A new therapeutic combination to combat resistant sarcomas has shown promise in a trial in 19 patients. The new treatment could stabilize the growth of these tumors.

Sarcomas are a rare and complex type of tumor with several subtypes. They can affect patients in childhood through to older persons. Sarcomas are usually diagnosed in advanced stages and seldom at localized stages. This results in about 50% of patients with sarcoma being cured through major surgeries and localized treatment, while the other 50% are resistant to conventional therapies and experience metastasis.

The research was conducted by the Sarcomas Research Group at the Bellvitge Biomedical Research Institute (IDIBELL), which is led by Oscar Martinez-Tirado, PhD, and by the Catalan Institute of Oncology (ICO). This study was published in the British Journal of Cancer (2014; doi:10.1038/bjc.2014.370).

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The researchers tested different combinations of conventional chemotherapy with new drugs aimed at molecular targets in cell sarcomas. This led them to try a trial in mice of a combination of conventional chemotherapy used to treat these tumors and rapamycin, a drug that acts specifically in mTOR, an altered protein in various types of cancer.

“With the results in the cell lines we thought it was the best option to test in mice, but the truth is that the results in animals were spectacular,” said Martinez-Tirado. “In mice that had the tumor and received this combination, the tumor stopped growing. Weeks after stopping treatment the tumor was not recovered, as it does if we treat them with chemotherapy alone or only with rapamycin.”

This phase I clinical trial, led by Javier García del Muro, MD, PhD, tested this new combination in 19 patients. Most of the patients had sarcoma, but the trial also included patients with other tumor types that have no treatment.

“Although Phase I trials are used to determine the recommended dose and discard toxicities, we have seen that the combination is active in various tumor types, as we have seen prolonged stabilizations in advanced and resistant tumors to chemotherapy,” said Martinez-Tirado. With these encouraging results, the group has launched a phase II clinical trial.

“We have completed the recruitment of patients, in this case, only sarcomas, to test whether this combination really works in these patients and whether it is better than current treatments,” said Martinez-Tirado.