Preliminary results from phase I studies of CD20 × CD3 bispecific antibodies in R/R B-cell non-Hodgkin lymphoma

For patients with B-cell non-Hodgkin lymphoma (NHL) who relapse or become refractory to chemotherapy and anti-CD20 immunotherapy, there are limited treatment options and these often result in poor outcomes. Bispecific antibodies, which bind to two different epitopes, are currently undergoing phase I trials in such patients.

During the 62nd American Society of Hematology (ASH) Annual Meeting and Exposition, three abstracts were presented from ongoing phase I studies of bispecific antibodies in relapsed/refractory (R/R) B-cell NHL. Rajat Bannerji covered the updated preliminary safety and efficacy analyses of odronextamab (REGN1979; NCT02290951).¹ Martin Hutchings presented early data on epcoritamab (NCT03625037),² and from a subset of patients treated with step-up dosing of glofitamab (CD20-TCB; NCT03075696).³ These data on glofitamab supplement those from the wider cohort of patients included the trial, which were presented at the 25th European Hematology Association (EHA) Annual Congress.⁴

These bispecific antibodies bind to both CD3 on T cells and CD20 on malignant B cells, triggering T-cell-mediated cytotoxicity independent of T-cell receptor recognition. This article summarizes the data presented at the ASH meeting for these three novel drugs.

Study designs

Odronextamab¹

Primary objectives were the evaluation of safety, tolerability, and dose-limiting toxicities. Secondary objectives were to assess antitumor activity (by Lugano criteria), pharmacokinetics, and to determine the recommended phase II dosing regimen (RP2DR). The dose regimen consisted of dexamethasone premedication and an initial split dose of odronextamab at Weeks 1 and 2, followed by a single intravenous (IV) infusion weekly for 12 weeks, then every 2 weeks until disease progression or discontinuation.

At data cut-off on September 18, 2020, 136 patients with R/R CD20+ B-cell NHL (including diffuse large B-cell lymphoma [DLBCL], follicular lymphoma [FL], mantle cell lymphoma [MCL], and marginal zone lymphoma [MZL]) who had previously received anti-CD20 therapy were enrolled. Of these, 24 patients (17.6%) remain in the study, 99 (72.8%) have discontinued, and 13 (9.6%) have completed. Chimeric antigen receptor (CAR) T-cell therapy had previously been given to 35 patients (25.7%).

Epcoritamab²

The primary objectives were maximum tolerated dose (MTD) and RP2DR. Safety, tolerability, and antitumor activity (Lugano criteria) were assessed as secondary objectives. In the dose escalation part of the study, patients received subcutaneous injection of a flat dose of epcoritamab (0.0128–60 mg) in 28-day cycles until disease progression or unacceptable toxicity.

At the data cut-off on October 10, 2020, 68 adult patients with R/R CD20+ B-cell NHL who had previously had anti-CD20 therapy were enrolled, including patients with DLBCL, FL, MCL, MZL, and small lymphocytic lymphoma. Six patients (9%) had received prior CAR T-cell therapy. Treatment in the study is ongoing for 17 (25%) patients, and 51 (75%) patients have discontinued.

Glofitamab^3,4

Primary objectives included safety, tolerability, pharmacokinetics, antitumor efficacy (Lugano criteria), and determination of MTD and RP2DR. Patients received 1,000 mg obinutuzumab pretreatment 1 week prior to the first cycle to mitigate cytokine release syndrome (CRS). In the step-up dosing subset, patients were administered IV glofitamab on Days 1 (2.5 mg) and 8 (10 mg) of Cycle 1. Patients subsequently received the target dose (either 16 or 30 mg) on Day 1 of Cycle 2 and then every 3 weeks for up to 12 cycles. The wider study included patients on a fixed dose of ≥ 0.6 mg glofitamab every 2 or 3 weeks for a maximum of 12 cycles.

At the clinical cut-off date of August 3, 2020, 52 adult patients with R/R CD20+ B-cell NHL who had previously received ≥ 1 line of therapy were enrolled in the step-up dosing subset. Of these, 28 patients had aggressive NHL (aNHL; including DLBCL, FL Grade 3B, and MCL) and 24 patients had indolent NHL (iNHL; FL Grade 1–3A). Three patients had received prior CAR T-cell therapy. In the wider study, 190 patients were enrolled as of April 17, 2020, of which 156 received ≥ 0.6 mg glofitamab. Of these patients, 130 had aNHL and 24 had iNHL.

Efficacy

Odronextamab¹

Overall response rate (ORR) and rate of complete response (CR) are shown in Table 1.

Table 1. Efficacy of odronextamab by diagnosis and prior CAR T-cell therapy¹

Epcoritamab²

Table 2 shows the rates of overall response, complete response (CR), and partial response (PR). All patients with DLBCL who received ≥ 12 mg and achieved CR remained in remission.

Table 2. Efficacy of epcoritamab by diagnosis²

Of the four patients who had previously received CAR T-cell therapy and for whom data were available, all had DLBCL and all responded to epcoritamab (two with CR and two with PR).

Glofitamab^3,4

Efficacy results for patients with available data who received fixed and step-up dosing schedules of glofitamab are given in Table 3.

Table 3. Efficacy of glofitamab for all patients and stratified by diagnosis^3,4

Safety

Treatment-emergent adverse advents (TEAEs) from the three studies are summarized in Table 4.

In the odronextamab study, the most frequent TEAEs classified as Grade 3 or above (occurring in 10% of patients or more) were anemia (24.3%), lymphopenia (20.6%), neutropenia (18.4%), and hypophosphatemia (18.4%).¹ Of the 46 patients in the epcoritamab study who experienced serious adverse events, the most common were pyrexia (n = 21), disease progression (n = 11), and pneumonia (n = 8).² With stepped-up dosing of glofitamab, the safety profile was consistent with that seen in the wider patient cohort,⁴ and the most frequent adverse events were CRS (61.0%), neutropenia (38.5%), pyrexia, and thrombocytopenia,³

Table 4. Summary of odronextamab, epcoritamab, and glofitamab TEAEs^1–4

Conclusion

Limited treatments are currently available for patients with R/R B-cell NHL, who have often undergone many lines of prior therapy and have aggressive disease histologies. Novel bispecific antibodies, which crosslink CD20 and CD3, could therefore offer potential new options for these patients. The authors of the phase I studies of odronextamab, epcoritamab, and glofitamab summarized here concluded that safety profiles were acceptable and high clinical response rates were demonstrated in heavily pretreated patients, including those who had received prior CAR T-cell treatment. Previously reported phase I/Ib trial data for mosunetuzumab has similarly shown tolerable and efficacious results for R/R NHL patients, including those exposed to prior CAR T-cell therapy. These bispecific antibodies are also off-the-shelf, offering faster availability than custom-manufactured CAR T-cell therapies. Furthermore, epcoritamab can be given subcutaneously, making it more convenient than IV administration. An expert opinion on these trials is available below.

Whilst these promising phase I studies are continuing, recruitment is currently underway for a phase II trial of odronextamab (NCT03888105), and several clinical trials are in progress investigating glofitamab and epcoritamab in combination with other therapeutics across B-cell NHL subtypes.