Long-Term Follow up of Pediatric Patients with Hodgkin Lymphoma Treated with High Dose Therapy and Autologous Stem Cell Transplantation

Introduction: Despite improved outcomes for children with Hodgkin lymphoma (HL), relapsed and refractory disease remain a challenge for a subset of patients. High dose therapy followed by autologous stem cell transplantation (ASCT) is the standard of care for relapsed disease, largely based on data from studies in adults. As new therapies emerge for HL, risk stratification of pediatric patients with relapsed disease will be essential to determine which patients are likely to benefit from ASCT and which patients should be selected for alternative therapy. In this study we report the long-term outcome of 34 pediatric patients with HL who underwent ASCT at a single institution.

Methods: We conducted a retrospective analysis of 34 consecutive pediatric patients with HL who underwent ASCT at Memorial Sloan Kettering Cancer Center from 1989-2013. Data collected included age, histology, treatment prior to ASCT, disease status at the time of transplant, conditioning regimen, and outcome after ASCT. Given recent data supporting a Childhood Hodgkin International Prognostic Score (CHIPS) for risk stratification in first-line therapy(Schwartz et al, ASH Abstract #3649, 2011), this score was calculated at the time of relapse to evaluate its prognostic relevance in the relapse setting. One point was awarded for each of the following: stage IV disease, bulky mediastinal adenopathy, albumin <3.5, and fever. Kaplan-Meier survival analysis was used to estimate the probability of overall survival (OS) and disease-free survival (DFS).

Patient Characteristics: Pathologic classification included nodular sclerosis (n=30), mixed cellularity (n=1), lymphocyte predominant (n=2), or subtype unspecified (n=1). The median age was 17.9 yrs (range 9.7-21) and 47% of patients were male. Thirty-three patients had relapsed disease; one patient had primary refractory disease. The median time from diagnosis to first relapse was 13 months (range 5-60). Twenty-five patients (73.5%) had chemotherapy responsive disease at the time of transplant (CR or PR). Others had stable disease (n=6), mixed response (n=2) or progressive disease (n=1). Thirty-one of 34 patients received radiation therapy either during initial treatment or as part of a salvage regimen. Four patients received brentuximab vedotin at the time of relapse. ASCT preparative regimen consisted of cyclophosphamide-etoposide + total lymphoid irradiation (n=14) or + carmustine (n=16), while 4 patients received the BEAM regimen. All but two patients treated after 1997 received chemotherapy-only preparative regimens.

Results: The median follow up for the cohort was 70.5 months (range 2.5-144). The 12-year OS and DFS were 65.1% and 63.6% respectively. The cause of death included HL (n=7), sepsis (n=1) and end stage renal disease (n=1). Patient age, stage at diagnosis, and time from diagnosis to relapse were not associated with differences in DFS. Patients who received an ASCT after 1997 had a better outcome than those who received an ASCT before 1997 (DFS 44.9% vs. 81.8%, p=0.012). Patients with chemotherapy sensitive disease at the time of transplant had a superior DFS (74.5% vs. 33.3%, p=0.005). Although not statistically significant, there was a trend toward improved outcome among patients with early stage disease at relapse (stage I/II) compared to advanced stage (III/IV) (DFS 81.3% vs. 54.2%, p=0.098). Among 21 patients with data available to calculate CHIPS at time of relapse, there was a superior OS among those with a lower CHIPS with OS of 100%, 70%, 50%, and 0% for patients with a CHIPS of 0, 1, 2, and 3 respectively (p=0.021). There were no patients with a CHIPS of 4. There was a trend toward improved DFS among patients with a low CHIPS, however this was not statistically significant (DFS of 100%, 70%, 66.7%, and 0% in patients with a CHIPS of 0, 1, 2, and 3 respectively, p=0.176).

Conclusions: ASCT offers the prospect of durable, disease free survival for a significant proportion of pediatric patients with relapsed HL. The outcome among patients who received an ASCT in recent years (1997-2013) was high (DFS 81.8%). Chemotherapy sensitive disease at the time of transplant was associated with superior DFS. To our knowledge this is the first report evaluating the potential utility of CHIPS in the relapse setting. Despite the small sample size (n=21) CHIPS was predictive of OS, suggesting that this measure should be studied further as a potential prognostic marker in relapsed HL.