The predictive role of interim PET after the first chemotherapy cycle and sequential evaluation of response to ABVD in Hodgkin lymphoma patients - the Polish Lymphoma Research Group (PLRG) Observational Study

Abstract

Background: Interim PET after 2 ABVD cycles (iPET2) predicts treatment outcome in classical Hodgkin lymphoma (cHL). To test if an earlier assessment of chemosensitivity would improve the prediction accuracy, we launched a prospective, multicenter observational study aimed at assessing the predictive value (PV) of iPET after 1 ABVD (iPET1) and the kinetics of response assessed by sequential PET scanning.Patients and Methods: Consecutive patients with newly diagnosed cHL underwent interim PET scan after one ABVD course (iPET1). PETs were interpreted according to the Deauville score (DS) as negative (-) (DS 1-3) and positive (+) (DS 4,5). Patients with iPET1 DS 3-5 underwent iPET2.Results: 106 early (I-IIA) and 204 advanced (IIB-IV) patients were enrolled between 01/2008 and 10/2014. iPET1 was (-) in 87/106(82%) or (+) in 19/106(18%) of early, and (-) in 133/204(65%) or (+) in 71/204(35%) of advanced stage patients, respectively. Twenty-four patients were excluded from response analysis due to treatment escalation. After a median follow-up of 38.2 (3.2-90.2) months, 9/102-(9%) early and 43/184-(23%) advanced patients experienced a PFS event. At 36 months, negative and positive PV for iPET1 were 94% and 41% (early) and 84% and 43% (advanced), respectively. The kinetics of PET response was assessed in 198 patients with both iPETs. All 116 patients with iPET1(-) remained iPET2(-) (fast responders), 41/82 with IPET1(+) became iPET2(-) (slow responders), and the remaining 41 stayed iPET2(+) (non-responders); PFS at 36 months for fast, slow and non-responders was 0.88, 0.79 and 0.34, respectively.Conclusion: The optimal tool to predict ABVD outcome in HL remains iPET2 since it distinguishes responders, whatever their time to response, from non-responders. However, iPET1 identified fast-responders with the best outcome and might guide early treatment de-escalation both in early and advanced-stage HL.

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