PDGF-? and PDGF-? are expressed in endometrial stromal sarcoma: a potential therapeutic target for tyrosine kinase inhibitors?

Potential Therapeutic Targets in Uterine Sarcomas

Uterine sarcomas are rare tumors accounting for 3,4% of all uterine cancers. Even after radical hysterectomy, most patients relapse or present with distant metastases. The very limited clinical benefit of adjuvant cytotoxic treatments is reflected by high mortality rates, emphasizing the need for new treatment strategies. This review summarizes rising potential targets in four distinct subtypes of uterine sarcomas: leiomyosarcoma, low-grade and high-grade endometrial stromal sarcoma, and undifferentiated uterine sarcoma. Based on clinical reports, promising approaches for uterine leiomyosarcoma patients include inhibition of VEGF and mTOR signaling, preferably in combination with other targeted or cytotoxic compounds. Currently, the only targeted therapy approved in leiomyosarcoma patients is pazopanib, a multitargeted inhibitor blocking VEGFR, PDGFR, FGFR, and c-KIT. Additionally, preclinical evidence suggests effect of the inhibition of histone deacetylases, tyrosine kinase receptors, and the mitotic checkpoint protein aurora kinase A. In low-grade endometrial stromal sarcomas, antihormonal therapies including aromatase inhibitors and progestins have proven activity. Other potential targets are PDGFR, VEGFR, and histone deacetylases. In high-grade ESS that carry the YWHAE/FAM22A/B fusion gene, the generated 14-3-3 oncoprotein is a putative target, next to c-KIT and the Wnt pathway. The observation of heterogeneity within uterine sarcoma subtypes warrants a personalized treatment approach.

Endometrial stromal sarcoma arising from endometriosis: a clinicopathological study and literature review

OBJECTIVES

We aimed to investigate the nature of endometrial stromal sarcoma (ESS) arising from endometriosis.

METHODS

The clinical data of 5 patients with ESS arising from endometriosis were reviewed retrospectively. The expression of CD117, HER2/neu, EGFR, VEGF, and PDGFR was analyzed by immunohistochemical staining.

RESULTS

The median age of the 5 patients was 45 years. The primary tumor sites were the ovary in 2, the pelvis in 2, and the cervical canal in 1 patient. Three patients had disseminated disease at diagnosis. Four patients underwent complete tumor resection. All of the 5 cases received adjuvant chemotherapy and 2 received progesterone therapy, while none were treated with radiotherapy. No recurrence occurred in the 4 cases who had complete tumor resection, and the only patient who progressed was the patient in whom the tumor was unresectable. Tumor cells in all cases exhibited positive staining for PDGFR and were negative for CD117 and HER2/neu. The expression of EGFR and VEGF was observed in 2 and 4 cases, respectively.

CONCLUSION

ESS arising from endometriosis is rare. Complete tumor resection in ESS arising from endometriosis may reduce the recurrence rate.

Recurrence patterns and prognosis of endometrial stromal sarcoma and the potential of tyrosine kinase-inhibiting therapy

OBJECTIVE

Endometrial stromal sarcoma (ESS) is a rare uterine malignancy. The current treatment approaches yield unsatisfactory results, and potential therapeutic targets need exploration.

METHODS

We reviewed the electronic medical records of 74 patients with low-grade ESS who had been evaluated at the University of Texas MD Anderson Cancer Center between 1995 and 2006. Using immunohistochemistry, we tested the expression of targets in paraffin-embedded tissue samples taken from 13 of the patients.

RESULTS

Forty-seven patients (64%) had a recurrence, and 16 (22%) had died of their disease at last follow-up. The 10-year progression-free survival (PFS) rate was 43% (median PFS duration, 108months), and the overall survival (OS) rate was 85% (median OS, 288months). Patients who received hormonal therapy had an overall response rate of 27%; another 53% had stable disease, with a median time to progression of 24months. No complete response or partial response was observed among patients who received radiotherapy or chemotherapy. In the paraffin-embedded specimens we tested, c-abl was expressed universally. Expression of PDGF-α, PDGF-β, VEGF, and c-Kit was detected in 33%, 36%, 54%, and 8%, of specimens, respectively. EGFR and HER-2 were not detectable in any specimens.

CONCLUSIONS

Our study suggests that ESS is a hormone-dependent malignancy, with hormonal therapy having activity in recurrent disease. Targeted therapy, specifically targeting c-abl may be a potential treatment for this disease.

Molecular profiling of endometrial malignancies

Molecular profiling of endometrial neoplasms reveals genetic changes in endometrial carcinomas that support the dualistic model, in which type I carcinomas are estrogen-dependent, low grade lesions and type II carcinomas are nonestrogen dependent and high grade. The molecular changes in type I endometrial carcinomas include mutations in PTEN, PIK3CA, KRAS, and β-catenin, along with microsatellite instability, whereas type II endometrial carcinomas are characterized by genetic alterations in p53, HER2/neu, p16, and E-cadherin. For endometrial neoplasms with a malignant mesenchymal component, C-MYC mutations and loss of heterozygosity are frequently seen in carcinosarcomas, and a fusion gene, JAZF1/JJAZ1, is distinctive for endometrial stromal sarcoma. In addition, p53 mutations may play an important role in tumorigenesis of undifferentiated endometrial sarcoma. These molecular changes can help in the diagnosis of endometrial neoplasms, as well as form the basis of molecular targeted therapy.

The role of angiogenesis in solid tumours: an overview

Angiogenesis is the physiological process of the formation of new blood vessels from pre-existing ones. Multiple molecules regulate angiogenesis, such as the vascular endothelial growth factor, angiopoietins, the fibroblast growth factor, the platelet-derived growth factor and the transforming growth factor-beta. Angiogenesis plays an important role in the growth, progression and metastasis of a tumour. Inhibiting the angiogenic process or targeting existing tumour vessels can be used for treatment of tumours as an alternative or in parallel with conventional chemotherapy. Many anti-angiogenic factors are under investigation and some are already being used in clinical practice with various results.

Hormonal therapy of endometrial stromal sarcoma

PURPOSE OF REVIEW

Low-grade endometrial stromal sarcomas are steroid receptor positive tumors with slow tumor progression and high recurrence rates, which lack established treatment protocols. We present an update on hormonal therapy options.

RECENT FINDINGS

In the past, hormonal therapy consisted of progestins for advanced/recurrent/metastatic low-grade endometrial stromal sarcomas. Aromatase inhibitors and gonadotropin-releasing hormone analogues have become new effective alternatives for first and second line treatment. The high recurrence rates after short disease free intervals in low-grade endometrial stromal sarcoma patients were partly due to inadvertent growth stimulation during estrogen-containing hormone replacement therapy and tamoxifen treatment, which - according to current knowledge - are contraindicated. Recently, hormonal therapy has been introduced for the prevention of recurrences. Aromatase inhibitors are becoming the treatment of choice, since progestins are poorly tolerated due to side effects. The effective duration of preventive hormonal therapy is still undetermined.

SUMMARY

Hormonal therapy with progestins, aromatase inhibitors and gonadotropin-releasing hormone analogues has become an effective treatment alternative to radiation and chemotherapy for low-grade endometrial stromal sarcoma patients. Preventive hormonal therapy is of particular interest in the setting of concomitant endometriosis.

Expression of platelet-derived growth factor receptor in low-grade endometrial stromal sarcomas in the absence of activating mutations

AIMS

To investigate platelet-derived growth factor receptor (PDGFR)alpha and PDGFRbeta expression and a mutational analysis of PDGFRalpha (exons 11, 12, 17 and 18) and PDGFRbeta (exon 12) genes in endometrial stromal sarcomas (ESS). Gastrointestinal stromal tumours (GISTs), which have somatic mutations of the transmembrane tyrosine kinase receptor, respond to tyrosine kinase inhibitors, which act through an inhibitory effect on class 3 receptor tyrosine kinase members such as PDGFRalpha, PDGFRbeta and c-kit.

METHODS AND RESULTS

The immunohistochemical expression of PDGFRalpha and PDGFRbeta was investigated in 37 archival c-kit- ESS. Staining was scored as negative (0-10% positive tumour cells) and positive (weakly positive 11-50% positive cells; strongly positive > 50% positive cells). PDGFRalpha was expressed in 24/37 ESS [65%; strongly by 19/37 (51.5%) and weakly by 5/37 ESS (13.5%)]. ESS tumour cells were negative for PDGFRbeta, but endothelial cells stained positive. A mutational analysis of PDGFRalpha (exons 11, 12, 17 and 18) and PDGFRbeta (exon 12) genes on frozen metastatic ESS from three patients detected no mutations leading to amino acid changes in the mature protein.

CONCLUSIONS

Patients with PDGFRalpha+ ESS may benefit from treatment with tyrosine kinase inhibitors by blocking autocrine and paracrine stimulation loops, blocking neovascularization and enhancing the effects of chemotherapy.