CD49d is the strongest flow cytometry-based predictor of overall survival in chronic lymphocytic leukemia
Pietro Bulian1, Tait D Shanafelt, Chris Fegan
1Pietro Bulian, Antonella Zucchetto, and Valter Gattei, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Centro di Riferimento Oncologico, Aviano; Lilla Cro and Luca Baldini, Fondazione IRCCS Cà Granda, Ospedale Maggiore Policlinico and Università degli Studi, Milan; Gianluca Gaidano and Davide Rossi, Amedeo Avogadro University of Eastern Piedmont, Novara; Giovanni Del Poeta, Tor Vergata University, S. Eugenio Hospital, Rome, Italy; Tait D. Shanafelt, Mayo Research Center, Rochester, NY; Chris Fegan and Chris Pepper, Institute of Cancer and Genetics, Cardiff University School of Medicine, Cardiff, United Kingdom; Holger Nückel, University of Duisburg-Essen, Essen, Germany; and Antonina V. Kurtova, Alessandra Ferrajoli, and Jan A. Burger, University of Texas MD Anderson Cancer Center, Houston, TX.
Insights
CD49d is the strongest flow cytometry marker predicting survival in chronic lymphocytic leukemia (CLL). High CD49d expression significantly reduces both overall survival (OS) and treatment-free survival (TFS) in CLL patients.
Area of Science:
- Hematology
- Oncology
- Immunology
Background:
- Chronic lymphocytic leukemia (CLL) is a B-cell malignancy with variable clinical courses.
- Prognostic markers are crucial for guiding treatment decisions in CLL.
- CD49d has been suggested as a prognostic marker, but requires further validation.
Purpose of the Study:
- To definitively validate CD49d as a prognostic marker in CLL.
- To evaluate the impact of CD49d on overall survival (OS) and treatment-free survival (TFS).
Main Methods:
- Worldwide multicenter analysis of published and unpublished CLL data.
- Training/validation strategy to determine optimal CD49d cutoff.
- Pooled analysis of 2,972 CLL cases using Cox regression, adjusting for confounders.
- Recursive partitioning to rank CD49d against other prognosticators (CD38, ZAP-70).
Main Results:
- CD49d positivity (≥30% of neoplastic cells) was associated with decreased OS and TFS.
- Pooled hazard ratio for CD49d in OS was 2.5 (2.3 for TFS), remaining significant after adjustment (HR=2.0).
- CD49d was identified as the most important flow cytometry biomarker, outperforming CD38 and ZAP-70.
Conclusions:
- CD49d is the strongest flow cytometry-based predictor of OS and TFS in CLL.
- CD49d provides independent prognostic information, crucial for risk stratification in CLL management.
Purpose:
Although CD49d is an unfavorable prognostic marker in chronic lymphocytic leukemia (CLL), definitive validation evidence is lacking. A worldwide multicenter analysis was performed using published and unpublished CLL series to evaluate the impact of CD49d as an overall (OS) and treatment-free survival (TFS) predictor.
Patients And Methods:
A training/validation strategy was chosen to find the optimal CD49d cutoff. The hazard ratio (HR) for death and treatment imposed by CD49d was estimated by pooled analysis of 2,972 CLLs; Cox analysis stratified by center and stage was used to adjust for confounding variables. The importance of CD49d over other flow cytometry-based prognosticators (eg, CD38, ZAP-70) was ranked by recursive partitioning.
Results:
Patients with ≥ 30% of neoplastic cells expressing CD49d were considered CD49d+. Decrease in OS at 5 and 10 years among CD49d+ patients was 7% and 23% (decrease in TFS, 26% and 25%, respectively). Pooled HR of CD49d for OS was 2.5 (2.3 for TFS) in univariate analysis. This HR remained significant and of similar magnitude (HR, 2.0) in a Cox model adjusted for clinical and biologic prognosticators. Hierarchic trees including all patients or restricted to those with early-stage disease or those age ≤ 65 years always selected CD49d as the most important flow cytometry-based biomarker, with negligible additional prognostic information added by CD38 or ZAP-70. Consistently, by bivariate analysis, CD49d reliably identified patient subsets with poorer outcome independent of CD38 and ZAP-70.
Conclusion:
In this analysis of approximately 3,000 patients, CD49d emerged as the strongest flow cytometry-based predictor of OS and TFS in CLL.
