SAN FRANCISCO – A variety of emerging therapies are being incorporated into the management of follicular lymphoma, which is typically a long-term endeavor requiring strategic use of multiple treatments, Dr. Andrew D. Zelenetz said at the National Comprehensive Cancer Network (NCCN) 10th Annual Congress: Hematologic Malignancies.
“Follicular lymphoma is a disease of paradox. The reality is that overall survival is excellent, but patients are not going to be able to do that with one treatment; they are going to get a series of treatments,” he said. “Survival is the sum of your exposures to treatment, time on active therapy, time in remission, and actually time with relapse not needing treatment.”
Dr. Andrew D. Zelenetz
Risk stratification
Overall survival for patients with follicular lymphoma diagnosed today and treated with modern therapy is only slightly inferior to that for age-matched controls, noted Dr. Zelenetz of the department of medicine at Memorial Sloan-Kettering Cancer Center and professor of medicine at Cornell University, both in New York.
But patients who are faring poorly at 12 months (American Society of Hematology [ASH] 2014, Abstract 1664) or at 24 months (J Clin Oncol. 2015;33[23]:2516-22) into care have a much worse prognosis. “This shows the importance of identifying those patients with poor biology, and [the question of] whether we can identify them without treating them first and having them progress,” he said.
Hematologists have historically looked to the Follicular Lymphoma International Prognostic Index (FLIPI) to estimate outcome. “The FLIPI clearly works; it’s an important clinical tool. But the FLIPI high-risk patients are still identifying more than those very high-risk patients,” he said.
Therefore, a clinicogenomic risk model was developed that incorporates seven mutations having poor prognostic impact, the m7-FLIPI (Lancet Oncol. 2015;16[9]:1111-22). Adding the mutations split the previously defined high-risk patients into a group with a prognosis similar to that of low-risk patients and a small group with a very poor prognosis.
“This actually represents something very close to the 20% of patients that we think have bad biology,” Dr. Zelenetz noted. “There will be some additional data at ASH looking at this exact question, because the holy grail is to know when you diagnose someone if they are in that bad-risk group because those are the patients you want to do novel clinical trials on. If your overall survival is equivalent to the general population, it’s going to be hard to ever prove an overall survival advantage for an intervention in an unselected group of patients.”
Advanced-stage disease with low tumor bulk
For patients who have advanced-stage follicular lymphoma but with low tumor bulk, the NCCN endorses a modification of criteria developed by the Follicular Lymphoma Study Group (GELF) in deciding when to start treatment (J Clin Oncol. 1998;16[7]:2332-8).
Roughly a fifth of patients who are eligible for and managed with a watch-and-wait approach will not need chemotherapy or die of their disease in the next 10 years (Lancet. 2003;362[9383]:516-22). Furthermore, this strategy nets a median delay in the need for chemotherapy of 2.6 years.
Compared with observation, treatment with the anti-CD20 antibody rituximab (Rituxan) improves progression-free survival but not overall survival in this setting (ASH 2010, Abstract 6). “Though in selected patients, rituximab may be appropriate as initial treatment for the observable patient, I would argue for the observable patient with no survival disadvantage, the standard of care remains observation,” Dr. Zelenetz said.
Advanced-stage disease requiring treatment
A meta-analysis has shown a clear survival benefit from adding rituximab to chemotherapy (R-chemo) in patients with advanced follicular lymphoma who need treatment (J Natl Cancer Inst. 2007;99[9]:706-14). “Based on the results, it is the standard of care to add rituximab to a chemotherapy backbone, but the optimum R-chemo actually remains undefined and would be customized to the individual clinical situation,” he commented.
A variety of emerging agents are being tested in this setting. Among the subset of patients with untreated follicular lymphoma in a single-center trial, the combination of rituximab with the immunomodulator lenalidomide (Revlimid) yielded an overall response rate of 98% and a complete response rate of 87%, as well as excellent progression-free and overall survival (Lancet Oncol. 2014;15[12]:1311-8). The main grade 3 or 4 toxicity was neutropenia, seen in 35% of all patients studied. Efficacy results were much the same in a multicenter trial (International Conference on Malignant Lymphoma [ICML] 2013, Abstract 63).
This combination is now being tested as front-line therapy for follicular lymphoma in the RELEVANCE (Rituximab and Lenalidomide Versus Any Chemotherapy) phase III trial. “The trial is now done, but we don’t have results, and we won’t have results until 2019, so don’t hold your breath,” Dr. Zelenetz commented. “That’s because this was an unselected trial; we took all patients, all comers. And if you don’t try to identify bad-risk patients, you actually have to do very large trials, and the effect size is relatively small.”