PET-Directed therapy for early-stage diffuse large B-cell lymphoma
Prof Daniel Persky - University of Arizona Cancer Center, Tucson, USA
S1001 was an NCTN study where there were three cooperative groups, SWOG, Alliance and ECOG-ACRIN. This was a study in limited stage diffuse large B-cell lymphoma. Diffuse large B-cell lymphoma is the most common non-Hodgkin’s lymphoma diagnosed in the United States and it’s about 30-40% of it. It presents at limited stage as opposed to advanced stage about 30% of the time. The typical standard treatment for limited stage diffuse large B-cell lymphoma that is recommended by NCCN guidelines is three cycles of R-CHOP followed by involved-field radiation therapy. This study used a PET scan after three cycles of R-CHOP to direct further therapy. So patients who were PET scan negative after three cycles of R-CHOP only received one more cycle of R-CHOP while patients who were still PET scan positive received radiation therapy and the radioimmunotherapy agent called ibritumomab tiuxetan, the brand name is Zevalin.
It turned out that almost 90% of the patients were PET negative and only received one more cycle of R-CHOP. They did extremely well with overall only five relapses in the whole group out of 159 patients. The patients who received radiation followed by ibritumomab tiuxetan actually also did very well. So the group in general did very well with a five year progression free survival rate of 87% and a five year overall survival rate of 90%.
This tells us that in the case of the absolute majority of patients four cycles of R-CHOP is enough to get an excellent outcome in limited stage diffuse large B-cell lymphoma and that radiation could potentially be used only in a small proportion of patients where it gives reasonable results. In this case it was given together with ibritumomab tiuxetan which is not FDA approved in this indication. So the radiation would probably be the most important part in this case.
There was a lively discussion in general during the session as well. Together with a trial that was reported at the 2018 ASH session in younger, more favourable patients it could produce a change in the treatment paradigm to R-CHOP times four. Because this trial enrolled older patients who had more risk factors for relapse it’s more relevant to that group.