Phase 2b STORM Data Evaluating Selinexor in Patients with Penta-Refractory Multiple Myeloma Presented at the Society of Hematologic Oncology 2018 Annual Meeting
-- Oral Selinexor Achieves 26.2% Overall Response Rate and Duration of Response of 4.4 Months in Overall Study Population; Responses Typically Occurred Within 1 Cycle (4 Weeks) of Treatment --
-- Median Survival of 8.6 Months in All Patients; Median Survival of 15.6 Months in Patients with MR or Better --
-- Commercial Preparation Underway; New Drug Application Submitted to FDA --
-- Management to Host Conference Call Tomorrow,
“The additional Phase 2b clinical results presented today are very encouraging for the patients suffering from penta-refractory multiple myeloma and their families. Most notably, the overall response rate (ORR) for patients treated with oral selinexor and dexamethasone (dex; Sd) was 26.2% with median duration of response (DOR) of 4.4 months based on the Independent Review Committee (IRC) assessment, along with a median overall survival (OS) across the entire study of 8.6 months,” said
“Patients with highly resistant myeloma have very few treatment options available, which underscores the urgent need for the advancement of therapies with novel mechanisms, like selinexor,” said
Karyopharm has submitted an NDA to the FDA, with a request for accelerated approval for oral selinexor with low dose dexamethasone as a new treatment for patients with penta-refractory multiple myeloma. Selinexor has been granted Orphan Drug Designation in multiple myeloma and Fast Track designation for the patient population evaluated in the STORM study. The Company also plans to submit a MAA to the EMA in the first quarter of 2019 with a request for conditional approval. In parallel, Karyopharm is conducting the pivotal, randomized Phase 3 BOSTON study evaluating selinexor in combination with the proteasome inhibitor Velcade® and dex (SVd) for the treatment of patients with multiple myeloma who have had one to three prior lines of therapy. The Company expects to complete enrollment in the
Phase 2b STORM Results
These clinical results are from Part 2 of the international, multi-center, single-arm Phase 2b STORM (Selinexor Treatment of Refractory Myeloma) study, which enrolled 122 heavily pretreated patients (median of seven prior treatment regiments) with penta-refractory myeloma. Each patient started 80mg oral selinexor twice weekly in combination with low-dose dexamethasone (dex; 20mg twice weekly). Patients with penta-refractory myeloma have previously received the two proteasome inhibitors (PIs), Velcade® (bortezomib) and Kyprolis® (carfilzomib), the two immunomodulatory drugs (IMiDs), Revlimid® (lenalidomide) and Pomalyst® (pomalidomide), and the anti-CD38 monoclonal antibody Darzalex® (daratumumab), as well as alkylating agents, and their disease is refractory to glucocorticoids, at least one PI, at least one IMiD, Darzalex and their most recent therapy.
For the STORM study’s primary objective, oral selinexor achieved a 26.2% ORR, which included two stringent complete responses (sCRs), six very good partial responses (VGPRs) and 24 partial responses (PRs) in these patients with penta-refractory myeloma. The two sCRs were negative for minimal residual disease, one at the level of 1x10-6 and one at 1x10-4; this is particularly significant in this penta-refractory population. The ORR in patients who had previously received Darzalex® combination therapy (n=86) was 29.1%. The Disease Control Rate for patients who had achieved stable disease or better was 78.6%. All responses were confirmed by an IRC. Median progression-free survival (PFS) was 3.7 months and the median DOR was 4.4 months (range <1 to 9.9 months). Median OS across the study was 8.6 months. Median OS in the ~40% of patients with at least a MR on selinexor + dex was 15.6 months compared to a median OS of 1.7 months in patients whose disease progressed or were not evaluable (p<0.0001). The short median OS of patients with no response to selinexor is consistent with the lack of available effective therapies for the very heavily pretreated population who entered the study.
Across the relevant patient population, side effects of oral selinexor were generally predictable and often managed with dose adjustments and/or supportive care, with safety results that were consistent with those previously reported from Part 1 of this study (Vogl et al., J Clin Oncol, 2018) and from other selinexor studies. As anticipated, the most common non-hematologic treatment-related adverse events (AEs) were largely Grade 1/2 and included fatigue (70%), nausea (69%), anorexia (52%) and weight loss (47%). The most common Grade 3/4 AEs were cytopenias (thrombocytopenia (54%) and anemia (29%)) and were generally not associated with clinical sequelae. No significant major organ toxicities were observed, and bleeding and infection rates were low.
Conference Call Information
Karyopharm will host a conference call tomorrow,
Selinexor is a first-in-class, oral Selective Inhibitor of Nuclear Export (SINE) compound. Selinexor functions by binding with and inhibiting the nuclear export protein XPO1 (also called CRM1), leading to the accumulation of tumor suppressor proteins in the cell nucleus. This reinitiates and amplifies their tumor suppressor function and is believed to lead to the selective induction of apoptosis in cancer cells, while largely sparing normal cells. To date, over 2,600 patients have been treated with selinexor. In
Further Information About Potential Accelerated Approval for Selinexor in Multiple Myeloma
The FDA instituted its Accelerated Approval Program to allow for expedited approval of drugs that treat serious conditions and that fill an unmet medical need based on a surrogate endpoint or an intermediate clinical endpoint thought to predict clinical benefit, like overall response rate. Accelerated approval is available only for drugs that provide a meaningful therapeutic benefit over existing treatments at the time of consideration of the application for accelerated approval, which the FDA has reiterated in its feedback to the Company. Particularly in disease areas with multiple available and potential new therapies, such as multiple myeloma, accelerated approval carries a high regulatory threshold. Consistent with its general guidance, the FDA has noted to the Company its preference for randomized studies geared toward full approval, which the Company has undertaken with the ongoing pivotal, Phase 3 BOSTON study, and has reminded the Company that accelerated approval requires patients to have exhausted all available approved therapies. FDA’s Fast Track designation is available to therapeutics treating an unmet medical need in a serious condition; the Company has received Fast Track designation from the FDA specifically for the population treated in the STORM trial. In light of this recognition that the STORM patient population represents an unmet medical need and the positive top-line data reported, the Company believes that the STORM study should support its request to the FDA for accelerated approval.
This press release contains forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. Such forward-looking statements include those regarding the submissions to regulatory authorities, including the anticipated timing of such submissions, and the potential availability of accelerated approval pathways, the therapeutic potential of and potential clinical development plans for Karyopharm's drug candidates, especially selinexor, and the plans for commercialization. Such statements are subject to numerous important factors, risks and uncertainties that may cause actual events or results to differ materially from Karyopharm's current expectations. For example, there can be no guarantee that regulators will agree that selinexor qualifies for accelerated approval in the
Velcade® is a registered trademark of Takeda Pharmaceutical Company Limited
Revlimid® and Pomalyst® are registered trademarks of Celgene Corporation
Kyprolis® is a registered trademark of
Darzalex® is a registered trademark of
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Source: Karyopharm Therapeutics Inc.