CHICAGO – It doesn’t seem to matter whether patients with newly diagnosed, diffuse large B-cell lymphoma receive a standard chemotherapy regimen in a dose-dense fashion every 14 days for six cycles, or every 21 days for eight cycles, said investigators in a multinational trial that was presented at the annual meeting of the American Society of Clinical Oncology.
There were no significant differences in the primary outcome of overall survival or the secondary outcome of failure-free survival among 1,080 patients who were randomly assigned to the two R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone) regimens, reported Dr. David Cunningham of the Royal Marsden Hospital in London, on behalf of colleagues in the U.K. National Cancer Research Institute’s lymphoma clinical study group.
Half the population received R-CHOP every 3 weeks for eight cycles (R-CHOP-21), and the other half was assigned to R-CHOP every 2 weeks for six cycles, followed by two additional rituximab infusions (R-CHOP-14).
Dr. Cunningham highlighted the following findings:
• The 2-year overall survival rates were 81% in the R-CHOP-21 arm, and 83% in the R-CHOP-14 arm (log rank P = .70).
• Overall response rates (a combination of complete responses [CR], complete unconfirmed responses [CRu], and partial responses [PR]) were 88% in R-CHOP-21 and 90% in R-CHOP-14 (P = .11).
• Rates of combined CR/CRu were 63% and 58%, respectively (P = .15).
• The 2-year failure-free survival rates were identical, at 75% in each group.
Toxicities were also generally similar between the treatment groups, except for a lower incidence of neutropenia in the R-CHOP-14 arm, which reflected primary prophylaxis with granulocyte-colony-stimulating factor (G-CSF) in that group.
There were no differences in failure-free survival between the treatment arms when patients were stratified by age, sex, disease stage, bulky disease, B symptoms, prognostic score, IPI (International Prognostic Index) score, cell proliferation (as measured by the MIB-1 monoclonal antibody), or diffuse large B-cell lymphoma (DLBCL) phenotype.
"We couldn’t actually identify any of the subsets or subgroups that benefited from one or the other treatment," Dr. Cunningham said.
Dr. Julie Vose of the University of Nebraska Medical Center in Omaha, the invited discussant, commented that the study "compared some questions that have been burning in our minds for a long time," calling it a "very robust analysis of a very important study."
Summing up this study and three other abstracts that looked at alternative therapies for DLBCL, Dr. Vose said that R-CHOP-21 is still the standard of care for young patients with low, low/intermediate, or high/intermediate IPI scores, although R-CHOP-14 plus two rituximab infusions or R-CHOEP (R-CHOP plus etoposide) are acceptable alternatives. For young patients with high IPI, R-CHOP-21 followed by consolidation autologous transplant should be offered. For older patients, R-CHOP-21 for eight cycles is equivalent to R-CHOP-14 for six cycles plus two rituximab infusions.
The trial began recruiting after a 2004 German study showed that a dose-dense regimen of six cycles of CHOP-14 improved 5-year overall survival in patients older than 60 years by 13%, compared with six cycles of CHOP-21 (Blood 2004;104:634-41).
Since that publication, however, the addition of rituximab to six or eight cycles of CHOP or similar chemotherapy regimens was shown to improve overall survival of DLBCL by 10%-16% in two trials. Those findings raised interest in whether CHOP-14 might still be superior to CHOP-21 in patients who also receive rituximab, and whether such an effect would be seen across all age groups, Dr. Cunningham said.
He reported the final results of the trial, which involved 1,080 adults who had newly diagnosed CD20-positive DLBCL and were recruited from 119 sites. The patients were stratified by IPI score, age (60 years and younger, or older than 60), and treatment center.
In all, 23% of patients on R-CHOP-21 and 22% on R-CHOP-14 had died by the time of the final study analysis. DLBCL was the leading cause of death in both arms. Other causes included treatment-related toxicity, cardiac causes (all cardiac deaths occurred 3-15 months after completion of therapy), secondary malignancy, and other/unknown causes.
In her discussion, Dr. Vose pointed out that R-CHOP-14, which requires G-CSF support after every cycle, costs about $31,308, compared with $29,247 for R-CHOP-21, in which G-CSF is used only to treat (but not to prevent) neutropenia or febrile neutropenia. In the trial, G-CSF was used in 38% of R-CHOP-21 cycles, compared with 100% of R-CHOP-14 cycles.
In addition, R-CHOP every 21 days for six cycles (not eight) is generally considered to be the standard of care in the United States, she noted; a direct comparison of this shorter regimen with R-CHOP-14 would have been welcome, she said.