2001, Wagner, Crews et al. 2004, Wagner, McAllister et al. 2007, Navid, Billups et al. 2008, Navid, Willert et al. 2008, Casey, Wexler et al. 2009, Mora, Cruz et al. 2009, Wagner 2010, Wagner, Perentesis et al. 2010, McGregor, Stewart et al. 2011, Rapkin, Qayed et al. 2012, Raciborska, Bilska et al. 2013, Wagner, Turpin et al. 2013). Although results of progression free survival (PFS) and OS do not significantly vary between dose regimens (Yildiz, Sen et al. 2014), PFS in patients treated with second-line irinotecan/temozolomide, the most commonly used regimen, varies Ph III Ewing’s Sarcoma Vigil ± Irinotecan +Temozolomide IND 014205 CL-PTL-130 Version: 03 Page 19 of 74 Confidential and proprietary information of Gradalis, Inc. Effective: 05-DEC-2018 It is the user’s responsibility to verify adequate training before executing a document. Do not make unauthorized copies. between 3 and 8 months with most commonly reported PFS of 6 months (Casey, Wexler et al. 2009, Raciborska, Bilska et al. 2013, Palmerini, Jones et al. 2016) . Clinical studies have demonstrated the combination of irinotecan and temozolomide to have synergy and significant antitumor activity. Casey et al. showed that the combination of temozolomide and irinotecan is well -tolerated and an active regimen for recurrent or refractory Ewing’s sarcoma patients (first relapse) with an overall response of 63% and median TTP of 8.3 months (Casey, Wexler et al. 2009) . A retrospective study of 22 patients with relapsed or refractory Ewing’s sarcoma treated with the combination of vincristine, irinotecan, and temozolomide reviewed a shorter treatment course of 5 days for irinotecan instead of the protracted 10 -day course. Results showed comparable response rates (68.1 %) with a median TTP of 3 months and suggests the use of the short schedule of administration (Raciborska, Bilska et al. 2013) . In a similar study orally administered irinotecan, temozolomide and vincristine showed milder cumulative toxicities employing a 5-day treatment course rather than 10 days in sarcoma patients (Wagner, Perentesis et al. 2010) . A pediatric study has directly compared the efficacy of irinotecan with a daily for 5 days versus daily for 5 days for 2 weeks schedule (Mascarenhas, Lyden et al. 2010) in 89 evaluable patients with recurrent rhabdomyosarcoma were randomized to receive vincristine combined with irinotecan. The overall incidence of grade 3– 4 adverse events was similar and no significant difference in efficacy was observed. Casey and colleagues showed that irinotecan (iv dx5 x2) and temozolomide (orally dx5) was well tolerated and an active regimen in Ewing’s sarcoma in first recurrence (n=11), second recurrence (n=3) or refractory to primary chemotherapy (n=6) (Casey, Wexler et al. 2009). A more recent review of irinotecan of the past 15 years evaluated oral versus intravenous administration in pediatric sarcoma patients (Wagner, Perentesis et al. 2010, Wagner 2015). Even though the oral dosing requires a higher total dose of irinotecan (bioavailability is less) the metabolism of orally administered irinotecan appears to be more efficient, given that the intestinal tract contains high levels of carboxylesterases, which may pre- systemically metabolize irinotecan to the active moiety, SN -38 and increase the SN-38/irinotecan ratio by threefold or more (Drengler, Kuhn et al. 1999). Although there have been no studies directly comparing the efficacy of the two routes of administration, at similar SN -38 lactone exposures (60 mg/m 2/day oral vs. 20 mg/m2/day IV), response rates, and toxicity profiles appear to be equivalent. A phase 1 dose escalation (Irinotecan 50mg/m2/dose escalated to a maximum of 90mg/m2/dose, and temozolomide 100mg/m2/dose escalated to a maximum of 150mg/m2/dose) study in pediatric patients with relapsed or refractory solid tumors of oral irinotecan, temozolomide and temsirolimus demonstrated that lower dose level of irinotecan (50mg/m 2/dose) and temozolomide (100mg/m2/dose) was well tolerated with less toxicities (Bagatell, Norris et al. 2014) . An additional study recommends 50mg/m2 per day for 5 consecutive days for phase II studies of oral irinotecan (Soepenberg, Dumez et al. 2005). The benefit of oral administration includes not only greater patient convenience, shorter hospitalization and decrease in costs, but most importantly improved quality of life. Thus, summarizing studies of oral irinotecan and temozolomide and in agreement with participating investigators a lower dose regimen of 50mg/m2/d irinotecan and 100mg/m2/d temozolomide administered orally appears to be an acceptable standard of care regimen for second -line Ewing’s sarcoma providing clinical activity with low toxicity profiles. In those occasional patients with difficulty taking oral medication (e.g. severe nausea, chronic gastrointestinal complaints, and age -related oral aversion) intravenous Ph III Ewing’s Sarcoma Vigil ± Irinotecan +Temozolomide IND 014205 CL-PTL-130 Version: 03 Page 20 of 74 Confidential and proprietary information of Gradalis, Inc. Effective: 05-DEC-2018 It is the user’s responsibility to verify adequate training before executing a document.