Improved Response Rate with Bortezomib Consolidation After High Dose Melphalan: First Results of a Nordic Myeloma Study Group Randomized Phase III Trial.
Authors: Mellqvist Ulf-Henrik , Westin Jan , Gimsing Peter , Hjertner Oyvind , Lenhoff Stig , Laane Edward , Remes Kari , Steingrimsdottir Hlif , Abildgaard Niels , Ahlberg Lucia , Carlsson Kristina , Dahl Inge Marie , Forsberg Karin , Gedde-Dahl Tobias , Gregersen Henrik , Gruber Astrid , Guldbrandsen Nina , Haukås Einar , Linder Olle , Nahi Hareth , Nesthus Ingerid , Toffner-Clausen Nilsaage , Silvennoinen Raija , Andersen Niels Frost , Turesson Ingemar , Waage Anders 
Published: October 2019

Abstract 530

An open, multi-center, randomized phase III trial performed by the Nordic Myeloma Study Group (NMSG) was designed to explore the effect of a 21-week consolidation period of single agent bortezomib, given during months 3-8 after ASCT. Primary end-point was event free survival and secondary end-points were response rate, toxicity, overall survival, quality of life and cost utility.

Between November 2005 and April 2009 404 patients were included, 372 of whom were randomized. This report comprises preliminary data concerning feasibility, toxicity and response rate for the initial 299 randomized patients.

Patients were randomized 3 months post ASCT to either no consolidation therapy (current standard in Scandinavia), or to a period of bortezomib consolidation. Initial treatment before ASCT was optional. Patients were stratified for single or double ASCT. Bortezomib was given in a dose of 1.3 mg/m2 twice weekly (days 1, 4, 8 and 11) in a 3 week schedule for the first 2 cycles. In the following four cycles, bortezomib was given once weekly (days 1, 8 and 15) in a 4 week schedule, in total 20 injections over 21 weeks. Before each dose of study drug, the patients were evaluated for possible toxicities.

Baseline characteristics were well balanced between the 149 patients in the bortezomib group and the 150 in the control group. All analyses were performed on an intention to treat basis.

The mean number of bortezomib injections was 15, median 19 of optimal 20. The mean total dose given was 82 %, median 90 %, of the planned dose. Thirty-one patients (21 %) had to reduce the dose to zero for one cycle or more, mainly due to neuropathy, 11 patients, or progression, 8 patients. Hematological toxicity according to CTC included neutropenia grade ≥ III in 33 patients (22 %), thrombocytopenia grade ≥ III in 14 patients (9 %). Neurological pain grade ≥ III was seen in 7 patients (5 %). Sensory neuropathy grade ' III was seen in 5 patients (3 %).

A significant difference in improvement of response was noted between the two arms. At the time of randomization the proportion of CR/nCR was 23 % for patients in the bortezomib arm and 21 % in the control arm. However, when measured six months after randomization (9 months after ASCT), the proportion of CR/nCR was 54 % in the bortezomib group versus 35 % for the controls, p < 0.005. The proportion of patients improving their response from PR to CR/nCR was 20 % and 12 % for the bortezomib and control groups respectively, p = 0.06 NS. The proportion of patients who relapsed during the initial 6 month observation period did differ significantly, 1 % versus 6 %, p<0.05.

Our results indicate that consolidation with bortezomib given as a single agent is feasible and does improve treatment response after ASCT.

Disclosures:

Mellqvist: Jansen-Cilag: Speakers Bureau; Celgene: Speakers Bureau; Johnson and Johnson: Research Funding. Off Label Use: Bortezomib. Consolidation therapy after high dose melphalan.. Westin:Celgene: Membership on an entity's Board of Directors or advisory committees. Gimsing:Jansen-Cilag: Membership on an entity's Board of Directors or advisory committees; GenMab: Membership on an entity's Board of Directors or advisory committees; Schering-Plough: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees. Laane:Schering-Plough: Membership on an entity's Board of Directors or advisory committees. Remes:Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jansen-Cilag: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Waage:Jansen-Cilag: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Genzyme: Membership on an entity's Board of Directors or advisory committees.