Background: Because most patients with advanced non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukemia (CLL) respond to radioimmunotherapy (RIT), the study was designed to evaluate the relationship between response and survival in patients treated with radiolabeled Lym-1.
Methods: Fifty-seven patients with NHL (52) or CLL (5) were treated with radiolabeled Lym-1 antibody between 1985 and 1994. Influence of response to treatment on survival was examined directly and was also adjusted for other factors previously found to be significant predictors of survival. A multivariate model that was based on baseline Karnofsky performance status (KPS) and serum lactic dehydrogenase (LDH) predicted response and survival and was used to define risk groups. Proportional-hazards, Kaplan-Meier, and Landmark models were used to evaluate parameters for their ability to predict outcome.
Results: By using a proportional-hazards model with response as a time-dependent variable, overall response (P < 0.001) and complete response (P = 0.006) were predictive of increased survival in univariate analyses. Overall response continued to be significant (P = 0.02) in multivariate analyses, even when risk groups that also predicted survival were included. Median survival of responders was 84 weeks, whereas that of nonresponders was 22 weeks when the Landmark method, based on response status at 16 weeks from start of therapy, was used to generate survival curves.
Conclusions: Response to treatment with radiolabeled Lym-1 was associated with increased survival, even when adjusted for baseline clinical parameters that also predicted for survival. The results provide the first unbiased evidence for survival effects of RIT in patients.