Douglas Letson

Wee1 Inhibition by MK-1775 Leads to Tumor Inhibition and Enhances Efficacy of Gemcitabine in Human Sarcomas

Sarcomas are rare and heterogeneous mesenchymal tumors affecting both pediatric and adult populations with more than 70 recognized histologies. Doxorubicin and ifosfamide have been the main course of therapy for treatment of sarcomas; however, the response rate to these therapies is about 10–20% in metastatic setting. Toxicity with the drug combination is high, response rates remain low, and improvement in overall survival, especially in the metastatic disease, remains negligible and new agents are needed. Wee1 is a critical component of the G2/M cell cycle checkpoint control and mediates cell cycle arrest by regulating the phosphorylation of CDC2. Inhibition of Wee1 by MK1775 has been reported to enhance the cytotoxic effect of DNA damaging agents in different types of carcinomas. In this study we investigated the therapeutic efficacy of MK1775 in various sarcoma cell lines, patient-derived tumor explants ex vivo and in vivo both alone and in combination with gemcitabine, which is frequently used in the treatment of sarcomas. Our data demonstrate that MK1775 treatment as a single agent at clinically relevant concentrations leads to unscheduled entry into mitosis and initiation of apoptotic cell death in all sarcomas tested. Additionally, MK1775 significantly enhances the cytotoxic effect of gemcitabine in sarcoma cells lines with different p53 mutational status. In patient-derived bone and soft tissue sarcoma samples we showed that MK1775 alone and in combination with gemcitabine causes significant apoptotic cell death. Magnetic resonance imaging (MRI) and histopathologic studies showed that MK1775 induces significant cell death and terminal differentiation in a patient-derived xenograft mouse model of osteosarcoma in vivo. Our results together with the high safety profile of MK1775 strongly suggest that this drug can be used as a potential therapeutic agent in the treatment of both adult as well as pediatric sarcoma patients.

Familial gigantiform cementoma with brittle bone disease, pathologic fractures, and osteosarcoma: A possible explanation of an ancient mystery

We describe four individuals of an African‐American family with a predominantly diaphyseal bone disease associated with familial gigantiform cementoma (FGC), a disorder typically seen in Caucasians. The mother and her children presented with deformities of the jaws, abnormalities of the long bones, and pre‐pubertal pathologic fractures. The index patient carried the diagnosis of osteosarcoma (OS). In addition, we provide a possible explanation for the jaw abnormalities of King Tutankhamens father in the 18th dynasty in Egypt around 1350 BC.

Outcomes and clinical predictors of improved survival in a patients undergoing pulmonary metastasectomy for sarcoma

Pulmonary metastasectomy (PM) for metastatic sarcoma can result in long‐term survival. The purpose of this study was to describe factors associated with survival in a series of patients undergoing PM for metastatic sarcoma.

Prognostic significance of soft tissue extension, International Prognostic Index, and multifocality in primary bone lymphoma: a single institutional experience

Primary bone lymphoma (PBL) is a rare disease. The literature is inconsistent in regard to definition, stage and prognostic factors. We examined the PBL cases seen at the Moffitt Cancer Center between 1998 and 2013 using the 2013 World Health Organization criteria for bone/soft tissue tumours. Seventy PBL patients were included, of whom 53 (75·7%) patients were histologically classified as primary bone diffuse large B‐cell lymphoma (PB‐DLBCL). Femur was the most commonly involved site in PBLs with unifocal bone lesions, whereas PBLs with multifocal bone lesions most frequently presented with spine disease. Further analysis of the PB‐DLBCL subgroup showed that these patients had 3‐ and 5‐year progression‐free survival (PFS) of 61·2% and 46·9%, respectively and 5‐ and 10‐year overall survival (OS) of 81·1% and 74·7%, respectively. Multivariate analysis identified soft tissue extension and International Prognostic Index (IPI) score as the most important unfavourable prognostic factors for both PFS and OS. Multifocality was also highly significantly associated with a worse PFS (P = 0·002) and OS (P < 0·001), although it was not identified in multivariate analysis due to its incorporation into the IPI. The results warrant further investigation regarding whether PBL with multifocal bone lesions could be considered as a systemic and more aggressive disease rather than a conventional PBL.

ASSESSMENT OF MUSCARINIC AND NICOTINIC ACETYLCHOLINE RECEPTOR EXPRESSION IN PRIMITIVE NEUROECTODERMAL TUMOR/EWING FAMILY OF TUMOR AND DESMOPLASTIC SMALL ROUND CELL TUMOR: AN IMMUNOHISTOCHEMICAL AND WESTERN BLOT STUDY OF TISSUE MICROARRAY AND CELL LINES

The primitive neuroectodermal tumor (PNET)/Ewing family of tumors (EFT) and desmoplastic small round cell tumor (DSRCT) portend a grave prognosis. Ongoing research in similar neurocrest-derived neoplasms has implicated both the muscarinic acetylcholine receptor (mAChR) and nicotinic acetylcholine receptor (nAChR) in the pathogenesis of these neoplasms. Acetylcholine has been reported to impart a modulatory effect on chemotaxis and proliferation, an effect ameliorated by anticholinergic drugs. The aim of our study is to characterize the pattern of expression of mAChR and nAChR in PNET/EFT and DSRCT, in hopes of discovering a potential target for therapeutic improvements. We examined 34 cases of PNET/EFT and 2 DSRCT retrospectively by immunohistochemical studies. We found that AChRs are overexpressed in a significant number of PNET/EFT and DSRCT. The Western blot analysis of 3 human Ewing sarcoma cell lines confirms the presence of AChRs. Future studies are planned to confirm these results as well as to investigate their potential therapeutic implications.

The use of isolated limb infusion in limb threatening extremity sarcomas

This paper reports a single-institution experience with the use of isolated limb infusion for limb salvage in locally advanced, unresectable, recurrent limb threatening soft tissue sarcomas. Background: Locally advanced, limb threatening soft tissue sarcomas (STS) pose a significant treatment challenge. We report our experience using isolated limb infusion (ILI) in patients with unresectable extremity STS. Methods: A total of 22 patients with extremity STS underwent 26 ILIs with melphalan and dactinomycin. Patient characteristics, intra-operative parameters and toxicity were recorded. Outcome measures included limb-salvage and in-field response rates. Results: Of the 19 lower and 7 upper extremity ILIs, Wieberdink grade III toxicity or less was observed in all. Median followup was 11 months. A total of 17 patients were evaluable at 3 months post-ILI with an overall response rate of 42%. Four (24%) had complete response (CR), three (18%) partial response (PR), three (18%) stable disease (SD) and seven (41%) progressive disease (PD). Twelve of 17 (71%) underwent successful limb preservation at a median of 9 months post-ILI. Two (12%) were downstaged to resectable disease and remain showing no evidence of disease (NED) after surgery at 30 and 22 months post-ILI. Conclusions: ILI is an attractive modality that provides regional disease control and limb preservation in patients with limb threatening sarcoma. Although short-term results appear encouraging, long-term follow-up is needed to fully assess the role of ILI in unresectable extremity STS.

Recurrence and survival analysis of resected soft tissue sarcomas of pelvic retroperitoneal structures.

The purpose is to determine the clinicopathologic factors related to survival and recurrence of primary resected pelvic soft tissue sarcomas (STS).

Ewing’s Sarcoma of the Sacrum

Ewing’s Sarcoma (ES) is a small round cells malignant tumor that accounts for 6–8% of all primary bone tumors. Together with osteosarcoma, are the most common primary malignant bone tumors in children, most occurring during the first two decades [1, 2]. Primary ES of the spine and sacrum presents unique anatomic limitations specific to the neurological structures, vertebral column, and pelvic involvement, that challenge our ability to offer good local control. The use of multidrug chemotherapy, together with radiation therapy (RT) and surgery for local control, has significantly improved the prognosis of ES, even if it is still considered worse in the spine compared to other site [3–5]. Owing to the rarity of sacral tumors, the observations on long-term function and survival after treatment for high-grade sarcomas are limited to case reports or small series [6–10], surgical techniques [6, 11–14], or cooperative studies reporting cohorts that include but are not limited to sacrum [11, 15–22].

Computer navigation and distal femoral reconstruction in the oncologic patient

OBJECTIVES As adjuvant treatments for musculoskeletal malignancies improve expectations of preserved function increase. We questioned whether computer navigation for distal femoral reconstruction would improve outcomes. METHODS Twenty oncology patients were reviewed after distal femoral reconstruction using navigation. Outcomes included local recurrence, implant revision, patient function, patellofemoral complications and leg-length inequality. RESULTS Implant survivorship was 85% at 26 months. There were no local recurrences and 3 failures for aseptic loosening. Good functional outcomes were observed in remaining cases. CONCLUSION Computer navigation for distal femoral reconstruction resulted in acceptable functional outcomes and implant survivorship. Reduced local recurrence were observed at intermediate follow-up. Level of Evidence: Level IV.

Abstract 3047: MK1775, a selective Wee1 inhibitor shows antitumor activity against sarcoma cells

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Sarcomas are rare and heterogeneous mesenchymal tumors affecting both pediatric and adult populations with more than 70 recognized histologies. Doxorubicin and ifosfamide have been the main course of therapy for treatment of sarcomas; however, the response rate to these therapies is about 10-20% in metastatic setting. Toxicity with the drug combination is high, response rates remain low, and improvement in overall survival, especially in the metastatic disease, remains negligible. Accordingly, new agents are needed for the treatment of this heterogeneous group of diseases. Wee1 is a critical component of the G2/M cell cycle checkpoint control and mediates cell cycle arrest by regulating the phosphorylation of CDC2. Inhibition of Wee1 by a selective small molecule inhibitor MK1775 has been reported to to enhance the cytotoxic effect of DNA damaging agents. However, its role in the treatment of mesenchymal tumors has not been explored. In this study we investigated the therapeutic efficacy of MK1775 in various sarcoma cell lines and patient-derived tumor explants ex vivo both alone and in combination with other chemotherapeutic drugs frequently used in the treatment of sarcomas. Our data demonstrate that MK1775 treatment as a single agent at clinically relevant concentrations leads to unscheduled entry into mitosis and initiation of apoptotic cell death in all sarcomas tested. Additionally, MK1775 significantly enhances the cytotoxic effect of the DNA damaging agents, gemcitabine and doxorubicin. In MK1775 treated cells CDC2 activity was enhanced and G2/M ceheckpoint was impaired as assessed by increased expression of phosphorylated histone H3, a marker of mitotic entry. The cytotoxic effect of Wee1 inhibition on sarcoma cells appears to be independent of p53 status as all sarcoma cell lines with different p53 mutation were highly sensitive to treatment. Additionally, in patient-derived bone and soft tissue sarcoma samples we showed that MK1775 in combination with gemcitabine causes significant apoptotic cell death suggesting that this treatment may represent a novel approach in the treatment of sarcomas. In patient-derived xenograft mouse models of sarcoma we are currently analyzing the therapeutic efficacy of MK1775 in vivo by utilizing magnetic resonance imaging (MRI) and diffusion MRI methods. Our results together with the high safety profile of MK1775 strongly suggest that this drug can be used as a potential therapeutic agent in the treatment of both adult as well as pediatric sarcoma patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3047. doi:1538-7445.AM2012-3047