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Low response rate with trofosfamide for advanced STS in elderly



CHICAGO – In elderly patients with previously untreated metastatic soft-tissue sarcomas (STSs), the oral alkylating agent trofosfamide was associated with a lower overall response rate but long-lasting remissions among patients who had complete responses, investigators reported.

In a randomized phase 2 trial that compared trofosfamide with doxorubicin (Adriamycin), the 6-month progression-free survival (PFS) rate with trofosfamide, the primary endpoint, was 27. 6% versus 35.9% in the doxorubicin arm, said Joerg Thomas Hartmann, MD, from Franziskus Hospital in Bielefeld, Germany.

“Median age was 70 years, which means that the population included [patients] 10-15 years older as compared to other trials in metastatic adult sarcoma. The trial met its predefined endpoint, demonstrating that patients treated with trofosfamide attained a 6-month progression-free rate of more than 20%,” he said at the annual meeting of the American Society of Clinical Oncology.

Trofosfamide is an oral alkylating agent chemically related to cyclophosphamide and ifosfamide. It has been evaluated in a variety of hematologic and solid malignancies and has shown particular activity in patients with chemotherapy-naive and treatment-refractory adult STSs.

Dr. Hartmann and his colleagues conducted the phase 2 study to determine whether oral continuous or “metronomic” therapy with trofosfamide could produce a 6-month PFS rate of at least 20% in patients older than 60 years with previously untreated STSs. They selected this rate of 20% or higher based on the European Organisation for Research and Treatment of Cancer (EORTC) target criterion for doxorubicin of 25%.

They also compared grade 3 or greater toxicities of the two regimens, as well as overall response rate according to Response Evaluation Criteria in Solid Tumors (RECIST) 1,0, and overall survival.

A total of 120 patients with histologically confirmed STSs with no prior first-line chemotherapy and with adequate bone marrow, renal, and liver function were enrolled. The histologies included pleomorphic sarcoma not otherwise specified, leiomyosarcoma, liposarcoma, and others not specified by Dr. Hartmann.

The patients were randomly assigned on a 1:2 basis to receive either intravenous doxorubicin 60 mg/m2 on day 1 of each 21-day cycle for a total of 6 cycles (40 patients) or oral trofosfamide 300 mg/day for days 1 through 7 followed by 150 mg/day until disease progression or unacceptable toxicities (80 patients).

The median patient age in each arm was 70 years.

After a median follow-up of 18.4 months, the trial met its primary endpoint of a 6-months PFS with trofosfamide exceeding 20% (27.6%).

Overall response rates were 7.7% in the doxorubicin arm and 6.6% in the trofosfamide arm.

All three responses in the doxorubicin arm were partial. In the trofosfamide arm there were five responses, including two complete responses and three PR.

The duration of responses in the patients treated with trofosfamide who achieved a complete response were 8.8 and 46.6 months (median, 27.7 months). The median duration of response for trofosfamide-treated patients with a partial response was 8.2 months (range, 1.4-14.9 months).

In contrast, the median duration of response in the patients treated with doxorubicin who achieved a partial response was 4.3 months (range, 2.2-5.6 months).

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