Prognostic Impact of Early and Late ¹⁸fluorodeoxyglucose Positron Emission Tomography (FDG-PET) Prior to Autologous Stem Cell Transplantation in Children and Adolescents with Relapsed or Refractory Hodgkin Lymphoma

Functional imaging is widely used for response assessment in Hodgkin lymphoma (HL) patients treated for first line in addition to conventional imaging (magnetic resonance imaging, computed tomography). Insufficient information is available on the prognostic value of ¹⁸Fluorodeoxyglucose positron emission tomography (FDG-PET) status in pediatric and adolescent patients with recurrent HL undergoing high-dose therapy and autologous stem cell transplantation (HDT/ASCT).

Thirty-five patients (20 male, 15 female) with classical HL who received first-line therapy according to the GPOH HD-2002 study (n=31), GPOH HD-2002/VECOPA study (n=3) or during interim observation (n=1) and subsequently relapsed before the start of the EuroNet-PHL-C1 trial were analyzed. Ten patients progressed during first-line therapy, 23 patients had an early relapse and in two patients disease recurred late (>12 months after end of therapy). Patients received salvage therapy mainly based on IEP (ifosfamide, etoposide, prednisone) and ABVD (adriamycine, bleomycin, vinblastine, dacarbazine) regimens according to treatment recommendations followed by HDT/ASCT. Tandem transplantations were excluded and follow-up of surviving patients had to be at least six months. FDG-PET was reviewed centrally based on a quadrinomial scale and was assessed before relapse treatment, after one or two salvage therapy cycles (early response assessment [ERA], n=33 patients) and/or immediately before ASCT or followed by one more cycle prior to HDT (late response assessment [LRA], n=23 patients).

Median age of the 35 patients at relapse was 15.7 years (range, 5.5 to 17.5) and 16.9 years (range, 6.5 to 19.0) at ASCT. At a median follow-up of 59 months, 29 patients were alive. The overall survival rate at 4 years was 82.4±6.5%. Eight patients relapsed following HDT/ASCT. The proportion of patients without second failure at 4 years was 77.0±7.1%. At ERA, 19 patients were PET negative and 14 patients were PET positive. PFS of ERA-PET-negative patients at 4 years is 94.7±5.1% compared to 56.3±13.5% in PET-positive patients (P =.009). PFS of LRA-PET-negative patients at 4 year was 94.1±5.7% vs 44.4±22% for PET- positive patients (P =.014). In addition, five of ten patients with progressive disease could be successfully salvaged. Six patients with subsequent relapse underwent allogeneic SCT; two of these patients are alive.

Overall survival of this cohort is favorable, even patients with progressive disease have a fair chance for second long term remission. ERA-PET-negative patients have an excellent prognosis after salvage treatment including HD-chemotherapy and autologous stem cell transplantation. New options may be required for those patients who remain PET positive prior to HDT.

No relevant conflicts of interest to declare.