This study examines the safety and efficacy of mavorixafor in combination with ibrutinib in patients with WM with MYD88 and CXCR4 mutations….Six out of 7 patients showed decrease in IgM after 1 cycle. Four patients were treated for ≥3 cycles; all had decrease in serum IgM, with 2 achieving a ≥50% decrease from baseline consistent with partial response after 3 cycles (median decrease, 51.0%; range, 4.4%–84.5%).