Interim PET-guided treatment for early-stage NLPHL: a subgroup analysis of the randomized GHSG HD16 and HD17 studies.

The optimal first-line treatment for nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) diagnosed in early stages is largely undefined. We therefore analyzed 100 NLPHL patients (early-stage favorable: 85 patients; early-stage unfavorable: 15 patients) treated within the randomized HD16 (early-stage favorable) and HD17 (early-stage unfavorable) studies. These studies investigated the omission of consolidation radiotherapy (RT) in patients with a negative interim positron emission tomography (iPET) (defined as a Deauville score < 3) at the end of chemotherapy (HD16: 2xABVD; HD17: 2xBEACOPPescalated plus 2xABVD). Patients with NLPHL treated within the HD16 and HD17 studies had 5-year progression-free survival (PFS) rates of 90.3% (95%-CI: 83.8%-96.7%) and 92.9% (95%-CI: 79.4%-100%), respectively. Thus, the 5-year PFS did not differ significantly from patients with classical Hodgkin lymphoma treated within the same studies (p=0.88 for HD16; p=0.50 for HD17). Patients with early-stage favorable NLPHL who had a negative iPET after 2xABVD and did not undergo consolidation RT (n=25) tended to have a worse PFS than iPET-negative patients who received consolidation RT (n=21) (5-year PFS: 83% (95%-CI: 67.8%-98.2%) vs 100%; p=0.05). Overall, there were 10 cases of NLPHL recurrence (HD16: 9 patients; HD17: 1 patient). However, no NLPHL patient died during follow-up. Hence, the 5-year overall survival rate was 100%. Taken together, contemporary HL-directed treatment approaches result in excellent outcomes for patients with newly diagnosed early-stage NLPHL and thus represent valid treatment options. In patients with early-stage favorable NLPHL, consolidation RT appears necessary after 2xABVD to achieve the optimal disease control irrespective of the iPET result.