Risk Stratification for Relapsed/Refractory Classical Hodgkin Lymphoma Integrating Pretransplant Deauville Score and Residual Metabolic Tumor Volume

Abstract Introduction Positron emission tomography (PET) positivity before autologous stem cell transplantation (ASCT) predicts poor prognosis in relapsed/refractory (rel/ref) classical Hodgkin lymphoma (cHL). However, there is limited data regarding the value of pre-ASCT residual metabolic tumor volume (rMTV) assessed by PET to predict post-ASCT outcomes. We aimed to evaluate the role of pre-ASCT Deauville score (DS) combined with rMTV in patients with rel/ref cHL who underwent salvage ASCT, and also to establish a risk model integrating pre-ASCT DS, rMTV, and other clinical risk factors. Methods This is a retrospective cohort study using clinical data of patients with rel/ref cHL identified from the lymphoma database and the ASCT database of the Princess Margaret Cancer Center, Toronto, Canada. Following criteria were required: (1) patients (≥18 yrs) with histologically confirmed rel/ref cHL between January 2014 to March 2019; (2) treatment with doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) or ABVD-equivalent regimens; (3) chemosensitive disease after salvage therapy; (4) restaging PET before ASCT clearance. Pre-ASCT PET scans were assessed using the Deauville 5-point scale, and rMTV was computed in the scans with DS 4 or 5 using the 41% maximum standardized uptake value threshold method. Receiver operating characteristics analysis was used to determine an optimal cutoff of rMTV 41% for event prediction. The primary endpoint was event-free survival (EFS), defined as time form ASCT to first documented disease progression, any new lymphoma therapy, death from any cause, or last follow-up. Results A total of 106 patients fulfilled the eligibility criteria and were included. Median age was 33.5 yrs (range, 18-70), and 72 (68%) were male. The cohort characteristics at time of progression were 55 (52%) patients with advanced stage, 28 (26%) with B symptoms, 39 (37%) with extranodal disease, and 39 (37%) with primary refractory disease, defined as achieving less than a complete response, disease progression during first-line therapy, or time to relapse (TTR) 3 months or less. All patients received gemcitabine, dexamethasone, cisplatin (GDP) regimen as salvage therapy. Based on the response to GDP therapy, 24 patients required second (N=20) or third (N=4) salvage regimens before ASCT (brentuximab vedotin [BV] alone or combination with bendamustine [N=16], pembrolizumab [N=9], and mini-BEAM [N=3]). 32 patients (30%) received planned pre- or post-ASCT involved field radiation for DS 4-5 lesions. 4 patients received post-ASCT BV consolidation. With a median follow-up of 26.2 months (interquartile range [IQR], 14.4-49.2), 2-year EFS and overall survival rates were 72.1% and 93.1%, respectively. Pre-ASCT DS was determined as 1-3 (N=63, 59%) and 4-5 (N=43, 41%). None of the patients with DS 5 had new lesions. Patients with pre-ASCT DS 1-3 had significantly better EFS than those with DS 4-5 (2-year; 80.8% vs 59.2%; P=0.002; Fig 1A). Median rMTV 41% of the 43 patients with DS 4-5 was 5.1 cm 3 (IQR, 2.0-24.7). The optimal cutoff of rMTV 41% was 4.4 cm 3. Patients with rMTV low (< 4.4cm 3, N=21) had better EFS than those with rMTV high (N=22; 2-year, 75.0% vs 45.4%; P=0.009), but had similar 2-year EFS when compared with patients with DS 1-3 (80.8%, P=0.280; Fig 1B) In the multivariable analysis for EFS, a combined assessment of pre-ASCT DS/rMTV 41% and rel/ref status at time of progression were independently associated with EFS (for DS 4-5/rMTV low, hazard ratio [HR] 1.58; for DS 4-5/rMTV high, HR 4.72; P<0.001: for primary refractory disease, HR 2.26; P=0.026). Based on these results, we stratified patients into 3 groups according to the post-ASCT outcomes: low-risk (relapsed disease [i.e., TTR > 3 months] and either pre-ASCT DS 1-3 or DS 4-5/rMTV low, N=54), intermediate-risk (refractory disease and either pre-ASCT DS 1-3 or DS 4-5/rMTV low, N=30), and high-risk (pre-ASCT DS 4-5/rMTV high irrespective of rel/ref status, N=22) groups. The risk model was significantly associated with EFS (intermediate vs low, HR 3.26, 95%CI 1.20-8.83, P=0.020; high vs low, HR 7.61, 95% CI 2.89-20.01, P<0.001; Fig 1C). Conclusion We propose a risk stratification model integrating a combination of DS and rMTV 41% on pre-ASCT PET and rel/ref status at time of progression, which allow discrimination of post-ASCT outcomes in patients with rel/ref cHL. The model may serve as a tool to facilitate risk-stratified treatment decisions. Figure 1 Figure 1. Disclosures Metser: POINT Biopharm Inc: Consultancy. Prica: Astra-Zeneca: Honoraria; Kite Gilead: Honoraria. Crump: Roche: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees; Epizyme: Research Funding; Kyte/Gilead: Membership on an entity's Board of Directors or advisory committees. Kuruvilla: Seattle Genetics: Honoraria; Amgen: Honoraria; Antengene: Honoraria; AbbVie: Honoraria; Janssen: Honoraria, Research Funding; BMS: Honoraria; Medison Ventures: Honoraria; TG Therapeutics: Honoraria; AstraZeneca: Honoraria, Research Funding; Gilead: Honoraria; Incyte: Honoraria; Karyopharm: Honoraria, Other: Data and Safety Monitoring Board; Roche: Honoraria, Research Funding; Novartis: Honoraria; Merck: Honoraria; Pfizer: Honoraria. Kridel: Gilead Sciences: Research Funding.

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