Idelalisib Shows Durable Response in FL
Dr. Salles: In follicular lymphoma, we have seen a couple of interesting studies that are bringing new insight into the prognosis of these patients. We carried out a study with R-CHOP in France, showing that combining lenalidomide with R-CHOP actually increased the response rate compared with historical data of R-CHOP. We presented a study evaluating a different form of consolidation after R-CHOP using maintenance rituximab; this was the 6-year follow-up of the PRIMA trial [which confirmed benefit of 2-year rituximab maintenance]. Also presented was a study evaluating radioimmunotherapy -- unfortunately with disappointing results. We see patients treated without chemotherapy (with rituximab only), and a rituximab maintenance study was presented by our colleagues in Switzerland.
There have been no tremendous breakthroughs in this field during this meeting, but we continue to understand more about the biology of this disease. What is more interesting are a couple of small molecules -- the kinase inhibitors -- that have confirmed activity in follicular lymphoma. During this meeting, a study was presented in which120 patients who were refractory to classic agents, such as rituximab and alkylating agents, were treated with a PI-3 kinase delta inhibitor called idelalisib, and it clearly showed that the response rate was in the range of 50% for patients who had failed any kind of therapy and were refractory to classic therapy. It is quite encouraging that for these patients who do not have many options, there is a novel molecule that can maintain response for many months. The response duration is about 12 months. It is quite encouraging, and that is probably one of the most exciting results presented during this meeting.
Dr. Cheson: We have moved these molecules upfront in Alliance group (formerly the Cancer and Leukemia Group B) studies in follicular, and now have a study using R(rituximab and lenalidomide) plus ibrutinib upfront. Do you foresee a time when chemotherapy will be gone in patients with follicular lymphoma?
Dr. Salles: It is too early to say. We are also running a study with European and US and North American centers called RELEVANCE, in which we compare R-CHOP to R already. That randomized study is running very well, with more than 500 patients.
Dr. Cheson: Is it closed to the United States?
Dr. Salles: No, it is still open. More than 500 patients have been accrued for this randomized study, so it will provide information. I am quite convinced that we will see major changes in the way we manage these patients. Whether it will be agents that increase the activity of rituximab, such as the kinase inhibitors -- either PI-3 kinase only or also Bruton's tyrosine kinase (BTK) inhibitors -- remains to be seen and evaluated, but clearly we are moving away from chemotherapy for these patients. Whether it will be for all patients or for selected groups, we still have to define that and evaluate the long-term results.
Dr. Cheson: One of the biggest problems that we have to deal with is the cost of these agents.
Dr. Salles: Definitely.
Dr. Cheson: CHOP costs about $39 and rituximab and idelalisib and ibrutinib are going to be $100,000 [a year], so we really have to show some benefit with these agents to make them worth the incredible expense.