GLASGOW – Most older patients with primary central nervous system lymphoma (PCNSL) can tolerate high-dose methotrexate-based chemotherapy and achieve similar outcomes as younger and fitter patients, according to a retrospective analysis of 244 patients in the United Kingdom.
For older patients – at least 65 years old – who received methotrexate-based regimens, treatment-related mortality was 6.8%, which is comparable with rates seen in trials involving younger patients, reported lead author Edward Poynton, MD, of University College Hospital in London.
Specifically, Dr. Poynton cited the phase 2trial, which had a treatment-related mortality rate of 6% among patients up to age 70 years. These patients were treated with the established protocol for younger patients: chemotherapy with methotrexate, cytarabine, thiotepa, and rituximab (MATRix) followed by autologous stem cell transplant or whole-brain radiotherapy.
Introducing Dr. Poynton’s presentation at the annual meeting of the British Society for Haematology,, of the University of Plymouth (England), added historical context to the new findings.
“When I started in hematology ... [PCNSL] was a universally fatal disease, pretty much,” Dr. Rule said. “And then we had methotrexate, and it worked occasionally. And then we had a randomized trial, which was randomization of methotrexate plus or minus high-dose cytarabine, showing benefit.”
This combination became the benchmark against which subsequent randomized trials were measured; however, such high-intensity regimens have raised concerns about safety and efficacy in older patients, Dr. Rule said, noting that the present study serves to inform clinicians about real-world outcomes in this population.
The retrospective analysis reviewed 244 patients who were aged at least 65 years when histologically diagnosed with PCNSL at 14 U.K. tertiary centers between 2012 and 2017. All patients received first-line care of any kind, ranging from best supportive care to clinical trial therapy. Patients were grouped into three treatment cohorts divided by level of frailty. Analysis showed that these divisions correlated with age, renal function, Eastern Cooperative Oncology Group performance status, and treatment intensity.
The frail group received palliative treatment consisting of whole-brain radiotherapy, an oral alkylator, or best supportive care. The less-fit group received methotrexate in combination with rituximab, an oral alkylator, or both. The fit group was most intensively treated, receiving high-dose methotrexate and cytarabine – with or without rituximab – or MATRix.
The primary objective was overall response rate, while the secondary objectives were median overall survival and progression-free survival.
The analysis showed that 79% of patients (n = 193) received methotrexate-based therapy of some kind, with 61% receiving three or more cycles of therapy and 30% requiring dose reductions. The overall response rate was 63%.
Dr. Poynton noted that about two-thirds of patients who achieved a partial response in early assessment went on to achieve a complete response. Patients in the fit group more often responded than those who were less fit (87% vs. 65%; P = .01) and more often received consolidation therapy (42% vs. 23%; P = .01).
Fitness level was also associated with median overall survival, which was longest in the fit group at 42 months. The other two groups had dramatically shorter survival times: 8 months in the less-fit group and just 2 months in the frail group.
A closer look at the data revealed some patterns, Dr. Poynton said.
“What we see is that age at diagnosis is significantly correlated with progression-free survival but not with overall survival,” he said, noting that, in contrast, performance status was associated with both survival measures.
Methotrexate dose also impacted both survival measures. Patients who received 75% or more of their induction dose over the course of treatment had better median overall survival and progression-free survival than those who received less than 75%. Similarly, consolidation therapy improved both survival measures.
Patients aged older than 70 years who received intensive chemotherapy had a treatment-related mortality rate of 4.8%, which is lower than the overall treatment-related mortality, Dr. Poynton reported.
Considering the correlation between methotrexate dose and survival, Dr. Poynton suggested that “dose reductions should be carefully considered.”
He also noted that patients in the fit cohort who received intensive chemotherapy had comparable outcomes with younger patients in prospective trials, and yet 44% of patients older than 65 years in the real world who received high-dose methotrexate with cytarabine would have been ineligible for the IELSG32 trial.
“We’ve been able to identify this cohort of patients retrospectively,” Dr. Poynton said. “They definitely exist, and I think we need to work harder at how are going to identify these patients prospectively in the future, so we know which of our patients who are older can benefit from intensive chemotherapy and which patients won’t.”
Dr. Poynton reported having no relevant financial disclosures. His coinvestigators reported relationships with AbbVie, Merck, Takeda, Jazz Pharmaceuticals, and others.