Prognostic Value of Circulating Bcl-2/Igh Levels before and after Treatment in 415 Patients with Advanced Follicular Lymphoma Receiving First-Line Immuno-Chemotherapy in 2 Prospective StiL Trials - the Effect of Rituximab Maintenance
Authors: Kobbe Guido , Pechtel Sabrina , Zohren Fabian , Barth Jürgen , Burchardt Alexander Christoph , Buske Christian , Dienst Ariane , Germing Ulrich , Greil Richard , Hertenstein Bernd , Kauff Frank , Koenigsmann Michael , Lerchenmüller Christian , Schroeder Thomas Michael , Haas Rainer , Rummel Mathias J 
Published: October 2019

Abstract
Introduction. The prognosis of patients with follicular lymphoma (FL) has improved during recent years following the introduction of immuno-chemotherapy and Rituximab maintenance. Nevertheless, some patients still relapse early and have a poor prognosis. Several prognostic scoring systems have been developed using clinical, laboratory as well as molecular data, while the early identification of high-risk patients remains a challenge. In this context, the relevance of circulating bcl2/IgH levels for patient stratification is not clear. We could show that high circulating bcl2/IgH levels in the peripheral blood (PB) before therapy were an independent adverse prognostic factor for progression free survival (PFS) in patients receiving R-CHOP or Bendamustine-Rituximab (B-R) in the NHL1 study of the German StiL group (Zohren et al, Blood 2015).
Methods. Using a sensitive quantitative PCR method as previously described (Zohren et al, Blood 2015), a total of 2,491 circulating bcl-2/IgH level analyses were performed on PB samples before (n=415) and after (n=305) 6 cycles first-line immuno-chemotherapy and during follow-up (n=1,771). Results of these molecular studies were correlated with clinical outcome. We first present a 10-year update of the 107 bcl2/IgHpositive patients from the StiL-NHL1-trial. Secondly, we report the results from the StiL-NHL7-trial including bcl2/IgH analyses of 308 bcl2/IgHpositive patients who received B-R and Rituximab maintenance.
Results. With a median follow-up of 10 years in the 107 bcl2/IgHpositive patients from the StiL-NHL1-trial, high PB bcl-2/IgH levels (bcl-2/IgH to reference gene (tPA) ratio >1) before treatment as compared to low (ratio <1) levels remained a major independent prognostic factor for PFS (median 22 vs 71 months, HR 2.27, 95% CI 1.37-3.75; p=0.001). We also confirm that patients who were still bcl-2/IgHpositive after six cycles of immuno-chemotherapy had significantly inferior PFS (13 vs 79 months, Hazard Ratio (HR) 2.97, 95% CI 1.53-5.78; p=0.001) and overall survival (OS, 128 months vs not reached , HR 3.90, 95% CI 1.39-11.00; p=0.010).
In contrast, among the 308 bcl-2/IgHpositive patients of the StiL-NHL7-trial, who all received B-R and Rituximab maintenance, PB bcl-2/IgH levels (ratio >1 vs <1) before therapy were no longer prognostic for PFS (99 months vs not reached, HR 1.06, 95% CI 0.66 - 1.69; p=0.814) or OS. On the other hand, being bcl-2/IgHpositive after 6x B-R remained a poor prognostic factor for PFS (43 months vs not reached, HR 2.44, 95% CI 1.18-5.04; p=0.016 ) and OS (72 months vs not reached, HR 4.03, 95% CI 1.82-8.96; p=0.001) despite Rituximab maintenance.
When comparing StiL-NHL1 and StiL-NHL7 patients with respect to bcl-2/IgH levels and the effect of Rituximab maintenance, we found that Rituximab maintenance led to a significantly better PFS. In patients with low (ratio <1) bcl-2/IgH levels before therapy the hazard ratio of 1.7 was modest (71 months vs not reached, HR 1.70, 95% CI 1.16-2.50; p=0.006) in comparison to 3.46 as observed in patients with high (ratio >1) bcl-2/IgH levels (22 vs 99 months, HR 3.46, 95% CI 1.93-6.20; p<0.000). These findings suggest that patients with high bcl-2/IgH levels before therapy have a greater benefit from Rituximab maintenance therapy. There was no difference with regard to OS between StiL-NHL1 and StiL-NHL7 patients who were still bcl-2/IgHpositive after 6 cycles of immuno-chemotherapy implying that these patients may not benefit from Rituximab maintenance.
Conclusion. High circulating bcl-2/IgH levels in the PB before first line therapy identify a subgroup of patients with advanced FL who have significantly shorter PFS after standard immuno-chemotherapy. These patients greatly benefit from the addition of Rituximab maintenance, because pre-treatment bcl-2/IgH levels lose their predictive value with Rituximab maintenance therapy. On the other hand, patients who remain bcl-2/IgHpositive after standard immuno-chemotherapy have short PFS and OS despite treatment with Rituximab maintenance and therefore are candidates for experimental treatment approaches.

Disclosures
Kobbe: Amgen: Honoraria, Research Funding; Roche: Honoraria, Research Funding; Celgene: Honoraria, Other: Travel Support, Research Funding. Zohren:Pfizer Inc.: Employment. Buske:Roche: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Bayer: Research Funding. Germing:Celgene: Honoraria, Research Funding; Janssen: Honoraria; Novartis: Honoraria, Research Funding. Greil:Sandoz: Honoraria, Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; MSD: Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astra Zeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Other: TRAVEL, ACCOMMODATIONS, EXPENSES, Research Funding; Janssen: Other: TRAVEL, ACCOMMODATIONS, EXPENSES. Schroeder:Celgene: Consultancy, Honoraria, Research Funding. Rummel:Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria; Astellas: Honoraria; Eisai: Honoraria; Mundipharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Symbio: Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees.