A Randomized Phase 2 Trial Comparing Carfilzomib-Dexamethasone Vs Observation As Maintenance after Induction with Carfilzomib-Cyclophosphamide-Dexamethasone in Salvage ASCT in Multiple Myeloma: A Trial By the Nordic Myeloma Study Group
Authors: Gregersen Henrik , Peceliunas Valdas , Remes Kari , Schjesvold Fredrik H. , Abildgaard Niels , Nahi Hareth , Andersen Niels Frost , Vangsted Annette Juul , Klausen Tobias Wirenfeldt , Helleberg Carsten , Carlson Kristina , Frølund Ulf Christian , Axelsson Per , Stromberg Olga , Blimark Cecilie Hveding , Linder Olle , Tsykunova Galina , Waage Anders , Hansson Markus , Gulbrandsen Nina 
Published: February 2020

Background: Salvage autologous stem cell transplantation (ASCT) is used in selected patients with relapsed multiple myeloma after up-front ASCT. However, there are limited data on the optimal induction therapy before salvage ASCT. There is strong support for the use of maintenance therapy after upfront ASCT in newly diagnosed multiple myeloma whereas data on maintenance therapy after salvage ASCT are sparse.
The Nordic Myeloma Study Group (NMSG) initiated the CARFI trial (NCT02572492), an open randomized phase II study, to investigate the efficacy and safety of carfilzomib as part of induction and conditioning in salvage ASCT and to evaluate the role of carfilzomib/dexamethasone maintenance after salvage ASCT.
Methods: Patients with first relapse after up-front ASCT were treated with an induction regime containing four cycles of CAR-CY-DEX (iv carfilzomib 20 mg/sqm → 36 mg/sqm on days 1, 2, 8, 9, 15 and 16, tablet cyclophosphamide 300 mg/sqm on days 1, 8 and 15 and tablet dexamethasone 20 mg on days 1, 2, 8, 9, 15 and 16 in each 28-days cycle). The subsequent conditioning regimen contained iv carfilzomib 27 mg/sqm on day -2 and -1, and iv melphalan 200 mg/sqm on day -2. The patients had not received any maintenance therapy after upfront ASCT. Two months after ASCT patients were randomized (1:1) to observation or maintenance therapy with iv carfilzomib 27 mg/sqm → 56 mg/sqm every second week and tablet dexamethasone 20 mg every second week. The randomization was stratified according to relapse 1 - 2 year or &gt; 2 years after up-front ASCT, ISS stage and standard versus high-risk cytogenetics. Primary endpoint was comparison of time to progression (TTP) after up-front ASCT and TTP after salvage ASCT with CAR-CY-DEX induction. Another primary endpoint was to compare TTP between carfilzomib-dexamethasone maintenance and observation in patients treated with salvage ASCT.
Results: 200 patients were enrolled in the study and 32 of these went off study during the induction and after ASCT. The remaining 168 patients were randomized to carfilzomib-dexamethasone (82 patients) or observation (86 patients). The median age was 62 (interquartile range: 56; 66) years and the median follow-up from time of inclusion was 20.1 (14.1 - 27.6) months. The median TTP after up-front ASCT was 33.2 (31.0-37.8) months compared with 28.1 (24.9-31.5) months after salvage ASCT. The two groups randomised to maintenance therapy or observation were balanced regarding age, time from myeloma diagnosis, treatment at diagnosis, performance status, ISS stage and high-risk cytogenetics (Table 1). The median TTP from randomisation was 28.8 (95% CI: 24.4-NR) months in the maintenance group and 18.5 (95% CI: 14.3-22.0) months in the observation group (hazard ratio 0.42 (95% CI: 0.26-0.68, P = 0.0003)) (Figure I). For the maintenance group TTP from inclusion was 35.4 (30.9-NR) months compared with TTP of 31.3 (29.4-37.8) months (P = 0.71) after up-front ASCT for these patients. A total of 53 serious adverse events (SAE) were reported in 25 patients on carfilzomib-dexamethasone maintenance and 33 SAEs in 21 patients in the observation group. The majority of the SAEs were infections; 39 in the maintenance group and 25 in the observation group, divided into viral infection (10 versus 3), septicemia (2 versus 0) and pneumonia (12 versus 7). Three SAEs classified as cardiac-pulmonary were observed in the maintenance group (syncope, atrial fibrillation and pulmonary embolism) in contrast to three in the observation group (atrial fibrillation and dyspnea(2)).
Conclusion: In this randomized phase 2 trial, maintenance therapy with carfilzomib and dexamethasone prolonged median TTP with approximately 10 months following salvage ASCT in multiple myeloma. The difference between TTP after upfront ASCT and TTP after salvage ASCT with carfilzomib based induction therapy was small which supports the use of salvage ASCT followed by maintenance in selected patients at first relapse.

Disclosures
Remes: Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Other: Congress Support; Takeda: Membership on an entity's Board of Directors or advisory committees, Other: Congress Support; Amgen: Other: Congress Support; Celgene: Other: Congress Support; Sanofi: Other: Congress Support. Schjesvold:Janssen: 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; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; MSD: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; SkyliteDX: Honoraria; Oncopeptides: Membership on an entity's Board of Directors or advisory committees. Abildgaard:Amgen: Research Funding; Celgene: Research Funding; Janssen: Research Funding; Takeda: Research Funding. Vangsted:Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria; Jansen: Honoraria. Blimark:Amgen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees.