The activity of the combination of rituximab, bendamustine, and low dose cytarabine (R-BAC) was evaluated in a phase 2 multicentre trial from the Fondazione Italiana Linfomi (FIL RBAC500) in previously untreated patients with mantle cell lymphoma (MCL) who were not eligible to stem cell transplant. Maintenance treatment was not planned after induction therapy, and no patient in the study received rituximab maintenance. Fifty-seven patients (median age 71 years, range 61-79) were recruited and treated with 4 to 6 cycles between 2012 and 2014. Despite some concern in terms of hematological toxicity, the R-BAC regimen was associated with high complete remission (CR) rate (91%), 2-years overall survival (OS) of 86% (74-93), and 2-years progression free survival (PFS) of 81% (68-89). Here, we present long-term survival outcomes.

After 7 years of median follow-up (86 months, range 57-107), the median OS and PFS for all patients were not reached (Figure 1A and 1B). The 7-years PFS and OS rates were 56% (95%CI 41-67) and 63% (95%CI 46-72), respectively. Patients who achieved CR (n=53) had a 7 years PFS of 59% (95% CI 44-71), with the curve that appears to plateau after 6 years. Adverse predictive factors affecting PFS were blastoid morphology (p<0.05), elevated Ki67 > 30% (p<0.05), and failure to achieve CR after 2 cycles (p=0.03). Early-progression of disease (<24 months from start of R-BAC) was associated with impaired overall survival (p<0.05).

Eight patients (14%) developed a secondary neoplasia: 1 parotid heteroplasia, 1 parotid nodular hyperplasia, 1 prostate cancer, 1 bladder cancer, 1 larynx, 1 thyroid cancer, 1 lung cancer and 1 secondary acute myeloid leukemia.

Among the 25 relapsed patients, 8 did not receive any other treatment. Six had Ibrutinib monotherapy as second line, of whom 4 responded (3 are still in CR), 4 had CHOP or CHOP-like regimens with only partial responses.

As per protocol, 31 patients with molecular marker at diagnosis and available samples were followed-up for minimal residual disease (MRD) with ASO-droplet digital polymerase chain reaction (D-PCR). Patients with MRD persistence at the end of induction, either in peripheral blood or bone marrow, had significantly worse 7 years-PFS (p<0.05 for them both).

In conclusion, in elderly patients with newly diagnosed MCL, R-BAC showed sustained efficacy over time, which compared favorably with any other reported immuno-chemotherapy regimen (with or without maintenance) in similar populations. With a median OS exceeding 60% after 7-years this regimen has significantly impacted on the life-expectancy of elderly patients with MCL.

Figure 1
Figure 1.
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Disclosures

Tisi: Incyte: Membership on an entity's Board of Directors or advisory committees; BWS: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees. Nassi: Takeda: Consultancy; Incyte: Consultancy; Kyowa Kirin: Consultancy; Roche: Consultancy. Ferrero: Gilead: Research Funding, Speakers Bureau; Morphosys: Research Funding; Incyte: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Servier: Speakers Bureau; EUSA Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Clinigen: Membership on an entity's Board of Directors or advisory committees. Zilioli: Takeda: Other: travel expenses, accommodation; MSD, Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations; Roche, Italfarmaco: Consultancy, Honoraria; Gentili, Takeda, Gilead, Servier: Consultancy, Speakers Bureau. Merli: Janssen: Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accomodations, Expenses; Gilead Science: Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accomodations, Expenses; MSD: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accomodations, Expenses; Roche: Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accomodations, Expenses; EUSA Pharma: Other: Travel, Accomodations, Expenses; Celgene: Other: Travel, Accomodations, Expenses.

© 2021 by The American Society of Hematology
2021
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