‘Impressive’ Outcomes Sans Chemo in Poor-Prognosis ALL

The days of using chemotherapy to treat Philadelphia chromosome–positive acute lymphoblastic leukemia (Ph+ ALL) may be numbered.

In a phase 2 trial, up-front chemo-free induction/consolidation with the tyrosine kinase inhibitor dasatinib (Sprycel) and the bispecific T-cell engager antibody blinatumomab (Blincyto) yielded high rates of molecular response, “impressive” survival at 18 months, and few toxic effects of grade 3 or higher, say researchers.

With this approach, “60% of adult Ph+ ALL patients, of all ages, can obtain a molecular response, and this percent can increase further with more cycles of blinatumomab,” lead researcher Robin Foà, MD, from Sapienza University of Rome, in Italy, told Medscape Medical News.

“The rates of disease-free survival and overall survival at 18 months are highly favorable, and the protocol is associated with limited toxicity,” Foà added.

“I see this chemo-free approach becoming a realistic approach for a substantial proportion of adult Ph+ ALL patients, particularly for the older patients, keeping in mind that the incidence of Ph+ ALL increases with age,” Foà said.

The results of the study were published October 22 in The New England Journal of Medicine.

“Innovative” and “Highly Successful”

This “innovative” chemo-free approach proved “highly successful” with “surprisingly” few toxic effects, writes Dieter Hoelzer, MD, PhD, University of Frankfurt, Germany, in a linked editorial.

The Italian GIMEMA LAL2116 D-ALBA trial enrolled 63 adults (median age, 54 years; range, 24 – 82 years) with newly diagnosed Ph+ ALL. All patients received a glucocorticoid for 31 days beginning 7 days before starting treatment with dasatinib.

Dasatinib (140 mg once daily) induction therapy lasted 85 days. All patients who completed the induction phase received blinatumomab (28 μg/d) consolidation therapy. Dexamethasone (20 mg) was administered before each blinatumomab cycle. To prevent central nervous system adverse events, levetiracetam (500 mg twice daily) was administered.

All but two patients completed dasatinib induction. One was a 73-year-old woman who withdrew from the trial because of toxic effects after 10 days of dasatinib treatment. She later died of pneumonia. The other was an 82-year-old woman who had a complete hematologic response but left the trial because of pneumonia and pneumonitis.

At the end of the induction phase, 98% of the patients (62 of 63) had a complete hematologic response, including the patient with a complete hematologic response who withdrew; 29% (17 of 59 patients) had a molecular response.

Of the 61 patients who completed the induction phase, 58 received one cycle of blinatumomab, 56 received two cycles, 45 received three cycles, 37 received four cycles, and 29 received five cycles. At the end of the second blinatumomab cycle, 60% of the patients (33 of 55 patients) had a molecular response.

The percentage of patients with a molecular response increased further after receiving additional cycles of blinatumomab — to 70% (28 of 40 patients) after the third cycle, 81% (29 of 36 patients) after the fourth cycle, and 72% (21 of 29 patients) after the fifth cycle.

At a median follow-up of 18 months, overall survival was 95%, and disease-free survival (DFS) was 88%.

There were no significant differences in DFS between patients with p190-kd fusion protein (85%) and those with p210-kd fusion protein (95%). However, DFS was lower in patients with IKZF1 deletion plus additional genetic aberrations (CDKN2A or CDKN2B, PAX5, or both [ie, IKZF1plus]).

ABL1 mutations were present in six patients who had increased minimal residual disease during induction therapy. All these mutations were cleared by blinatumomab.

There were six relapses, of which three were hematologic. One occurred in a patient with a major protocol violation (a delay of more than 2 months in receiving blinatumomab), one occurred after 12 months in the patient who discontinued the trial after receiving dasatinib for 12 days, and one occurred in a patient after the second cycle of blinatumomab.

A total of 21 adverse events of grade 3 or higher were noted. They included cytomegalovirus reactivation or infection in six patients, neutropenia in four patients, persistent fever in two patients, and pleural effusion, pulmonary hypertension, and a neurologic disorder in one patient each.

Of the 24 patients who received a stem-cell allograft, two died, but only one death was related to transplant (4%).

The very low nonrelapse mortality among patients who underwent transplant during remission is “remarkable,” Hoelzer writes in his editorial. It suggests that toxicity from induction chemotherapy puts the patient at risk for toxic effects and death from subsequent stem-cell transplant — “a consequence that is avoided with targeted therapy.”

Unanswered Questions

“Will the excellent outcomes be preserved with longer follow-up? The answer is probably yes, given that the majority of relapses in ALL occur within the first 1.5 to 2.0 years after the initiation of treatment,” editorialist Hoelzer notes.

He says other outstanding questions include whether long-term outcomes will differ between patients who undergo transplant and those who do not; whether ABL1 mutations emerge; whether minimal residual disease recurs with longer follow-up; and whether this treatment approach can be used for patients with other subtypes of ALL, such as Ph-negative, B-lineage ALL, or even T-cell ALL.

“If these promising trial results hold, chemotherapy-free induction without the immediate and long-term toxic effects of intensive chemotherapy regimens could also be used in adolescents and, finally, in children. These questions will need to be addressed with longer follow-up and large, prospective trials,” Hoelzer concludes.

The study was supported by grants from the Italian Association for Cancer Research and Sapienza University of Rome. Disclosures for the authors and the editorialist are available with the full article at NEJM.org.

N Engl J Med. Published October 22, 2020.

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