HORIZON (OP-106): MELFLUFEN PLUS DEXAMETHASONE IN 55 PATIENTS WITH
RELAPSED/REFRACTORY MULTIPLE MYELOMA (RRMM) WITH EXTRAMEDULLARY DISEASE
(EMD)—SUBGROUP ANALYSIS
Paul G. Richardson1, María-Victoria Mateos2, Albert Oriol3, Alessandra Larocca4, Michele Cavo5, Paula
Rodríguez-Otero6, Xavier Leleu7, Maxim Norkin8, Omar Nadeem1, John W. Hiemenz9, Hani Hassoun10,
Cyrille Touzeau11,12,13, Adrián Alegre14, Agne Paner15, Christopher Maisel16, Amitabha Mazumder17,
Anastasios Raptis18, Noemí Puig19, Elena Zamagni20, Marcus Thuresson21, Johan Harmenberg21, Olof
Harlin21 and Joan Bladé22
(1)Dana-Farber Cancer Institute, Harvard Medical School, Boston
(2)Hospital Clinico Universitario de Salamanca/IBSAL/CIC, Salamanca, Spain
(3)Institut Català d’Oncologia, Institut Josep Carreras, Hospital Germans Trias i Pujol, Barcelona, Spain
(4)Myeloma Unit, Division of Hematology, University of Torino, Azienda Ospedaliero – Universitaria
Città della Salute e della Scienza, Torino, Italy
(5)Seràgnoli Institute of Hematology, Bologna University School of Medicine, Bologna, Italy
(6)Clinica Universidad de Navarra, Pamplona, Spain
(7)CHU de Poitiers, Poitiers, France
(8)Baptist MD Anderson Cancer Center, Jacksonville
(9)Division of Hematology-Oncology, Department of Medicine, University of Florida, Gainesville
(10)Myeloma Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York
(11)Centre de Recherche en Cancérologie et Immunologie Nantes-Angers (CRCINA), Institut National de
la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS),
Université d'Angers, Université de Nantes, Nante, France
(12)Site de Recherche Intégrée sur le Cancer (SIRIC), Imaging and Longitudinal Investigations to
Ameliorate Decision-making (ILIAD), Nante, France
(13)Service d'hématologie Clinique, Centre Hospitalier Universitaire, Place Alexis Ricordeau, Nante,
France
(14)Hospital Universitario La Princesa and Hospital Universitario Quironsalud, Madrid, Spain
(15)Rush University Medical Center, Chicago
(16)Baylor Scott & White Charles A. Sammons Cancer Center, Dallas
(17)The Oncology Institute of Hope and Innovation, Glendale
(18)Division of Hematology-Oncology, Department of Medicine, University of Pittsburgh School of
Medicine, Pittsburgh
(19)Hospital Clínico Universitario de Salamanca/IBSAL/CIC, Salamanca
(20)University of Bologna, Bologna, Italy
(21)Oncopeptides AB, Stockholm, Sweden
(22)Hematology Department, IDIBAPS, Hospital Clinic, Barcelona, Spain
Background: EMD is characterized by a subclone of aggressive MM cells that grows independent of
the bone marrow (Bladé, et al. J Clin Oncol. 2011;29:3805). Prognosis for patients with EMD is worse
than that for patients without EMD, particularly for patients with soft-tissue (vs bone-related)
plasmacytomas (Mangiacavalli, et al. Ann Hematol. 2017;96:73), and no standard therapy
exists (Beksac, et al. EHA 2020. Abs. EP978; Jimenez-Segura, et al. Eur J Haematol. 2019;102:389).
Melphalan flufenamide (melflufen) is a first-in-class peptide-drug conjugate (PDC) that leverages
aminopeptidases and rapidly releases alkylating agents into tumor cells. Melflufen plus
dexamethasone showed clinically meaningful efficacy and a manageable safety profile in 157 patients
with heavily pretreated RRMM in the phase 2 HORIZON study (NCT02963493; Richardson, et al. J Clin
Oncol. 2020 Dec 9 Epub). This analysis presents additional data on patients with EMD in HORIZON.