AFM13 in Patients with Relapsed or Refractory Hodgkin Lymphoma: Final Results of an Open-Label, Randomized, Multicenter Phase II Trial

INTRODUCTION: The outcome of patients (pts) with classical Hodgkin Lymphoma (cHL) experiencing relapse after high dose chemotherapy, brentuximab vedotin (BV) and anti-PD1 antibody (Ab) treatment is poor and in most patients the duration of the response to this treatment is rather short. Thus, there still is a need for new treatment options. A promising immunotherapeutic approach is the bispecific anti-CD30/CD16A antibody AFM13.

METHODS: Pts ≥ 18 years with relapsed or refractory cHL after standard therapy including BV and anti-PD1 Ab were included in this two-stage trial (NCT02321592). In stage I pts were initially assigned in a 1:1 ratio to either Arm A with 1.5 mg/kg AFM13 3x/ week for 8 weeks or Arm B with 1.5 mg/kg AFM13 3x/ week for 2 weeks followed by 1 infusion of 7.0 mg/kg/week for 6 weeks.

After an amendment to this trial, all further pts received 7 mg/kg per week, with 1 mg/kg loading dose and 6 mg/kg as continuous infusion for 5 days/ week thereafter (Arm C). If ≥ 2 overall responders were observed in 10 pts, the respective trial arm qualified for stage 2. Primary endpoint was the objective response (complete/partial remission (CR/PR)) after the first cycle. Secondary endpoints included efficacy (Overall survival (OS), Progression free survival (PFS)) and safety analyses.

RESULTS: Between June 26, 2015 and May 31, 2019, 25 pts were assigned to arm A (n=5), B (n=12), or C (n=8), respectively, and qualified for statistical analyses. Median age of the study population was 45 (range 21-73) years. 24/25 patients were male. Clinical stages 2, 3 and 4 were diagnosed in 8 (32%), 9 (36%), and 8 (32%) patients, respectively. Patients had received a median of 3 (range 1-11) salvage-therapy lines after first-line therapy. Since the trial was terminated in stage I due to a lack of recruitment, all statistical analyses of primary and secondary endpoints are also of descriptive nature. The central response evaluation panel included 24 of 25 pts: The objective response rate was 16.6% including 1 complete response (CR) and 3 partial responses (PR). Stable disease (SD) was documented in 6 pts and progressive disease (PD) in 14 pts. The responses were distributed as follows to the treatment arms: Two responses were documented in arm C and one response was documented in arm A and B, respectively. Second cycle AFM13 was started in 5 patients. Two patients had PD during or after cycle 2, and one patient each was diagnosed with CR, PR, or SD. During follow-up, there were 22 cases of PD and 9 deaths. With a median observation time for PFS of 5.5 months (95% CI 2.6 - 11.0), the 12-months PFS estimate was 12.6% (95%-CI 3.2 - 28.9) (Fig.1). With a median observation time of 14.5 months (95% CI 12.9-16.8) the 12-months OS estimate was 62% (95% CI 39.6-78.1). In only 5/25 pts serious adverse events due to hospitalization were observed; two events were characterized as serious adverse reaction: one CTC grade 4 and one CTC grade 2 infusion related reaction. All events resolved completely.

CONCLUSION: Treatment with AFM13 was well tolerated and showed modest activity in heavily pretreated pts. The responses documented in arm C qualified this arm with continuous AFM13 application over 5 days for further evaluation in trial stage 2 and thus indicated its potential. However, the trial was prematurely stopped due to low recruitment leading to the conclusion that the acceptance of the application schedule is extremely important.

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