Patients with transformed lymphomas treated with rituximab have excellent survival outcomes without autologous stem cell transplantation consolidation (ASCT), Victorian clinicians say.
A retrospective study of 45 lymphoma patients with histological transformation treated at the Department of Clinical Haematology, Monash Health, between 2002 and 2017 found that they had a five-year overall survival (OS) of 69% with rituximab treatment, which the investigators said was comparable to that of de novo DLBCL.
The cohort included high-risk patients (poor R-IPI risk group in 59%) and comprised of patients with DLBCL, according to the study results published in the Internal Medicine Journal.
Rituximab-containing induction was given for all treated patients (R-CHOP in 69%), with ASCT employed in only 17%, while rituximab maintenance given to 31% of patients.
With a median follow-up of 47 months there was an overall response rate of 82% and complete response of 75%.
Poor R-IPI risk-group assignment and chemotherapy exposure prior to HT were adverse prognostic factors. Chemotherapy‐naivety at HT was associated with a superior rate of complete response (84% vs. 54%, p = 0.057) and 5‐year OS (82% vs. 46%, p = 0.012).
Rituximab maintenance was associated with a durable progression‐free survival in induction‐responders.
Underlying indolent histology (FL vs. non-FL), manner of presentation (transformed vs. composite or discordant DLBCL) and early time-to-HT (HT < 18 months post indolent diagnosis) did not statistically affect outcomes.
The study investigators said the excellent five-year OS rate of 69% compared favourably to previous reports which might be explained by the cohort solely comprising of patients with DLBCL, rather than more aggressive histologies with potentially poorer outcomes.
Improved survival might also be related to the use of PET/CT for response assessment, which offers higher sensitivity and specificity for residual disease than conventional CT and thus allowed for accurate longitudinal disease evaluation.
Also, most of the patients (70%) were naïve to chemotherapy, which was shown to be associated with more favourable treatment-responsiveness compared to patients with prior exposure to chemotherapy.
This might be due to selection bias for patients who were already of poor prognosis due to their history of progression after systemic therapy. But it might also be due to the generation of ‘hyper -aggressive’ clones which surface at HT, such as with a biology conferring treatment-refractoriness, they suggested
Nevertheless the first data on outcomes from Australian patients with histologic transformation offer guidance on choices of therapy and consolidation and maintenance algorithms, they said.
“Specifically, whilst ASCT has historically been widely advocated, its benefit appears to be confined to the chemotherapy-exposed patients in HT in the era of rituximab-containing induction,” they wrote.
“In our study, where 70% of patients were chemotherapy-naïve, ASCT appeared not to be required to achieve a prolonged survival, in line with other studies.”
They noted that other means to consolidate induction-responders, based on de novo DLBCL practice, could be used, and about 30% of patients received HD-MTX and/or involved-field radiotherapy.