(177) Lu-Lilotomab Satetraxetan, A Novel Cd37-Targeted Antibody-Radionuclide Conjugate In Relapsed Non-Hodgkin'S Lymphoma (Nhl): Updated Results Of An Ongoing Phase I/Ii Study (Lymrit 37-01)

The incidence of indolent NHL (iNHL) is increasing, with approximately 63,000 new cases per year in the US. The highest unmet medical need is for rituximab (RTX)-refractory patients (pts), with inferior 5 year overall survival rates for RTX-refractory follicular lymphoma (FL) vs all FL pts (58% vs 87.7%) (Abdollahi S et al. Blood 2008; www.seer.cancer.gov). Many pts develop resistance to RTX or RTX-containing regimens, thus targets other than CD20 are important. CD37 is highly expressed (>90%) in most B-cell NHL, providing an alternative target to CD20. Lutetium (177Lu) lilotomab satetraxetan (Betalutin®) is a novel beta-emitting anti-CD37 antibody radionuclide conjugate (ARC) in a ready-to-use formulation that is being evaluated in a phase I/II, open-label, dose-escalation study (LYMRIT 37-01) to determine the safety and preliminary efficacy of Betalutin® monotherapy in pts with relapsed/refractory NHL, and establish a recommended phase II dose (RP2D). Lilotomab (cold antibody) pre-dosing was determined to be essential to optimize Betalutin® biodistribution and safety, and dosimetry data indicate less bone marrow (bm) uptake of Betalutin® with lilotomab pre-dosing with no impact on tumor absorbed dose (Blakkisrud et al. J Nucl Med 2017). Arms 1 and 4 are evaluating 2 different lilotomab pre-doses (Arm 1 - 40 mg; Arm 4 -100mg/m2) with escalating doses of Betalutin®. We provide here an update on safety/efficacy for the 2 arms.