Anti-PD-1 therapy provides high response rates in Hodgkin lymphoma (HL) patients who have relapsed or are refractory (R/R) to autologous stem cell transplantation (ASCT) and brentuximab vedotin (BV), but median progression free survival (PFS) is only one year. The efficacy of treatment following anti-PD-1 is not well known.

In this context, the optimal treatment for patients who failed after anti-PD-1 therapy is an issue. To better assess their outcome, the investigators retrospectively analyzed the characteristics and outcome of patients from 14 LYSA (The Lymphoma Study Association) centers who lost response to anti-PD-1 therapy and received additional CT.

Inclusion Criteria:

• Initial diagnosis of classical HL
• Optional histopathology confirmation of relapse/refractory HL, (2) age ≥ 18 years
• Eastern Cooperative Oncology Group (ECOG) Performance Status from 0 to 2
• Patients must be have received: at least 2 prior regimens and have received or be ineligible for autologous stem cell transplant and must have received prior BV, and at least 2 cycles of single agent anti-PD-1 as last treatment before entering the study,
• Patients must have inadequate response to anti-PD-1 monotherapy (progressive disease or partial response according to Lugano criteria) with at least one hypermetabolic lesion over the liver and mediastinum background at time of inclusion in the study
• Previous allogeneic stem cell transplant was allowed. Patients treated with radiotherapy alone after anti-PD1 or combined with anti-PD1 treatment were not included in the study.

Exclusion Criteria:

- radiotherapy in the treatment after anti-PD1

The initial diagnosis of classical HL was established from biopsies in accordance with the 2008 World Health Organization classification14. We retrospectively analyzed 30 R/R classical HL patients from 14 LYSA centers who received anti-PD-1 therapy as part of a clinical trial (n=4), from an off-label program authorization for temporary use (ATU) from the French medical drug agency (Agence Nationale de Sécurité du Médicament, ANSM) (n=22), from the Belgian national system for the reimbursement of health care (Institut National d'Assurance Maladie Invalidité, INAMI) (n=4).