Response-Adapted Therapy with Nivolumab and Brentuximab Vedotin (BV), Followed By BV and Bendamustine for Suboptimal Response, in Children, Adolescents, and Young Adults with Standard-Risk Relapsed/Refractory Classical Hodgkin Lymphoma

Introduction: Classical Hodgkin lymphoma (cHL) is among the most common malignancies in adolescents and young adults. High-dose chemotherapy (HDCT) and autologous hematopoietic stem cell transplantation (ASCT) are standard for most patients with relapsed/refractory (R/R) disease. Current salvage therapies are associated with excessive toxicity and variable complete remission rates (Harker-Murray et al, Pediatr Blood Cancer 2014). Novel regimens that increase remission rates and reduce late effects of therapy are needed, particularly for young patients. Nivolumab (nivo) is a fully human IgG4 anti-programmed death-1 monoclonal antibody. Brentuximab vedotin (BV) is a CD30-directed antibody-drug conjugate. In a phase 1/2 study of adults with R/R cHL, the combination of nivo + BV was well tolerated, with a high response rate as first salvage regimen (Herrera et al, Blood 2018). CheckMate 744 (AHOD1721; NCT02927769) is the first risk-stratified, response-adapted, phase 2 study of nivo + BV, followed by BV + bendamustine for suboptimal response, in children, adolescents, and young adults with R/R cHL with low or standard risk of relapse. Here we report preliminary, investigator (INV)-assessed results from the standard-risk (R2) cohort. Methods: This open-label study enrolled patients aged 5-30 years with pathologically confirmed cHL, excluding nodular lymphocyte-predominant HL, after failure/non-response to first-line therapy and without prior ASCT. Stratification to R2 was based on refractory disease or early relapse; B symptoms, extranodal disease, or extensive disease with radiation therapy (RT) contraindicated at relapse; relapse in a prior RT field; or stage IIIB or IV at initial diagnosis. Patients in R2 received induction (IND) with 4 cycles of nivo + BV. Patients without complete metabolic response (CMR; Deauville score 1-3) received intensification (INT) with 2-4 cycles of BV + bendamustine. Patients with CMR after IND or INT discontinued study treatment, proceeded to HDCT/ASCT, and entered follow-up. Tumors were assessed by INV and blinded independent central review (BICR) per Lugano 2014 criteria (Cheson et al, J Clin Oncol 2014) every 2 treatment cycles. Treatment decisions were based on BICR assessment. The primary endpoint was CMR rate by BICR prior to HDCT/ASCT. Secondary endpoints included INV-assessed response and safety. Results: At database lock (DBL), 32 patients in R2 had entered IND. Median age was 16 y (range 9-30), 78% were aged