Phase III study of aldoxorubicin vs investigators' choice as treatment for relapsed/refractory soft tissue sarcomas.

11000 Background: Aldoxorubicin (A) is a novel drug that binds covalently to albumin in the circulation, accumulates in tumors and releases doxorubicin in the acidic tumor environment. It has demonstrated enhanced antitumor activity in several murine models and in a phase IIb STS study when compared with doxorubicin. Trial Design: Phase III open-label study evaluating efficacy and safety of A compared to investigators' choice (IC) of treatment in subjects with soft tissue sarcomas (STS) who have relapsed or were refractory to prior chemotherapy. Objectives: (1) Primary: Efficacy of A vs IC: progression-free survival (PFS); (2) Secondary: Efficacy of A vs IC: tumor response (ORR), disease control rate (DCR; CR+PR+SD > 4 months), overall survival (OS) and safety. Methods: A: 350 mg/m 2 (260 mg/m 2 dox. equiv.) iv q3 wks. IC drugs: dacarbazine, doxorubicin, pazopanib, ifosfamide, gemcitabine/docetaxel administered per package insert or study site's standard practice; provided, with G-CSF, by the sponsor. AEs, serum chemistries, CBCs, EKG and ECHOs obtained frequently. CT scans every 6 weeks for 30 weeks, then every 12 weeks; analyzed using RECIST 1.1 by Blinded Independent Central Review. Results: Randomized 433 subjects; 79 countries; 313 (72%) in North America (NA) and 121 (28%) in Rest of World (ROW). Leiomyosarcoma 42.5%, liposarcoma 15%, synovial sarcoma 9%, others 33.5%, L-sarcomas (lipo+leiomyo) 57.5%. Median PFS Total Pop. (months): A= 4.06; IC= 2.96; p = 0.12; HR = 0.82 (0.64-1.06). Median PFS NA (months): A= 4.21; IC= 2.96; p = 0.027; HR = 0.71 (0.53-0.97). Median PFS L-sarcomas (months): A= 5.32; IC= 2.96; p = 0.007; HR = 0.62 (0.44-0.88). DCR Total Pop.(%): A= 30.3; IC= 20.9; p = 0.028; DCR NA (%): A= 32.9; IC= 19.2; p = 0.007; DCR L-Sarcomas (%): A= 37.5; IC= 23.0; p = 0.018. ORR and OS will be reported. TEAEs gr 3 or 4 (%): A= 61.0; IC= 46.4. Trtmt Rel. SAEs (%): A= 27.0; IC= 14.0. TEAEs leading to Drug Discontinue (%): A= 4.2; IC= 6.3. Trtmt Related Deaths (#); A= 3; IC= 0; LVEF < 50% expected (%): A= 2.8%;Dox = 12.8%. Conclusions: Aldox is an active, well-tolerated drug for treating relapsed or refractory STS and is significantly better than standard treatments for patients with L-sarcomas. Clinical trial information: NCT02049905.