ISHL10 Abstract T020

Strong predictive value of PET based metabolic tumor volume on survival after autologous HCT for Hodgkin Lymphoma

Background: High-dose chemotherapy with autologous hematopoietic cell transplant (AHCT) is a standard treatment for relapsed/refractory Hodgkin lymphoma patients (R/R HL); however, 40-50% fail therapy. Metabolic FDG-PET is a powerful tool to predict treatment responses in HL. The value of more precise quantitative measurements combining volume with the metabolic activity in patients having residual HL before AHCT is unknown. Aim: To determine the predictive value of total metabolic volume (TMV) and total lesion glycolysis (TLG) in R/R HL patients undergoing AHCT. Methods: We analyzed 96 consecutive patients with R/R HL undergoing AHCT in 2004-2014. All had PET/CT ≤4 weeks before AHCT. Two independent radiologists assessed PET images using semi-quantitative Deauville (D) 5-point scale and selected all hypermetabolic sites to determine regions of interests. Analytic software was used to calculate TMV and TLG. Results: Median age at transplant was 33.1 years (range 18.0-71.3); 51% of patients were males. Patients were limited stage (60%) or advanced, commonly with extranodal (32%) and bone marrow (11%) disease. Nodular sclerosis (86%) was most common. Most patients (69%) relapsed in <1 year or were refractory to front-line therapy. PET negativity (neg) was achieved in 61 patients (63.5%), whereas 35 remained PETpos, with D1-2 (n=61), D3 (n=11), D4 (n=19), and D5 (n=5). Median TMV was 8.0 cm3 (range 1.3-102.1), median TLG was 23.7 (range 4.0-813.1), and median SUVmax was 5.2 (range 2.7-23.2). Two-year PFS in PETneg patients (63%; 95% CI 50-74%) was significantly better than in PETpos patients (35%; 19-51%; p=0.014). In Cox regression analysis, D4-5 was associated with a 3.7-fold increased risk of failure compared to D1-3 (HR 3.73; 95% CI 1.92-7.28; p<0.01). PETpos patients with high TMV (>8 cm3) had significantly lower 2-year PFS than those with low TMV (11% vs 53%; p=0.03). High TLG (>24) identified patients with poor 2-year PFS (12% vs 57%; p=0.04). Conclusion: Patients with R/R HL and low MTV and TLG prior to AHCT have similar outcomes to PETneg patients. Quantitative pretransplant PET may identify subgroups of very poor AHCT responders in whom alternative therapies should be considered. Acknowledgement: supported by the Fulbright commission grant.