LUGANO, Switzerland – Hot on the heels of the phase 3 ROBUST study showing that adding lenalidomide to standard chemotherapy did not improve outcomes for patients with untreated diffuse large B-cell lymphoma come results of a different study showing a significant benefit with the therapy.
Although, as previously reported, adding lenalidomide (Revlimid) to standard chemotherapy for patients with newly diagnosed ABC-type diffuse large B-cell lymphoma (DLBCL) – the so-called R2-CHOP regimen – did not significantly improve either progression-free or overall survival, compared with R-CHOP alone in, results from the randomized phase 2 study showed that R2-CHOP was associated with a 34% reduction in the risk of disease progression or death, compared with R-CHOP alone.
“The efficacy endpoints are consistent, with trends toward higher PET complete response rate and improved overall survival with R-squared CHOP,”, of the Mayo Clinic, Rochester, Minn., said at the International Conference on Malignant Lymphoma.
So what’s behind the conflicting findings?
The differences between the results of the two studies may be accounted for by the higher lenalidomide dose used in ECOG-ACRIN 1412, the patient populations – all comers in ECOG-ACRIN versus only patients with activated B-cell (ABC) type DLBCL in ROBUST – and by a 10-day shorter median time to treatment in ECOG-ACRIN 1412, said invited discussant, of the Dana-Farber Cancer Institute in Boston.
The rationale for adding lenalidomide to R-CHOP came from in vitro studies showing antiproliferative and immunomodulatory action of lenalidomide against DLBCL, as well as two proof-of-concept clinical studies (and ) indicating efficacy against non-germinal center-like B (GCB) type DLBCL.
ECOG-ACRIN 1412 details
Goals of the ECOG-ACRIN 1412 study were to evaluate the effect of lenalidomide both in all DLBCL subtypes and in the ABC subtype, maximize the synergy of the immunomodulator with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone) while maintaining R-CHOP dose intensity, and facilitate the enrollment of patients with rapidly progressive disease.
To accomplish the last goal, the study was designed to allow enrollment based on local laboratory findings, scans, and diagnostic pathology, without required identification of the cell of origin. Built in to the design was the plan for final eligibility to be based on central pathology review. In other words, the trial design took into account the likelihood that some enrolled patients would not qualify for eligibility based on later pathology review.
The investigators enrolled 349 adults aged 18 years or older with pathologically confirmed DLBCL (regardless of the cell of origin), stage II bulky to stage IV disease, International Prognostic Index (IPI) scores of 2 or greater, and Eastern Cooperative Oncology Group performance status scores of 2 or less.
The patients were stratified by age (younger than 60 years vs. 60 years and older) and by IPI score (2/3 vs. 4/5), and then randomized to receive either six cycles of R-CHOP or R2-CHOP. Lenalidomide was given in a dose of 25 mg on days 1-10 of each cycle. In contrast, the dose used in ROBUST was 15 mg given on days 1-14 of each cycle.
In ECOG-ACRIN 1412, patients assigned to lenalidomide received mandatory neutropenia prophylaxis with granulocyte-colony stimulating factor.
The time from diagnosis to treatment was a median of 21 days, with only 61 of 280 evaluable patients starting treatment more than 31 days after diagnosis. In ROBUST, the median time to start therapy was 31 days.
Dr. Nowakowski and his colleagues hadthat time to treatment is an important prognostic factor in DLBCL.
The efficacy evaluation included 145 patients assigned to R2-CHOP, and 135 assigned to R-CHOP. Primary reasons for exclusion were ineligibity following central pathology review or lack of diagnostic material for review.
After a median follow-up of 2.5 years, R2-CHOP was associated with a 34% improvement in progression-free survival, the primary endpoint (hazard ratio [HR] 0.66, P = .03). The 1-year progression-free survival rates were 83% with R2-CHOP and 73% with R-CHOP. Respective 2-year progression-free survival rates were 76% and 70%.
There was no significant difference, however, in the secondary overall survival endpoints with 1-year and 2-year overall survival of 93% vs. 87% and 86% vs. 80%, respectively.
Similarly, there was no difference in rates of PET-ascertained complete response, at 72% with R2-CHOP and 67% with R-CHOP.
R2-CHOP showed greater benefit across most subgroups, including patients with lower IPI score, patients with bulky disease, patients younger than 60 years, women, and patients with shorter time to treatment. There were also nonsignificant trends hinting at better outcomes with R2-CHOP, regardless of cell of origin.
Toxicities were typical for R-CHOP, although patients on R2-CHOP had significantly higher rates of grade 3 or 4 diarrhea, febrile neutropenia, and thrombocytopenia.
In addition to the trial differences mentioned previously, the differences in outcomes might be explained by the possibility that lenalidomide activity is not restricted to ABC DLBCL, Dr. Shipp said.
“One of the things that’s important to remember about lenalidomide is that it’s an immunomodulating agent and it has also has effects on tumor-infiltrating T cells,” she said.
Differences in response to therapy may also be explained by recent findings showing genetic heterogeneity in transcription-defined ABC DLBCLs, she said.
ECOG-ACRIN 1412 was supported by the National Cancer Institute and by Celgene. Dr. Nowakowski reported consulting/advising for and research funding from Celgene and others. Dr. Shipp reported consulting/advising for Bristol-Myers Squibb, honoraria from BMS and AstraZeneca, and institutional research funding from BMS and Bayer.
SOURCE: Nowakowski GS et al. 15-ICML, .