On September 30, 2019 Deciphera Pharmaceuticals, Inc. (Nasdaq:DCPH), a clinical-stage biopharmaceutical company addressing key mechanisms of tumor drug resistance, reported the late-breaking presentation of results from the INVICTUS pivotal Phase 3 clinical study of ripretinib in patients with advanced gastrointestinal stromal tumors (GIST) in an oral session at the European Society for Medical Oncology (ESMO) (Free ESMO Whitepaper) 2019 Congress (Press release, Deciphera Pharmaceuticals, SEP 30, 2019, View Source [SID1234539912]).
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"For GIST patients who have failed currently approved agents, there exists an urgent need for effective and well-tolerated treatment options," said Margaret von Mehren, MD, Department of Medical Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania. "With a statistically significant improvement observed in progression free survival compared with placebo, and a clinically meaningful increase in overall survival compared with placebo, ripretinib represents a potential standard of care for patients harboring a broad spectrum of mutations known to drive GIST in patients who have no approved treatment options."
"Results from the INVICTUS study support our belief that ripretinib has the potential to transform the current treatment landscape for advanced GIST," said Steve Hoerter, President and Chief Executive Officer of Deciphera. "We are now working with the FDA as we prepare the NDA submission for ripretinib, which we expect in the first quarter of 2020."
Today’s presentation featured new data as well as top-line results previously announced by the Company in August 2019. A copy of the presentation will be available following the session at www.deciphera.com.
INVICTUS Study Results
The INVICTUS Phase 3 clinical study is a randomized (2:1), double-blind, placebo-controlled, international, multicenter study to evaluate the safety, tolerability, and efficacy of ripretinib compared to placebo in 129 patients with advanced GIST whose previous therapies have included at least imatinib, sunitinib, and regorafenib. As previously reported, the study achieved the primary endpoint of improved progression free survival (PFS) compared to placebo in patients with fourth-line and fourth-line plus GIST, as determined by blinded independent central radiologic review using modified Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.
Progression Free Survival (PFS)
Ripretinib significantly reduced the risk of disease progression or death by 85% compared to placebo and demonstrated a median PFS of 6.3 months compared to 1.0 month in the placebo arm (HR=0.15, 95% CI (0.09,0.25), p<0.0001). This PFS benefit was consistent across all assessed patient subgroups.
Objective Response Rate (ORR) and Duration of Response
Eight patients (9.4%) had a confirmed objective response with ripretinib (p=0.0504) compared to no confirmed responses in the placebo arm, as measured by blinded independent central review, which was not statistically significant. As of the cutoff date of May 31, 2019, the median duration of response had not been reached with seven of the eight patients still responding to treatment. All responders had partial responses.
Overall Survival (OS)
Ripretinib reduced the risk of death by 64% compared to placebo and demonstrated a median OS of 15.1 months vs. 6.6 months in the placebo arm (HR=0.36, 95% CI (0.20,0.62), nominal p=0.0004). Since statistical significance was not achieved for the secondary endpoint of ORR, the hypothesis testing of OS was not formally performed. According to the pre-specified hierarchical testing procedure of the endpoints, the hypothesis testing of OS cannot be formally conducted unless the test for ORR is statistically significant.
Safety
Ripretinib was generally well tolerated and the adverse events observed in INVICTUS were consistent with data from previously presented Phase 1 study results. Treatment-emergent adverse events (TEAEs) occurred in 99% of patients on the ripretinib arm compared to 98% on the placebo arm. Grade 3 or 4 TEAEs occurred in 49% of patients on the ripretinib arm compared to 44% on the placebo arm. Grade 3 or 4 TEAEs greater than 5% of patients on the ripretinib arm were anemia (9%), abdominal pain (7%) and hypertension (7%). Grade 3 or 4 TEAEs greater than 5% of patients on the placebo arm were anemia (14%). TEAEs leading to dose reduction occurred in 7% of patients on the ripretinib arm compared to 2% on the placebo arm. TEAEs leading to dose interruption occurred in 24% of patients on the ripretinib arm compared to 21% on the placebo arm. TEAEs leading to study treatment discontinuation occurred in 8% of patients on the ripretinib arm compared to 12% of patients on the placebo arm. TEAEs leading to death occurred in 6% of patients on the ripretinib arm compared to 23% on the placebo arm.
New Drug Application (NDA) Submission
Based on the positive INVICTUS data, the Company expects to submit an NDA to the U.S. Food and Drug Administration (FDA) for ripretinib for the treatment of patients with advanced GIST who have received prior treatment with imatinib, sunitinib and regorafenib in the first quarter of 2020.
About the INVICTUS Phase 3 Study
The INVICTUS Phase 3 clinical study is a randomized, double-blind, placebo-controlled, international, multicenter study to evaluate the safety, tolerability, and efficacy of ripretinib compared to placebo in patients with advanced GIST whose previous therapies have included imatinib, sunitinib, and regorafenib. This study was designed to provide evidence of clinical benefit in fourth-line and fourth-line plus patients with GIST that would be required to secure a regulatory approval. Patients were randomized 2:1 to either 150 mg of ripretinib or placebo once daily. The primary efficacy endpoint is progression-free survival (PFS) as determined by independent radiologic review using modified Response Evaluation Criteria in Solid Tumors (RECIST). Secondary endpoints as determined by independent radiologic review using modified RECIST include Objective Response Rate (ORR), Time to Tumor Progression (TTP) and Overall Survival (OS). See www.clinicaltrials.gov for further information (NCT03353753).
About Ripretinib
Ripretinib is an investigational tyrosine kinase switch control inhibitor that was engineered to broadly inhibit KIT and PDGFRα mutated kinases by using a unique dual mechanism of action that regulates the kinase switch pocket and activation loop. Ripretinib is currently in clinical development for the treatment of KIT and/or PDGFRα-driven cancers, including gastrointestinal stromal tumors, or GIST, systemic mastocytosis, or SM, and other cancers. Ripretinib inhibits initiating and secondary KIT mutations in exons 9, 11, 13, 14, 17, and 18, involved in GIST, as well as the primary D816V exon 17 mutation involved in SM. Ripretinib also inhibits primary PDGFRα mutations in exons 12, 14 and 18, including the exon 18 D842V mutation, involved in a subset of GIST. In June 2019, the U.S. FDA granted Fast Track Designation to ripretinib for the treatment of patients with advanced GIST who have received prior treatment with imatinib, sunitinib and regorafenib.
Deciphera Pharmaceuticals has an exclusive license agreement with Zai Lab (Shanghai) Co., Ltd. for the development and commercialization of ripretinib in Greater China (Mainland China, Hong Kong, Macau and Taiwan). Deciphera Pharmaceuticals retains development and commercial rights for ripretinib in the rest of the world.