MIPI (Mantle Cell Lymphoma International Prognostic Index)

What is measured: prognosis at diagnosis of mantle cell lymphoma. How: MIPI (2008) combines age, ECOG performance status, LDH relative to normal and leucocyte count into low, intermediate and high risk (median survival not reached, 51 months and 29 months in the derivation cohort); MIPI-b adds the Ki-67 index and MIPI-c combines MIPI with Ki-67 at a 30 percent cut-off into four groups. The high-risk biology sits alongside: TP53 mutation or del(17p) by sequencing and FISH, blastoid or pleomorphic morphology, complex karyotype, CDKN2A deletion and Ki-67 of 30 percent or more. What a result changes: TP53-mutated patients respond poorly to cytarabine-based induction and autologous transplant, so they are steered to BTK inhibitor combinations (ibrutinib with venetoclax, acalabrutinib or zanubrutinib with rituximab), brexucabtagene autoleucel CAR-T and pirtobrutinib after BTK inhibitor failure, and to trials; the TRIANGLE trial (ibrutinib added to induction and maintenance) has questioned transplant for the rest; Ki-67 and MIPI-c stratify maintenance and trial arms. Where it matters: mantle cell lymphoma.