Intratumoral Immune Infiltration in Follicular Lymphoma: Novel Insights into Early Relapse and Survival

TRANSCRIPT

This JCO Podcast provides observations and commentary on the JCO article “Progression of Disease Within 24 Months (POD24) in Follicular Lymphoma Is Associated With Reduced Intratumoral Immune-Infiltration” by Dr. Tobin and colleagues. My name is Dr. Carla Casulo, and I am Associate Professor of Medicine, Hematology and Oncology at the Wilmot Cancer Institute of the University of Rochester in Rochester, NY, USA. My oncologic specialty is Lymphoma.

Follicular lymphoma is the most frequently occurring indolent non-Hodgkin lymphoma and has a long natural history, with median overall survival nearing two decades. Patients with follicular lymphoma may experience a variable clinical course, with periods of long remission punctuated by episodes of recurrent lymphoma requiring re-treatment. Among all patients, up to one third will have early disease recurrence, defined as occurring within 24 months of diagnosis. Please note that progression of disease within 24 months will be referred to as POD24 for the remainder of this podcast. These patients have inferior survival, ranging from 25-50% at 5 years. Consequently, POD24 has become a robust and well accepted indicator of identifying high-risk patients.

The implications of POD24 were first identified through our analysis of the National Lymphocare Study, which sought to test the hypothesis that time to disease progression had an impact on subsequent patient outcomes. 588 patients treated with RCHOP were included. Patients with POD24 were defined as early progressors, and those without relapse or death within 24 months were defined as the reference group. Patients with POD24 had OS of 50% at 5 years compared to 90% in the reference group. These findings have subsequently been independently validated by numerous investigators worldwide, corroborating the adverse prognostic impact of an early disease related event in follicular lymphoma. The largest of these validation studies pooled individual patient data from 5,453 patients on 13 Clinical Trials using the Follicular Lymphoma Analysis of Surrogacy Hypothesis (FLASH) Investigation.

In the FLASH analysis, we identified that male gender, poor performance status, high follicular lymphoma international Prognostic index (FLIPI) score, and elevated baseline beta 2 microglobulin B2M as predictors of early death and progression. Moreover, it confirmed POD24 as an early clinical endpoint of poor survival in follicular lymphoma that should be utilized to identify patients for prospective clinical trials.

The current status of biomarkers in follicular lymphoma has emerged from a wealth of clinical and laboratory-based factors to classify risk, towards a biologic based, molecular approach merging clinical factors with our current understanding of the follicular lymphoma genomic landscape.

There are numerous well-established and emerging clinical prognostic indices used at the time of diagnosis in follicular lymphoma that can help discriminate general outcome. These include the FLIPI and FLIPI -2. To an extent, these prognostic markers can identify subsets of patients with an expected POD24 with a sensitivity between 60-78%, and a specificity between 56-58%. However, in an attempt to use a precision approach, investigators from the German Low-Grade Lymphoma Study Group harmonized clinical and pathologic data to create a clinico-genetic risk model aimed at more accurate risk prognostication in patients receiving front line chemoimmunotherapy. They performed deep DNA sequencing from formalin fixed pre-treatment biopsies to analyze the mutational status of genes in 151 patients with follicular lymphoma tumor samples. The resulting prognostic tool, called the m7-FLIPI, distilled down 74 genes into 7 genes with non-silent mutations occurring at a variant allele frequency of 10% or greater, and combined these with high risk FLIPI status and ECOG performance status. These included genes that increased risk of progression, including EP300, FOX01, CREBBP, CARD11, and those that decreased risk of progression, including EZH2, ARID1A, and MEF2B. The cumulative risk score was calculated by combining relative weights of these genes in a multivariate analysis predicting failure-free survival. This m7-FLIPI score was tested to identify POD24 but only captured about 50% of patients as high risk. A later model included only 3 genes, including EP300, FOX01 and EZH2, performance status and FLIPI score. Defined as the POD24-PI, this was more sensitive at identifying POD24 patients but did not outperform other metrics due to lower specificity.

Biologic classification of POD24 patients remains an ongoing international research priority to seek actionable targets that might change the natural history of follicular lymphoma and improve survival of patients more likely to have morbidity and death from their disease. Several years ...