A successful case of allogeneic bone marrow transplantation for osteosarcoma with multiple metastases of lung and bone

The generation and use of animal models of osteosarcoma in cancer research

Osteosarcoma is the most common malignant bone tumor affecting children and adolescents. Currently, the most common treatment is surgery combined with neoadjuvant chemotherapy. Although the survival rate of patients with osteosarcoma has improved in recent years, it remains poor when the tumor(s) progress and distant metastases develop. Therefore, better animal models that more accurately replicate the natural progression of the disease are needed to develop improved prognostic and diagnostic markers, as well as targeted therapies for both primary and metastatic osteosarcoma. The present review described animal models currently being used in research investigating osteosarcoma, and their characteristics, advantages, and disadvantages. These models may help elucidate the pathogenic mechanism(s) of osteosarcoma and provide evidence to support and develop clinical treatment strategies.

Natural Killer Cells: Development, Maturation, and Clinical Utilization

Natural killer (NK) cells are the predominant innate lymphocyte subsets that mediate anti-tumor and anti-viral responses, and therefore possess promising clinical utilization. NK cells do not express polymorphic clonotypic receptors and utilize inhibitory receptors (killer immunoglobulin-like receptor and Ly49) to develop, mature, and recognize “self” from “non-self.” The essential roles of common gamma cytokines such as interleukin (IL)-2, IL-7, and IL-15 in the commitment and development of NK cells are well established. However, the critical functions of pro-inflammatory cytokines IL-12, IL-18, IL-27, and IL-35 in the transcriptional-priming of NK cells are only starting to emerge. Recent studies have highlighted multiple shared characteristics between NK cells the adaptive immune lymphocytes. NK cells utilize unique signaling pathways that offer exclusive ways to genetically manipulate to improve their effector functions. Here, we summarize the recent advances made in the understanding of how NK cells develop, mature, and their potential translational use in the clinic.

KIR receptor-ligand incompatibility predicts killing of osteosarcoma cell lines by allogeneic NK cells

BACKGROUND

The effectiveness of killer immunoglobulin-like receptor (KIR) incompatible, alloreactive natural killer (NK) cells has been primarily documented in hematological malignancies following stem-cell transplant. This effect has not been thoroughly evaluated for pediatric solid tumors. In this study, we evaluated KIR receptor-ligand incompatibility of NK cells against osteosarcoma cell lines.

PROCEDURE

Following the KIR receptor-ligand mismatch model, MHC I cell surface expression and KIR ligand mRNA content of 3 osteosarcoma cell lines was determined by flow cytometry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR), respectively. NK cells were isolated from healthy volunteer donor peripheral blood mononuclear cells (PBMCs) and KIR surface expression determined by flow cytometry. An Annexin-V based flow cytometric killing assay was used to determine % of dying osteosarcoma target cells by donor NK effector cells.

RESULTS

One of seven healthy volunteer donors tested lacked phenotypic expression of one KIR. However, variable expression of KIR ligands was observed in 3 osteosarcoma cell lines. The highest rates of dying cells were seen in osteosarcoma cells with the lowest KIR ligand expression. Following down-regulation of KIR ligand expression, an increased susceptibility to NK cell-mediated killing was observed in a previously NK-resistant osteosarcoma cell line.

CONCLUSIONS

Variable MHC I and KIR ligand expression was observed in osteosarcoma cell lines and this resulted in variable susceptibility to NK cell-mediated killing predicted by the degree of KIR receptor-ligand incompatibility. Collectively, these data provide rationale for the study of KIR incompatible stem-cell transplant for osteosarcoma, although further studies with fresh osteosarcoma samples are necessary.

KIR-HLA receptor-ligand mismatch associated with a graft-versus-tumor effect in haploidentical stem cell transplantation for pediatric metastatic solid tumors

Killer immunoglobulin-like receptors (KIRs) on natural killer cells (NKs) recognize groups of human leukocyte antigen (HLA) class I alleles. Cells without an inhibitory HLA ligand may trigger NK activation. Reduced risk of relapse has been reported in malignant hematologic diseases after haploidentical transplantation when HLA ligands against the inhibitory KIRs present in the donor were absent in the recipient. We performed haploidentical transplant in three children with refractory solid tumors. Our results showed that beneficial antitumor effects could be observed in the presence of inhibitory KIR-HLA mismatch. These preliminary results suggest a possible association between disease control and NK cell alloreactivity.

Poor prognosis osteosarcoma: new therapeutic approach

Over the past 30 years, a significant improvement in the prognosis of localized osteosarcoma of the extremities has been observed. Despite these results, approximately 30-40% of patients will relapse, mostly within the first 3 years from diagnosis. The prognosis of patients with recurrent disease or metastases at diagnosis is poor. To improve the survival in this patient population, several attempts have been made. An increased dose intensity of chemotherapy induces short lasting remission but does not increase the survival. In the era of targeted therapy, few drugs have been tested with dismal results. The use of biological agents endowed with immunomodulant activity (that is IL-2) or reduced-intensity allogeneic hemopoietic SCT has produced intriguing results that need further confirmation. In this context, an ongoing study explores the antitumor activity of specific T-cytotoxic lymphocytes.