A Phase II Lysa Study of Obinutuzumab Combined with Lenalidomide for Advanced Untretated Follicular B-Cell Lymphoma in Need of Systemic Therapy

BACKGROUND: Obinutuzumab is a type II anti-CD20 monoclonal antibody that induces antibody-dependent cellular cytotoxicity, antibody-dependent cell-mediated phagocytosis, and direct cell death better than rituximab. Given promising results with lenalidomide and rituximab (R²), we assessed the safety and efficacy of lenalidomide combined with obinutuzumab (GALEN)in a large phase Ib/II study in separate patient populations (NCT01582776). In relapsed/refractory follicular B-cell lymphoma (FL), we found the GALEN regimen might be even more efficient than R² while retaining a similarly manageable safety profile. Here, we report the results for the phase II part assessing efficacy and safety of GALEN in advanced untreated FL patients (pts) in need of systemic therapy.

METHODS: Eligible pts had grade 1-3a FL and required systemic therapy per GELF criteria. Induction treatment consisted of lenalidomide (LEN) 20 mg on day (d) 1-21 of a 28-d cycle for the first cycle and on d2-22 of a 28-d cycle from cycles 2 to 6. Obinutuzumab (GA) 1000 mg was given IV on d8, 15, and 22 of cycle 1 and d1 of cycles 2 to 6. Responding pts then received maintenance with LEN at 10 mg on d2-22 every 28d for 12 cycles and GA 1000 mg every 8 wk for 12 cycles until progression or unacceptable toxicity. The primary study endpoint was complete response (CR)/CR unconfirmed (CRu) rate by investigator assessment at the end of induction according to 1999 IWG criteria. Secondary endpoints included overall response rate (ORR) and CR according to IWG 2007, progression-free survival (PFS), duration of response (DOR), overall survival (OS) and safety.

RESULTS: 100 pts with WHO FL gr 1-2 (91%) and 3a (9%) according to local pathology reports were enrolled between October 2015 and February 2017. Median age was 60.5 years (range, 32-89), 43% had FLIPI score ≥3, 89% stage III/IV, and 31% bulky disease (>7 cm). All 100 pts were evaluable for safety and efficacy. At a median follow-up of 2.1 years, 96 pts (96%) completed induction, 41 completed maintenance, 36 were ongoing in maintenance, and 23 prematurely discontinued treatment due to disease progression (n=12, including 2 during induction), toxicity (n=6, including 2 during induction), concurrent illness (n=3), consent withdrawal (n=1), or other cause (n=1). At the end of induction, 61 pts had regression by more than 75% of sum of the product of the greatest diameters (SPD) of target lesions and 83/97 (85.6%) with PET assessment were PET negative (Juweid criteria) including 79/93 (84.9%) with a 5PS (Deauville scale) score of 1-3. Sixteen pts with SPD regression >75% and 25 pts with negative PET were conservatively downgraded to PR due to missing bone marrow evaluation, leading to 47% CR/CRu rate and 59% CR rate at the end of induction per IWG1999 and 2007 criteria, respectively. Response rates at the end of induction, PFS, DOR and OS are summarized in the Table and Figure.

Most common AEs (>10% of pts) during induction (% all gr/% gr 3/4) were neutropenia (43/42), asthenia (35/2), constipation (32/0), infusion-related reactions (23/3), diarrhea (21/2), rash (21/2), cough (18/0), nausea (13/0), pruritus (12/1), weight decrease (12/0), bronchitis (11/0), muscle spasms (11/1), and pyrexia (11/0). Febrile neutropenia occurred in 2% of pts. Eight second primary malignancies were reported in 8 pts, including 2 deemed unrelated since they were misdiagnosed at baseline. Three (3%) pts had died, 1 each due to lymphoma, toxicity of additional treatment, and intestinal adenocarcinoma.

CONCLUSION: The immunomodulatory GALEN regimen is highly effective with no unexpected toxicity in advanced, untreated FL pts in need of systemic therapy and has the potential to challenge immunochemotherapy in this setting.

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