Is Chronic Lymphocytic Leukemia Still Incurable?

Up until now, Chronic Lymphocytic Leukemia (CLL) has been considered incurable except with an allogeneic stem cell transplant. In the last 10 years, evidence has demonstrated that chemo-immuotherapy with fludarabine, cyclophosphamide, and rituximab, (FCR) has significantly improved CR rates, overall survival (OS), and progression free survival ¹. Long term follow up data for FCR at MDACC demonstrated that a significant proportion of patients (pts.) were free at 8 years² raising the question of whether pts. are potentially cured.

Definition of cure in a chronic disease such as CLL has not been addressed. To investigate this possibility we evaluated the outcome characteristics of 222 of the 300 patients (who commenced FCR more than 10 years ago) in our previously reported study of initial therapy with FCR in CLL².

Seventy eight (35%) pts were free of relapse and 127 (58%) were alive at 10 years (Fig. 1). Thirty three patients died in CR/PR of infection (5), second malignancies (8), Richter's transformation (8). MDS (9), and other causes (3). One hundred and sixty three pts. (73%) achieved CR, 22 pts. (10%) a nodular PR (nPR), 27 pts. (12%) a PR, and 10 (5%) failed treatment. The 10 year PFS correlates strongly with response, CR (41%), nPR+PR (15%) (Fig. 2). None of these patients were transplanted in remission.

FISH analysis was not available at the time of this study. Conventional karyotyping demonstrated +12 (24 pts), del 11q (15), del 17p (4), other abnormalities (15), diploid (105), and in 59 patients the test was not done or had no metaphases. The worst outcomes were del 17p and del 11q each significantly inferior to diploid (+12) patients had the best time-to-treatment failure (TTF) with P<.09 compared to diploid.

The 10-year TTF was significantly higher for Rai <3 versus 3 – 4 (P=.02), serum beta-2-microglobulin (β2M) value of ≤ 4 mg/L (p<.001), mutation status of IgVh (P<.001) and number of courses of FCR received. (Table 1) The causes for receiving <6 courses of FCR were persistent cytopenia (15), infections (6), resistance (5), Richter's transformation and other malignancies (9), autoimmune hemolysis (5), and other causes and lost to follow-up (16).

Of the 77 patients who are still in remission at 10 years, two have relapsed and one developed Richter's transformation. Four of 21 patients checked had no residual disease in their blood at 10 years by 4-parameter flow cytometry. All other 10 yr. TTF patients are being contacted to provide blood for 4-parameter flow residual disease.

The present data suggest that one-third of patients treated with chemoimmunotherapy are potentially cured of CLL. The characteristics most strongly associated with 10 yr. TTF were Rai stage, serum β2M level, mutation status, and tolerance of chemotherapy. Second malignancies and transformations are emerging as significantly impairing the likelihood of cure.

Figure 1.

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Survival vs. Time to Fail

Figure 1.

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Survival vs. Time to Fail

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Figure 2.

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Time to Fail By Response

Figure 2.

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Time to Fail By Response

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No relevant conflicts of interest to declare.