Thomas E. Witzig, MD
Cure rates in diffuse large B-cell lymphoma (DLBCL) remain relatively unchanged, even following therapeutic additions to the armamentarium and an improved understanding of disease biology.
“We are still stuck . . . on this idea that we’re only curing 60% to 80% of patients,” said Thomas E. Witzig, MD, a hematologist-oncologist with Mayo Clinic in Rochester, Minnesota. “Studies [from the early 2000s] showed that R-CHOP was better than CHOP and we’ve been trying for the past 15 years to move on from that.”
However, ongoing studies evaluating novel combinations have the potential to finally move the field forward, according to Witzig, who gave a presentation on DLBCL at the 2018 SOHO Annual Meeting.
The history of DLBCL care is littered with promising treatments that did not pan out, and after years of research, the standard of care remains 6 cycles of R-CHOP-21. Yet pending results of studies combining R-CHOP with ibrutinib (Imbruvica) or lenalidomide (Revlimid), could advance treatment paradigms. In the meantime, Witzig said data from recent trials show just how challenging getting past that 80% threshold has been.
Findings from the phase III GOYA trial (NCT01287741) showed that the addition of obinutuzumab (Gazyva) to CHOP (G-CHOP) did not significantly improve progression-free survival (PFS) compared with R-CHOP in patients with treatment-naïve DLBCL. Patients were assigned to eight 21-day cycles of obinutuzumab (n = 706) or rituximab (Rituxan; n = 712) followed by 6 or 8 cycles of CHOP.
At a median follow-up of 29 months, the estimated 3-year PFS was 69.6% for G-CHOP versus 66.9% for R-CHOP (HR, 0.92; 95% CI, 0.76-1.11; P
Findings from the REMARC trial published last year showed that maintenance therapy with lenalidomide may not provide much benefit for patients with DLBCL. Following 6 to 8 cycles of R-CHOP, patients aged 60 to 80 years with treatment-naïve DLBCL or another aggressive B-cell lymphoma were randomly assigned to 25 mg daily lenalidomide maintenance (n = 323) or placebo (n = 327) for 21 days of every 28-day cycle for 24 months.2
At a median follow-up of 39 months, the median PFS was not reached for the experimental group compared with 58.9 months for placebo (HR, 0.708; 95% CI, 0.537-0.933; P
= .013). The result was consistent among subgroups including sex, age-adjusted International Prognostic Index (IPI) score, age younger than 70 versus ≥70 years, response after induction, and PET status at assignment.
However, the median overall survival (OS) was similar between the 2 arms (87% vs 89%; HR, 1.218; 95% CI, 0.861-1.721; P
= .26) at a median follow-up of 52 months.
“That was the first study that showed a PFS advantage,” Witzig said. “But for reasons that weren’t clear, this did not translate into an overall survival advantage. This is somewhat of a positive study, but it may not be practice changing because it did not translate into an overall survival benefit.”
The mTOR inhibitor everolimus (Afinitor) demonstrated single-agent efficacy and a small OS benefit in the phase III PILLAR-2 trial (NCT00790036). The trial included 742 patients with an IPI score ≥3 who were at increased risk for relapse following a complete response (CR) while on R-CHOP. Patients were randomly assigned to adjuvant everolimus (n = 372) or placebo (n = 370).3
Everolimus did not significantly improve disease-free survival (DFS). The 2-year disease-free survival (DFS) rate was 77.8% (95% CI, 72.7%-82.1%) with everolimus versus 77.0% (95% CI, 72.1%-81.1%) with placebo. Everolimus was associated with a slight OS benefit at 2 years (90.7% vs 88.3%; HR, 0.75; 95% CI, 0.51-1.01), but the trial did not meet the statistical criteria showing significant improvement.
Investigators are awaiting results of large trials looking at activated B cell-like (ABC) and non-germinal center B-cell (GBC) DLBCL. Data have not yet been released from the phase III PHOENIX trial (NCT01855750) comparing ibrutinib/R-CHOP versus R-CHOP, but a press release from Janssen Pharmaceuticals released in July said the trial did not meet its primary endpoint for DFS for newly diagnosed GBC DLBCL.
Lenalidomide/R-CHOP (R2CHOP) induced an overall response rate (ORR) of 98%, with a CR rate of 80%, among 60 patients with DLBCL in phase II findings from Nowakowski et al. At 24 months, the EFS rate was 59% (95% CI, 48%-74%) and the OS rate was 78% (95% CI, 68%-90%). The 24-month PFS for patients with non-GCB disease treated with R-CHOP was 28% compared with 64% for GCB patients (P
<.001) and the 24-month OS was 46% versus 78% (P
<.001), respectively. There was no difference in 24-month PFS or OS in patients treated with R2CHOP.4
Although there was some controversy surrounding the use of immunohistochemistry to identify subtypes and the potential effect of possible errors in subtyping may have had on results, the trial proceeded to phase III based on these findings.