Phase II trial of the mTOR inhibitor, temsirolimus and evaluation of circulating tumor cells and tumor biomarkers in persistent and recurrent epithelial ovarian and primary peritoneal malignancies: A Gynecologic Oncology Group study ★

ObjectivePatients with persistent/recurrent epithelial ovarian cancer/primary peritoneal cancer (EOC/PPC) have limited treatment options. AKT and PI3K pathway activation is common in EOC/PPC, resulting in constitutive activation of downstream mTOR. The GOG conducted a phase II evaluation of efficacy and safety for the mTOR inhibitor, temsirolimus in EOC/PPC and explored circulating tumor cells (CTC) and AKT/mTOR/downstream tumor markers.MethodsEligible women with measurable, persistent/recurrent EOC/PPC who had received 1–3 prior regimens were treated with 25 mg weekly IV temsirolimus until progression or intolerable toxicity. Primary endpoints were progression-free survival (PFS) ≥ 6-months, tumor response, and toxicity. CellSearch® system was used to examine CTC, and AKT/mTOR/downstream markers were evaluated by archival tumor immunohistochemistry. Kendall's tau-b correlation coefficient (r) and Cox regression modeling were used to explore marker associations with baseline characteristics and outcome.ResultsSixty patients were enrolled in a two-stage sequential design. Of 54 eligible and evaluable patients, 24.1% (90% CI 14.9%–38.6%) had PFS ≥ 6 months (median 3.1 months), 9.3% (90% CI 3.7%–23.4%) experienced a partial response. Grade 3/4 adverse events included metabolic (8), gastrointestinal (8), pain (6), constitutional (5) and pulmonary (4). Suggested associations were between cyclin D1 and PFS ≥ 6 months, PFS or survival; positive CTC pre-treatment and lack of response; and high CTC expression of M30 and PFS ≥ 6 months/longer PFS.ConclusionsTemsirolimus appears to have modest activity in persistent/recurrent EOC/PPC; however, PFS is just below that required to warrant inclusion in phase III studies in unselected patients. Cyclin D1 as a selection marker and CTC measures merit further study.

Research highlights
► Single agent temsirolimus exhibited modest activity in unselected patients with 24% progression-free ≥ 6 months and 9% partial responders.
► Cyclin D1 expression appeared to be associated with longer PFS and survival following temsirolimus treatment, and high p4E-BP1 in tumors.
► Detectable circulating tumor cells pre-treatment appeared to be associated with lack of response to temsirolimus.