Synergistic effects of imatinib (STI 571) in combination with chemotherapeutic drugs in head and neck cancer

RTKs in pathobiology of head and neck cancers

Non-communicable diseases contribute to 71% of the deaths worldwide, of which cancers rank second after cardiovascular diseases. Among all the cancers, head and neck cancers (HNC) are consequential in augmenting the global cancer incidence as well as mortality. Receptor tyrosine kinases (RTKs) are emphatic for the matter that they serve as biomarkers aiding the analysis of tumor progression and metastasis as well as diagnosis, prognosis and therapeutic progression in the patients. The extensive researches on HNC have made significant furtherance in numerous targeted therapies, but for the escalating therapeutic resistance. This review explicates RTKs in HNC, their signaling pathways involved in tumorigenesis, metastasis and stemness induction, the association of non-coding RNAs with RTKs, an overview of RTK based therapy and associated resistance in HNC, as well as a sneak peek into the HPV positive HNC and its therapy. The review extrapolates the cardinal role of RTKs and RTK based therapy as superior to other existing therapeutic interventions for HNC.

PLAG1 enhances the stemness profiles of acinar cells in normal human salivary glands in a cell type-specific manner

OBJECTIVES

Details of the histogenesis of salivary gland tumors are largely unknown. The oncogenic role of PLAG1 in the salivary gland has been demonstrated in vivo. Herein, we demonstrate PLAG1 roles in the acinar and ductal cells of normal human salivary glands to clarify the early events that occur during the histogenesis of salivary gland tumors.

METHODS

Normal salivary gland cells with acinar and ductal phenotypes were transfected with PLAG1 plasmid DNA. Subsequently, PLAG1 overexpressed and mock cells were examined by cell proliferation, transwell migration, and salisphere formation assays. Differentiation and salivary and pluripotent stem cell marker expression levels were evaluated by quantitative reverse transcription-polymerase chain reaction and immunofluorescence. Alterations in transcriptional expressions were investigated via cap analysis of gene expression with gene-enrichment and functional annotation analysis.

RESULTS

PLAG1 promoted cell proliferation and transwell migration in the acinar and ductal cells, and markedly enhanced the stemness profiles and luminal cell-like profiles in acinar cells; the stemness profiles were partially increased in the ductal cells.

CONCLUSION

PLAG1 enhanced the stemness profiles in the acinar cells of normal human salivary glands in a cell type-specific manner. Thus, it may be involved in salivary gland tumorigenesis by increasing the stemness character of the normal salivary gland cells.

Salivary gland stem cells: A review of development, regeneration and cancer

Salivary glands are responsible for maintaining the health of the oral cavity and are routinely damaged by therapeutic radiation for head and neck cancer as well as by autoimmune diseases such as Sjögren's syndrome. Regenerative approaches based on the reactivation of endogenous stem cells or the transplant of exogenous stem cells hold substantial promise in restoring the structure and function of these organs to improve patient quality of life. However, these approaches have been hampered by a lack of knowledge on the identity of salivary stem cell populations and their regulators. In this review we discuss our current knowledge on salivary stem cells and their regulators during organ development, homeostasis and regeneration. As increasing evidence in other systems suggests that progenitor cells may be a source of cancer, we also review whether these same salivary stem cells may also be cancer initiating cells.

Low-fidelity alternative DNA repair carcinogenesis theory may interpret many cancer features and anticancer strategies

We have proposed that the low-fidelity compensatory backup alternative DNA repair pathways drive multistep carcinogenesis. Here, we apply it to interpret the clinical features of cancer, such as mutator phenotype, tissue specificity, age specificity, diverse types of cancers originated from the same type of tissue, cancer susceptibility of patients with DNA repair-defective syndromes, development of cancer only for a selected number of individuals among those that share the same genetic defect, invasion and metastasis. Clinically, the theory predicts that to improve the efficacy of molecular targeted or synthetic lethal therapy, it may be crucial to inhibit the low-fidelity compensatory alternative DNA repair either directly or by blocking the signal transducers of the sustained microenvironmental stress.

A Phase I clinical trial of the combination of imatinib and paclitaxel in patients with advanced or metastatic solid tumors refractory to standard therapy

PURPOSE

Pre-clinical data suggest that combining imatinib with traditional cytotoxic chemotherapy may improve imatinib efficacy. We conducted a Phase I study of imatinib in combination with paclitaxel in patients with advanced or metastatic solid tumors.

METHODS

Patients were accrued to the study in a standard 3 + 3 design. Patients were restaged every two cycles, and those with stable disease (SD), or better, continued study treatment without interruption. Maximally tolerated doses (MTDs) and pharmacokinetic profiles of combination imatinib and paclitaxel were assessed.

RESULTS

Fifty-eight patients were enrolled, including 40 in the Phase I dose escalation portion. Alternating dose escalation of imatinib and paclitaxel on a 28-day cycle resulted in MTDs of 800 mg imatinib daily, on days 1-4, 8-11, 15-18, and 22-25, and 100 mg/m(2) paclitaxel weekly, on days 3, 10, and 17. Two expansion cohorts, comprising 10 breast cancer patients and 8 patients with soft-tissue sarcomas, were enrolled at the MTDs. The most common adverse events were flu-like symptoms (64 %) and nausea/vomiting (71 %). The most common Grade 3/4 toxicities were neutropenia (26 %), flu-like symptoms (12 %), and pain (12 %). There were no relevant differences in the pharmacokinetic profiles of either drug when given in combination compared with alone. Thirty-eight subjects were evaluable for response, 18 (47.4 %) of whom experienced clinical benefit. Five patients (13.2 %) had a partial response (PR) and 13 patients (34.2 %) had SD; the average time to progression in those with clinical benefit was 17 weeks (range: 7-28 weeks).

CONCLUSIONS

This combination of imatinib and paclitaxel was reasonably safe and tolerable, and demonstrated evidence of anti-tumor activity. Further exploration in disease-specific Phase II trials is warranted.

Mutations in the c-Kit gene disrupt mitogen-activated protein kinase signaling during tumor development in adenoid cystic carcinoma of the salivary glands

The Ras/mitogen-activated protein kinase (MAPK) pathway is considered to be a positive regulator of tumor initiation, progression, and maintenance. This study reports an opposite finding: we have found strong evidence that the MAPK pathway is inhibited in a subset of adenoid cystic carcinomas (ACCs) of the salivary glands. ACC tumors consistently overexpress the receptor tyrosine kinase (RTK) c-Kit, which has been considered a therapeutic target. We performed mutational analysis of the c-Kit gene (KIT in 17 cases of ACC and found that 2 cases of ACC had distinct missense mutations in KIT at both the genomic DNA and messenger RNA levels. These mutations caused G664R and R796G amino acid substitutions in the kinase domains. Surprisingly, the mutations were functionally inactive in cultured cells. We observed a significant reduction of MAPK (ERK1/2) activity in tumor cells, as assessed by immunohistochemistry. We performed further mutational analysis of the downstream effectors in the c-Kit pathway in the genes HRAS, KRAS, NRAS, BRAF, PIK3CA, and PTEN. This analysis revealed that two ACC tumors without KIT mutations had missense mutations in either KRAS or BRAF, causing S17N K-Ras and V590I B-Raf mutants, respectively. Our functional analysis showed that proteins with these mutations were also inactive in cultured cells. This is the first time that MAPK activity from the RTK signaling has been shown to be inhibited by gene mutations during tumor development. Because ACC seems to proliferate despite inactivation of the c-Kit signaling pathway, we suggest that selective inhibition of c-Kit is probably not a suitable treatment strategy for ACC.

Phase II study of cisplatin and imatinib in advanced salivary adenoid cystic carcinoma

Patients with adenoid cystic carcinoma of the salivary glands show over-expression of KIT in a high proportion of cases. Options for systemic treatment are limited in locally advanced and metastatic disease. We explored the efficacy of imatinib and cisplatin combined in this group of patients. A Gehan's two-stage, phase II trial was conducted on 28 patients. Those with progressive, locally advanced, and metastatic disease with an over-expression of KIT were treated with single agent imatinib 800 mg daily for two months, followed by a combination of imatinib 400mg daily and cisplatin 80 mg/m(2) at four-weekly intervals for six cycles. This was followed by maintenance single agent imatinib 400mg daily until the disease progressed. Response was monitored using fluorodeoxyglucose positron emission tomography (FDG-PET) and morphological imaging using computed tomography, magnetic resonance, and chest radiographs (CT/MRI/CXR). Morphological imaging showed partial response in three of 28 patients, and five patients showed a response on FDG-PET. In addition, 19 patients had useful stabilisation of disease. The median time to progression and overall survival was 15 months (range 1-43) and 35 months (range 1-75), respectively. The combination of imatinib and cisplatin was reasonably well tolerated. This combination may provide stabilisation in locally advanced and metastatic adenoid cystic carcinoma of the salivary glands.

Should We Treat Lung Metastases from Adenoid Cystic Carcinoma of the Head and Neck in Asymptomatic Patients?

Adenoid cystic carcinoma is a rare malignant tumor that is well known for its deceptively encouraging 5-year survival rate and its dismal survival rate at longer intervals. Controversy exists as to the benefit of regularly following asymptomatic patients to look for distant metastases because even if one is found, the options for further management are limited. When a metastasis is limited to the lung in an asymptomatic patient with no locoregional recurrence, metastasectomy might provide some long-term benefit, although we cannot know for certain. We encountered such a case, and we opted for surgical resection rather than a conservative approach. There is a need for multicenter trials so that the management of such patients, be it active or conservative, can be evidence-based.

Metronomic scheduling of imatinib abrogates clonogenicity of neuroblastoma cells and enhances their susceptibility to selected chemotherapeutic drugs in vitro and in vivo

Imatinib is currently in early clinical trials as targeted therapy for relapsed neuroblastomas and other childhood solid tumors expressing platelet-derived growth factor receptors (PDGFR) or c-Kit. Short-term treatment with imatinib in clinically achievable concentrations is ineffective in neuroblastoma in vitro. However, clinically, imatinib is administered daily over long time periods. The effects of combining imatinib with chemotherapy in neuroblastoma are unknown. Here, a panel of neuroblastoma cell lines (n = 5) were studied, representing tumors with different biological (MYCN-amplification +/-) and clinical (drug resistance) features. Using a protracted low-dose treatment schedule (1-3 weeks; 0.5-5microM) imatinib dose-dependently inhibited proliferation and clonogenic survival for all tested cell lines with IC50 <2.5microM. In contrast, short-term treatment (<96 hrs) was ineffective. Low-dose imatinib was synergistic in combination with doxorubicin and caused increased G2/M- and S-phase arrest and apoptosis as evidenced by enhanced caspase-3 activation and sub-G1 DNA accumulation. A significant but less pronounced effect was observed when imatinib was combined with etoposide or vincristine, as opposed to cisplatin, melphalan, or irinotecan. All cell lines expressed PDGFRbeta, whereas no protein expression of PDGFRalpha was detected in MYCN amplified cell lines. PDGF-BB caused PDGFRbeta phosphorylation and partially rescued neuroblastoma cells from doxorubicin-induced apoptosis, in an imatinib-sensitive manner. In vivo, treatment with imatinib in combination with doxorubicin induced a significant growth inhibition of established neuroblastoma xenografts. These findings suggest clinical testing of imatinib in combination with selected chemotherapeutic drugs, in particular doxorubicin, in children with high-risk neuroblastoma.

Salivary gland carcinomas, paranasal sinus cancers and melanoma of the head and neck: an update about rare but challenging tumors

PURPOSE OF REVIEW

This is a review about recent clinical developments in rare cancers of the head and neck.

RECENT FINDINGS

Progress in molecular biology techniques has allowed the identification of new prognostic factors, and potential molecular-targeted therapies. This is of importance since chemotherapy continues to play a role but is still limited in this group of malignancies. New techniques of irradiation such as intensity-modulated radiotherapy and three-dimensional conformal radiotherapy appear to improve the locoregional control of these tumors. Surgery continues to be the cornerstone of treatment, with a growing interest in the technique of sentinel lymph node biopsy.

SUMMARY

As salivary gland carcinomas, paranasal sinus cancers and melanoma of the head and neck are rare malignancies, these tumors must be treated in specialized anticancer centers with access to the latest surgical and irradiation techniques. Moreover, clinical studies with translational research are needed to identify strong prognostic and predictive factors, and effective molecular-targeted therapies.

Expression of platelet-derived growth factor-AA and platelet-derived growth factor-alpha receptor in ameloblastomas

BACKGROUND

Platelet-derived growth factor (PDGF)-AA isoform and its receptor, PDGF-alpha receptor (PDGFRA) regulate tooth development and growth. We investigated the expression of both proteins in ameloblastomas, to contribute the understanding of the potential role of the PDGF/PDGFR system in this odontogenic neoplasm.

METHOD

Twenty-nine specimens of ameloblastoma were analyzed for PDGF-AA and PDGFRA expression using immunohistochemistry. The proliferation activity was investigated with the MIB-1 antibody. Additionally, capillary sequencing of genomic DNA was performed to search for mutations in therapeutically relevant exons 12 and 18 of the PDGFRA gene.

RESULTS

PDGF-AA and PDGFRA expression were detectable in all cases with the exception of one tumor. However, protein expression levels did neither correlate with each other nor with MIB-1 expression. Unicystic ameloblastomas did not differ from solid tumors with regard to PDGF-AA, PDGFRA, and MIB-1 expression. One tumor revealed a somatic mutation of exon 12 of the PDGFRA gene.

CONCLUSION

PDGF-AA and PDGFRA proteins are regularly expressed in variable levels in ameloblastomas, and somatic mutations of exon 12 and exon 18 of the PDGFRA gene are rare findings.

Expression de c-kit dans les carcinomes nasopharyngés nord africains, corrélations avec l'âge et LMP1

PURPOSE

To determine the level and prognostic significance of c-kit expression in the two age groups of North African nasopharyngeal carcinomas.

PATIENTS AND METHODS

A retrospective study of 99 NPC specimens from Tunisian patients was investigated by immunohistochemistry. Immunohistochemical data were correlated with Epstein-Barr virus LMP1 expression and pathological, clinical and survival parameters.

RESULTS

c-kit was detected in 79% of the cases for patients under 30 years of age (juvenile form) but in only 56% of specimens in patients over 30 years (P=0.039) and was significantly over-expressed for patients with lymph node involvement (P=0.015). LMP1 score was 5.78 (+/-1.84) for c-kit negative tumors compared to 8,23 (+/-2.39) for c-kit positive tumors (P=0.002). Multivariate analysis including age, lymph nodes involvement and LMP1 expression as co-variables, showed that only age (P=0.027) and LMP1 expression (P=0.005) were significantly correlated to the c-kit expression.

CONCLUSION

c-kit is highly expressed in the juvenile form of North African nasopharyngeal carcinomas. There is a significant association between LMP1 and c-kit expression. The contrasted levels of C-kit expression in the two age groups strengthen the hypothesis that these clinical forms result from distinct oncogenic mechanisms.

Recent advances in the treatment of salivary gland cancers: emphasis on molecular targeted therapy

Salivary gland cancers include tumors of different histologic characteristics and biological behavior. Radical surgery, followed or not by radiation therapy, represents the main treatment approach for this disease. The role of systemic chemotherapy is less clearly defined since trials of single-agent chemotherapy have consistently shown low response rates. Polychemotherapy is likely to induce a higher response rate, but does not improve survival. The determination of the molecular abnormalities underlying the different subtypes of salivary gland cancers might lead to more active targeted therapies. C-kit is overexpressed in a wide percentage of salivary gland carcinomas, but clinical trials with single-agent imatinib have been negative. ErbB1 and ErbB2 are also frequently overexpressed in salivary gland cancers and this has provided the rationale for clinical trials with trastuzumab, cetuximab, gefitinib, lapatinib. Finally, new pathways, such as vascular endothelial growth factor, might be worth targeting and clinical trials with anti-angiogenic agents are ongoing.

Potent antitumor activity of a novel cationic pyridinium-ceramide alone or in combination with gemcitabine against human head and neck squamous cell carcinomas in vitro and in vivo

In this study, a cationic water-soluble ceramide analog L-threo-C6-pyridinium-ceramide-bromide (L-t-C6-Pyr-Cer), which exhibits high solubility and bioavailability, inhibited the growth of various human head and neck squamous cell carcinoma (HNSCC) cell lines at low IC50 concentrations, independent of their p53 status. Consistent with its design to target negatively charged intracellular compartments, L-t-C6-Pyr-Cer accumulated mainly in mitochondria-, and nuclei-enriched fractions upon treatment of human UM-SCC-22A cells [human squamous cell carcinoma (SCC) of the hypopharynx] at 1 to 6 h. In addition to its growth-inhibitory function as a single agent, the supra-additive interaction of L-t-C6-Pyr-Cer with gemcitabine (GMZ), a chemotherapeutic agent used in HNSCC, was determined using isobologram studies. Then, the effects of this ceramide, alone or in combination with GMZ, on the growth of UM-SCC-22A xenografts in SCID mice was assessed following the determination of preclinical parameters, such as maximum tolerated dose, clearance from the blood, and bioaccumulation. Results demonstrated that treatment with L-t-C6-Pyr-Cer in combination with GMZ significantly prevented the growth of HNSCC tumors in vivo. The therapeutic efficacy of L-t-C6-Pyr-Cer/GMZ combination against HNSCC tumors was approximately 2.5-fold better than that of the combination of 5-fluorouracil/cis-platin. In addition, liquid chromatography/mass spectroscopy analysis showed that the levels of L-t-C6-Pyr-Cer in HNSCC tumors were significantly higher than its levels in the liver and intestines; interestingly, the combination with GMZ increased the sustained accumulation of this ceramide by approximately 40%. Moreover, treatment with L-t-C6-Pyr-Cer/GMZ combination resulted in a significant inhibition of telomerase activity and decrease in telomere length in vivo, which are among downstream targets of ceramide.