Charles Theuer, M.D., Ph.D., President and CEO of TRACON, said: “The SPA agreement represents a significant milestone for TRACON, as it provides us with a clearly defined development and regulatory pathway for TRC105, our lead clinical program, for the treatment of angiosarcoma.
"We appreciate the FDA’s engagement and guidance during the SPA process and look forward to dosing the first patients in the trial during early 2017."
TRACON intends to conduct the Phase 3 TAPPAS trial (a randomized Phase 3 trial of TRC105 And Pazopanib versus Pazopanib alone in patients with advanced AngioSarcoma) at sites in both the United States and Europe. This one-to-one randomized trial of TRC105 in combination with Votrient (pazopanib) versus Votrient alone will initially enroll 124 patients.
The trial features an adaptive design that, based on an interim analysis, can allow for sample size re-estimation up to a maximum of 200 patients, as well as possible enrichment of more responsive patients with cutaneous angiosarcoma. The primary endpoint of the trial is progression-free survival (PFS), with overall survival (OS) as a secondary endpoint.
About Special Protocol Assessment (SPA)
The SPA process is one in which a sponsor asks the FDA to evaluate the proposed design and size of Phase 3 clinical trials that are intended to form the primary basis for determining a drug product’s efficacy. An SPA agreement indicates concurrence with the adequacy and acceptability of specific critical elements of protocol design, endpoints and analysis.
Additionally, it provides a binding agreement with FDA’s review division with respect to the elements agreed to in the SPA process that are considered critical to ensuring the trial has the potential to support a future marketing application.
However, final marketing approval depends upon the results of efficacy, the safety profile, and an evaluation of the risk/benefit of treatment demonstrated in the Phase 3 clinical trial, among other requirements, and the FDA may revoke or alter its agreement under certain circumstances.
About TRC105 (carotuximab)
TRC105 is a novel, clinical stage antibody to endoglin, a protein overexpressed on proliferating endothelial cells that is essential for angiogenesis, the process of new blood vessel formation.
TRC105 is currently being studied in multiple Phase 2 clinical trials sponsored by TRACON or the National Cancer Institute (NCI) for the treatment of solid tumor types in combination with VEGF inhibitors.
The ophthalmic formulation of TRC105, DE-122, is currently in a Phase 1/2 trial for patients with wet AMD. TRC205, a second generation antibody to endoglin, is undergoing preclinical testing in models of fibrosis.
About Angiosarcoma
Angiosarcoma is an aggressive form of soft tissue sarcoma (STS) of endothelial cell origin that is associated with poor prognosis. Angiosarcoma has a 5-year survival rate of less than 12%, which highlights the aggressive nature of this tumor when compared to a 5-year survival rate of approximately 56% for all STS.
Angiosarcoma can arise in any soft tissue structure. About half of patients present with a primary cutaneous lesion. Risk factors include prior radiation exposure as well as inflammatory damage in chronically sun exposed skin.
Angiosarcoma has also been associated with chronic lymphedema. Although resection with curative intent followed by adjuvant radiotherapy is the treatment of choice for localized disease amenable to surgery, approximately 50% of these patients will develop metastases and die from the disease.
Furthermore, metastases are frequently present at diagnosis, and resection of metastases is rarely feasible.
Angiosarcoma is an extremely rare disease and meets the definition for an orphan disease in the US and European Union (EU), the two regions for which the Phase 3 TAPPAS study is planned. TRC105 has received orphan designation for the treatment of soft tissue sarcoma in both the US and EU.
The annual incidence of angiosarcoma in the US was reported by the NCI in 2015 to be 475 cases. In the EU the incidence of angiosarcoma is 0.01 per 10,000, accounting for an estimated 508 cases annually.