Lenalidomide and Rituximab (ReRi) As Front Line Chemo-Free Therapy of Elderly Frail Patients with Diffuse Large B-Cells Lymphoma. a Phase II Study of the Fondazione Italiana Linfomi (FIL)

INTRODUCTION

Treatment of Diffuse Large B cell lymphoma (DLBCL) in the elderly population is challenging as many patients (pts) are not eligible to receive standard curative therapy, due to comorbid conditions and to a higher susceptibility to the side effects of standard anthracycline containing regimens.

Among currently available active drugs, Lenalidomide has been used in the setting of relapsed/refractory DLBCL both as monotherapy and in combination with rituximab, showing a good activity and an acceptable safety profile.

We started a prospective, multicenter, single arm, phase II trial to demonstrate activity and safety of a chemofree combination of lenalidomide + rituximab in elderly (≥ 70 years) untreated pts with DLBCL who were prospectively defined as frail according to a simplified comprehensive geriatric assessment (sCGA) (Tucci A. et al., Leuk Lymphoma. 2015 Apr).

PATIENTS AND METHODS

Pts were eligible if they were previously untreated DLBCL patients, older than 69 years and defined as frail according to sCGA.

The treatment consisted of a 28-day cycle (R2) combining oral Lenalidomide (20 mg on days 1 to 21) and i.v. Rituximab (375 mg/m2 on day 1); a maximum number of 6 cycles was planned; response assessment was performed after cycles 4 and 6. At the end of the 6^thcycle, patients with partial or complete response continued treatment with Lenalidomide 10mg/d on days 1 to 21 every 28 days, until cycle 12or unacceptable toxicity. Final response was evaluated within 28 days after the last study drug administration. Primary study endpoint was Overall Response Rate (ORR) after 6 R2 cycles, defined according to Lugano 2014 criteria; co-primary endpoint was the rate of extra-hematological toxicity with CTCAE grade >2 and of death for any cause during the treatment

The study was planned according to a two stage Simon design. A total of 68 pts had to be enrolled to complete the study: 23 pts were required in the first stage. Second stage could be activated withat least 12 patients showing a Partial or Complete Response (PR/CR) in stage I. According to the Ray and Rai method less than 15/23 adverse events were also required for the safety coprimary endpoint.

RESULTS

From January 2017 to December 2017, 24 newly diagnosed frail DLBCL were enrolled in 8 Italian centers. Median age was 83 years (range 76-89) and 79% had stage III/IV; 42% of pts were male, and 44%, had elevated LDH, 45% had High risk IPI (i.e. 3-5 risk factors). All pts were confirmed eligible and started R2 treatment. The planned 6 courses of R2 were completed in 13 pts (54%). The median number of R2 cycles was 6 (1-6). Treatment was discontinued in 11 pts for the following reasons: lymphoma progression in 4 cases, second malignancy in 2, extra-hematological toxicity in 3 cases, consent withdrawal and investigator choice after 4 cycles in CR in 1 case each.

Response assessment after 6 R2 cycles showed12 responding pts (ORR 50%), 4 CR and 8 PR, that was higher than by the inferior limit required by the Simon optimal design.

Regarding safety coprimary endpoint 13 events were reported including 9 extra-hematological toxicities > grade 2 CTCAE (3 cardio-vascular and 6 respiratory events, all resolved) and 4 deaths (2 patients due visceral arterial ischemia and 2 due infectious disease). The rate of adverse events was lower than the superior limit of 15 allowed the first stage of the study.Since August 2018 the enrollment in the stage II of the trial has been resumed and it is currently ongoing with 45 patients enrolled.

CONCLUSIONS

The ReRi is the first study to evaluate activity and safety of a chemo-free therapy in patients with diffuse large B-Cell Lymphoma who are not eligible for conventional cytotoxic therapy. The results of the planned interim analysis of our study confirmed the initial efficacy and safety hypotheses of R2 combination in untreated elderly pts with DLBCL. Treatment of elderly frail DLBCL pts with R2 holds promise in terms of both ORR and safety.