversible binding to AAG and binding to albumin, in addition to solubility-limited absorption and slow metabolic elimination properties.
The anti-angiogenic agent bevacizumab has been approved for the treatment of non-small cell lung cancer, although the survival benefit associated with this agent is marginal, and toxicities and cost are substantial. A recent screen for selective inhibitors of endothelial cell proliferation identified the oral anti-fungal drug itraconazole as a novel agent with potential anti-angiogenic activity. Here we define and characterize the anti-angiogenic and anti-cancer activities of itraconazole in relevant preclinical models of angiogenesis and lung cancer. Itraconazole consistently demonstrated potent, specific, and dose-dependent inhibition of endothelial cell proliferation, migration, and tube formation in response to both vascular endothelial growth factor (VEGF)- and basic fibroblast growth factor (bFGF)-mediated angiogenic stimulation. In vivo, using primary xenograft models of human non-small cell lung cancer, oral itraconazole showed single agent growth-inhibitory activity associated with induction of tumor HIF1α expression and marked inhibition of tumor vascularity. Itraconazole significantly enhanced the anti-tumor efficacy of the chemotherapeutic agent cisplatin in the same model systems. Taken together, these data suggest that itraconazole has potent and selective inhibitory activity against multiple key aspects of tumor-associated angiogenesis in vitro and in vivo, and strongly support clinical translation of its use. Based on these observations we have initiated a randomized phase II study comparing the efficacy of standard cytotoxic therapy with or without daily oral itraconazole in patients with recurrent metastatic non-small cell lung cancer.
New therapies are urgently needed for patients with small cell lung cancer (SCLC). Chemotherapy and targeted therapies, including the Bcl-2 inhibitor ABT-737, may induce tumor cell autophagy. Autophagy can promote survival of cancer cells under stress and comprise a pathway of escape from cytotoxic therapies.
We explored the combination of ABT-737 and chloroquine, an inhibitor of autophagy, in preclinical models of SCLC. These included cell culture analyses of viability and of autophagic and apoptotic pathway induction, as well as in vivo analyses of efficacy in multiple xenograft models.
Combination treatment of SCLC lines with ABT-737 and chloroquine decreased viability and increased caspase-3 activation over treatment with either single agent. ABT-737 induced several hallmarks of autophagy. However, knockdown of beclin-1, a key regulator of entry into autophagy, diminished the efficacy of ABT-737, suggesting either that the effects of chloroquine were nonspecific or that induction but not completion of autophagy is necessary for the combined effect of ABT-737 and chloroquine. ABT-737 and chloroquine in SCLC cell lines downregulated Mcl-1 and upregulated NOXA, both of which may promote apoptosis. Treatment of tumor-bearing mice demonstrated that chloroquine could enhance ABT-737-mediated tumor growth inhibition against NCI-H209 xenografts, but did not alter ABT-737 response in three primary patient-derived xenograft models.
These data suggest that although ABT-737 can induce autophagy in SCLC, autophagic inhibition by choroquine does not markedly alter in vivo response to ABT-737 in relevant preclinical models, arguing against this as a treatment strategy for SCLC.
Autophagy; Apoptosis; ABT-737; Chloroquine; Primary xenograft
Small-cell lung cancer (SCLC) is an exceptionally aggressive disease with poor prognosis. Here, we obtained exome, transcriptome and copy-number alteration data from approximately 53 samples consisting of 36 primary human SCLC and normal tissue pairs and 17 matched SCLC and lymphoblastoid cell lines. We also obtained data for 4 primary tumors and 23 SCLC cell lines. We identified 22 significantly mutated genes in SCLC, including genes encoding kinases, G protein–coupled receptors and chromatin-modifying proteins. We found that several members of the SOX family of genes were mutated in SCLC. We also found SOX2 amplification in ~27% of the samples. Suppression of SOX2 using shRNAs blocked proliferation of SOX2-amplified SCLC lines. RNA sequencing identified multiple fusion transcripts and a recurrent RLF-MYCL1 fusion. Silencing of MYCL1 in SCLC cell lines that had the RLF-MYCL1 fusion decreased cell proliferation. These data provide an in-depth view of the spectrum of genomic alterations in SCLC and identify several potential targets for therapeutic intervention.
More than 161,000 lung cancer deaths are projected to occur in the U.S. in 2008. Of these, an estimated 10–15% will be caused by factors other than active smoking, corresponding to 16,000–24,000 deaths annually. Thus lung cancer in never smokers would rank among the most common causes of cancer mortality in the U.S. if considered to be a separate category. Slightly more than half of the lung cancers caused by factors other than active smoking occur in never smokers. As summarized in the accompanying article, lung cancers that occur in never smokers differ from those that occur in smokers in their molecular profile and response to targeted therapy. These recent laboratory and clinical observations highlight the importance of defining the genetic and environmental factors responsible for the development of lung cancer in never-smokers. This article summarizes available data on the clinical epidemiology of lung cancer in never smokers, and the several environmental risk factors that population-based research has implicated in the etiology of these cancers. Primary factors closely tied to lung cancer in never smokers include exposure to known and suspected carcinogens including radon, second-hand tobacco smoke, and other indoor air pollutants. Several other exposures have been implicated. However, a large fraction of lung cancers occurring in never-smokers cannot be definitively associated with established environmental risk factors, highlighting the need for additional epidemiologic research in this area.
Bcl-2 is a central regulator of cell survival that is overexpressed in the majority of small cell lung cancers (SCLC) and contributes to both malignant transformation and therapeutic resistance. We compared primary SCLC xenografts prepared from de novo human tumors with standard cell line–based xenografts in the evaluation of a novel and highly potent small molecule inhibitor of Bcl-2, ABT-737. ABT-737 induced dramatic regressions in tumors derived from some SCLC cell lines. In contrast, only one of three primary xenograft SCLC tumors showed significant growth inhibition with ABT-737. Explanations for this apparent dichotomy may include relatively low expression of Bcl-2 in the primary xenografts or inherent differences in the model systems. The addition of etoposide to ABT-737 in the primary xenografts resulted in significant decreases in tumor growth, underscoring the clinical potential of ABT-737 in combination therapy. To identify factors that may contribute to resistance to ABT-737 and related inhibitors, we isolated resistant derivatives of an initially sensitive cell line–based xenograft. Acquired resistance in this model was associated with decreases in the expression of the primary target Bcl-2, of proapoptotic partners of Bcl-2 (Bax and Bim), and of Bcl-2:Bim heterodimers. Expression profiling reveals 85 candidate genes demonstrating consistent changes in gene expression with acquired resistance. Taken together, these data have specific implications for the clinical development of Bcl-2 inhibitors for SCLC and broader implications for the testing of novel anti-cancer strategies in relevant preclinical models.
Aberrant activation of the Hedgehog (Hh) signaling pathway is one of the most prevalent abnormalities in human cancer. Tumors with cell autonomous Hh activation (e.g., medulloblastomas) can acquire secondary mutations at the Smoothened (Smo) antagonist binding pocket, which render them refractory to conventional Hh inhibitors. A class of Hh Pathway Inhibitors (HPIs) has been identified that block signaling downstream of Smo; one of these compounds, HPI-1, is a potent antagonist of the Hh transcription factor Gli1, and functions independent of upstream components in the pathway. Systemic administration of HPI-1 is challenging due to its minimal aqueous solubility and poor bioavailability. We engineered a polymeric nanoparticle from poly(lactic-co-glycolic acid) (PLGA) conjugated with polyethylene glycol (PEG), encapsulating HPI-1 (NanoHHI). NanoHHI particles have an average diameter ~60nM, forms uniform aqueous suspension, and improved systemic bioavailability compared to the parent compound. In contrast to the prototype targeted Smo antagonist, HhAntag (Genentech), NanoHHI markedly inhibits the growth of allografts derived from Ptch−/+;Trp53−/− mouse medulloblastomas that harbor a SmoD477G binding site mutation (P<0.001), which is accompanied by significant downregulation of mGli1, as well as bona fide Hh target genes (Akna, Cltb, Olig2). Notably, NanoHHI combined with gemcitabine also significantly impedes the growth of orthotopic Pa03C pancreatic cancer xenografts that have a ligand-dependent, paracrine mechanism of Hh activation, when compared to gemcitabine alone. No demonstrable hematological or biochemical abnormalities were observed with NanoHHI administration. NanoHHI should be amenable to clinical translation in settings where tumors acquire mutational resistance to current Smo antagonists.
Hedgehog; smoothened; Gli1; HPI-1; polymeric nanoparticle; NanoHHI; HhAntag
The majority of lung cancers are caused by long term exposure to the several classes of carcinogens present in tobacco smoke. While a significant fraction of lung cancers in never smokers may also be attributable to tobacco, many such cancers arise in the absence of detectable tobacco exposure, and may follow a very different cellular and molecular pathway of malignant transformation. Recent studies summarized here suggest that lung cancers arising in never smokers have a distinct natural history, profile of oncogenic mutations, and response to targeted therapy. The majority of molecular analyses of lung cancer have focused on genetic profiling of pathways responsible for metabolism of primary tobacco carcinogens. Limited research has been conducted evaluating familial aggregation and genetic linkage of lung cancer, particularly among never smokers in whom such associations might be expected to be strongest. Data emerging over the past several years demonstrates that lung cancers in never smokers are much more likely to carry activating mutations of the Epidermal Growth Factor Receptor (EGFR), a key oncogenic factor and direct therapeutic target of several newer anti-cancer drugs. EGFR mutant lung cancers may represent a distinct class of lung cancers, enriched in the never smoking population, and less clearly linked to direct tobacco carcinogenesis. These insights followed initial testing and demonstration of efficacy of EGFR-targeted drugs. Focused analysis of molecular carcinogenesis in lung cancers in never smokers is needed, and may provide additional biologic insight with therapeutic implications for lung cancers in both ever smokers and never smokers.
AT-101 is an oral inhibitor of the anti-apoptotic Bcl proteins (Bcl-2, Bcl-XL, Bcl-W, and Mcl-1) and an inducer of the pro-apoptotic proteins noxa and puma. We studied the efficacy of AT-101 in patients with recurrent chemosensitive extensive stage – small cell lung cancer (ES-SCLC).
Patients with recurrent “sensitive” SCLC (defined as no progression during and no disease recurrence < 2 months after completion of first-line platinum-based chemotherapy) were eligible. AT-101 was administered 20 mg orally daily for 21 out of 28 days each cycle for up to 6 cycles. The primary endpoint was the objective response rate.
At the time of planned interim evaluation, none of the 14 evaluable patients enrolled in the first stage had any response to therapy and the study was closed permanently for further accrual. Three patients (21 %) achieved stable disease after two cycles of therapy. Grade 3 toxicities included anorexia, fatigue, and nausea/vomiting.
AT-101 is not active in patients with recurrent chemosensitive SCLC. Supported by N01-CM62205.
Itraconazole is an antifungal drug that was recently found to possess potent antiangiogenic activity and anti-hedgehog (Hh) pathway activity. To search for analogues of itraconazole with greater potency and to understand the structure–activity relationship in both antiangiogenic and Hh targeting activity, 25 itraconazole side chain analogues were synthesized and assayed for inhibition of endothelial cell proliferation and Gli1 transcription in a medulloblastoma (MB) culture. Through this analysis, we have identified analogues with increased potency for inhibiting endothelial cell proliferation and the Hh pathway, as well as VEGFR2 glycosylation that was recently found to be inhibited by itraconazole. An SAR analysis of these activities revealed that potent activity of the analogues against VEGFR2 glycosylation was generally driven by side chains of at least four carbons in composition with branching at the α or β position. SAR trends for targeting the Hh pathway were divergent from those related to HUVEC proliferation or VEGFR2 glycosylation. These results also suggest that modification of the sec-butyl side chain can lead to enhancement of the biological activity of itraconazole.
To establish the safety, maximum tolerated dose (MTD), recommended phase II dose, and preliminary anti-tumor activity of obatoclax mesylate (GX15-070MS), a Bcl-2 antagonist, in combination with topotecan in patients with solid tumor malignancies.
Patients and methods
Patients with solid tumor malignancies for whom topotecan was an appropriate treatment were administered obatoclax mesylate and topotecan on a 3-week cycle in a pre-defined, standard 3 + 3 dose escalation scheme. The starting dose for obatoclax mesylate was 14 mg/m2 by 3-h intravenous (IV) infusion. Topotecan 1.25 mg/m2 was given concurrently as an IV infusion on days 1–5 of each cycle.
Fourteen patients received 40 cycles of obatoclax mesylate at the following doses: 14 mg/m2 on day 1, 14 mg/m2 on days 1 and 3, and 20 mg/m2 on day 1. The most common toxicities related to obatoclax were neurologic, including ataxia, mood alterations, somnolence, and cognitive dysfunction. The majority of these were grades 1 and 2 (88%). Two of five patients experienced dose-limiting grade 3 neurologic toxicity at a dose of 20 mg/m2; no patients experienced grade 4 neurologic toxicities, and no other patients experienced grade 3 neurologic toxicity. Of the patients who experienced grade 3 neurologic events, one later developed febrile neutropenia, which was also a dose-limiting toxicity (DLT). After an additional three patients were treated without DLT at the previously tolerated dose of 14 mg/m2 on day 1, the level was escalated to 14 mg/m2 on days 1 and 3. Three patients were treated at this dose and, with none experiencing a DLT, 14 mg/m2 on days 1 and 3 was defined as the recommended phase II dose. Two patients with small-cell lung cancer (SCLC) achieved partial responses and four patients had stable disease. Median time to progression (TTP) was 12 weeks.
Obatoclax mesylate administered at 14 mg/m2 IV on days 1 and 3 is safe and well tolerated when given in combination with topotecan 1.25 mg/m2 IV on days 1–5 of an every 3-week cycle. A phase II trial to assess the efficacy of this combination for patients with relapsed SCLC is currently accruing patients.
Small-cell lung cancer; Obatoclax mesylate; Topotecan; Apoptosis
This study assessed the effects of race and place of residence on clinical trial participation by patients seen at a designated NCI comprehensive cancer center. Clinical trial accrual to cancer case ratios were evaluated using a database of residents at the continental United States seen at The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins from 2005 to 2007. Place of residence was categorized into 3 nonoverlapping geographic areas: Baltimore City, non–Baltimore City catchment area, and non–catchment area. Controlling for age, sex, county poverty level, and cancer site, significant race and place of residence differences were seen in therapeutic or nontherapeutic clinical trials participation. White non–Baltimore City catchment area residents, the designated reference group, achieved the highest participation rate. Although the test of interaction (control group compared with all others) was not significant, some race–geographic area group differences were detected. In therapeutic trials, most race–place of residence group levels were statistically lower and different from reference; in nontherapeutic trials, race-specific Baltimore City groups participated at levels similar to reference. Baltimore City residents had lower participation rates only in therapeutic trials, irrespective of race. County poverty level was not significant but was retained as a confounder. Place of residence and race were found to be significant predictors of participation in therapeutic and nontherapeutic clinical trials, although patterns differed somewhat between therapeutic and nontherapeutic trials. Clinical trial accruals are not uniform across age, sex, race, place of residence, cancer site, or trial type, underscoring that cancer centers must better understand their source patients to enhance clinical trial participation.
Catchment area; health services area; clinical trials; accruals to cases ratio; accruals to cases ratio relative risk; Poisson regression; disparities