Pediatric gastrointestinal stromal tumors (GIST) are rare and occur
preferentially in females as multifocal gastric tumors, typically lacking
mutations in KIT and PDGFRA. As KIT
oncoprotein is consistently overexpressed in pediatric GIST, we sought to
investigate the activation of KIT downstream targets and alterations of
KIT/PDGFRA gene copy number, mine novel therapeutic
targets by gene expression, and test tyrosine kinase receptor activation by
Seventeen pediatric GISTs were investigated for
KIT/PDGFRA genotype and biochemical activation of KIT
downstream targets. The transcriptional profile of 13 nodules from 8
pediatric patients was compared with 8 adult wild-type (WT) GISTs, including
3 young adults. The drug sensitivity of second-generation kinase inhibitors
was tested in murine Ba/F3 cells expressing human WT KIT, as well as in
short-term culture of explants of WT GIST cells.
A KIT/PDGFRA WT genotype was identified in all 12
female patients, whereas two of five males had either a KIT
exon 11 or PDGFRA exon 18 mutation. KIT downstream targets
were consistently activated. Pediatric GISTs showed a distinct
transcriptional signature, with overexpression of BAALC, PLAG1,
IGF1R, FGF4, and NELL1. In vitro studies
showed that nilotinib, sunitinib, dasatinib, and sorafenib are more
effective than imatinib against WT KIT.
Rare cases of pediatric GIST may occur in male patients and harbor
activating KIT/PDGFRA mutations. Pediatric GISTs show
distinct transcriptional signature, suggesting a different biology than WT
GIST in adults. In vitro drug screening showed that
second-generation kinase inhibitors may provide greater clinical benefit in
To evaluate the efficacy of saracatinib (AZD0530), an oral Src inhibitor, in colorectal cancer (CRC) and to identify biomarkers that predict antitumor activity.
Twenty-three CRC cell lines were exposed to saracatinib, and baseline gene expression profiles of three sensitive and eight resistant cell lines in vitro and in vivo were used to predict saracatinib sensitivity in an independent group of 10 human CRC explant tumors using the gene array K-Top Scoring Pairs (K-TSP) method. In addition, fluorescence in situ hybridization (FISH) and immunoblotting determined both Src gene copy number and activation of Src, respectively.
Two of 10 explant tumors were determined to be sensitive to saracatinib. The K-TSP classifier (TOX>GLIS2, TSPAN7>BCAS4, and PARD6G>NXN) achieved 70% (7 of 10) accuracy on the test set. Evaluation of Src gene copy number by FISH showed a trend toward significance (P = 0.066) with respect to an increase in Src gene copy and resistance to saracatinib. Tumors sensitive to saracatinib showed an increase in the activation of Src and FAK when compared with resistant tumors.
Saracatinib significantly decreased tumor growth in a subset of CRC cell lines and explants. A K-TSP classifier (TOX>GLIS2, TSPAN7>BCAS4, and PARD6G>NXN) was predictive for sensitivity to saracatinib. In addition, increased activation of the Src pathway was associated with sensitivity to saracatinib. These results suggest that FISH, a K-TSP classifier, and activation of the Src pathway have potential in identifying CRC patients that would potentially benefit from treatment with saracatinib.
The adoptive transfer of T-cells modified to express a chimeric antigen receptor (CAR) comprised of an extracellular single chain antibody (scFV) fragment specific for a tumor cell surface molecule, and linked to an intracellular signaling module has activity in advanced malignancies. ROR1 is a tumor-associated molecule expressed on prevalent B-lymphoid and epithelial cancers, and is absent on normal mature B-cells and vital tissues, making it a candidate for CAR T-cell therapy.
We constructed ROR1-CARs from scFVs with different affinities and containing extracellular IgG4-Fc spacer domains of different lengths, and evaluated the ability of T-cells expressing each CAR to recognize ROR1+ hematopoietic and epithelial tumors in vitro, and to eliminate human mantle cell lymphoma engrafted into immunodeficient mice.
ROR1-CARs containing a short ‘Hinge-only’ extracellular spacer conferred superior lysis of ROR1+ tumor cells and induction of T-cell effector functions compared to CARs with long ‘Hinge-CH2-CH3’ spacers. CARs derived from a higher affinity scFV conferred maximum T-cell effector function against primary CLL and ROR1+ epithelial cancer lines in vitro without inducing activation induced T-cell death. T-cells modified with an optimal ROR1-CAR were equivalently effective as CD19-CAR modified T-cells in mediating regression of JeKo-1 mantle cell lymphoma in immunodeficient mice.
Our results demonstrate that customizing spacer design and increasing affinity of ROR1-CARs enhances T-cell effector function and recognition of ROR1+ tumors. T-cells modified with an optimized ROR1-CAR have significant anti-tumor efficacy in a preclinical model in vivo, suggesting they may be useful to treat ROR1+ tumors in clinical applications.
Adoptive immunotherapy; Chimeric antigen receptor (CAR); ROR1; Tumor antigen
Carfilzomib is a selective, irreversible inhibitor of the chymotrypsin-like activity of the proteasome and is undergoing clinical evaluation in myeloma. ONX 0912 (oprozomib) is an orally bioavailable derivative. The activities of carfilzomib and ONX 0912 against solid tumor malignancies are less well understood. We investigated the impact and mechanisms of action of carfilzomib and ONX 0912 in preclinical models of head and neck squamous cell carcinoma (HNSCC).
The effects of carfilzomib and ONX 0912 on HNSCC cell survival and xenograft tumor growth were evaluated. The impact and mechanisms of both agents on apoptosis and autophagy induction were also investigated. The contribution of the unfolded protein response (UPR) to autophagy induction and the role of autophagy in attenuating HNSCC cell death was determined.
Carfilzomib and ONX 0912 potently induced apoptosis in HNSCC cell lines via upregulation of proapoptotic Bik. Upregulation of Mcl-1 by these agents served to dampen their efficacies. Carfilzomib and ONX 0912 also induced autophagy, mediated, in part, by activation of the UPR pathway involving upregulation of ATF4 transcription factor. Autophagy induction served a prosurvival role. Oral administration of ONX 0912 inhibited the growth of HNSCC xenograft tumors in a dose-dependent manner.
These results show that carfilzomib and ONX 0912 are potently active against HNSCC cells, and the activities of these agents can be enhanced via suppresion of Mcl-1 or inhibition of autophagy. Oral ONX 0912 exhibits in vivo activity against HNSCC tumors, and may represent a useful therapeutic agent for this malignancy.
NUT midline carcinoma (NMC) is a poorly differentiated squamous cancer characterized by rearrangement of the NUT gene. Research advances have provided opportunities for targeted therapy in NMC, yet the clinical features of this rare disease have not been systematically characterized. We report on a large population of such patients to identify the disease characteristics and treatments, correlate them with outcome, and to consider clinical recommendations.
A clinical database was established using retrospective demographic and outcomes data available on all known cases of NMC. Questionnaires were completed by treating physicians. Pathologic, demographic, and clinical variables were assessed for 63 patients, the largest cohort of NMC patients studied to date. Outcome data from 54 patients were available for survival analyses.
The diagnosis of NMC has increased annually since 2007. Since 2009, there has been an observed increase in the age at diagnosis (p<0.05). Geographic distribution of NMC patients has been concentrated in the United States (n=41, 65%). The median overall survival for patients with NMC was 6.7 months. The 2-year progression-free survival (PFS) was 9% with a 95% CI of 1%–17% (1-year PFS 15% (5%–24%)) and 2-year overall survival (OS) was 19% with a 95% CI of 7%–31% (1-year OS: 30% (27%–34%). Multivariate analysis suggested that extent of surgical resection and initial radiotherapy were independent predictors of PFS and OS. Notably, no chemotherapeutic regimen was associated with improved outcome.
NMC portends a poor prognosis among all squamous cell neoplasms and appears to be frequently unrecognized. The finding that conventional chemotherapy has been inadequate indicates a pressing need for the development of targeted therapeutics. Intensive local therapies such as gross total resection and radiotherapy might be associated with enhanced survival.
NUT midline carcinoma; outcomes; registry
The understanding that oncogenes can have profound effects on cellular metabolism and the discovery of mutations and alterations in several metabolism-related enzymes (IDH1, IDH2, SDH, FH, PKM2) has renewed interest in cancer metabolism and renewed hope of taking therapeutic advantage of cancer metabolism. Otto Warburg observed that aerobic glycolysis was a characteristic of cancer cells. More than 50-years later, we understand that aerobic glycolysis and uptake of glutamine and glycine allow cancer cells to produce energy (ATP) and the nucleotides, amino acids and lipids required for proliferation. Expression of the MYC oncogene drives the increase in cellular biomass facilitating proliferation. PKM2 expression in cancer cells stimulates aerobic glycolysis. Amongst intermediary metabolism enzyme, mutations in succinate dehydrogenase (SDH) occur in gastointestinal stromal tumors and result in a pseudohypoxic metabolic milieu. Fumarate hydratase (FH) mutations lead to a characteristic renal cell carcinoma. Isocitrate dehydrogenase (IDH1/2) mutations have been found in leukemias, gliomas, prostate cancer, colon cancer, thyroid cancer and sarcomas. These recently recognized oncogenic metabolic lesions may be selective targets for new anticancer therapeutics.
Cancer metabolism; IDH1/2; PKM2; MYC; succinate dehydrogenase; fumarate hydratase
Accurate classification of Glioblastoma Multiforme (GBM) is crucial for understanding its biological diversity, and informing diagnosis and treatment. The Cancer Genome Atlas (TCGA) project identified four GBM classes using gene expression data, and separately, identified three classes using methylation data. We sought to integrate multiple data types in GBM classification, understand biological features of the newly defined subtypes, and reconcile with prior studies.
We used allele-specific copy number data to estimate the aneuploid content of each tumor, and incorporated this measure of intratumor heterogeneity in class discovery. We estimated the potential cell of origin of individual subtypes and the euploid and aneuploid fractions using reference datasets of known neuronal cell types.
There exists an unexpected correlation between aneuploid content and the observed among-tumor diversity of expression patterns. Joint use of DNA and mRNA data in ab initio class discovery revealed a distinct group that resembles the Proneural subtype described in a separate study and the G-CIMP+ class based on methylation data. Three additional subtypes, Classical, Proliferative, and Mesenchymal, were also identified, and revised the assignment for many samples. The revision showed stronger differences in patient outcome and clearer cell type-specific signatures. Mesenchymal GBMs had higher euploid content, potentially contributed by microglia/macrophage infiltration.
We clarified the confusion regarding the "Proneural" subtype that was defined differently in different prior studies. The ability to infer within-tumor heterogeneity improved class discovery, leading to new subtypes that are closer to the fundamental biology of GBM.
GBM; classification; aneuploid content; survival time; data integration
Surgical resection remains the most effective therapy for solid tumors worldwide. The most important prognostic indicator for cure following cancer surgery is a complete resection with no residual disease. However, intraoperative detection of retained cancer cells after surgery is challenging, and residual disease continues to be the most common cause of local failure. We hypothesized visual enhancement of tumors using near-infrared imaging could potentially identify tumor deposits in the wound after resection.
A small animal model of surgery and retained disease was developed. Residual tumor deposits in the wound were targeted using an FDA approved imaging agent, indocyanine green, by the enhanced permeability and retention (EPR) effect. A novel hand-held spectrometer was used to optically visualize retained disease after surgery.
We found residual disease using near-infrared imaging during surgery that was not visible to the naked eye or microCT. Furthermore, examination of tumor nodules was remarkably precise in delineating margins from normal surrounding tissues. This approach was most successful for tumors with increased neovasculature.
The results suggest that near-infrared examination of the surgical wound after curative resection can potentially enable the surgeon to locate residual disease. The data in this study is the basis of an ongoing Phase I/II clinical trial in patients who undergo resection for lung and breast cancer.
intraoperative imaging; surgical oncology; infrared; margins; indocyanine green
Recently, we showed that intratumoral delivery of low-dose, immunostimulatory CpG oligodeoxynucleotides conjugated with carbon nanotubes (CNT-CpG) was more effective than free CpG and not only eradicated intracranial (i.c.) gliomas, but also induced antitumor immunity that protected mice from subsequent i.c. or systemic tumor rechallenge. Here, we examined if the same “intracerebral immunotherapy” strategy could be applied to the treatment of metastatic brain tumors.
Mice with both i.c. and subcutaneous (s.c.) melanomas were injected intratumorally with CNT-CpG into either location. Antitumor responses were assessed by flow cytometry, bioluminescent imaging, and animal survival.
When given s.c., CNT-CpG response was mostly local, and it only modestly inhibited the growth of i.c. melanomas. However, i.c. CNT-CpG abrogated the growth of not only brain, but also s.c. tumors. Furthermore, compared to s.c. injections, i.c. CNT-CpG elicited a stronger inflammatory response that resulted in more potent antitumor cytotoxicity and improved in vivo trafficking of effector cells into both i.c. and s.c. tumors. To investigate factors that accounted for these observations, CNT-CpG biodistribution and cellular inflammatory responses were examined in both tumor locations. Intracranial melanomas retained the CNT-CpG particles longer and were infiltrated by TLR-9-positive microglia. In contrast, myeloid-derived suppressive cells were more abundant in s.c. tumors. Although depletion of these cells prior to s.c. CNT-CpG therapy enhanced its cytotoxic responses, antitumor responses to brain melanomas were unchanged.
These findings suggest that intracerebral CNT-CpG immunotherapy is more effective than systemic therapy in generating antitumor responses that target both brain and systemic melanomas.
Brain neoplasm; immunotherapy; immune-privilege; nanoparticle; toll-like receptor-9
To investigate the role of ontogeny in sorafenib metabolism to the equipotent active metabolite sorafenib N-oxide.
Steady-state pharmacokinetic studies of sorafenib and metabolites were performed in thirty children and young adults (17 males; median age, 9.5 years) receiving sorafenib 150 mg/m2 or 200 mg/m2 twice daily. Sorafenib metabolism was evaluated in vitro at 10 µM using a panel of purified human cytochrome P450 (CYP) enzymes. Sorafenib metabolism and CYP3A4 expression was evaluated in 52 human liver samples from donors ≤ 20 years old. The drug-drug interaction potential between sorafenib and azole antifungal agents was evaluated in vitro and in vivo.
No age-related differences in sorafenib apparent oral clearance were observed. Mean sorafenib N-oxide metabolite ratio was 0.27±0.14. In children ≤ 10 years of age, boys had approximately 2-fold higher N-oxide ratios than girls (0.40±0.15 versus 0.22±0.12, P = 0.026). Of the CYPs evaluated, sorafenib was exclusively metabolized to sorafenib N-oxide by CYP3A4. A trend for increased N-oxide formation in boys was observed in liver samples, which correlated with CYP3A4 mRNA expression. Posaconazole and voriconazole potently inhibited sorafenib N-oxide formation in vitro, and reduced sorafenib N-oxide formation in 3 children given sorafenib concurrent with azoles.
We have identified several factors affecting inter-patient variability in sorafenib metabolism to the active N-oxide metabolite including age, sex, and concurrent treatment with azole antifungals. This knowledge may provide important considerations for the clinical use of sorafenib in children and possibly other kinase inhibitors undergoing CYP3A4-mediated metabolism.
sorafenib; ontogeny; metabolism; CYP3A4; UGT1A9; drug-drug interaction
The processes of cellular growth regulation and cellular metabolism are closely inter-related. The c-Myc oncogene is a “master regulator” which controls many aspects of both of these processes. The metabolic changes which occur in transformed cells, many of which are driven by c-Myc overexpression, are necessary to support the increased need for nucleic acids, proteins and lipids necessary for rapid cellular proliferation. At the same time, c-Myc overexpression results in coordinated changes in level of expression of gene families which result in increased cellular proliferation. This interesting duality of c-Myc effects places it in the mainstream of transformational changes and gives it a very important role in regulating the “transformed phenotype”. The effects induced by c-Myc can occur either as a “primary oncogene” which is activated by amplification or translocation; or as a downstream effect of other activated oncogenes. In either case, it appears that c-Myc plays a central role in sustaining the changes which occur with transformation. Although efforts to utilize c-Myc as a therapeutic target have been quite frustrating, it appears that this may change in the next few years.
c-Myc; Glycolysis; Cancer Metabolism; Metabolic Transformation
We tested the hypothesis that allosteric Akt inhibitor MK-2206 inhibits tumor growth, and that PTEN/PIK3CA mutations confer MK-2206 sensitivity.
MK-2206 effects on cell signaling were assessed in vitro and in vivo. Its antitumor efficacy was assessed in vitro in a panel of cancer cell lines with differing PIK3CA and PTEN status. Its in vivo efficacy was tested as a single agent and in combination with paclitaxel.
MK-2206 inhibited Akt signaling and cell-cycle progression, and increased apoptosis in a dose-dependent manner in breast cancer cell lines. Cell lines with PTEN or PIK3CA mutations were significantly more sensitive to MK-2206; however, several lines with PTEN/PIK3CA mutations were MK-2206 resistant. siRNA knockdown of PTEN in breast cancer cells increased Akt phosphorylation concordant with increased MK-2206 sensitivity. Stable transfection of PIK3CA E545K or H1047R mutant plasmids into normal-like MCF10A breast cells enhanced MK-2206 sensitivity. Cell lines that were less sensitive to MK-2206 had lower ratios of Akt1/Akt2 and had less growth inhibition with Akt siRNA knockdown. In PTEN-mutant ZR75-1 breast cancer xenografts, MK-2206 treatment inhibited Akt signaling, cell proliferation, and tumor growth. In vitro, MK-2206 showed a synergistic interaction with paclitaxel in MK-2206–sensitive cell lines, and this combination had significantly greater antitumor efficacy than either agent alone in vivo.
MK-2206 has antitumor activity alone and in combination with chemotherapy. This activity may be greater in tumors with PTEN loss or PIK3CA mutation, providing a strategy for patient enrichment in clinical trials.
Although cyclooxygenase (COX)-2 inhibitors could represent the most effective chemopreventive tool against colorectal cancer (CRC), their use in clinical practice is hampered by cardiovascular side effects. Consumption of ω-3-polyunsaturated fatty acids (ω-3-PUFAs) is associated with a reduced risk of CRC. Therefore, in this study, we assessed the efficacy of a novel 99% pure preparation of ω-3-PUFA eicosapentaenoic acid as free fatty acids (EPA-FFA) on polyps in ApcMin/+ mice.
ApcMin/+ and corresponding wild-type mice were fed control diet (Ctrl) or diets containing either EPA-FFA 2.5% or 5%, for 12 weeks while monitoring food intake and body weight.
We found that both EPA-FFA diets protected from the cachexia observed among ApcMin/+ animals fed Ctrl diet (P < 0.0054), without toxic effect, in conjunction with a significant decrease in lipid peroxidation in the treated arms. Moreover, both EPA-FFA diets dramatically suppressed polyp number (by 71.5% and 78.6%, respectively; P < 0.0001) and load (by 82.5% and 93.4%, respectively; P < 0.0001) in both small intestine and colon. In addition, polyps less than 1 mm in size were predominantly found in the EPA-FFA 5% arm whereas those 1 to 3 mm in size were more frequent in the Ctrl arm (P <0.0001). Interestingly, in the EPA-FFA groups, mucosal arachidonic acid was replaced by EPA (P < 0.0001), leading to a significant reduction in COX-2 expression and β-catenin nuclear translocation. Moreover, in the EPA-FFA arms, we found a significant decrease in proliferation throughout the intestine together with an increase in apoptosis.
Our data make 99% pure EPA-FFA an excellent candidate for CRC chemoprevention.
Previous studies have demonstrated that the replication checkpoint, which involves the kinases ATR and Chk1, contributes to cytarabine resistance in cell lines. In the present study, we examined whether this checkpoint is activated in clinical AML during cytarabine infusion in vivo and then assessed the impact of combining cytarabine with the recently described Chk1 inhibitor SCH 900776 in vitro.
AML marrow aspirates harvested before and during cytarabine infusion were examined by immunoblotting. Human AML lines treated with cytarabine in the absence or presence of SCH 900776 were assayed for checkpoint activation by immunoblotting, nucleotide incorporation into DNA and flow cytometry. Long-term effects in AML lines, clinical AML isolates, and normal myeloid progenitors were assayed using clonogenic assays.
Immunoblotting demonstrated increased Chk1 phosphorylation, a marker of checkpoint activation, in over half of Chk1-containing AMLs after 48 h of cytarabine infusion. In human AML lines, SCH 900776 not only disrupted cytarabine-induced Chk1 activation and S phase arrest, but also markedly increased cytarabine-induced apoptosis. Clonogenic assays demonstrated that SCH 900776 enhanced the anti-proliferative effects of cytarabine in AML cell lines and clinical AML samples at concentrations that had negligible impact on normal myeloid progenitors.
These results not only provide evidence for cytarabine-induced S phase checkpoint activation in AML in the clinical setting, but also show that a selective Chk1 inhibitor can overcome the S phase checkpoint and enhance the cytotoxicity of cytarabine. Accordingly, further investigation of the cytarabine/SCH 900776 combination in AML appears warranted.
To assess the efficacy of Rapamycin treatment in chemoprevention and chemotherapy of tumorigenesis in a genetically-defined mouse model of head and neck squamous cell carcinoma (HNSCC).
Knockdown of Tgfbr1 and/or Pten using siRNA-mediated RNA interference was carried out in human HNSCC cell lines to analyze molecular changes in the mTOR pathway. Tgfbr1flox/flox; Ptenflox/flox; K14-CreERtam mice were treated with oral gavage of tamoxifen for the conditional deletion of Tgfbr1 and Pten in oral mucosa, resuting in HNSCC (Bian et al 2011). Tgfbr1 and Pten conditonal deletion (2cKO) mice were treated with Rapamycin before or after the onset of HNSCC, and the efficacy of this treatment was assessed by determining tumor burden, longevity, and molecular analysis of the mTOR pathway. Molecular changes observed in human HNSCC cell lines and 2cKO mice were compared to identify key alterations in the mTOR pathway.
Knockdown of Tgfbr1 and/or Pten in human HNSCC cell lines resulted in activation of mTORC1 and increased levels of survivin. Furthermore, we observed similar changes in HNSCC of the 2cKO mouse. In the human HNSCC tissue array, a loss of Tgfbr1 expression correlated with increased survivin levels. Chemopreventive Rapamycin treatment significantly delayed the onset of the HNSCC tumors and prolonged survival in 2cKO mice. Additionally, we also found that Rapamycin had a therapeutic effect on squamous cell carcinomas in these mice. In 2cKO HNSCC tongue tumors, Rapamycin treatment induced apoptosis, inhibited cell proliferation and phosphorylation of Akt and S6, and decreased survivin expression.
These findings indicate that tumorigenesis in 2cKO HNSCC is associated with activation of the Akt/mTOR/survivin pathway, and inhibition of this pathway by Rapamycin treatment successfully ameliorates the onset and progression of tumorigenesis.
TGF-β; Pten; head and neck cancer; mTOR; survivin
Recent high throughput genomic sequencing studies of solid tumors, including head and neck squamous cell carcinoma (SCC), ovarian cancer, lung adenocarcinoma, glioblastoma, breast cancer and lung SCC, have highlighted DNA mutation as a mechanism for aberrant Notch signaling. A primary challenge of targeting Notch for treatment of solid malignancies is determining whether Notch signaling is cancer-promoting or tumor-suppressing for a specific cancer. We compiled reported Notch receptor and ligand missense and nonsense mutations in order glean insights into aberrant Notch signaling.
Frequencies of coding mutations differed for the four Notch genes. 4.7% of tumors harbored NOTCH1 missense or nonsense mutations. NOTCH2 and NOTCH3 had similar overall mutation rates of 1.5% and 1.3%, respectively, while NOTCH4 mutations were rarer. Notch ligand genes were rarely mutated.
The combined mutation frequency and position spectra of the four Notch paralogs across the different cancers provide an opportunity to begin to illuminate the different contributions of each Notch paralog to each tumor type and to identify opportunities for therapeutic targeting. Notch signaling pathway activators and inhibitors are currently in early clinical development for treatment of solid malignancies. Defining the status and consequences of altered Notch signaling will be important for selection of appropriate treatment.
The rate of observed dose-limiting toxicities (DLTs) determines the maximum tolerated dose (MTD) in phase I trials. There are cases in which non-drug-related toxicities or other cause toxicities (OCTs) are flagged as DLTs, or vice versa, due to attribution errors. We aim to assess the impact of such errors on the final estimate of MTD. We compared the impact of attribution errors using two trial designs—the “3+3” dose-escalation scheme and the Continual Reassessment Method (CRM). Two attribution errors are considered: when a DLT is classified as an OCT (Type A error) and when an OCT is misclassified as a DLT (Type B error). The impact of these errors on accuracy, patient safety, sample size, and study duration was evaluated by varying the probability of occurrence of each error through simulated trials. Under no errors, CRM is on average 35% more accurate than 3+3 in finding the true MTD. This improved accuracy is maintained in the presence of errors. At a 15% Type B error rate, CRM recommends a dose within 2 levels of the true MTD 68% of the time, compared to 17% of the time using the 3+3 method. A DLT must be attributed as an OCT 30% of the time in order to increase the accuracy of 3+3, otherwise the method recommends a wrong dose approximately 75% of the time. CRM is more robust to toxicity attribution errors compared to the 3+3 since it uses information from all treated patients, leading to a more accurate MTD estimation at the frequency of attribution errors anticipated in phase I clinical trials.
The Ewing Sarcoma Family of Tumors (ESFTs) comprises a group of aggressive, malignant bone and soft tissue tumors that predominantly affect children and young adults. These tumors frequently share expression of the EWS-FLI-1 translocation, which is central to tumor survival but not present in healthy cells. In this study, we examined EWS-FLI-1 antigens for their capacity to induce immunity against a range of ESFT types.
Computer prediction analysis of peptide binding, HLA-A2.1 stabilization assays, and induction of Cytotoxic T-Lymphocytes (CTL) in immunized HLA-A2.1 transgenic mice were used to assess the immunogenicity of native and modified peptides derived from the fusion region of EWS-FLI-1 type 1. CTL-killing of multiple ESFT family members in vitro, and control of established xenografts in vivo, was assessed. We also examined whether these peptides could induce human CTLs in vitro.
EWS-FLI-1 type 1 peptides were unable to stabilize cell surface HLA-A2.1 and induced weak CTL activity against Ewing Sarcoma cells. In contrast, peptides with modified anchor residues induced potent CTL killing of Ewing Sarcoma cells presenting endogenous (native) peptides. The adoptive transfer of CTL specific for the modified peptide YLNPSVDSV resulted in enhanced survival of mice with established Ewing Sarcoma xenografts. YLNPSVDSV-specific CTL displayed potent killing of multiple ESFT types in vitro: Ewing Sarcoma, pPNET, Askin’s Tumor, and Biphenotypic Sarcoma. Stimulation of human Peripheral Blood Mononuclear Cells with YLNPSVDSV peptide resulted in potent CTL-killing.
These data show that YLNPSVDSV peptide is a promising antigen for ESFT immunotherapy and warrants further clinical development.
Ewing Sarcoma Family of Tumors; Ewing Sarcoma; pPNET; Askin’s Tumor; Biphenotypic sarcoma; EWS-FLI-1; Immunotherapy; vaccine; cancer; HLA-A2.1; HLA-A*0201
Malignant mesothelioma (MM) is an aggressive cancer, resistant to current therapies. Membrane Chondroitin Sulphate Proteoglycan 4 (CSPG4), which has been successfully targeted in melanoma and breast cancer, was found highly expressed in MM, but not in normal mesothelium. Therefore, we explored CSPG4 as a suitable target for monoclonal antibody (mAb)-based immunotherapy of MM.
We assayed adhesion, motility, invasiveness, wound-healing, apoptosis and anchorage-independent growth of MM cells on cell cultures. CSPG4 expression and signaling was studied by immunoblotting. The growth of MM SCID mice xenografts induced by PPM-Mill cells, engineered to express the luciferase reporter gene, was monitored by imaging, upon treatment with CSPG4 mAb TP41.2. Animal toxicity and survival were assayed in both tumor inhibition and therapeutic experiments.
CSPG4 was expressed on 6 out of 8 MM cell lines and in 25 out of 41 MM biopsies, with minimal expression in surrounding healthy cells. MM cell adhesion was mediated by CSPG4-dependent engagement of extracellular matrix components (ECM). Cell adhesion was inhibited by mAb TP41.2 resulting in decreased phosphorylation of FAK and AKT, reduced expression of cyclin D1 and apoptosis. Moreover, TP41.2 significantly reduced MM cell motility, migration and invasiveness, and inhibited MM growth in soft agar. In vivo, treatment with mAb TP41.2 prevented or inhibited the growth of MM xenografts in SCID mice, with a significant increase in animal survival.
These results establish the safety of CSPG4 mAb-based immunotherapy and suggest that CSPG4 mAb-based immunotherapy may represent a novel approach for the treatment of MM.
Mesothelioma; CSPG4; immunotherapy; neutralizing antibodies; xenografts
In this study, we assessed the specific role of BRAF(V600E) signaling in modulating the expression of immune regulatory genes in melanoma, in addition to analyzing downstream induction of immune suppression by primary human melanoma tumor-associated fibroblasts (TAFs).
Primary human melanocytes and melanoma cell lines were transduced to express WT or V600E forms of BRAF, followed by gene expression analysis. The BRAF(V600E) inhibitor vemurafenib was used to confirm targets in BRAF(V600E)-positive melanoma cell lines and in tumors from melanoma patients undergoing inhibitor treatment. TAF lines generated from melanoma patient biopsies were tested for their ability to inhibit the function of tumor antigen-specific T-cells, prior to and following treatment with BRAF(V600E)-upregulated immune modulators. Transcriptional analysis of treated TAFs was conducted to identify potential mediators of T-cell suppression.
Expression of BRAF(V600E) induced transcription of IL-1α and IL-1β in melanocytes and melanoma cell lines. Furthermore, vemurafenib reduced the expression of IL-1 protein in melanoma cell lines and most notably in human tumor biopsies from 11 of 12 melanoma patients undergoing inhibitor treatment. Treatment of melanoma-patient-derived TAFs with IL-1α/β significantly enhanced their ability to suppress the proliferation and function of melanoma-specific cytotoxic T cells, and this inhibition was partially attributable to upregulation by IL-1 of COX-2 and the PD-1 ligands PD-L1 and PD-L2 in TAFs.
This study reveals a novel mechanism of immune suppression sensitive to BRAF(V600E) inhibition, and suggests that clinical blockade of IL-1 may benefit patients with BRAF wild-type tumors and potentially synergize with immunotherapeutic interventions.
Melanoma; BRAF(V600E); interleukin-1; tumor-associated fibroblasts (TAFs); cytotoxic T lymphocytes (CTL)
We conducted a phase I study of dasatinib, an oral SRC-family tyrosine kinase inhibitor, in combination with paclitaxel and carboplatin in advanced and recurrent epithelial ovarian cancer.
The primary objective was to determine the maximum tolerated dose (MTD). Secondary objectives included defining toxicity, response rate (RR), pharmacokinetics and pharmacodynamics. Using a “3+3” design, cohorts of 3–6 patients received paclitaxel (175 mg/m2) and carboplatin (AUC 6) every three weeks with escalating doses of dasatinib (100, 120, 150 mg daily), followed by an 8 patient expansion cohort.
Twenty patients were enrolled between 06/07 and 12/09. The median age was 61 years (42–82) with a median of 2 prior regimens (0–6), and 71% had platinum-sensitive disease. There were 3–6 patients in each cohort, and 8 in the expansion cohort. Pharmacokinetics were observed over the first 2 cycles of therapy. One DLT was observed in the 100 mg dasatinib cohort (grade 3 myalgia). Other toxicities in all cycles included neutropenia (95% grade 3–4; 91% in the 150 mg dosing cohort), thrombocytopenia (35% grade 3–4), and fatigue (10% grade 3). The RR was 40% (3 complete responses, (15%); 5 partial responses, (25%)),10 (50%) had stable disease, and 2 were not evaluable. The PFS6-month actuarial estimate was 86%. The median PFS and OS were 7.8 and 16.2 months, respectively.
Due to the high incidence of myelosuppression with subsequent cycles the recommended phase II dose of dasatinib is 150 mg daily in combination with paclitaxel and carboplatin. The combination was safe with evidence of clinical activity.
dasatinib; chemotherapy; ovarian cancer
Active surveillance (AS) has been endorsed for low-risk prostate cancer, but information about long-term outcomes and comparative effectiveness of AS is lacking. The purpose of this study is to project prostate cancer mortality under AS followed by radical prostatectomy (RP) versus under immediate RP.
A simulation model was developed to combine information on time from diagnosis to treatment under AS and associated disease progression from a Johns Hopkins AS cohort (n=769), time from RP to recurrence from cases in the CaPSURE database with T-stage ≤ T2a (n=3,470), and time from recurrence to prostate cancer death from a T-stage ≤ T2a Johns Hopkins cohort of patients whose disease recurred after RP (n=963). Results were projected for a hypothetical cohort aged 40–90 years with low-risk prostate cancer (T-stage ≤ T2a, Gleason score ≤ 6, and PSA level ≤ 10 ng/mL).
The model projected that 2.8% of men on AS and 1.6% of men with immediate RP would die of their disease in 20 years. Corresponding lifetime estimates were 3.4% for AS and 2.0% for immediate RP. The average projected increase in life expectancy associated with immediate RP was 1.8 months. On average, the model projected that men on AS would remain free of treatment for an additional 6.4 years relative to men treated immediately.
AS is likely to produce a very modest decline in prostate-cancer-specific survival among men diagnosed with low-risk prostate cancer but could lead to significant benefits in terms of quality of life.
Active surveillance; radical prostatectomy; prostaticneoplasms; Gleason score
To identify mediators of glioblastoma anti-angiogenic therapy resistance and target these mediators in xenografts.
We performed microarray analysis comparing bevacizumab-resistant glioblastomas (BRGs) to pre-treatment tumors from the same patients. We established novel xenograft models of anti-angiogenic therapy resistance to target candidate resistance mediator(s).
BRG microarray analysis revealed upregulation versus pre-treatment of receptor tyrosine kinase c-Met, which underwent further investigation because of its prior biologic plausibility as a bevacizumab resistance mediator. BRGs exhibited increased hypoxia versus pre-treatment in a manner correlating with their c-Met upregulation, increased c-Met phosphorylation, and increased phosphorylation of c-Met-activated focal adhesion kinase (FAK) and STAT3. We developed two novel xenograft models of anti-angiogenic therapy resistance. In the first model, serial bevacizumab treatment of an initially responsive xenograft generated a xenograft with acquired bevacizumab resistance, which exhibited upregulated c-Met expression versus pre-treatment. In the second model, a BRG-derived xenograft maintained refractoriness to the MRI tumor vasculature alterations and survival-promoting effects of bevacizumab. Growth of this BRG-derived xenograft was inhibited by a c-Met inhibitor. Transducing these xenograft cells with c-Met shRNA inhibited their invasion and survival in hypoxia, disrupted their mesenchymal morphology, and converted them from bevacizumab-resistant to bevacizumab-responsive. Engineering bevacizumab-responsive cells to express constitutively active c-Met caused these cells to form bevacizumab-resistant xenografts.
These findings support the role of c-Met in survival in hypoxia and invasion, features associated with anti-angiogenic therapy resistance; and growth and therapeutic resistance of xenografts resistant to anti-angiogenic therapy. Therapeutically targeting c-Met could prevent or overcome anti-angiogenic therapy resistance.
bevacizumab; resistance; glioblastoma; invasion; c-Met
Cytokines such as IL-6 and G-CSF are important metastasis promoters. This study has investigated the functional significance of the increased circulation of galectin-3, a common feature in cancer patients and in particular those with metastasis, on cytokine secretion from the blood vascular endothelium in cancer.
The effects of galectin-3 on secretion of cytokines from human microvascular lung endothelial cells were assessed in vitro by cytokine array and in vivo in mice. The consequences of galectin-3-induced cytokine secretion on endothelial cell behaviors were determined and the relationship between the levels of circulating galectin-3 and cytokines in colorectal cancer patients with and without metastasis was investigated.
Galectin-3 at pathological concentrations found in cancer patients induces secretion of IL-6, G-CSF, sICAM-1 and GM-CSF from blood vascular endothelial cells in vitro and in mice. These cytokines autocrinely/paracrinely interact with the vascular endothelium to increase the expressions of endothelial cell surface adhesion molecules integrinαvβ1, E-selectin, ICAM-1 and VCAM-1, resulting in increased cancer cell-endothelial adhesion and increased endothelial cell migration and tubule formation. In patients with metastatic colon cancer, higher serum galectin-3 levels correlated significantly with increased serum G-CSF, IL-6 and sICAM1 concentrations.
The increased circulation of galectin-3 in cancer patients induces secretion of several metastasis-promoting cytokines from the blood vascular endothelium that enhances endothelial cell activities in metastasis. Targeting the actions of circulating galectin-3 in cancer patients therefore represents a promising therapeutic strategy to reduce metastasis and improve survival.
galectin-3; cytokines; adhesion; metastasis
Because dexamethasone remains a key component of myeloma therapy, we wished to examine the impact of baseline and relapse expression levels of the glucocorticoid receptor gene NR3C1 on survival outcomes in the context of treatment with or without thalidomide.
We investigated the clinical impact of gene expression profiling (GEP)–derived expression levels of NR3C1 in 351 patients with GEP data available at baseline and in 130 with data available at relapse, among 668 subjects accrued to Total Therapy 2 (TT2).
Low NR3C1 expression levels had a negative impact on progression-free survival (PFS, HR=1.47; p=0.030) and overall survival (OS, HR=1.90; p=0.002) in the no-thalidomide arm. Conversely, there was a significant clinical benefit of thalidomide for patients with low receptor levels (OS, HR=0.54, p=0.015; PFS, HR=0.54, p=0.004), mediated most likely by thalidomide’s up-regulation of NR3C1. In the context of both baseline and relapse parameters, post-relapse survival (PRS) was adversely affected by low NR3C1 levels at relapse in a multivariate analysis (HR=2.61, p=0.012).
These findings justify the inclusion of NR3C1 expression data in the work-up of patients with myeloma as it can significantly influence the choice of therapy and, ultimately, OS. The identification of an interaction term between thalidomide and NR3C1 underscores the importance of pharmacogenomic studies in the systematic study of new drugs.
Myeloma; Glucocorticoids; Glucocorticoid Receptor; Total Therapy 2; Thalidomide