|The following article features coverage from the Connective Tissue Oncology Society (CTOS) in Maui, Hawaii. Click here to read more of Cancer Therapy Advisor‘s conference coverage.|
Olaratumab monotherapy is safe and may improve outcomes among patients with advanced or metastatic soft tissue sarcoma (STS) who were previously treated with doxorubicin or doxorubicin plus olaratumab, according to a poster presentation at the Connective Tissue Oncology Society (CTOS) 2017 Annual Meeting.1
Olaratumab, which inhibits PDGFRα expression, was previously shown to improve progression-free survival (PFS) and overall survival (OS) among patients with advanced or metastatic STS when given with doxorubicin compared with doxorubicin alone. Positive results from a phase 1b/2 trial (ClinicalTrials.gov Identifier: NCT01185964) led to the accelerated approval of olaratumab by the US Food and Drug Administration.
It was previously open to question, however, whether olaratumab monotherapy benefits patients previously treated with olaratumab plus doxorubicin or doxorubicin alone. At the CTOS 2017 Annual Meeting, researchers presented olaratumab monotherapy subgroup results from the phase 2 trial. Patients were treated until disease progression or unacceptable toxicity.
Of 64 patients who received olaratumab monotherapy, 34 were previously treated with olaratumab plus doxorubicin and 30 were previously treated with doxorubicin only. The median age was 56 years in both groups.
In patients previously treated with the drug combination, the median number of olaratumab monotherapy cycles was 4.5. The 2-year OS rate was 67.6%, the median PFS was 9.8 months, and the median OS was 31.7 months. Two patients discontinued treatment because of adverse events (AEs). AEs occurred in 94.1% of patients; the most common AE was diarrhea.
Of patients previously treated with doxorubicin only, the median number of olaratumab monotherapy cycles was 2. The 2-year OS rate was 28.7% and the median OS was 13.5 months. No patients discontinued treatment because of an AE, though AEs occurred in 86.7% of patients. The most common AEs were fatigue and nausea.
The authors concluded that “[patients] treated with olaratumab monotherapy following olaratumab plus [doxorubicin] had efficacy outcomes longer than any historically reported OS for [patients] with advanced or metastatic soft tissue sarcoma.”
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- Barker S, Peterson P, Ilaria RL, et al. Olaratumab after treatment with olaratumab + doxorubicin: monotherapy (mono) outcomes from the JGDG phase 2 clinical trial. Poster presentation at: Connective Tissue Oncology Society (CTOS) 2017 Annual Meeting. November 8-11, 2017; Maui, Hawaii.