FDA Removes Full Clinical Hold On CTI BioPharma’s Pacritinib for Myelofibrosis

SEATTLE, Jan. 5, 2017 /PRNewswire/ — CTI BioPharma Corp. (CTI BioPharma) (NASDAQ and MTA: CTIC) today announced that the full clinical hold (February 2016) implemented by the U.S. Food and Drug Administration (FDA) on all clinical trials conducted under the Investigational New Drug (IND) application for pacritinib has now been removed. The Company’s complete response submission included, among other items, final Clinical Study Reports for both PERSIST-1 and 2 trials and a dose-exploration clinical trial protocol that the FDA requested.  The new trial, PAC203 plans to enroll up to approximately 105 patients with primary myelofibrosis who have failed prior ruxolitinib therapy to evaluate the safety and the dose response relationship for efficacy (spleen volume reduction at 24 weeks) of three dose regimens: 100 mg once-daily, 100 mg twice-daily (BID) and 200 mg BID. The 200 mg BID dose regimen was used in PERSIST-2. The Company expects to start the trial in the second quarter of 2017.

“We are pleased to resolve the full clinical hold through working diligently with the FDA to provide a comprehensive response to their requests,” said Richard Love, Interim President and CEO of CTI BioPharma. “We look forward to discussing with the FDA the future development of pacritinib.   We believe pacritinib can ultimately address the unmet need of patients with myelofibrosis who are ineligible to receive or are not benefitting from the approved JAK1/JAK2 inhibitor, ruxolitinib, as these patients have limited treatment options.”

About the Phase 3 Development Program of Pacritinib

Pacritinib was evaluated in two Phase 3 clinical trials, known as the PERSIST program, for patients with myelofibrosis, with one trial in a broad set of patients without limitations on platelet counts, the PERSIST-1 trial; and the other in patients with low platelet counts, the PERSIST-2 trial. In August 2014, pacritinib was granted Fast Track designation by the FDA for the treatment of intermediate and high risk myelofibrosis including, but not limited to, patients with disease-related thrombocytopenia (low platelet counts); patients experiencing treatment-emergent thrombocytopenia on other JAK2 inhibitor therapy; or patients who are intolerant of, or whose symptoms are not well controlled (sub-optimally managed) on other JAK2 therapy.

Clinical studies under the investigational new drug (IND) for pacritinib were subject to a full clinical hold issued by the FDA in February 2016. The FDA noted interim overall survival results from the PERSIST-2 showing a detrimental effect on survival were consistent with the results from PERSIST-1 and that deaths in PERSIST-2 in pacritinib-treated patients include intracranial hemorrhage, cardiac failure and cardiac arrest.

PERSIST-1 was a randomized (2:1), controlled, open-label, multinational Phase 3 trial evaluating the efficacy and safety of pacritinib compared to BAT, excluding JAK2 inhibitors, which included a broad range of currently utilized treatments – in 327 patients with myelofibrosis, regardless of the patients’ platelet counts. The study included patients with severe or life-threatening thrombocytopenia. Patients were randomized to receive 400 mg pacritinib once daily or BAT, excluding JAK2 inhibitors. The trial met its primary endpoint of spleen volume reduction (35 percent or greater from baseline to Week 24 by MRI/CT scan).

PERSIST-2 was a randomized (1:1:1), controlled, open-label, multinational Phase 3 clinical trial evaluating pacritinib compared to best available therapy (BAT), including the approved JAK1/JAK2 inhibitor ruxolitinib, for patients with myelofibrosis whose platelet counts were less than or equal to 100,000 per microliter (≤100,000/μL). Patients were randomized to receive 200 mg pacritinib twice daily (BID), 400 mg pacritinib once daily (QD) or BAT. Results of the trial were presented at the American Society of Hematology Annual meeting in Dececember 2016. The trial met one of its co-primary endpoints, that of spleen volume reduction (35 percent or greater from baseline to Week 24 by MRI/CT scan). The co-primary endpoint of reduction of Total Symptom Score (TSS) was not achieved but trended toward improvement in TSS. Irrespective of prior ruxolitinib treatment, pacritinib therapy resulted in a statistically significant higher proportion of patients with SVR than patients on BAT. Although secondary objectives could not be evaluated formally due to the study not achieving one of the primary objectives, when the two pacritinib dosing arms were evaluated separately versus BAT, pacritinib BID showed a higher percent of SVR and TSS responses compared to BAT; whereas, pacritinib given QD showed only a higher percent SVR responses compared to BAT. There was no significant difference in overall survival (OS) across treatment arms, censored at the time of clinical hold. The most common treatment-emergent adverse events (AEs), occurring in 20 percent or more of patients treated with pacritinib within 24 weeks, of any grade, were gastrointestinal (generally manageable diarrhea, nausea and vomiting) and hematologic (anemia and thrombocytopenia) and were generally less frequent for BID versus QD administration.  The most common serious treatment-emergent AEs (incidence of ≥5 percent reported in any treatment arm irrespective of grade) were anemia, thrombocytopenia, pneumonia and acute renal failure none of which exceeded 8 percent individually in any arm.

About Pacritinib

Pacritinib is an investigational oral kinase inhibitor with specificity for JAK2, FLT3, IRAK1 and CSF1R. The JAK family of enzymes is a central component in signal transduction pathways, which are critical to normal blood cell growth and development, as well as inflammatory cytokine expression and immune responses. Mutations in these kinases have been shown to be directly related to the development of a variety of blood-related cancers, including myeloproliferative neoplasms, leukemia and lymphoma. In addition to myelofibrosis, the kinase profile of pacritinib suggests its potential therapeutic utility in conditions such as acute myeloid leukemia, or AML, myelodysplastic syndrome, or MDS, chronic myelomonocytic leukemia, or CMML, and chronic lymphocytic leukemia, or CLL, due to its inhibition of c-fms, IRAK1, JAK2 and FLT3.

About Myelofibrosis and Myeloproliferative Neoplasms

Myelofibrosis is one of three main types of myeloproliferative neoplasms (MPN), which are a closely related group of progressive blood cancers. The three main types of MPNs are primary myelofibrosis (PMF), polycethemia vera (PV) and essential thrombocythemia (ET).1

Myelofibrosis is a serious and life-threatening bone marrow disorder caused by the accumulation of malignant bone marrow cells that triggers an inflammatory response and scars the bone marrow. The replacement of bone marrow with scar tissue limits its ability to produce red blood cells, prompting the spleen and liver to take over this function. Symptoms that arise from this disease include enlargement of the spleen, anemia, extreme fatigue and pain.

The estimated prevalence of MPNs suggest there are approximately 300,000 people living with the disease in the U.S., of which myelofibrosis accounts for approximately 18,000 patients.2 In Europe, there is a wide variation of prevalence observed across data sources. Myelofibrosis has a median age of 64 at the time of diagnosis3 and is a progressive disease with approximately 20 percent of patients eventually developing acute myeloid leukemia (AML).4 The median survival for high-risk myelofibrosis patients is less than 1.5 years, while the median survival for patients with myelofibrosis overall is approximately 6 years.4

About CTI BioPharma

CTI BioPharma Corp. is a biopharmaceutical company focused on the acquisition, development and commercialization of novel targeted therapies covering a spectrum of blood-related cancers that offer a unique benefit to patients and healthcare providers. CTI BioPharma has a commercial presence in Europe with respect to PIXUVRI® and a late-stage development pipeline, including pacritinib for the treatment of patients with myelofibrosis. CTI BioPharma is headquartered in Seattle, Washington, with offices in London and Milan under the name CTI Life Sciences Limited. For additional information and to sign up for email alerts and get RSS feeds, please visit www.ctibiopharma.com.

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