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The addition of nelarabine can improve treatment outcomes for certain patients with T-cell acute lymphoblastic leukemia (T-ALL), according to a phase 3 trial.

Patients with newly diagnosed, intermediate- or high-risk T-ALL had a significant improvement in 4-year disease-free survival (DFS) if they received nelarabine in addition to chemotherapy and cranial irradiation.

The DFS benefit with nelarabine was significant for patients who received high-dose methotrexate but not for those who received escalating-dose methotrexate.

This study also included patients with T-cell lymphoblastic lymphoma (T-LL), and they did not experience an improvement in DFS with the addition of nelarabine.

Kimberly Dunsmore, MD, of Virginia Tech Carilion School of Medicine in Roanoke, presented these results in a press briefing in advance of the 2018 ASCO Annual Meeting. Additional results are scheduled to be presented at the meeting as abstract 10500.

This research was supported by the National Cancer Institute/National Institutes of Health and St. Baldrick’s Foundation. The researchers’ disclosures are listed with the abstract.

Patients and treatment

The trial enrolled 1895 patients, ages 1 to 30, who were newly diagnosed with T-ALL (94%) or T-LL (6%).

Patients received standard 4-drug induction chemotherapy, and 1307 of these patients were then randomized to 1 of 4 treatment arms.

Regardless of which arm they were randomized to, patients received an 11-drug chemotherapy regimen—the augmented Berlin-Frankfurt-Munster regimen. Intermediate- and high-risk patients in all 4 arms also received cranial irradiation.

In the first treatment arm, T-LL (n=58) and T-ALL (n=372) patients received escalating-dose methotrexate without leucovorin rescue and pegaspargase (C-MTX).

In the second treatment arm, patients with intermediate- and high-risk T-ALL (n=147) and T-LL (n=60) received C-MTX plus nelarabine (six 5-day courses at 650 mg/m2/day).

In the third arm, T-ALL patients (n=451) received high-dose methotrexate with leucovorin rescue (HD-MTX). T-LL patients were not eligible for this arm or the fourth treatment arm.

In the fourth arm, intermediate- and high-risk T-ALL patients (n=219) received HD-MTX and nelarabine (same schedule as above). This included 43 T-ALL patients who had induction failure and were assigned to this arm non-randomly.

Results

For T-ALL patients, the 4-year disease-free survival (DFS) rate was 84%, and the 4-year overall survival rate was 90%.

There was a significant improvement in DFS for T-ALL patients who received nelarabine compared to those who did not—89% and 83%, respectively (P=0.0332).

“Historically, about 80% of people [with T-ALL] live at least 4 years after being treated for their disease, but we felt we could and must do better,” Dr Dunsmore said. “Our trial shows that we could further increase survival rates by about 10%, which is very encouraging.”

Dr Dunsmore also noted that patients who received nelarabine had fewer central nervous system relapses.

Among T-ALL patients who received C-MTX, there was no significant difference in DFS for those who received nelarabine and those who did not—92% and 90%, respectively (P=0.3825).

However, for patients who received HD-MTX, the difference in DFS was significant. The DFS rate was 86% in patients who received nelarabine and 78% in those who did not (P=0.024).

For the T-ALL patients who failed induction and were assigned to HD-MTX and nelarabine, the 4-year DFS rate was 55%.

Patients with T-LL did not benefit from the addition of nelarabine. The 4-year DFS rate was 85% in the nelarabine recipients and 89% in non-recipients (P=0.2788).

There were no significant differences in overall toxicity or peripheral neurotoxicity between the treatment arms.

Dr Dunsmore said the next step with this research will be to examine the implications and potential benefits of using nelarabine in treatment protocols that do not include cranial radiation.


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