On December 3, 2018 Onconova Therapeutics, Inc. (NASDAQ:ONTX), a Phase 3 clinical-stage biopharmaceutical company focused on discovering and developing novel products to treat cancer, reported the presentation of the efficacy and safety results of oral rigosertib in combination with azacitidine (Vidaza) in patients with HR-MDS reported at an oral presentation during the 60th American Society of Hematology (ASH) (Free ASH Whitepaper) Annual Meeting and Exposition in San Diego (Press release, Onconova, DEC 3, 2018, View Source [SID1234531818]). Rigosertib, the Company’s lead compound, is being evaluated in both intravenous and oral forms.
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ORAL PRESENTATION:
Phase 2 Expansion Study of Oral Rigosertib Combined with Azacitidine treatment in Patients with Higher-Risk (HR) Myelodysplastic Syndromes (MDS): Efficacy and Safety Results in HMA Treatment Naïve & Relapsed (Rel)/Refractory (Ref) Patients
Session Name: 637. Myelodysplastic Syndromes — Clinical Studies: Novel Therapeutics I
Date: Saturday, December 1, 2018
Presentation Time: 4:15 PM PST
Seventy-four (74) patients were treated with a median age of 69 years (range 42-90) at 9 clinical sites, and received either 840 mg or 1,120 mg of oral rigosertib daily divided into two doses, in combination with a standard dose of injectable azacitidine. Of the 55 evaluable patients, 29 patients were treated with a daily dose of 1,120 mg of oral rigosertib, either 560 mg twice daily (12 patients) or 840 mg in the a.m. and 280 mg in the afternoon (17 patients). Twenty-six patients were treated with 560 mg in the AM and 280 mg in the PM (daily dose of 840 mg) for the first three weeks of a four-week cycle. All patients also received 75 mg/m2/day SC or IV azacitidine during the second week of the four-week cycle. The median duration of treatment for the HMA naïve and HMA failed patients was 7.8 and 4.9 months respectively. The median duration of response in these groups was 12.2 and 10.8 months, respectively.
The overall response rate (ORR) using the IWG 2006 criteria, in 29 HMA naïve patients, was 90%; including 10 patients (34%) with Complete Remission (CR). Among the 26 evaluable HMA-
failed patients the ORR was 54% including 8% CR or PR. The median time to initial and best response were 1 and 4 cycles in the HMA naïve group and 2 and 5 cycles in the HMA failed group.
The safety population (n = 74) received at least 1 dose of oral rigosertib. The combination was well tolerated. Other than genitourinary adverse events (AEs), the AE profile was similar to those described for azacitidine alone in this patient population. Genitourinary AEs, including hematuria (45% incidence of all grades, including 9% grade 3, and dysuria (38% all grades and 9% grade 3) were observed. A Safety Optimization Strategy was implemented for the higher dose cohort of 1,120 mg of oral rigosertib. These strategies included earlier in the day administration of the PM dose, oral hydration, monitoring of urinary pH and mandatory bladder emptying at night. Collectively these strategies resulted in mitigation of the target genitourinary AEs, including reduction of genitourinary grade 3 AEs reported from an earlier cohort despite receiving a higher dose of oral rigosertib.
In conclusion, oral rigosertib in combination with azacitidine was well tolerated in HMA naïve and HMA failed HR-MDS patients. The combination produced an encouraging rate of overall response and complete remission in both groups. The safety optimization strategies and increased dose exploration of oral rigosertib in the combination is leading to the development of a pivotal Phase 3 trial in HMA and chemotherapy naïve patients.
Drs. Lewis Silverman and Guillermo Garcia Manero, the lead investigators of the study at Mount Sinai Medical Center and MD Anderson Cancer Center, respectively, commented, "This multi-institutional collaborative study based on earlier laboratory research showing synergistic activity of rigosertib in combination with azacitidine led to a clinical trial of this combination in higher-risk MDS patients for both HMA naive and failed patients. The high overall response rate reported today is impressive, as is the durability and rate of achieving complete remission. We are excited about progressing these studies to a randomized pivotal placebo-controlled Phase 3 trial. The overall tolerability of the combination and convenience of administration of oral rigosertib could be key advantages for these future studies."
Dr. Steve Fruchtman, President of Onconova Therapeutics, Inc, sponsor of this study and developer of rigosertib commented, "We are most grateful to the patients, their families and our dedicated collaborating investigators for their participation in this study. The impressive results presented here have led to our plan for a pivotal trial for these patients ultimately hoping to improve upon their current therapeutic options. Based on End of Phase 2 Meetings with the Health Authorities, we have developed a randomized controlled pivotal trial. We expect to start the regulatory process for the approval of this trial plan very shortly. We are hopeful that both intravenous and oral formulations of rigosertib will be useful in serving the needs of higher risk MDS patients".
This oral presentation was delivered by Shyamala Navada, MD, Mount Sinai Medical Center on Saturday, December 1, 2018.
A copy of the presentation is available by visiting the Scientific Presentations section of Onconova’s website.
Onconova plans to meet with the FDA to discuss the results of the Phase 2 trial and the planned Phase 3 trial, and to seek a Special Protocol Assessment. The Company has partnered rigosertib with SymBio Pharmaceuticals, for Japan and Korea, and with Pint Pharma for Latin American countries. Both partners have indicated their interest in participating in the proposed new pivotal Phase 3 trial by enrolling patients in their respective territories. SymBio is currently conducting Phase 1 studies with oral rigosertib in Japan and also participating in the Phase 3 global INSPIRE trial. The Company is also actively seeking additional collaborations for rigosertib in other geographies.