Refractoriness to immunochemotherapy in follicular lymphoma: Predictive factors and outcome.

Follicular lymphoma is characterized by a good response to immunochemotherapy (ICT). However, a small percentage of patients responds poorly to treatment and seems to have a worse outcome. This study attempted to identify the predictive factors and outcome of refractoriness to first-line ICT. All patients diagnosed with stage II to IV follicular lymphoma between 2002 and 2014 and treated with first-line ICT in 4 Spanish institutions were analyzed. Those with no response or progression or relapse within 6 months of first-line response assessment were considered ICT refractory. Three hundred forty-three patients were included (median age 58 years, 48% male), of whom 53 (15%) were ICT refractory. On multivariate analysis, high-risk follicular lymphoma international prognostic index (FLIPI) score, B symptoms, and elevated β2-microglobulin were correlated with refractoriness, and refractoriness, high-risk FLIPI score, and β2-microglobulin were correlated with overall survival (OS). Compared with ICT-sensitive, ICT-refractory patients had a higher incidence of histological transformation (5-year cumulative incidence 25% [14%-39%] vs. 6% [3%-10%], P < .001), a higher rate of refractoriness to second-line therapy (16/33 [48%] vs. 13/57 [23%], P = .01), and a lower OS (5-year OS probability 38% [95% CI 23%-53%] vs. 87% [82%-92%%], P < .001). In conclusion, refractoriness to ICT was seen in 15% of patients and was predicted by high-FLIPI scores, B symptoms, and elevated serum β2-micrglobulin. Immunochemotherapy-refractory patients had a worse prognosis than ICT-sensitive patients, and current treatment options for this subgroup are not satisfactory.