Establishment and Characterization of Histologically and Molecularly Stable Soft-tissue Sarcoma Xenograft Models for Biological Studies and Preclinical Drug Testing

Abstract

Soft-tissue sarcomas (STS) represent a heterogeneous group of rare, malignant tumors of mesenchymal origin. Reliable in vivo sarcoma research models are scarce. We aimed to establish and characterize histologically and molecularly stable patient-derived xenograft (PDX) models from a broad variety of STS subtypes. A total of 188 fresh tumor samples from consenting patients with localized or advanced STS were transplanted subcutaneously in NMRI-nu/nu-immunodeficient mice. Once tumor growth was observed, the material was passaged to a next generation of mice. A patient-derived tumor sample was considered "successfully engrafted" whenever the sample was transplanted to passage 1. A PDX model was considered "established" when observing stable morphologic and molecular features for at least two passages. With every passage, histologic and molecular analyses were performed. Specific genomic alterations and copy-number profile were assessed by FISH and low coverage whole-genome sequencing. The tumor engraftment rate was 32% (61/188) and 188 patient samples generated a total of 32 PDX models, including seven models of myxofibrosarcoma, five dedifferentiated liposarcoma, five leiomyosarcoma, three undifferentiated pleomorphic sarcoma, two malignant peripheral nerve sheet tumor models, and single models of synovial sarcoma and some other (ultra)rare subtypes. Seventeen additional models are in early stages of engraftment (passage 1-2). Histopathologic and molecular features were compared with the original donor tumor and were stable throughout passaging. The platform is used for studies on sarcoma biology and suited for in vivo preclinical drug testing as illustrated by a number of completed and ongoing laboratory studies.

A Novel Anionic-phosphate-platinum Complex Effectively Targets a Cisplatinum-resistant Osteosarcoma in a Patient-derived Orthotopic Xenograft Mouse Model

“…The present study showed that the safety and antitumor efficacy of 3Pt was superior to that of CDDP in a CDDPresistant osteosarcoma PDOX model. PDOX models (12,(26)(27)(28) have important advantages over subcutaneous models (29) in that the tumors are growing in the proper microenvironment as in the present case in the bone.…”

Plocabulin, a novel tubulin inhibitor, has potent antitumor activity in patient-derived xenograft models of gastrointestinal stromal tumors

“…Absolute tumor volumes within groups at start and end of experiment were compared using the Wilcoxon matched-pairs signed rank test to assess tumor volume evolution. Two tumors engrafted on the same mouse were regarded as independent entities, as was demonstrated previously by our group and were thus analyzed separately [ 39 ].…”

<p>Animal models of well-differentiated/dedifferentiated liposarcoma: utility and limitations</p>

“…However, it should be advised that one recent study has reported that PDX models of varied tumor types develop mutations with serial passages that diverge from those observed in the patients 35. Recently, 5 PDX models were successfully established from surgical specimens and biopsies of 31 DDL patients 36. The tumors fragments were implanted bilaterally into the subcutaneous space of immunodeficient mice.…”

“…Bilateral tumor engraftment and cryopreservation approaches of PDX models were used to reduce the number of mice required over time. Cryopreserved PDX tumors were successfully re-engrafted in mice 36. Such strategies are not avoid of limitations, including the need of a sufficient amount of fresh tumor tissue, the time of propagation and the failure rate of about 20% of the tumor implantation that, however, may predict lower aggressiveness.…”

“…In this regard, it has been proposed to keep the tumors inside a vascularized chamber during their growth into host mice to improve the engraftment success 39Table 1Mouse xenograft models for DDLXenograftCell linesTumor driversTime to tumor formationTreatment inhibitorsTreatment responseRef.CDXLipo246Lipo224Lipo863 RTKs 10 days-6 months––(37)IB115 MDM2 / CDK4 2 weeksRG7388/palbociclib co-treatmentEffective(44)IB115PI3K/Akt/mTOR1 monthBEZ-235/RG7388 co-treatmentEffective(55)Lipo246Lipo863 AXL 1 monthAXL knockoutEffective(56)Lipo246 MET 2 weeksEMD1214063Effective(59)SW872IL-62 months––(63)Lipo246miR-1553–6 weeksmiR-155 knockdownEffective(72)PDX MDM2 / CDK4 / JAK2 mutations2–6 monthsP1446A-05/ruxolitinib co-treatmentModerately effective(34)ifosfamideEffective MDM2 2–4 months––(36)…”