medwireNews: Patients with follicular lymphoma who achieve a positron emission tomography (PET)-determined complete response to induction immunochemotherapy have a significantly better prognosis than those with a non-complete response, research shows.
Judith Trotman (University of Sydney, New South Wales, Australia) and co-investigators say their findings “support the use of end-of-induction PET response status as a practical, early predictor of progression-free and overall survival, helping to identify patients with the greatest risk of relapse.”
Trotman and team analyzed PET scans for 595 participants of the GALLIUM trial who had previously untreated, advanced, CD20-positive follicular lymphoma. The study compared the efficacy and safety of induction therapy with obinutuzumab versus rituximab, each in combination with chemotherapy and followed by maintenance with the same antibody as received during induction.
At the end of induction, 65.5% achieved a PET complete response according to International Harmonisation Project (IHP) 2007 criteria, and 75.6% had a PET complete metabolic response according to Lugano 2014 criteria, compared with 29.9% according to IHP 2007 criteria for computed tomography (CT).
The patients were followed-up for a median 43.3 months, and the researchers calculated that the 2.5-year progression free survival (PFS) rates (from the end of induction) were 87.8% and 87.4% in PET complete responders by IHP 2007 and Lugano 2014 criteria, respectively.
This was significantly higher that the corresponding rates of 72.0% and 84.0% in noncomplete responders by each criteria and amounted to significant 60% and 40% reductions, respectively, in the risk for disease progression or death at 2.5 years.
The same degree of risk reduction was seen for overall survival (OS) with each set of criteria. Specifically, OS at 2.5 years was 96.9% and 96.6% in IHP 2007 and Lugano 2014 complete responders, respectively, compared with 90.6% and 84.0% in noncomplete responders.
The researchers note that improvement in PFS among complete responders occurred irrespective of whether or not they achieved a complete response on CT, and although having a CT-based complete response predicted improved PFS at 2.5-years (90.5% vs 79.9% for nonresponders), there was no association with OS.
“In conclusion, these data suggest that PET is a better assessment modality than contrast-enhanced CT in patients with follicular lymphoma treated with first-line immunochemotherapy,” Trotman et al conclude in The Lancet Oncology.
They add: “Further studies, combining PET with other prognostic tools, might help to identify patients at high risk of both relapse and early death to optimise risk-adapted follow-up.
“Although additional validation is required, PET might be a useful, early surrogate marker of progression-free and overall survival in clinical trials, and provide the platform to guide response-adapted therapy in follicular lymphoma.”
By Laura Cowen
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