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1656 Interim Analyses of Overall Survival (OS) from the TOURMALINE MM3 & MM4 Studies of Ixazomib Maintenance Following Primary Therapy in Multiple Myeloma (MM)

Program: Oral and Poster Abstracts
Session: 653. Myeloma and Plasma Cell Dyscrasias: Clinical-Prospective Therapeutic Trials: Poster I
Hematology Disease Topics & Pathways:
Clinical Trials, Adults, Clinical Research, Plasma Cell Disorders, Diseases, Lymphoid Malignancies, Study Population
Saturday, December 11, 2021, 5:30 PM-7:30 PM

Meletios A. Dimopoulos, MD1, S. Vincent Rajkumar, MD2*, Sagar Lonial, MD, FACP3, Wee-Joo Chng4, Shinsuke Iida, MD, PhD5, Maria-Victoria Mateos6, Gareth J. Morgan, MD, PhD7, Arun Kumar8*, Kaveri Suryanarayan, MD8*, Alexander Vorog, MD9*, Andrew Fergus8* and Richard Labotka, MD8

1National and Kapodistrian University of Athens, Athens, Greece
2Division of Hematology, Mayo Clinic, Rochester, MN
3Department of Hematology and Medical Oncology, Winship Cancer Institute, Emory University Medical School, Emory University, Atlanta, GA
4Department of Hematology-Oncology, National University Cancer Institute Singapore, Singapore, Singapore
5Department of Hematology and Oncology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
6University Hospital of Salamanca, CIC, IBMCC, Salamanca, Spain
7Perlmutter Cancer Center, NYU Langone Health, New York, NY
8Takeda Development Center Americas, Inc. (TDCA), Lexington, MA
9Takeda Development Center Americas, Inc., Lexington, MA

Background:

Two global, randomized, placebo (pbo)-controlled phase 3 studies of single-agent ixazomib (ixa) maintenance therapy are currently ongoing for newly diagnosed MM patients following primary therapy that included autologous stem cell transplantation (ASCT) (MM3, NCT02181413) or excluded ASCT (MM4, NCT02312258). Both trials have demonstrated statistically significant and clinically meaningful improvement in their primary endpoint of progression-free survival (PFS): for MM3, median 26.5 months (mos) ixa vs 21.3 mos pbo (hazard ratio [HR] 0.720, 95% confidence interval [CI] 0.582-0.890, P=0.002); for MM4, median 17.4 mos for ixa vs 9.4 mos for pbo (HR 0.659, 95% CI 0.542-0.801, P<0.001). Data for the key secondary endpoint, OS, have not previously been published.

Methods:

Full methods have previously been reported (Dimopoulos, Lancet 2019; Dimopoulos, J Clin Oncol 2020). Eligible patients (MM3, N=656; MM4, N=706) were randomized 3:2 to receive maintenance therapy with single agent ixa or pbo for a maximum of approximately 24 mos (26 cycles, to the nearest complete cycle) or until progressive disease or unacceptable toxicity, whichever occurred first.

Results:

At the most recent data cut-off (MM3, 29 January 2021; MM4, 15 October 2020), with median follow up of 64 mos and 36 mos, respectively, 27% (MM3, 174/656) and 29% (MM4, 203/706) of the intention-to-treat (ITT) population had OS events. In MM3, the 5-year Kaplan-Meier estimate for OS was 74% for ixa and 73% for pbo, though the median OS had not yet been reached in either arm (HR 1.008, 95% CI 0.744-1.367, P=0.958; Figure). In MM4, the 5-year Kaplan-Meier OS estimate was 55% for ixa and 56% for pbo, though the median OS had also not yet been reached in either arm (HR 1.136, 95% CI 0.853-1.514, P=0.382; Figure). No new safety signals were identified, and the incidence of new primary malignancies in both studies was similar between ixa and pbo.

Conclusions:

These most current OS data for MM3 and MM4 have not demonstrated a statistically significant difference for the ixa or the pbo arm to date. After 64 mos of follow-up in MM3, the risk of OS does not differ between the study arms. After 36 mos of follow-up in MM4, the OS HR shows a trend that favors the pbo arm. Because interim analyses of OS may be overrepresented by deaths in patients who did not benefit from maintenance therapy, it is not known to what extent these results will be reflective of the ITT population at the time of the final analyses. As treatment options, including anti-CD38 mAb and other new mechanisms of action, for salvage therapies following progression continue to expand, OS is increasingly being confounded by subsequent therapies. Hence, demonstrating OS advantage for early line MM therapies is becoming increasingly challenging. OS data continue to be collected in these studies for later analyses.

Disclosures: Dimopoulos: Takeda: Honoraria; Amgen: Honoraria; Beigene: Honoraria; Janssen: Honoraria; BMS: Honoraria. Lonial: AMGEN: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Research Funding; Merck: Honoraria; GlaxoSmithKline: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees; BMS/Celgene: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria. Chng: Johnson and Johnson: Honoraria, Research Funding; BMS/Celgene: Honoraria, Research Funding; Takeda: Honoraria; Abbvie: Honoraria; Sanofi: Honoraria; Pfizer: Honoraria. Iida: Takeda: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Ono: Honoraria, Research Funding; Chugai: Research Funding; Celgene: Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; Daiichi Sankyo: Research Funding; Glaxo SmithKlein: Research Funding; Amgen: Research Funding; Abbvie: Research Funding; Bristol-Myers Squibb: Research Funding. Mateos: Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Regeneron: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sea-Gen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Honoraria; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria; Bluebird bio: Honoraria; GSK: Honoraria; Celgene - Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees. Morgan: BMS: Membership on an entity's Board of Directors or advisory committees; Jansen: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees. Kumar: Takeda: Current Employment, Current holder of stock options in a privately-held company. Suryanarayan: Takeda: Current Employment. Vorog: Takeda: Current Employment. Fergus: Takeda: Current Employment. Labotka: Takeda: Current Employment.

OffLabel Disclosure: Use of the oral proteasome inhibitor ixazomib as maintenance treatment for multiple myeloma following stem cell transplantation or induction therapy in newly diagnosed patients.

*signifies non-member of ASH