Surita Dalal

Vascular Endothelial Growth Factor: A Therapeutic Target for Tumors of the Ewing's Sarcoma Family

Purpose: We have reported previously that intratumoral microvessel density (MVD) is a significant prognostic indicator of event-free survival in the Ewings sarcoma family of tumors (ESFT). Here, the angiogenic growth factor expression profile and its relationship with MVD has been investigated in ESFT. Experimental Design and Results: Using ESFT model systems, the potential of these factors as therapeutic targets has been evaluated. A significant correlation (P = 0.02) was observed between vascular endothelial growth factor (VEGF) expression and MVD, consistent with the hypothesis that VEGF regulates the development of microvessels in ESFT. There was no correlation between MVD and any of the other growth factors studied. All six ESFT cell lines studied produced and secreted VEGF; five of six cell lines also secreted placental growth factor, one cell line (A673) at high levels. Tumor conditioned medium induced proliferation of human umbilical vein endothelial cells. Expression of VEGF receptors Flt-1 and Flk-1/KDR was heterogeneous across the cell lines. Both receptor tyrosine kinase inhibitors SU6668 (targets Flk-1/KDR, platelet-derived growth factor receptor-β, and fibroblast growth factor receptor 1) and SU5416 (targets Flk-1/KDR) as well as anti-VEGF agents rhuMAb-VEGF (bevacizumab) and VEGF Trap delayed s.c. growth of ESFT in mice compared with untreated groups: SU6668 (100 mg/kg/d), SU5416 (25 mg/kg/d), rhuMAb-VEGF (10 mg/kg twice weekly), and VEGF Trap (2.5 or 25 mg/kg twice weekly). Conclusions: These data suggest that VEGF is the single most important regulator of angiogenesis in ESFT and may be exploited for therapeutic advantage.

Preclinical evaluation of vascular-disrupting agents in Ewing’s sarcoma family of tumours☆

The effects of the tubulin-binding vascular-disrupting agents (VDAs), combretastatin A4 phosphate (CA4P), OXi4503/CA1P and OXi8007, in subcutaneous mouse models of the Ewings sarcoma family of tumours (ESFTs) have been investigated alone and in combination with doxorubicin. Delay in subcutaneous tumour growth was observed following treatment of mice with multiple doses of OXi4503/CA1P but not with CA4P or OXi8007. A single dose of OXi4503/CA1P caused complete shutdown of vasculature by 24h and extensive haemorrhagic necrosis by 48h. However, a viable rim of proliferating cells remained, which repopulated the tumour within 10 days following the withdrawal of treatment. Combined treatment with doxorubicin 1h prior to administration of OXi4503/CA1P enhanced the effects of OXi4503/CA1P causing a synergistic delay in tumour growth (p<0.001). This study demonstrates that OXi4503/CA1P is a potent VDA in ESFT and in combination with conventional cytotoxic agents represents a promising treatment strategy for this tumour group.

The rapid diagnosis of acute promyelocytic leukaemia using PML (5E10) monoclonal antibody

Acute promyelocytic leukaemia (APL) is characterized cytogenetically by t(15;17)(q22;q21) which results in the production of a PML/RARα fusion protein. Detection of the translocation or the fusion gene product is required for objective diagnosis of APL. This can be accomplished by conventional cytogenetic methods, fluorescence in situ hybridization or RT‐PCR. Such techniques are time consuming and not universally available. The intracellular distribution of the PML protein in promyelocytes is characteristically altered in APL and this can be detected by immunocytochemistry. We have assessed two immunocytochemical methods, immunofluorescence and alkaline phosphatase–anti‐alkaline phosphatase staining (APAAP), with regard to sensitivity, specificity and rapidity of diagnosis. 85 patients with AML including 15 cases of APL were studied. Immunofluorescence PML detection was concordant with RT‐PCR for t(15;17) in 14/15 (93.3%) cases with no false positives. The negative APL case in our series was a patient with a 5′ PML breakpoint who did not express the reciprocal t(17;15) fusion product. APAAP was concordant in only 6/13 (46%) APL cases with one false positive. In conclusion, immunofluorescent localization of PML using 5E10 monoclonal antibody is a rapid, sensitive and specific diagnostic tool for APL.

Outreach monitoring service for patients with indolent B-cell and plasma cell disorders: a UK experience.

Disease progression occurs in over 1% of monoclonal gammopathy of undetermined significance, monoclonal B‐cell lymphocytosis and early stage chronic lymphocytic leukaemia patients every year therefore regular monitoring is indicated. We assessed the efficacy of an outreach service to replace clinic monitoring using local phlebotomy with central haematologist review of laboratory parameters and symptoms identified by a patient self‐assessment questionnaire. The service was used by 299 patients for 2 years and provided accurate monitoring, improved patient satisfaction, support for primary care and reduced the burden on haematology clinics without an increase in inter‐assessment admissions due to disease progression.