Background Data from microarray analysis of 61 primary and metastatic osteosarcoma patient samples revealed that Src is expressed in all of the samples. In addition, a tissue array was tested for activation of Src, and its substrates, FAK and paxillin, by immunohistochemistry. 15 of 17 (88%) samples showed activated Src. 18 of 19 (94%) samples were positive for phosphorylated FAK. 10 of 20 (50%) samples were positive of phosphorylated paxillin. In total, 19 of 20 (95%) samples had activation of at least one of the above three genes. These findings demonstrate that the Src pathway is activated in 95% of patients with osteosarcoma. Saracatenib is a highly selective, orally bio-available, dual-specific Src/Abl kinase inhibitor that has high potency against all Src family members tested. This includes c-yes and c-fyn, the members that are most closely related to c-src. IC50 c-src = 2.7 nM. IC50 c-yes = 4 nM. IC50 c-fyn = 10 nM. Preliminary studies have utilized two metastatic osteosarcoma cell lines. K7M2 is a murine cell line and MNNG/HOS is a chemically transformed variant of the human osteosarcoma cell line HOS. Treatment of either of these osteosarcoma cell lines with Saracatenib did not lead to changes in cell proliferation in vitro as determined by MTT assays. This is similar to results found in breast, colon, lung and prostate tumor cell lines. However, treatment of both murine and human osteosarcoma cell lines with Saracatenib led to inhibition of tumor cell migration as determine by a wound-healing assay and migration through a porous membrane. Again, this effect is in concordance with data obtained using MDA-MB231 and MCF-7 breast cancer cell lines. Evaluation of Saracatenib monotherapy in healthy volunteers and patients with advanced cancer have demonstrated that dosing of Saracatenib is associated with a manageable safety and tolerability profile. To date, no formal evaluations of efficacy using Saracatenib have been performed. In the Phase 1 multiple ascending dose and cohort expansion study conducted in 81 patients with advanced cancer, 11 patients experienced a best objective response of stable disease, with 11 others having unconfirmed stable disease. There were no complete responses or confirmed partial responses. Thirteen out of 81 (16%) patients who participated in the Phase 1 study received Saracatenib therapy for over 12 weeks. There is a large body of in vitro data showing Src plays an important role in the motility of osteosarcoma cells, a function that can be abrogated by the use of Src inhibitors. More importantly, Src and other genes that are involved in the Src pathway are activated in 95% of patients with osteosarcoma. These data suggest that Saracatenib represents a promising candidate for the treatment of patients with recurrence of osteosarcoma. We utilized a newly described type of study, coined a Phase II.5 study. Phase II.5 studies examine outcome differences using a one-sided 0.10 alpha level significance test, rather than the traditional value of 0.05. The benefits of this type of study include enrollment of a fewer number of patients, which is important since patients with recurrent osteosarcoma are rare. In addition, it is a randomized, placebo-controlled trial, thus precluding the need to compare to historical controls, which is important since patients with recurrent osteosarcoma have previously received many different treatment modalities. The purpose of this design is to provide a sufficiently large, controlled, comparative evaluation to determine whether a sufficient effect is noted. Although the results are not definitive, if merited, they can then be used to estimate the parameters to design a definitive subsequent trial. The trial objective is to perform a randomized, double-blinded, placebo-controlled study to evaluate the addition of Saracatenib to pulmonary metastectomy, versus placebo and pulmonary metastectomy, in patients with relapsed osteosarcoma, localized to the lung. Currently, patients who achieve a surgical second remission have a progression free survival rate of 33% at two years and an overall survival rate of 45% at three years. An important caveat to this statement is that these patients have received a multitude of different treatments, including surgery alone, and/or radiation, and/or chemotherapy, and/or high dose chemotherapy with stem cell rescue. Therefore, historical data do not give a true indication of actual survival rates. This study will try to determine whether patients who receive Saracatenib will experience a 60% relative increase in progression free survival. Secondary objectives will determine whether patients who receive Saracatenib will experience a 56% relative increase in overall survival and an increase in the time to treatment failure. The randomized nature of this study will allow us to determine the actual survival rates in these two cohorts, thereby assessing the efficacy of Saracatenib in this patient population. Forty-four patients will need to be randomized in each arm, for a total of 88 patients, over a 48-month accrual period. Follow-up for survival of the last patient randomized must continue for an additional year. The primary objective of this study is to determine whether pulmonary metastectomy and treatment with Saracatenib, versus pulmonary metastectomy and treatment with placebo, results in an increase in progression free survival. A secondary objective is to determine whether pulmonary metastectomy and treatment with Saracatenib, versus pulmonary metastectomy and treatment with placebo, results in an increase in overall survival. Patients will be eligible for the study following the histological verification of recurrent osteosarcoma. Patients will be stratified based on the number of recurrences and the number of recurrent nodules. Randomization to the Saracatenib arm or the placebo arm will occur after complete surgical resection. Patients who are randomized to the Saracatenib arm will receive Saracatenib, 175 mg, orally, once daily, for a 28-day cycle, with no breaks between cycles. The total duration of treatment with Saracatenib will be 13 cycles (364 days total). Patients will receive one 125 mg tablet (9.5 mm diameter) and one 50 mg tablet (7 mm diameter). Patients who are randomized to the placebo arm will receive placebo, orally, once daily, for a 28-day cycle, with no breaks between cycles. The total duration of treatment with placebo will be 13 cycles (364 days total). Patients will receive one 9.5 mm tablet and one 7 mm tablet. These tablets will be indistinguishable from Saracatenib. This protocol was opened in July 2009 at the NIH. This is a multi-institutional study, coordinated by the Sarcoma Alliance for Research through Collaboration (SARC). Results from 2010 In 2010, this protocol opened at 14 institutions across the United States. Nine patients have enrolled to date. Plans for 2011 In 2011, we will continue to enroll patients at an expected pace of 22 per year. With 14 sites open, the enrollment of two patients per site yearly will allow us to complete the protocol in the expected time period five years. Significance and Goals The successful completion of the above objectives will allow us to determine if the addition of a Src kinase inhibitor will improve survival for patients who have received the standard of care for metastatic osteosarcoma. We will also be in a position to perform molecular genetic studies to try to identify determinants of metastasis in osteosarcoma.
