Small-cell lung cancer (SCLC), an aggressive neuroendocrine tumor with early dissemination and dismal prognosis, accounts for 15-20% of lung cancer cases and ∼200,000 deaths each year. Most cases are ...inoperable, and biopsies to investigate SCLC biology are rarely obtainable. Circulating tumor cells (CTCs), which are prevalent in SCLC, present a readily accessible 'liquid biopsy'. Here we show that CTCs from patients with either chemosensitive or chemorefractory SCLC are tumorigenic in immune-compromised mice, and the resultant CTC-derived explants (CDXs) mirror the donor patient's response to platinum and etoposide chemotherapy. Genomic analysis of isolated CTCs revealed considerable similarity to the corresponding CDX. Most marked differences were observed between CDXs from patients with different clinical outcomes. These data demonstrate that CTC molecular analysis via serial blood sampling could facilitate delivery of personalized medicine for SCLC. CDXs are readily passaged, and these unique mouse models provide tractable systems for therapy testing and understanding drug resistance mechanisms.
The monocarboxylate transporter 1 (MCT1) inhibitor, AZD3965, is undergoing phase I evaluation in the United Kingdom. AZD3965 is proposed, via lactate transport modulation, to kill tumor cells reliant ...on glycolysis. We investigated the therapeutic potential of AZD3965 in small cell lung cancer (SCLC) seeking rationale for clinical testing in this disease and putative predictive biomarkers for trial use.
AZD3965 sensitivity was determined for seven SCLC cell lines, in normoxia and hypoxia, and for a tumor xenograft model. Proof of mechanism was sought via changes in intracellular/tumor lactate. Expression of MCT1 and related transporter MCT4 was assessed by Western blot analysis. Drug resistance was investigated via MCT4 siRNAi and overexpression. The expression and clinical significance of MCT1 and MCT4 were explored in a tissue microarray (TMA) from 78 patients with SCLC.
AZD3965 sensitivity varied in vitro and was highest in hypoxia. Resistance in hypoxia was associated with increased MCT4 expression. In vivo, AZD3965 reduced tumor growth and increased intratumor lactate. In the TMA, high MCT1 expression was associated with worse prognosis (P = 0.014). MCT1 and hypoxia marker CA IX expression in the absence of MCT4 was observed in 21% of SCLC tumors.
This study provides a rationale to test AZD3965 in patients with SCLC. Our results suggest that patients with tumors expressing MCT1 and lacking in MCT4 are most likely to respond.
In most patients with small-cell lung cancer (SCLC)-a metastatic, aggressive disease-the condition is initially chemosensitive but then relapses with acquired chemoresistance. In a minority of ...patients, however, relapse occurs within 3 months of initial treatment; in these cases, disease is defined as chemorefractory. The molecular mechanisms that differentiate chemosensitive from chemorefractory disease are currently unknown. To identify genetic features that distinguish chemosensitive from chemorefractory disease, we examined copy-number aberrations (CNAs) in circulating tumor cells (CTCs) from pretreatment SCLC blood samples. After analysis of 88 CTCs isolated from 13 patients (training set), we generated a CNA-based classifier that we validated in 18 additional patients (testing set, 112 CTC samples) and in six SCLC patient-derived CTC explant tumors. The classifier correctly assigned 83.3% of the cases as chemorefractory or chemosensitive. Furthermore, a significant difference was observed in progression-free survival (PFS) (Kaplan-Meier P value = 0.0166) between patients designated as chemorefractory or chemosensitive by using the baseline CNA classifier. Notably, CTC CNA profiles obtained at relapse from five patients with initially chemosensitive disease did not switch to a chemorefractory CNA profile, which suggests that the genetic basis for initial chemoresistance differs from that underlying acquired chemoresistance.
Introduced in 1987, platinum-based chemotherapy remains standard of care for small cell lung cancer (SCLC), a most aggressive, recalcitrant tumor. Prominent barriers to progress are paucity of tumor ...tissue to identify drug targets and patient-relevant models to interrogate novel therapies. Following our development of circulating tumor cell patient-derived explants (CDX) as models that faithfully mirror patient disease, here we exploit CDX to examine new therapeutic options for SCLC.
We investigated the efficacy of the PARP inhibitor olaparib alone or in combination with the WEE1 kinase inhibitor AZD1775 in 10 phenotypically distinct SCLC CDX
and/or
These CDX represent chemosensitive and chemorefractory disease including the first reported paired CDX generated longitudinally before treatment and upon disease progression.
There was a heterogeneous depth and duration of response to olaparib/AZD1775 that diminished when tested at disease progression. However, efficacy of this combination consistently exceeded that of cisplatin/etoposide, with cures in one CDX model. Genomic and protein analyses revealed defects in homologous recombination repair genes and oncogenes that induce replication stress (such as MYC family members), predisposed CDX to combined olaparib/AZD1775 sensitivity, although universal predictors of response were not noted.
These preclinical data provide a strong rationale to trial this combination in the clinic informed by prevalent, readily accessed circulating tumor cell-based biomarkers. New therapies will be evaluated in SCLC patients after first-line chemotherapy, and our data suggest that the combination of olaparib/AZD1775 should be used as early as possible and before disease relapse.
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The lack of actionable mutations in patients with non‐small cell lung cancer (NSCLC) presents a significant hurdle in the design of targeted therapies for this disease. Here, we identify somatically ...mutated ABL1 as a genetic dependency that is required to maintain NSCLC cell survival. We demonstrate that NSCLC cells with ABL1 mutations are sensitive to ABL inhibitors and we verify that the drug‐induced effects on cell viability are specific to pharmacological inhibition of the ABL1 kinase. Furthermore, we confirm that imatinib suppresses lung tumor growth in vivo, specifically in lung cancer cells harboring a gain‐of‐function (GOF) mutation in ABL1. Consistent with structural modeling, we demonstrate that mutations in ABL1 identified in primary NSCLC tumors and a lung cancer cell line increase downstream pathway activation compared to wild‐type ABL1. Finally, we observe that the ABL1 cancer mutants display an increased cytosolic localization, which is associated with the oncogenic properties of the ABL1 kinase. In summary, our results suggest that NSCLC patients with ABL1 mutations could be stratified for treatment with imatinib in combination with other therapies.
Synopsis
Somatically mutated ABL1 is defined as a novel druggable driver in lung adenocarcinoma where mutant forms of ABL1 kinase promote increased survival and proliferation, altered localization, and enhanced downstream pathway activation.
Lung cancer cells harboring ABL1 mutations are sensitive to ABL inhibitors.
Depletion of mutant ABL1 suppresses lung cancer cell viability.
ABL1 mutations alter localization and increase downstream pathway activation.
ABL1 mutants promote cell survival and proliferation.
Somatically mutated ABL1 is defined as a novel druggable driver in lung adenocarcinoma where mutant forms of ABL1 kinase promote increased survival and proliferation, altered localization, and enhanced downstream pathway activation.
Circulating miRNA stability suggests potential utility of miRNA based biomarkers to monitor tumor burden and/or progression, particularly in cancer types where serial biopsy is impractical. ...Assessment of miRNA specificity and sensitivity is challenging within the clinical setting. To address this, circulating miRNAs were examined in mice bearing human SCLC tumor xenografts and SCLC patient derived circulating tumor cell explant models (CDX). We identified 49 miRNAs using human TaqMan Low Density Arrays readily detectable in 10 μl tail vein plasma from mice carrying H526 SCLC xenografts that were low or undetectable in non-tumor bearing controls. Circulating miR-95 measured serially in mice bearing CDX was detected with tumor volumes as low as 10 mm3 and faithfully reported subsequent tumor growth.
Having established assay sensitivity in mouse models, we identified 26 miRNAs that were elevated in a stage dependent manner in a pilot study of plasma from SCLC patients (n = 16) compared to healthy controls (n = 11) that were also elevated in the mouse models. We selected a smaller panel of 10 previously reported miRNAs (miRs 95, 141, 200a, 200b, 200c, 210, 335#, 375, 429) that were consistently elevated in SCLC, some of which are reported to be elevated in other cancer types. Using a multiplex qPCR assay, elevated levels of miRNAs across the panel were also observed in a further 66 patients with non-small cell lung, colorectal or pancreatic cancers. The utility of this circulating miRNA panel as an early warning of tumor progression across several tumor types merits further evaluation in larger studies.
•Simple miRNA assay developed suitable for plasma volumes as low as 10 μl.•Assay suitable for serial weekly monitoring of human xenograft growth in mice.•Can detect xenograft tumor volumes as low as 10 mm3 and correlates with tumor growth.•Selected miRNAs elevated in SCLC, NSCLC, colorectal and pancreatic cancers.
The Siberian hamster exhibits the key winter adaptive strategy of daily torpor, during which metabolism and heart rate are slowed for a few hours and body temperature declines by up to 20 degrees C, ...allowing substantial energetic savings. Previous studies of hibernators in which temperature drops by >30 degrees C for many days to weeks have revealed decreased transcription and translation during hypometabolism and identified several key physiological pathways involved. Here we used a cDNA microarray to define cardiac transcript changes over the course of a daily torpor bout and return to normothermia, and we show that, in common with hibernators, a relatively small proportion of the transcriptome (<5%) exhibited altered expression over a torpor bout. Pathways exhibiting significantly altered gene expression included transcriptional regulation, RNA stability and translational control, globin regulation, and cardiomyocyte function. Remarkably, gene representatives of the entire ubiquitylation pathway were significantly altered over the torpor bout, implying a key role for cardiac protein turnover and translation during a low-temperature torpor bout. The circadian clock maintained rhythmic transcription during torpor. Quantitative PCR profiling of heart, liver, and lung and in situ hybridization studies of clock genes in the hypothalamic circadian clock in the suprachiasmatic nucleus revealed that many circadian regulated transcripts exhibited synchronous alteration in expression during arousal. Our data highlight the potential importance of genes involved in protein turnover as part of the adaptive strategy of low-temperature torpor in a seasonal mammal.
Abstract
The lack of actionable mutations in patients with non‐small cell lung cancer (
NSCLC
) presents a significant hurdle in the design of targeted therapies for this disease. Here, we identify ...somatically mutated
ABL
1
as a genetic dependency that is required to maintain
NSCLC
cell survival. We demonstrate that
NSCLC
cells with
ABL
1
mutations are sensitive to
ABL
inhibitors and we verify that the drug‐induced effects on cell viability are specific to pharmacological inhibition of the
ABL
1 kinase. Furthermore, we confirm that imatinib suppresses lung tumor growth
in vivo
, specifically in lung cancer cells harboring a gain‐of‐function (
GOF
) mutation in
ABL
1. Consistent with structural modeling, we demonstrate that mutations in
ABL
1
identified in primary
NSCLC
tumors and a lung cancer cell line increase downstream pathway activation compared to wild‐type
ABL
1. Finally, we observe that the
ABL
1 cancer mutants display an increased cytosolic localization, which is associated with the oncogenic properties of the
ABL
1 kinase. In summary, our results suggest that
NSCLC
patients with
ABL
1
mutations could be stratified for treatment with imatinib in combination with other therapies.
Synopsis
image
Somatically mutated
ABL
1 is defined as a novel druggable driver in lung adenocarcinoma where mutant forms of
ABL
1 kinase promote increased survival and proliferation, altered localization, and enhanced downstream pathway activation.
Lung cancer cells harboring ABL1 mutations are sensitive to ABL inhibitors.
Depletion of mutant ABL1 suppresses lung cancer cell viability.
ABL1 mutations alter localization and increase downstream pathway activation.
ABL1 mutants promote cell survival and proliferation.
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