Jonathan Gill

New targets and approaches in osteosarcoma.

Osteosarcoma is the most common primary tumor of bone. Approximately 2/3 of patients who present with localized osteosarcoma can be expected to be cured of their disease with surgery and routine chemotherapy. Only 1/3 of patients with metastases detectable at presentation will be cured. These survival trends have stagnated over the past 20 years using conventional chemotherapy. New agents need to be rationally investigated to strive for improvement in the survival of patients diagnosed with osteosarcoma. This manuscript will review the rationale for conventional chemotherapy used in the treatment of osteosarcoma, as well as agents in varying stages of development that may have promise for treatment in the future.

Ganglioside GD2 as a therapeutic target for antibody‐mediated therapy in patients with osteosarcoma

Survival outcomes for patients with osteosarcoma have remained stagnant over the past 30 years. Targeting of ganglioside GD2, a glycosphingolipid on the cell surface of some tumors, with immunotherapy has resulted in improved outcomes for patients with neuroblastoma. In the current study, the expression pattern of GD2 was examined in osteosarcoma.

Immune infiltration and PD-L1 expression in the tumor microenvironment are prognostic in osteosarcoma

Osteosarcoma patient survival has remained stagnant for 30 years. Novel therapeutic approaches are needed to improve outcomes. We examined the expression of Programmed Death Ligand 1 (PD-L1) and defined the tumor immune microenvironment to assess the prognostic utility in osteosarcoma. PD-L1 expression in osteosarcoma was examined in two patient cohorts using immunohistochemistry (IHC) (n = 48, n = 59) and expression was validated using quantitative real time PCR (n = 21) and western blotting (n = 9). IHC was used to determine the presence of tumor infiltrating lymphocytes and antigen-presenting cells (APCs) in the tumor. Expression of PD-L1 was correlated with immune cell infiltration and event-free-survival (EFS). The 25% of primary osteosarcoma tumors that express PD-L1 were more likely to contain cells that express PD-1 than PD-L1 negative tumors (91.7% vs 47.2%, p = 0.002). Expression of PD-L1 was significantly associated with the presence of T cells, dendritic cells, and natural killer cells. Although all immune cell types examined were present in osteosarcoma samples, only infiltration by dendritic cells (28.3% vs. 83.9%, p = 0.001) and macrophages (45.5% vs. 84.4%, p = 0.031) were associated with worse five-year-EFS. PD-L1 expression was significantly associated with poorer five-year-EFS (25.0%. vs. 69.4%, p = 0.014). Further studies in osteosarcoma are needed to determine if targeting the PD-L1:PD-1 axis improves survival.

Insulin-like growth factor 1 receptor and response to anti-IGF1R antibody therapy in osteosarcoma

Background Survival outcomes for patients with osteosarcoma (OS) have remained stagnant over the past three decades. Insulin-like growth factor 1 receptor (IGF1R) is over-expressed in a number of malignancies, and anti-IGF1R antibodies have and are currently being studied in clinical trials. Understanding the molecular aberrations which result in increased tumor response to anti-IGF1R therapy could allow for the selection of patients most likely to benefit from IGF1R targeted therapy. Methods IGF1R mRNA expression was assessed by RT PCR in OS patient primary tumors, cell lines, and xenograft tumors. IGF1R copy number was assessed by 3 approaches: PCR, FISH, and dot blot analysis. Exons 1–20 of IGF1R were sequenced in xenograft tumors and 87 primary OS tumors, and surface expression of IGF1R was assessed by flow cytometry. Levels of mRNA and protein expression, copy number, and mutation status were compared with tumor response to anti-IGF1R antibody therapy in 4 OS xenograft models. Results IGF1R mRNA is expressed in OS. Primary patient samples and xenograft samples had higher mRNA expression and copy number compared with corresponding cell lines. IGF1R mRNA expression, cell surface expression, copy number, and mutation status were not associated with tumor responsiveness to anti-IGF1R antibody therapy. Conclusions IGF1R is expressed in OS, however, no clear molecular markers predict response to IGF1R antibody-mediated therapy. Additional pre-clinical studies assessing potential predictive biomarkers and investigating targetable molecular pathways critical to the proliferation of OS cells are needed.

Targeting Glycoprotein NMB With Antibody-Drug Conjugate, Glembatumumab Vedotin, for the Treatment of Osteosarcoma.

Cure rates for children and young adults with osteosarcoma have remained stagnant over the past three decades. Targeting glycoprotein non‐metastatic b (GPNMB) with the antibody‐drug conjugate glembatumumab vedotin has improved outcomes for patients with melanoma and breast cancer. The potential utility of targeting GPNMB in osteosarcoma was explored.

Ganglioside GD2 expression is maintained upon recurrence in patients with osteosarcoma.

BackgroundOsteosarcoma is the most common primary malignant bone tumor in children and young adults. Ganglioside GD2 has been previously found on the cell surface in various tumor types, including osteosarcomas.FindingsIn this study, forty-nine additional osteosarcoma samples from 14 individual patients were assessed for GD2 expression via immunohistochemistry, of which 47 samples were found to express GD2. In matched samples from patients, GD2 expression seen at initial biopsy was found to persist in 100% of tissues taken at recurrence.ConclusionsGD2 expression was found to persist upon recurrence. These results suggest a phase 2 trial in children with recurrent osteosarcoma should provide an appropriate read out on the efficacy of anti-GD2 antibody.

HER‐2 expression is not prognostic in osteosarcoma; a Children's Oncology Group prospective biology study

Since the initial reports of human epidermal growth factor receptor 2 (HER‐2) expression as being prognostic in osteosarcoma, numerous small studies varying in the interpretation of the immunohistochemical (IHC) staining patterns have produced conflicting results. The Childrens Oncology Group therefore embarked on a prospective biology study in a larger sample of patients to define in osteosarcoma the prognostic value of HER‐2 expression using the methodology employed in the initial North American study describing an association between HER‐2 expression and outcome.

Reconstruction of the pediatric midface following oncologic resection

BACKGROUND Sarcoma is the most common midface malignancy in children. While first-line treatment in adults is resection, the challenges associated with resection and reconstruction of these tumors in children often lead to radiation therapy as primary treatment. This report highlights the feasibility and efficacy of midface reconstruction in the pediatric population after resection. In most cases, the same principles utilized in reconstructing midface defects in adults hold for the pediatric population. PATIENTS AND METHODS From 2008 to 2013 seven pediatric patients underwent resection and reconstruction for maxillary sarcomas. These patients ranged in age from 18 months to 20 years. Five patients were reconstructed with six microvascular free flaps. Two patients received pedicled flaps. Follow-up ranged from 15 months to 4.5 years. Reconstructive, oncological, and functional outcomes were analyzed. RESULTS Seven patients underwent eight reconstructions for sarcomas of the maxilla. Flaps utilized included vertical rectus abdominis, anterolateral thigh, fibula, and temporoparietal fascia. One flap was complicated by venous thrombosis but was successfully salvaged after thrombectomy and revision using vein graft. One patient developed recurrence after initial flap placement and required salvage resection and a second free flap. Six patients were judged to have good facial symmetry and tolerated a regular oral diet with normal or near-normal dental occlusion. CONCLUSIONS Standard primary therapy for sarcomas of the maxilla in the pediatric population consists of nonsurgical management. However, a radiation-first approach is associated with significant morbidity and makes surgical salvage more difficult. Based on our experience, microsurgical reconstruction of the pediatric midface is safe and effective, and should be considered a first-line treatment option for midface sarcomas in children. In general, there is no significant area of departure between the principles that govern midface reconstruction in adults and children.

Her-2 involvement in osteosarcoma

The major goals of translational research in osteosarcoma entail the identification of prognostic factors and therapeutic targets. Given the relevance of epidermal growth factor receptor pathway to breast cancer and the finding that HER-2 was expressed in a proportion of osteosarcoma, it was reasonable to investigate this pathway further. Investigations of HER-2 in osteosarcoma have led to the publication of numerous conflicting reports with regard to the level and prognostic value of HER-2 expression, which are reviewed and discussed. Numerous lessons provided by this research experience are described. This pathway has also been explored as a therapeutic target with at least one study of trastuzumab for the treatment of osteosarcoma completed. Other studies utilizing alternative approaches to target the HER-2 receptor for the treatment of osteosarcoma have been considered.

HHLA2, a member of the B7 family, is expressed in human osteosarcoma and is associated with metastases and worse survival.

Over the past four decades there have been minimal improvements in outcomes for patients with osteosarcoma. New targets and novel therapies are needed to improve outcomes for these patients. We sought to evaluate the prevalence and clinical significance of the newest immune checkpoint, HHLA2, in osteosarcoma. HHLA2 protein expression was evaluated in primary tumor specimens and metastatic disease using an osteosarcoma tumor microarray (TMA) (n = 62). The association of HHLA2 with the presence of tumor infiltrating lymphocytes (TILs) and five-year-event-free-survival were examined. HHLA2 was expressed in 68% of osteosarcoma tumors. HHLA2 was expressed in almost all metastatic disease specimens and was more prevalent than in primary specimens without known metastases (93% vs 53%, p = 0.02). TILs were present in 75% of all osteosarcoma specimens. Patients whose tumors were ≥25% or ≥50% HHLA2 positive had significantly worse five-year event-free-survival (33% vs 64%, p = 0.03 and 14% vs 59%, p = 0.02). Overall, we have shown that HHLA2 is expressed in the majority of osteosarcoma tumors and its expression is associated with metastatic disease and poorer survival. Along with previously reported findings that HHLA2 is a T cell co-inhibitor, these results suggest that HHLA2 may be a novel immunosuppressive mechanism within the osteosarcoma tumor microenvironment.