Glofitamab for Relapsed or Refractory Diffuse Large B-Cell Lymphoma

BACKGROUND

The prognosis for patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) is poor. Glofitamab is a bispecific antibody that recruits T cells to tumor cells.

METHODS

In the phase 2 part of a phase 1-2 study, we enrolled patients with relapsed or refractory DLBCL who had received at least two lines of therapy previously. Patients received pretreatment with obinutuzumab to mitigate cytokine release syndrome, followed by fixed-duration glofitamab monotherapy (12 cycles total). The primary end point was complete response according to assessment by an independent review committee. Key secondary end points included duration of response, survival, and safety.

RESULTS

Of the 155 patients who were enrolled, 154 received at least one dose of any study treatment (obinutuzumab or glofitamab). At a median follow-up of 12.6 months, 39% (95% confidence interval [CI], 32 to 48) of the patients had a complete response according to independent review. Results were consistent among the 52 patients who had previously received chimeric antigen receptor T-cell therapy (35% of whom had a complete response). The median time to a complete response was 42 days (95% CI, 42 to 44). The majority (78%) of complete responses were ongoing at 12 months. The 12-month progression-free survival was 37% (95% CI, 28 to 46). Discontinuation of glofitamab due to adverse events occurred in 9% of the patients. The most common adverse event was cytokine release syndrome (in 63% of the patients). Adverse events of grade 3 or higher occurred in 62% of the patients, with grade 3 or higher cytokine release syndrome in 4% and grade 3 or higher neurologic events in 3%.

CONCLUSIONS

Glofitamab therapy was effective for DLBCL. More than half the patients had an adverse event of grade 3 or 4. (Funded by F. Hoffmann-La Roche; ClinicalTrials.gov number, NCT03075696.).

Glofitamab in patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) and ≥ 2 prior therapies: Pivotal phase II expansion results

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Background: Glofitamab is a T-cell engaging bispecific antibody (Ab) with a novel 2:1 configuration that confers bivalency for CD20 (B cells) and monovalency for CD3 (T cells). In a Phase I/II study (NCT03075696), escalating glofitamab doses were highly active and well tolerated in pts with R/R B-cell lymphomas, with obinutuzumab pretreatment (Gpt) and Cycle (C) 1 step-up dosing providing effective CRS mitigation. For the first time, we present pivotal Phase II expansion results in pts with R/R DLBCL and ≥2 prior therapies. Methods: All pts had DLBCL (DLBCL NOS, HGBCL, PMBCL, or trFL) and had received ≥2 prior regimens including ≥1 anti-(a) CD20 Ab and ≥1 anthracycline. IV Gpt (1000mg) was given 7 days before the first glofitamab dose. IV glofitamab was then given as step-up doses on Day (D) 1 (2.5mg) and D8 (10mg) of C1 and at the target dose (30mg) on D1 of C2–12 (21-day cycles). The primary endpoint was CR rate (best response during initial treatment) assessed by Independent Review Committee (IRC) using Lugano 2014 criteria. CRS was assessed using ASTCT criteria. Results: As of Sep 14, 2021, 107 pts had received ≥1 dose of study treatment (median age: 66 yrs [21–90]; Ann Arbor stage III–IV disease: 74%; IPI score ≥3: 54%; DLBCL NOS: 74%). Median prior therapies was 3 (2–7); 59% had ≥3 prior therapies and 35% had received prior CAR T-cells (CAR-Ts). Most pts were refractory to a prior aCD20 Ab-containing regimen (85%) and to their most recent regimen (85%). Many were refractory to their initial therapy (59%) and to prior CAR-Ts (32%). After a median follow-up of 9 months (0.1–16), ORR and CR rates by IRC were 50.0% and 35.2%, respectively. CR rates were consistent in pts with and without prior CAR-Ts (32% vs 37%). Median time to CR was 42 days (95% CI: 41–48). The majority of CRs (33/38; 87%) were ongoing at data cut. An estimated 84% of complete responders and 61% of responders remained in response at 9 months. At data cut, the projected 12-month OS rate was 48%, and 92% of complete responders were alive. These results are consistent with earlier Phase I data in 100 pts treated with target glofitamab doses ≥10mg (CR rate: 34%; estimated 20-month CR rate in complete responders: 72%). CRS occurred in 68% of pts, was primarily associated with the initial doses, and was mostly Gr 1 (51%) or Gr 2 (12%); Gr 3 (3%) and Gr 4 (2%) events were uncommon. All but 2 CRS events were resolved at data cut. Glofitamab-related neurologic AEs potentially consistent with ICANS occurred in 3 pts (all Gr 1–2). No glofitamab-related Gr 5 (fatal) AEs occurred. Glofitamab-related AEs leading to discontinuation were uncommon (3 pts, 3%). Conclusions: Fixed-duration glofitamab induces durable complete remissions and has favorable safety in pts with R/R DLBCL and ≥2 prior therapies, including those with prior exposure to CAR-Ts. Glofitamab is a promising new therapy for pts with heavily pretreated and/or highly refractory DLBCL. Clinical trial information: NCT03075696.

Glofitamab step-up dosing (SUD): Complete response rates in updated efficacy data in heavily pretreated relapsed/refractory (R/R) non-Hodgkin lymphoma (NHL) patients (pts)

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Background: Glofitamab (RG6026), a T-cell-engaging, bispecific, full-length antibody, allows bivalent binding to CD20 (B-cells), and monovalent binding to CD3 (T-cells). In NP30179 (NCT03075696), an ongoing multicenter, Phase I dose-escalation and expansion study, 0.6–25mg glofitamab fixed-dosing with obinutuzumab pretreatment (Gpt), showed high, durable complete responses and manageable safety in heavily pretreated R/R NHL (Dickinson, et al. EHA 2020). Glofitamab SUD, in addition to Gpt, allowed dose escalation up to 30mg to maximize efficacy, while mitigating cytokine release syndrome (CRS) (Hutchings, et al. JCO 2021). We present updated efficacy data from glofitamab monotherapy SUD cohorts. Methods: Gpt (1000mg) was given to pts 7 days pre-glofitamab initial dose. Intravenous SUD of glofitamab was given on Day (D) 1 and 8 of Cycle (C) 1 and then at the target dose from C2D1 (2.5/10/16mg or 2.5/10/30mg); treatment continued for up to 12 cycles, every 21 days. Response rates were based on the Lugano criteria (Cheson, et al. JCO 2014). Results: Fifty-two pts received glofitamab SUD; 17 and 35 pts received 2.5/10/16mg and 2.5/10/30mg, respectively. Twenty-eight pts (53.8%) had aggressive NHL (aNHL) and 24 pts had indolent NHL (iNHL). Pts had a median age of 68 (44–85) years and received a median of 3 (1–12) prior lines of therapy. Forty (76.9%) and 38 (73.1%) pts were refractory to their most recent and any prior CD20 therapy, respectively. After a median follow-up of 6.3 months, an updated efficacy analysis was conducted on December 1, 2020. For pts with aNHL (N = 28), the best overall response (OR) and complete metabolic response (CMR) rates were 64.3% and 57.1%, respectively; a trend of improved response was observed with increased target dose, with a CMR rate of 71.4% at 2.5/10/30mg (N = 14). Notably, 4/5 pts (80%) with mantle cell lymphoma (2.5/10/16mg, n = 2; 2.5/10/30mg, n = 2) had CMR. For aNHL, 13/16 CMRs are ongoing, with 8 CMRs lasting > 3 months. For pts with iNHL (N = 24), OR and CMR rates were 79.2% and 70.8%, respectively; 14/17 CMRs are ongoing, with 10 CMRs lasting > 3 months. As of August 3, 2020, common adverse events (52 pts) were CRS (63.5%), neutropenia (38.5%), and pyrexia (32.7%). CRS was mostly confined to C1: 24/50 pts had CRS after 2.5mg; 20/49 pts after 10mg; 2/16 and 8/32 pts had CRS after 16 and 30mg (C2D1), respectively. Grade [Gr] 1 and 2 CRS was reported in 18 (34.6%) and 12 (23%) pts, respectively; 3 pts had Gr 3 CRS; none had Gr 4/5 events (ASTCT 2019). Updated data, including biomarker data on baseline CD20 expression and CD8 levels in the tumor, will be presented. Conclusions: Updated data for glofitamab monotherapy SUD show higher preliminary response rates than previously reported in pts with R/R NHL who have failed multiple lines of therapy. CRS was mostly manageable, of low grade, and confined to the first cycle of treatment. Clinical trial information: NCT03075696.

Plasmid conferring increased sensitivity to mercuric chloride and cobalt chloride found in some laboratory strains of Escherichia coli K-12

Some lines of the widely used strain CR34 of Escherichia coli K-12 carry a plasmid. The plasmid has a mass of 12 +/- 2 X 10(6) megadaltons and is maintained at a low copy number per cell (1 to 2), and this number is not amplified by growth of cells in the presence of chloramphenicol. The plasmid is designated as pCU3. The presence of pCU3 confers on the strain increased sensitivity to mercuric chloride and cobalt chloride. The plasmid has also been observed to fuse or recombine with the plasmid R64-11.