Sierra Oncology Reports Decreased Transfusion Requirements for Patients Treated with Momelotinib Directly Compared to Ruxolitinib at ASH Annual Meeting

- New analyses of Phase 3 data highlighting momelotinib's meaningful anemia benefits in myelofibrosis presented in a poster at the 61^st American Society of Hematology Annual Meeting -

- Analyst & Investor Event featuring renowned myelofibrosis expert Dr. Ruben Mesa scheduled for 7:00 am ET on Sunday, December 8^th -

VANCOUVER, Dec. 7, 2019 /PRNewswire/ - Sierra Oncology, Inc. (Nasdaq: SRRA), a late-stage drug development company focused on the development and commercialization of momelotinib, a JAK1, JAK2 & ACVR1 inhibitor with a potentially differentiated therapeutic profile for the treatment of myelofibrosis, today reported new analyses of Phase 3 clinical data highlighting the anemia related benefits of momelotinib directly compared to ruxolitinib, which were presented at the 61^st American Society of Hematology (ASH) Annual Meeting in Orlando, Florida.

"Transfusion dependency and moderate to severe anemia are the most important negative prognostic factors for overall survival in myelofibrosis," said Dr. Ruben Mesa, Director of the Mays Cancer Center, home to UT Health San Antonio MD Anderson Cancer Center. "These novel analyses of RBC transfusion data from the Phase 3 SIMPLIFY-1 study further demonstrate momelotinib's compelling anemia benefits, including a substantively reduced transfusion burden compared directly with ruxolitinib, and further support momelotinib as a potentially desirable treatment option for patients with myelofibrosis."

"These retrospective analyses, performed using a variety of novel dynamic anemia benefit endpoints, underscore the demonstrably lower burden of transfusions experienced by myelofibrosis patients treated with momelotinib versus ruxolitinib in a large, blinded, randomized, clinical trial," said Dr. Nick Glover, President and CEO of Sierra Oncology. "Momelotinib uniquely inhibits ACVR1 in addition to JAK1 and JAK2, resulting in an array of distinct and clinically relevant mechanistically-based anemia benefits. While momelotinib's favorable effect on anemia was previously demonstrated in direct comparison to ruxolitinib using a variety of standard landmark analyses of data from SIMPLIFY-1, these new analyses further describe the relative patient burden of transfusions on study, and help contrast the differences in therapeutic options for clinicians."

"Transfusion burden is a fundamental consideration in myelofibrosis, a disease characterized by chronic, progressive anemia. Specifically, preventing transfusions for patients who are currently transfusion free, or reducing or eliminating the need for transfusions for patients who are actively receiving regular blood transfusions are clinically important outcomes of direct relevance to myelofibrosis patients and their clinicians, underscoring the importance of these data," said Dr. Barbara Klencke, Chief Development Officer of Sierra Oncology. "Myelofibrosis is a disease comprising three clinical dimensions – constitutional symptoms, anemia and splenomegaly. Critically, momelotinib's meaningful anemia benefits were achieved while also maintaining clinically comparable benefits on splenomegaly and constitutional symptoms as directly compared to ruxolitinib."

The new analyses demonstrate that:

• Patients who received momelotinib had significantly decreased transfusion requirements compared to those treated with ruxolitinib, including a nearly 10-fold higher odds of receiving no transfusions during the 24-week study period (covariate ZINB model; p < 0.0001).
• Patients receiving momelotinib had a significantly reduced chance of receiving one transfusion, two 'transfusion events' (≥ 3 RBC units) or three 'transfusion events' (≥ 5 RBC units).
• At any given time, the mean cumulative number of RBC units received for a typical patient receiving momelotinib is approximately half of that for patients receiving ruxolitinib (HR = 0.522; p < 0.0001). Thus, for patients on momelotinib, half as many RBC units are transfused at any time as compared to ruxolitinib.
• A Kaplan-Meier time-to-first RBC unit transfused analysis indicated an immediate and sustained momelotinib treatment effect compared to ruxolitinib (log-rank p < 0.0001).
• A sustained and durable period of transfusion independence (TI) was maintained over long-term treatment on momelotinib. The median time to loss of TI was not reached for momelotinib-treated patients, with a follow up period exceeding 3 years.

The SIMPLIFY-1 trial was a double-blind, active-controlled Phase 3 study in which 432 patients received randomized treatment with momelotinib or ruxolitinib for 24 weeks (JCO. 2017; 35:3844–50). In addition to a significant reduction in splenomegaly and improvements in constitutional symptoms, previously reported analyses of the SIMPLIFY-1 data demonstrated that patients in the momelotinib arm achieved nominal-statistical significance for all anemia endpoints tested, including a higher rate of transfusion independence (p < 0.001) and lower rates of transfusion dependence (p = 0.019) at Week 24, compared to patients on ruxolitinib.

Sierra management will host an Analyst & Investor Event on Sunday, December 8^th at 7:00 am ET to discuss these results. The event will include a presentation by renowned myelofibrosis expert, Dr. Ruben Mesa, Director of the Mays Cancer Center, home to UT Health San Antonio MD Anderson Cancer Center.

Sierra recently launched the MOMENTUM Phase 3 clinical trial, a randomized double-blind trial designed to enroll 180 myelofibrosis patients who are symptomatic and anemic, and who have been treated previously with a JAK inhibitor.

About Momelotinib
Momelotinib, Sierra's lead drug candidate, is a potent, selective and orally-bioavailable JAK1, JAK2 & ACVR1 inhibitor with a differentiated therapeutic profile in myelofibrosis encompassing robust constitutional symptom improvements, a range of meaningful anemia benefits, including eliminating or reducing the need for frequent blood transfusions, and comparable spleen control to ruxolitinib. More than 1,200 subjects have received momelotinib since clinical studies began in 2009, including more than 800 patients treated for myelofibrosis.

Chronic, progressive anemia is a key hallmark of myelofibrosis and transfusion dependence is the most important negative prognostic indicator of reduced survival in this disease. Approximately 60% of patients are anemic and 45% are transfusion dependent within one year of diagnosis, with most patients ultimately progressing to transfusion dependency. Unfortunately, currently approved JAK inhibitor therapies can induce or worsen anemia, exacerbating this significant unmet medical need in anemic myelofibrosis patients.

The marked systemic inflammation seen in myelofibrosis leads to increased ACVR1 activity which in turn increases secretion of hepcidin, resulting in perturbed iron homeostasis and an iron-restricted anemia. Momelotinib's inhibition of ACVR1 in addition to JAK1 and JAK2, unique amongst the JAK inhibitor class, results in notable reductions of both hepcidin and inflammation, restoring iron homeostasis and RBC production, thereby alleviating anemia and transfusion dependency.

Momelotinib is an investigational drug that is not approved for any use in any country. The U.S. Food and Drug Administration has granted Fast Track designation to momelotinib for the treatment of patients with intermediate/high-risk myelofibrosis who have previously received a JAK inhibitor. Momelotinib is wholly owned by Sierra Oncology and is protected by patents anticipated to provide potential exclusivity to 2040 in the United States and Europe (including Patent Term Extension or Supplementary Protection Certificate).

Analyst and Investor Event and Webcast Information
Sierra Oncology will host an Analyst & Investor Event to discuss these data being presented at the 61st American Society of Hematology (ASH) Annual Meeting in Orlando, Florida. The event will be led by Dr. Nick Glover, President and CEO of Sierra Oncology, and include a presentation by Dr. Ruben Mesa.

Date and Time: Sunday, December 8^th at 7:00 – 8:00 am ET
Location: Bayhill 33 Meeting Room, Hyatt Regency, 9801 International Dr., Orlando

Event registration and webcast information are available through the Sierra Oncology website at www.sierraoncology.com. The event will be webcast live, and an archive of the presentation will be accessible after the event through the Sierra Oncology website.

Domestic (Toll Free- US): 1 (844) 467-7642
International (Toll): 1 (417) 385-2994
Conference ID: 3577956
Webcast: www.sierraoncology.com 
Direct link: https://edge.media-server.com/mmc/p/y57zkifp

ASH 2019 Momelotinib Poster Presentation Information:
Title: Dynamic and Time-To-Event Analyses Demonstrate Marked Reduction in Transfusion Requirements for Janus Kinase Inhibitor–Naïve Myelofibrosis Patients Treated with Momelotinib Compared Head to Head with Ruxolitinib
Session Name: 634. Myeloproliferative Syndromes: Clinical: Poster I
Date: Saturday, December 7^th, 2019
Presentation Time: 5:30 pm - 7:30 pm ET
Location: Orange County Convention Center, Hall B

The poster will be available on Saturday, December 7^th, 2019 on the company's website at www.sierraoncology.com

About Sierra Oncology
Sierra Oncology is a late stage drug development company focused on advancing targeted therapeutics for the treatment of patients with significant unmet medical needs in hematology and oncology. Momelotinib, Sierra's lead drug candidate, is a potent, selective and orally-bioavailable JAK1, JAK2 & ACVR1 inhibitor with a differentiated therapeutic profile in myelofibrosis encompassing robust constitutional symptom improvements, a range of meaningful anemia benefits, including eliminating or reducing the need for frequent blood transfusions, and comparable spleen control to ruxolitinib.

Sierra is also developing a portfolio of DNA Damage Response (DDR) assets, consisting of SRA737 and SRA141, and is conducting a campaign intended to seek non-dilutive strategic options to support their further advancement. SRA737 is a potent, highly selective, orally bioavailable small molecule inhibitor of Checkpoint kinase 1 (Chk1), a key regulator of cell cycle progression and the DDR network, and has demonstrated preliminary clinical efficacy. SRA141 is a potent, selective, orally bioavailable small molecule inhibitor of Cell division cycle 7 kinase (Cdc7) with a potential novel mechanism of cytotoxicity, and has successfully completed the IND process with the FDA enabling the commencement of clinical trials. Sierra retains the global commercialization rights to SRA737 and SRA141.

For more information, please visit www.sierraoncology.com.

Cautionary Note on Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995, including, but not limited to, statements regarding Sierra Oncology's expectations from current data, anticipated clinical development activities, the expected timing of, and results of MOMENTUM, potential benefits of Sierra Oncology's lead product candidate and other product candidates and sufficiency of its capital resources. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. These statements are based on management's current expectations and beliefs and are subject to a number of risks, uncertainties and assumptions that could cause actual results to differ materially from those described in the forward-looking statements. Such forward-looking statements are subject to risks and uncertainties, including, among others, the risk that Sierra Oncology may be unable to successfully develop and commercialize product candidates, product candidates may not demonstrate safety and efficacy or otherwise produce positive results, Sierra Oncology may experience delays in the preclinical and anticipated clinical development of its product candidates, Sierra Oncology may be unable to acquire additional assets to build a pipeline of additional product candidates, Sierra Oncology's third-party manufacturers may cause its supply of materials to become limited or interrupted or fail to be of satisfactory quantity or quality, Sierra Oncology's cash resources may be insufficient to fund its current operating plans and it may be unable to raise additional capital when needed, Sierra Oncology may be unable to obtain and enforce intellectual property protection for its technologies and product candidates and the other factors described under the heading "Risk Factors" set forth in Sierra Oncology's filings with the Securities and Exchange Commission from time to time. Sierra Oncology undertakes no obligation to update the forward-looking statements contained herein or to reflect events or circumstances occurring after the date hereof, other than as may be required by applicable law.

SOURCE Sierra Oncology

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https://www.sierraoncology.com/