Gene expression profiling reveals 2 overarching types of ALCL with distinct targetable biology: an LLMPP study

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• Anaplastic large cell lymphomas (ALCLs) are heterogeneous CD30+ T-cell lymphomas.
• Current classification based on ALK status inadequately addresses molecular diversity and therapeutic targets.

Purpose of the Study:

• To develop an integrated molecular classification for ALCLs.
• To identify distinct molecular subtypes with prognostic and potential therapeutic relevance.

Main Methods:

• Analysis of 689 ALCL cases using expert review, genetic subtyping (ALK, DUSP22, TP63, triple-negative), and phospho-STAT3Tyr705 immunohistochemistry.
• RNA sequencing and gene expression profiling in 393 cases to identify molecular subtypes.
• Correlating molecular subtypes with clinical presentation, prognosis, and pathway enrichment.

Main Results:

• Two main molecular types of ALCL identified, predictable by phospho-STAT3Y705 expression.
• Type I ALCLs (ALK+ and a subset of triple-negative) enriched for JAK-STAT3 pathway.
• Type II ALCLs (DUSP22/TP63 rearranged and remaining triple-negative) enriched for epigenetic regulators like EZH2.
• Distinct prognostic outcomes observed for molecular subtypes: DUSP22-rearranged (favorable), ALK+ (favorable), triple-negative (intermediate), and TP63-rearranged (poor).

Conclusions:

• An integrated molecular classification stratifies ALCLs into four distinct ALK- subtypes.
• This classification is implementable in routine practice and clinical trials.
• The subtypes are diagnostically, prognostically, biologically, and potentially therapeutically relevant.