The Emerging Role of PET in Hodgkin Lymphoma Patients Receiving Autologous Stem Cell Transplant

Bastian von Tresckow; Andreas Engert

Disclosures

Expert Rev Hematol. 2012;5(5):483-486. 

In This Article

Discussion

Today, HDCT with ASCT is the standard of care for patients with relapsed or refractory HL. More than 50% of patients can be cured of their lymphoma with this aggressive approach. Several studies have analyzed risk factors in HL patients receiving HDCT: The most important variables affecting outcome in HDCT studies were time to relapse (late relapse > early relapse > progressive disease), clinical stage at relapse, anemia at relapse, chemosensitivity to conventional salvage chemotherapy and the remission status before HDCT (CR > PR > SD).[8,9] Additionally, the presence of B symptoms and extranodal disease have been characterized as risk factors for poor post-ASCT outcome.[10] The analyses of Cocorocchio et al. confirm the remission status after induction therapy as one of the most important risk factor for PFS and OS after ASCT.[1]

Additionally, Cocorocchio et al. report PET result before and after ASCT to be a prognostic factor for the treatment outcome. PET is known to have a high negative predictive value in HL during first-line therapy and is currently being evaluated for response-adapted treatment in first-line HL studies.[11] Less is known on its predictive value after salvage therapy. In addition to the article by Cocorocchio et al., a plethora of retrospective analyses on PET in HL patients receiving HDCT and ASCT have been published in recent years. Several studies have reported that PET positivity after salvage is associated with poorer outcome.[12–16] The largest series of patients treated with a relatively uniform salvage therapy reported functional imaging normalization (PET or gallium scan) after salvage therapy to be a significant factor for OS and event-free survival (EFS) in multivariate analyses.[13] The 5-year EFS for functional imaging was 75% for negative and 31% for positive patients, suggesting a role of functional imaging as predictive tool in HL. The use of PET might lead to improved risk-adapted treatment strategies. Fewer data are available on the role of PET after ASCT: one retrospective analysis on 43 patients with PET one month after transplant reported a significantly improved PFS of 72.9% for PET-negative versus 0% for PET-positive patients.[17] OS was 95.8 and 49.8% for PET-negative and PET-positive patients, respectively. By contrast, there was no significant association between PET after ASCT and prognosis in another retrospective analysis.[18] However, there were only 30 HL patients in this analysis. Therefore, the larger analysis of Cocorocchio et al. on 78 patients might provide new insights into the prognostic role of PET after ASCT. Nevertheless, prospective data are still lacking.

The key questions that arise from such analyses are whether therapy should already be adapted based on PET results, and if the answer is yes, which therapeutic approach should be chosen. Two recent reports have tried to answer these questions: in a large, retrospective analysis on 111 HL patients who achieved at least a PR before single or tandem ASCT, a positive PET was associated with significantly poorer outcome with 5-year OS rates of 90 and 55% and 5-year PFS rates of 79 and 23% for PET-negative and -positive patients, respectively.[19] More importantly, in the PET-positive subgroup, tandem ASCT improved 5-year PFS from 0 to 43% compared with single ASCT. Therefore, tandem ASCT might be an alternative for high-risk patients with positive PET before ASCT. More recently, the impact of second-line, non-cross-resistant chemotherapy for patients with positive PET after salvage has been assessed in a prospective trial.[20] Of note, to our knowledge, this is the first trial that prospectively assessed the role of PET before ASCT. Patients with a positive PET after ifosfamide, carboplatin, etoposide (ICE)/augmented ICE salvage therapy received additional chemotherapy with gemcitabine, vinorelbine and liposomal doxorubicin to achieve a negative PET and to thereby improve the prognosis. In the final analysis, PET-negative patients who were transplanted had an EFS of >80 versus 28.6% for PET-positive patients. The authors concluded that the goal of salvage therapy in patients with HL should be a negative PET before ASCT.

processing....