Immunity against soft-tissue sarcomas

Immunotherapy: A New (and Old) Approach to Treatment of Soft Tissue and Bone Sarcomas

Soft tissue and bone sarcomas are a rare and heterogeneous form of cancer. With standard of care treatment options including surgery, radiation, and chemotherapy, the long-term survival is still low for high-risk soft tissue sarcoma patients. New treatment strategies are needed. Immunotherapy offers a new potential treatment paradigm with great promise. Immunotherapy of soft tissue sarcomas dates back to Dr. Coley's first use of toxins in the late 1800s. A variety of strategies of immunotherapy have been tried in soft tissue and bone sarcomas, including various vaccines and cytokines, with limited success. Results of these early clinical trials with vaccines and cytokines were disappointing, but there are reasons to be optimistic. Recent advances, particularly with the use of adoptive T-cell therapy and immune checkpoint inhibitors, have led to a resurgence of this field for all cancer patients. Clinical trials utilizing adoptive T-cell therapy and immune checkpoint inhibitors in soft tissue and bone sarcomas are under way. This paper reviews the current state of evidence for the use of immunotherapy, as well as current immunotherapy strategies (vaccines, adopative T-cell therapy, and immune checkpoint blockade), in soft tissue and bone sarcomas. By understanding the tumor microenviroment of sarcomas and how it relates to their immunoresponsiveness, better immunotherapy clinical trials can be designed, hopefully with improved outcomes for soft tissue and bone sarcoma patients.

IMPLICATIONS FOR PRACTICE

Immunotherapy is a promising treatment paradigm that is gaining acceptance for the management of several cancers, including melanoma, renal cell carcinoma, prostate cancer, and lung cancer. There is a long history of immunotherapy in the treatment of soft tissue and bone sarcomas, although with little success. It is important to understand past failures to develop future immunotherapy treatment strategies with an improved possibility of success. This article reviews the history of and current state of immunotherapy research in the treatment of soft tissue and bone sarcomas, with particular regard to vaccine trials, adoptive T-cell therapy, and immune checkpoint blockade.

Potential for immunotherapy in soft tissue sarcoma

Soft tissue sarcomas (STS) are rare, heterogeneous tumors of mesenchymal origin. Despite optimal treatment, a large proportion of patients will develop recurrent and metastatic disease. For these patients, current treatment options are quite limited. Significant progress has been made recently in the use of immunotherapy for the treatment of other solid tumors (e.g. prostate cancer, melanoma). There is a strong rationale for immunotherapy in STS, based on an understanding of disease biology. For example, STS frequently have chromosomal translocations which result in unique fusion proteins and specific subtypes have been shown to express cancer testis antigens. In this review, we discuss the current status of immunotherapy in STS, including data from human studies with cancer vaccines, adoptive cell therapy, and immune checkpoint blockade. Further research into STS immunology is needed to help design logical, subtype-specific immunotherapeutic strategies.

Adult soft tissue sarcomas: Conventional therapies and molecularly targeted approaches

The therapeutic approach to soft tissue sarcomas (STS) has evolved over the past two decades based on the results from randomized controlled trials, which are guiding physicians in the treatment decision-making process. Despite significant improvements in the control of local disease, a significant number of patients ultimately die of recurrent/metastatic disease following radical surgery due to a lack of effective adjuvant treatments. In addition, the characteristic chemoresistance of STS has compromised the therapeutic value of conventional antineoplastic agents in cases of unresectable advanced/metastatic disease. Therefore, novel therapeutic strategies are urgently needed to improve the prognosis of patients with STS. Recent advances in STS biology are paving the way to the development of molecularly targeted therapeutic strategies, the efficacy of which relies not only on the knowledge of the molecular mechanisms underlying cancer development/progression but also on the personalization of the therapeutic regimen according to the molecular features of individual tumours. In this work, we review the state-of-the-art of conventional treatments for STS and summarize the most promising findings in the development of molecularly targeted therapeutic approaches.

Mechanisms of Sarcomagenesis

Sarcomas comprise a heterogeneous group of malignancies that are derived from mesenchymal cells, which under normal circumstances lead to the development of connective tissues such as bone, muscle, fat, and cartilage. During the past decade, insight has been gained regarding the aberrancies that occur during normal development that result in mesenchymal cells transforming into sarcomas. More recently, these insights have led to the development of successful therapies that target the specific mechanisms inherent to individual sarcomas. This overview discusses some of the aberrant molecular mechanisms shared in sarcomas and reviews several sarcoma subtypes in which the most advances have been made. Finally, the ways in which these advances in basic science are translating into and redefining clinical practice are highlighted.

Phase I/II trial of autologous tumor cell line-derived vaccines for recurrent or metastatic sarcomas

AIM

We previously reported the laboratory methodology for producing patient-specific irradiated autologous tumor-cell products derived from short-term cultured tumor cells. We attempted to determine the feasibility, safety, and clinical effects of autologous tumor vaccine-derived sarcomas.

PATIENTS AND METHODS

Efforts were made to establish tumor cell lines in tissue culture with expansion to 100 million cells for patients who were candidates for therapy. Cells were irradiated and cryopreserved in aliquots of 10 million cells for subcutaneous (s.c.) injections, once a week for 3 weeks, then once a month for 5 months.

RESULTS

Efforts were made to establish short-term tumor cell lines from 86 fresh sarcoma specimens (10 primary, 14 recurrent, and 62 metastatic). Initial growth was successful for 48 patients (56%), and cultures were expanded for 36 patients, with 25 patients treated. There were 23 evaluable patients, including 12 women and 11 men, with a median age of 52 years and a range from 16-79 years. Vaccine therapy was well tolerated. Delayed-type hypersensitivity (DTH) tests to irradiated tumor cells were positive in 0 of 20 patients tested at baseline, but converted to positive after 3 weekly vaccinations in 8 of 16 patients who were retested. Median survival for the 8 DTH converters was 16.6 months versus 8.2 months for the 8 responders whose tumor DTH test remained negative, and 6.0 months for the 7 patients who were not tested. No objective responses were recorded among 12 evaluable patients with measurable disease; 10 patients have survived more than 1 year.

CONCLUSIONS

This approach is feasible, well tolerated, and the resulting DTH conversion rate is of interest. Patients with minimal tumor burden would be preferred for further future testing.