A more accurate prognostic index for patients with MALT lymphoma may be possible by examining the level lymphocyte to monocyte ratio (LMR) at diagnosis. Researchers reported at the EHA 2022 Hybrid Congress that low level LMR at diagnosis may be associated with inferior progression-free survival (PFS) and overall survival (OS). Their findings suggest that incorporating LMR into MALT-IPI may permit a more accurate risk assessment of disease progression.
Extranodal marginal zone B-cell lymphoma of MALT is a unique type of indolent lymphoma and monocytes are closely linked to the pathogenesis and disease progression, according to the authors. The absolute monocyte count (AMC) and LMR previously had been shown to reflect the host systemic immunity states and provide prognostic benefits in different kinds of lymphoma.
The MALT-IPI prognostic index was developed using a database of 401 patients treated in an international trial with chlorambucil, rituximab, or both. The index was subsequently validated by merging 3 independent cohorts of patients with MALT lymphoma.
The researchers examined the prognostic significance of AMC and LMR in 316 patients with MALT lymphoma. A statistically evident dominance showed that LMR was related to age, LDH level, β 2-MG level, B symptom, ECOG PS and systemic therapy. The median PFS was 146.4 months and median OS was not reached with a median follow-up time of 39.1 months (1-237 months).
The estimated PFS rates at 3 years were 84.1% and 79.6% at 5 years. The estimated OS rates at 3 years were 94.9% and 92.4% at 5 years. The high AMC group (>0.6×109/L) and the low LMR group (<1.8) were associated with poor outcomes and MALT-IPI, ECOG PS and LMR were identified as having independent prognostic significance for PFS. Additionally, MALT-IPI, β 2-MG and LMR were independently associated with poor OS.
The prognostic value of low level of LMR for PFS was more pronounced based on age (P value for interaction =.020). The prognostic value of low level of LMR was consistent across a subgroup analysis of OS.
The team combined MALT-IPI and AMC and developed a new prognostic index named MALT-IPI-M. It includes four parameters: age 70 years or older, Ann Arbor stage III or IV, serum LDH level greater than UNL, and LMR less than 1.8. The researchers found that MALT-IPI-M was able to classify patients into low-risk group (the MALT-IPI-M=0), intermediate-risk group (the MALT-IPI-M=1) and high-risk group (the MALT-IPI- M≥2).
The researchers developed receiver-operator characteristic (ROC) curves to compare the prognostic prediction capability of MALT-IPI and MALT-IPI-M. They found that the area under the curves (AUCs) for MALT-IPI-M were 0.682 for PFS and 0.804 for OS. This indicated an improved capability of distinguishing MALT patients with different risk (MALT-IPI 0.654 for PFS and 0.788 for OS).
The researchers next hope to validate their findings in multicenter prospective studies.
Disclosures are not available for this presentation.
Li Y, Shang C, Ren Y, et al. Prognostic significance of absolute monocyte count and lymphocyte to monocyte ratio in mucosa-associated lymphoid tissue (MALT). Presented at EHA 2022; June 9-12, 2022. Abstract P1118.