Benzinga | Dec 6, 2021 07:03AM EST

Karyopharm Announces Dosing Of First Patient In A New Phase 2 Study Evaluating Single-Agent Selinexor Versus Physician's Choice In Previously Treated Myelofibrosis

Karyopharm Therapeutics Inc. (NASDAQ:KPTI), a commercial-stage pharmaceutical company pioneering novel cancer therapies, today announced dosing of the first patient in a new Phase 2 study evaluating oral selinexor, the Company's first-in-class, oral Selective Inhibitor of Nuclear Export (SINE) compound, as a monotherapy versus physician's choice in patients with myelofibrosis (MF) previously treated with a JAK 1/2 inhibitor (XPORT-MF-035; NCT04562870).

This randomized, multi-center, open-label Phase 2 study is designed to evaluate the safety and efficacy of selinexor monotherapy and is expected to enroll up to 112 patients, who will be randomized 1:1 to receive either low dose, once-weekly oral selinexor or physician's standard treatment choice (per clinical practice). The primary endpoint of the study is the percentage of patients with spleen volume reduction (SVR) of ?35% from baseline as assessed by an Independent Review Committee. The first patient has been dosed at the Instituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) Meldola, Italy, by the Lead Principal Investigator, Dr. Alessandro Lucchesi, Sr. Consultant and Research Hematologist under the guide of Professor Giovanni Martinelli, the Chief Scientific Director.

Initiation of this Phase 2 study follows encouraging preliminary data from the Phase 2 ESSENTIAL trial, which will be highlighted in an oral presentation given by Srinivas Tantravahi, MBBS, MRCP, University of Utah Hospital, at the upcoming American Society of Hematology (ASH) 2021 Annual and Exposition on Saturday, December 11, 2021 at 1:00 p.m. ET. In the investigator-sponsored ESSENTIAL study (NCT03627403), which is evaluating selinexor in patients with MF previously treated with a JAK inhibitor, preliminary data showed that 33% of patients that received at least 24 weeks of selinexor treatment achieved ?35% SVR. The responses were durable, and the first patient remained on study for more than two years. Patients had a median duration of 22 months of prior JAK inhibitor therapy with 11 out of 12 patients having disease refractory to ruxolitinib.

"As part of our strategic imperatives and pipeline priorities, we remain focused on diseases with the highest unmet needs and greatest potential to make an impact in patient outcomes," said Sharon Shacham, PhD, MBA, Co-Founder and Chief Scientific Officer of Karyopharm. "Myelofibrosis is a serious and life--threatening blood cancer defined by stem cell--derived clonal myeloproliferation, bone marrow fibrosis, anemia, enlarged spleen, low blood counts and short survival. With JAK inhibitors being the only class of drugs approved for this disease, there remains limited therapeutic options for patients who either progress following treatment with a JAK inhibitor or are intolerant. We believe selinexor has the potential to hold an important place in the myelofibrosis treatment paradigm and with dosing of the first patient underway, we plan to provide updates as the study progresses."