An international prognostic index for patients with chronic lymphocytic leukemia (CLL) may help to inform treatment decisions, based on a meta-analysis presented at the International Congress on Malignant Lymphoma in Lugano, Switzerland.

The International Prognostic Index for patients with CLL (CLL-IPI) combines the most important genetic risk factors and traditional clinical stage, age, and serum beta-2-microglobulin measures. By discriminating between prognostic groups, the index may aid in informing treatment of CLL patients, Dr. Jasmin Bahlo of the University Hospital Cologne, Köln, Germany, said.

The CLL-IPI consists of five risk factors – age, clinical stage, IgHV (immunoglobulin heavy-chain variable-region) gene mutation status, serum beta-2-microglobulin measure, and the presence of del(17p) and/or TP53 mutation, Dr. Bahlo said.

To develop the index, Dr. Bahlo and colleagues performed an analysis of 26 possible prognostic factors by using data from eight phase III trials from France, Germany, the United Kingdom, the United States, and Poland. The data included a full analysis set of 3,742 previously untreated patients at early and advanced stages of disease. The median age of the patients was 61 years, the median observation time was 80 months, and the main endpoint was overall survival.

From the 26 variables, the researchers identified five independent predictors for overall survival: age (65 years or more), clinical stage (Binet A/Rai 0 vs. Binet B-C/Rai I-IV), del(17p) and/or TP53 mutation status, IgHV mutation status, and serum beta-2-microglobulin measure (3.5 mg/L or more).

The index was used to identify four risk groups – low risk (score 0-1), intermediate (score 2-3), high (score 4-6), and very high (score 7-10)) – with significantly different overall survival rates at 5 years of 93%, 79%, 64%, and 23%, respectively.

The value of the index was then confirmed in 575 patients, with a 5-year overall survival rate of 91%, 80%, 52%, and 19%, respectively.

Similar findings were seen in an external data set of patients from the Mayo Clinic data set, with 5-year overall survivals of 97%, 91%, 68%, and 21%, respectively. The CLL-IPI also provided accurate estimation regarding time to first treatment; 81%, 47%, 30%, and 19% of patients in the respective risk groups were free from treatment at 5 years.

In the era of more effective treatments for CLL, the established clinical staging systems (Rai and Binet) do not accurately discriminate between prognostic groups because they do not integrate the major clinical, biologic, and genetic variables into one widely accepted prognostic system, Dr. Bahlo noted. The CLL-IPI is, therefore, an important contribution to management of this condition.

The researchers had no relevant financial disclosures.