Karyopharm Initiates Pivotal Phase 3 Study of XPO1 Inhibitor Selinexor and Ruxolitinib in JAK Inhibitor (JAKi) Naïve Myelofibrosis

On June 28, 2023 Karyopharm Therapeutics Inc. (Nasdaq: KPTI), a commercial-stage pharmaceutical company pioneering novel cancer therapies, reported the initiation of a pivotal Phase 3 clinical trial (XPORT-MF-034) (NCT04562389) to assess the efficacy and safety of once-weekly selinexor 60mg in combination with ruxolitinib in JAKi-naïve patients with myelofibrosis (Press release, Karyopharm, JUN 28, 2023, View Source [SID1234632963]).

Schedule your 30 min Free 1stOncology Demo!
Discover why more than 1,500 members use 1stOncology™ to excel in:

Early/Late Stage Pipeline Development - Target Scouting - Clinical Biomarkers - Indication Selection & Expansion - BD&L Contacts - Conference Reports - Combinatorial Drug Settings - Companion Diagnostics - Drug Repositioning - First-in-class Analysis - Competitive Analysis - Deals & Licensing

                  Schedule Your 30 min Free Demo!

The randomized, double-blind, placebo-controlled study is expected to enroll 306 JAKi-naive patients with intermediate or high-risk myelofibrosis. Patients will be randomized 2:1 to ruxolitinib plus selinexor 60mg or ruxolitinib plus placebo in 28-day cycles. Ruxolitinib dose will be determined by the investigators based on the patients’ baseline platelet count per the drug’s prescribing information. The co-primary endpoints of the study are spleen volume response rate of ≥ 35% (SVR35) and symptom improvement of ≥ 50% (TSS50) at week 24, with a key secondary endpoint of anemia response at week 24.

"Selinexor and ruxolitinib appear to work synergistically, resulting in meaningful improvements in spleen response and total symptom score for patients with myelofibrosis," said Reshma Rangwala, MD, PhD, Chief Medical Officer of Karyopharm. "We believe that an opportunity exists to expand upon the initial response, depth, and duration of JAK inhibitors to ultimately improve patient outcomes. This combination has the potential to become a cornerstone treatment in front-line myelofibrosis and we are excited to start this pivotal trial to deliver on our goal of bringing forward an innovative new approach for the treatment of myelofibrosis that can benefit MF patients."

"The substantial degree of spleen volume reduction observed across all subgroups with selinexor 60mg in combination with ruxolitinib is very encouraging. There is a significant unmet need in the treatment of patients with myelofibrosis, and these data demonstrate that the addition of XPO1 inhibition with selinexor with standard-of-care ruxolitinib has the potential to significantly improve outcomes for first-line myelofibrosis patients," said Dr. John Mascarenhas, Professor of Medicine at the Icahn School of Medicine at Mount Sinai and Director of the Center of Excellence for Blood Cancers and Myeloid Disorders. "As the principal investigator for the Phase 3 study, I look forward to defining a potential new standard of care for Jak naïve MF patients."

Updated data from the Phase 1 study recently presented at American Association for Cancer Research (AACR) (Free AACR Whitepaper) Annual Meeting 2023, American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) 2023 and European Hematology Association (EHA) (Free EHA Whitepaper) 2023 showed rapid, deep and sustained spleen responses and robust symptom improvement in patients treated with selinexor 60mg in combination with ruxolitinib as of the April 10, 2023 data cut-off date:

At week 24, 91.7% (11/12) of efficacy evaluable patients demonstrated SVR35 and 77.8% (7/9) achieved TSS50. The intent to treat population achieved a 78.6% (11/14) SVR35 and 58.3% (7/12) TSS50 respectively.
SVR35 responses were observed in 100% (12/12) of evaluable patients at any time and rates were consistent regardless of subgroups, including males and patients treated with low dose ruxolitinib.
Improvement in major spleen and cytokine-related symptoms were observed across all Myelofibrosis Symptom Assessment Form domains.
Selinexor was generally well tolerated with a manageable side effect profile, allowing most patients to remain on therapy, up to 74 weeks, as of the data cut-off date. The most common treatment emergent adverse events, regardless of grade, experienced with the 60mg selinexor dose, in combination with ruxolitinib were nausea (78.6%), anemia (64.3%), thrombocytopenia (64.3%) and fatigue (57.1%), and most common treatment emergent grade ≥3 adverse events experienced with the 60mg selinexor dose, in combination with ruxolitinib were anemia (42.9%), thrombocytopenia (28.6%) and back pain (14.3%)
75% of nausea events were grade 1, were mostly transient and did not lead to treatment-related discontinuations. Nausea rates and grades were reduced for patients who received prophylactic antiemetics. Meaningful weight gain was observed at week 24 despite the incidence of nausea and vomiting.
Further information about the Phase 3 study can be found at www.clinicaltrials.gov.

Karyopharm expects to present top-line data readout from this study in 2025. The company plans to expand its clinical development program in myelofibrosis by investigating selinexor in other front-line opportunities, such as novel combinations, to benefit the greatest number of myelofibrosis patients.

About XPOVIO (selinexor)

XPOVIO is a first-in-class, oral exportin 1 (XPO1) inhibitor and the first of Karyopharm’s Selective Inhibitor of Nuclear Export (SINE) compounds to be approved for the treatment of cancer. XPOVIO functions by selectively binding to and inhibiting the nuclear export protein XPO1. XPOVIO is approved in the U.S. and marketed by Karyopharm in multiple oncology indications, including: (i) in combination with Velcade (bortezomib) and dexamethasone (XVd) in patients with multiple myeloma after at least one prior therapy; (ii) in combination with dexamethasone in patients with heavily pre-treated multiple myeloma; and (iii) in patients with diffuse large B-cell lymphoma (DLBCL), including DLBCL arising from follicular lymphoma, after at least two lines of systemic therapy. XPOVIO (also known as NEXPOVIO in certain countries) has received regulatory approvals in various indications in a growing number of ex-U.S. territories and countries, including but not limited to the European Union, the United Kingdom, China, South Korea, Canada, Israel and Taiwan. XPOVIO and NEXPOVIO is marketed by Karyopharm’s partners, Antengene, Menarini, Neopharm and FORUS, in China, South Korea, Singapore, Australia, Hong Kong, Germany, Austria, Israel and Canada.

Please refer to the local Prescribing Information for full details.

Selinexor is also being investigated in several other mid- and late-stage clinical trials across multiple high unmet need cancer indications, including in endometrial cancer and myelofibrosis.

For more information about Karyopharm’s products or clinical trials, please contact the Medical Information department at:

Tel: +1 (888) 209-9326
Email: [email protected]

SELECT IMPORTANT SAFETY INFORMATION

Warnings and Precautions

Thrombocytopenia: Monitor platelet counts throughout treatment. Manage with dose interruption and/or reduction and supportive care.

Neutropenia: Monitor neutrophil counts throughout treatment. Manage with dose interruption and/or reduction and granulocyte colony–stimulating factors.

Gastrointestinal Toxicity: Nausea, vomiting, diarrhea, anorexia, and weight loss may occur. Provide antiemetic prophylaxis. Manage with dose interruption and/or reduction, antiemetics, and supportive care.

Hyponatremia: Monitor serum sodium levels throughout treatment. Correct for concurrent hyperglycemia and high serum paraprotein levels. Manage with dose interruption, reduction, or discontinuation, and supportive care.

Serious Infection: Monitor for infection and treat promptly.

Neurological Toxicity: Advise patients to refrain from driving and engaging in hazardous occupations or activities until neurological toxicity resolves. Optimize hydration status and concomitant medications to avoid dizziness or mental status changes.

Embryo–Fetal Toxicity: Can cause fetal harm. Advise females of reproductive potential and males with a female partner of reproductive potential, of the potential risk to a fetus and use of effective contraception.

Cataract: Cataracts may develop or progress. Treatment of cataracts usually requires surgical removal of the cataract.
Adverse Reactions

The most common adverse reactions (≥20%) in patients with multiple myeloma who receive XVd are fatigue, nausea, decreased appetite, diarrhea, peripheral neuropathy, upper respiratory tract infection, decreased weight, cataract and vomiting. Grade 3–4 laboratory abnormalities (≥10%) are thrombocytopenia, lymphopenia, hypophosphatemia, anemia, hyponatremia and neutropenia. In the BOSTON trial, fatal adverse reactions occurred in 6% of patients within 30 days of last treatment. Serious adverse reactions occurred in 52% of patients. Treatment discontinuation rate due to adverse reactions was 19%.

The most common adverse reactions (≥20%) in patients with multiple myeloma who receive Xd are thrombocytopenia, fatigue, nausea, anemia, decreased appetite, decreased weight, diarrhea, vomiting, hyponatremia, neutropenia, leukopenia, constipation, dyspnea and upper respiratory tract infection. In the STORM trial, fatal adverse reactions occurred in 9% of patients. Serious adverse reactions occurred in 58% of patients. Treatment discontinuation rate due to adverse reactions was 27%.

The most common adverse reactions (incidence ≥20%) in patients with DLBCL, excluding laboratory abnormalities, are fatigue, nausea, diarrhea, appetite decrease, weight decrease, constipation, vomiting, and pyrexia. Grade 3–4 laboratory abnormalities (≥15%) are thrombocytopenia, lymphopenia, neutropenia, anemia, and hyponatremia. In the SADAL trial, fatal adverse reactions occurred in 3.7% of patients within 30 days, and 5% of patients within 60 days of last treatment; the most frequent fatal adverse reactions was infection (4.5% of patients). Serious adverse reactions occurred in 46% of patients; the most frequent serious adverse reaction was infection (21% of patients). Discontinuation due to adverse reactions occurred in 17% of patients.
Use In Specific Populations
Lactation: Advise not to breastfeed.

For additional product information, including full prescribing information, please visit www.XPOVIO.com.

To report SUSPECTED ADVERSE REACTIONS, contact Karyopharm Therapeutics Inc. at 1–888–209–9326 or FDA at 1–800–FDA–1088 or www.fda.gov/medwatch.