Risk Factors Predicting Outcomes for Primary Refractory Hodgkin Lymphoma Patients Treated with Salvage Chemotherapy and Autologous Stem Cell Transplantation

Introduction:

Limited information exists on the best treatment strategy for Primary Refractory (ref) Hodgkin Lymphoma (HL). For the past 20 years, we have treated patients (pts) on sequential ifosfamide, carboplatin, etoposide (ICE)-based clinical trials with the intent to undergo high dose therapy (HDT) and autologous stem cell transplantation (ASCT). As previously reported (Moskowitz, Blood 2010) and confirmed by other centers, a negative PET scan prior to ASCT predicts for marked improvement in outcome in pts with relapsed HL. We aimed to identify risk factors that predict PET response to salvage chemotherapy in ref HL and evaluate outcomes following HDT and ASCT in this patient population.

Methods:

From 10/1/94 to 7/10/15, 192 ref HL pts were treated on sequential trials at MSKCC. Demographic and clinical factors were collected. Event free survival (EFS) and overall survival (OS) were calculated from the date of histologic confirmation of ref disease, estimated by Kaplan-Meier method, and compared by the log rank test. Events included relapse or death. Cox regression was used for the multivariate regression model. Patients were selected to receive a radiation-based conditioning regimen if all sites of nodal disease could be encompassed into a radiation field.

Results:

Patient characteristics included a median age of 31 (range 14-79) with 54% female. B symptoms, extranodal disease, stage IV disease, and disease bulk > 5cm were present in 31%, 48%, 44%, 40%, respectively.

In the intent-to-treat (ITT) population, 41% had a positive post-salvage PET scan. As analyzed by ITT, median EFS was 8.9 years with a median OS of 10.4 years. On multivariate analysis, the presence of B symptoms and bulk >5cm at documentation of ref disease predicted for a reduced chance of achieving a negative PET after salvage therapy, with an odds ratio (OR) of 2.03 for B symptoms and 2.13 for bulk >5cm.  

For the 169 (88%) transplanted patients, 68% had a negative pre-ASCT PET. Radiation based conditioning was used for 70% of the pts. Median EFS was 12.8 yrs and median OS was not reached with a median follow-up of 3.6 yrs (range, 0.55 to 18.04 yrs) for the surviving patients (Figure 1). On multivariate analysis, both stage (IV vs I-III) and persistent PET abnormality pre- ASCT correlated with a shorter EFS. A risk stratification model was created and pts could be divided into 4 groups. 1) stage I-III disease and a negative PET pre-ASCT, the median EFS was not reached;  2) stage I-III disease and a positive PET pre-ASCT scan-the OR of an event was 4.04 (95% CI 1.93 to 8.45) with the median EFS not reached, 3) Stage IV disease and a negative PET pre-ASCT, the OR was 3.78 (95% CI 1.64 - 8.74) with a median EFS of 8.9 yrs, 4) Stage IV disease and a positive PET pre-ASCT, the OR was 8.22 (95% CI 3.99 to 16.94) with a median EFS of 0.9 yrs (Figure 2).

Conclusions:

B symptoms and bulk >5cm predicted for residual PET avidity after salvage therapy in ref HL. Persistent PET abnormality pre-ASCT and stage were risk factors for earlier relapse and death and can be used to prognosticate survival. Further studies are needed to determine optimal therapy for patients with multiple risk factors.

Figure 1: EFS for the Transplanted Patients

Figure 2: EFS for the transplanted pts based on the presence of risk factors (PET avidity pre-HSCT and Stage)