DLBCL: Glofitamab Plus Chemo Boosts Survival
FROM EHA 2024
“Glofitamab is the first CD20xCD3 bispecific antibody to demonstrate an overall survival benefit in DLBCL in a randomized phase 3 trial,” said first author Jeremy Abramson, MD, of the Massachusetts General Hospital Cancer Center, Boston, Massachusetts, in a press briefing at the annual meeting of the European Hematology Association (EHA) in Madrid.
“These results support the use of glofitamab GemOx as new, off-the-shelf treatment for relapsed/refractory DLBCL in patients who are transplant ineligible in the second-line or later setting,” he said.
The findings are from the phase 3 STARGLO study involving 274 patients with R/R DLBCL who had previously been treated either with at least two prior lines of therapy, or—if only one prior line of therapy—were determined to be ineligible for autologous stem cell transplant (ASCT).
At a median follow-up of 21 months, those treated with glofitamab combined with GemOx had a significantly higher median overall survival of 25.5 months, compared with those treated with the standard of care of rituximab and GemOx (12.9 months; hazard ratio [HR], 0.62; P = .006).
“The results show a 38% lower risk of death with the glofitamab plus GemOx, compared with [the rituximab regimen],” Dr. Abramson said.
Secondary endpoints showed consistent benefits with the glofitamab regimen, with significant improvements in progression-free survival and complete remission.
Unmet Need for Accessible Therapies
Relapsed/refractory DLBCL, the most common form of non-Hodgkin lymphoma (NHL) in the United States, is an aggressive blood cancer. The standard second-line therapy is high-dose chemotherapy followed by ASCT. However, factors including older age or coexisting medical conditions can compromise response, and those who relapse or are refractory to subsequent therapies have poor outcomes.
“Relapsed DLBCL in the second-line setting or later continues to represent an area of medical need,” Dr. Abramson said.
While several CD20xCD3 bispecific antibody drugs are under development to address the need, glofitamab was the first off-the-shelf, fixed-duration bispecific antibody to receive accelerated approval from the US Food and Drug Administration (FDA) for the treatment of R/R DLBCL, specifically as monotherapy after two or more lines of systemic therapy.
That approval was based on results from a pivotal phase 1/2 study, which showed high rates of deep and durable complete remission with the monotherapy.
To further evaluate glofitamab in combination with GemOx, the authors conducted the multicenter, open-label STARGLO trial, which extended enrollment to patients with just one prior therapy if they were determined to be stem cell transplant ineligible. Patients were also required to have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2.
Patients were randomized 2:1 either to treatment with glofitamab combined with GemOx, involving 8 cycles, in addition to 4 cycles of glofitamab monotherapy (n = 183), or to the rituximab plus GemOx regimen in 8 cycles (n = 91).
Overall, 153 (55.8%) of patients had primary refractory disease and 166 (60.6%) were refractory to their last therapy. The median age was 68, and 37% had two or more lines of therapy, including some who had received chimeric antigen receptor T-cell (CAR T) therapy (8.8% in the glofitamab group and 7.1% in the rituximab group).
In addition to the significant overall survival benefit, the glofitamab regimen also showed significantly improved progression-free survival at a median follow-up of 16.1 months, as observed by IRC-assessed PFS, with a median progression-free survival rate of 13.8 months vs 3.6 months (HR, 0.40; P < .0001).
The complete remission rate was doubled with glofitamab-GemOx, with a rate of 58.5% vs 25.3%, respectively; P < .0001.
Similar results were observed in subgroups, including relapsed vs refractory patients and those treated as a second or third line of care.
The median number of cycles received was higher among those receiving glofitamab (11 vs four cycles).
Adverse event (AE) rates were higher with glofitamab vs rituximab, including grade 3-4 AEs (69.4 vs 36.4%), grade 5 AEs (8.3 vs 4.5%; primarily driven by an imbalance of COVID-19 AEs), and serious AEs (54.4 vs 17.0%; primarily cytokine release syndrome [CRS]).
CRS was the most frequently reported AE in the glofitamab group (grade 1: 31.4%; grade 2: 10.5%; and grade 3: 2.3%), and events consistent with immune effector cell–associated neurotoxicity syndrome were reported in four patients (2.3%), all of which were concurrent with CRS.
Other AEs were consistent with the known risks associated with the therapy regimens.
“We found that with glofitamab GemOx, the toxicities were manageable, and the most common toxicity of CRS was predominantly low-grade and occurred with step-up dosing in cycle one and was completely reversible,” Dr. Abramson said.
He noted that the higher rate of grade 5 AEs with glofitamab GemOx “was far outweighed by the survival benefit for disease control.”
Overall, “these findings represent the best outcomes observed in a phase 3 trial for relapsed/refractory diffuse large B-cell lymphoma patients who are considered transplant ineligible,” Dr. Abramson said in an interview.
