Children's Oncology Group Trial AALL1231: A Phase III Clinical Trial Testing Bortezomib in Newly Diagnosed T-Cell Acute Lymphoblastic Leukemia and Lymphoma.

PURPOSE: To improve the outcomes of patients with T-cell acute lymphoblastic leukemia (T-ALL) and lymphoblastic lymphoma (T-LL), the proteasome inhibitor bortezomib was examined in the Children's Oncology Group phase III clinical trial AALL1231, which also attempted to reduce the use of prophylactic cranial radiation (CRT) in newly diagnosed T-ALL. PATIENTS AND METHODS: Children and young adults with T-ALL/T-LL were randomly assigned to a modified augmented Berlin-Frankfurt-Münster chemotherapy regimen with/without bortezomib during induction and delayed intensification. Multiple modifications were made to the augmented Berlin-Frankfurt-Münster backbone used in the predecessor trial, AALL0434, including using dexamethasone instead of prednisone and adding two extra doses of pegaspargase in an attempt to eliminate CRT in most patients. RESULTS: AALL1231 accrued 824 eligible and evaluable patients from 2014 to 2017. The 4-year event-free survival (EFS) and overall survival (OS) for arm A (no bortezomib) versus arm B (bortezomib) were 80.1% ± 2.3% versus 83.8% ± 2.1% (EFS, P = .131) and 85.7% ± 2.0% versus 88.3% ± 1.8% (OS, P = .085). Patients with T-LL had improved EFS and OS with bortezomib: 4-year EFS (76.5% ± 5.1% v 86.4% ± 4.0%; P = .041); and 4-year OS (78.3% ± 4.9% v 89.5% ± 3.6%; P = .009). No excess toxicity was seen with bortezomib. In AALL0434, 90.8% of patients with T-ALL received CRT. In AALL1231, 9.5% of patients were scheduled to receive CRT. Evaluation of comparable AALL0434 patients who received CRT and AALL1231 patients who did not receive CRT demonstrated no statistical differences in EFS (P = .412) and OS (P = .600). CONCLUSION: Patients with T-LL had significantly improved EFS and OS with bortezomib on the AALL1231 backbone. Systemic therapy intensification allowed elimination of CRT in more than 90% of patients with T-ALL without excess relapse.

Outcome in Children With Standard-Risk B-Cell Acute Lymphoblastic Leukemia: Results of Children's Oncology Group Trial AALL0331.

PURPOSE: Children's Oncology Group (COG) AALL0331 tested whether intensified postinduction therapy that improves survival in children with high-risk B-cell acute lymphoblastic leukemia (ALL) would also improve outcomes for those with standard-risk (SR) ALL. PATIENTS AND METHODS: AALL0331 enrolled 5,377 patients between 2005 and 2010. All patients received a 3-drug induction with dexamethasone, vincristine, and pegaspargase (PEG) and were then classified as SR low, SR average, or SR high. Patients with SR-average disease were randomly assigned to receive either standard 4-week consolidation (SC) or 8-week intensified augmented Berlin-Frankfurt-Münster (BFM) consolidation (IC). Those with SR-high disease were nonrandomly assigned to the full COG-augmented BFM regimen, including 2 interim maintenance and delayed intensification phases. RESULTS: The 6-year event-free survival (EFS) rate for all patients enrolled in AALL0331 was 88.96% ± 0.46%, and overall survival (OS) was 95.54% ± 0.31%. For patients with SR-average disease, the 6-year continuous complete remission (CCR) and OS rates for SC versus IC were 87.8% ± 1.3% versus 89.1% ± 1.2% (P = .52) and 95.8% ± 0.8% versus 95.2% ± 0.8% (P = 1.0), respectively. Those with SR-average disease with end-induction minimal residual disease (MRD) of 0.01% to < 0.1% had an inferior outcome compared with those with lower MRD and no improvement with IC (6-year CCR: SC, 77.5% ± 4.8%; IC, 77.1% ± 4.8%; P = .71). At 6 years, the CCR and OS rates among 635 nonrandomly treated patients with SR-high disease were 85.55% ± 1.49% and 92.97% ± 1.08%, respectively. CONCLUSION: The 6-year OS rate for > 5,000 children with SR ALL enrolled in AALL0331 exceeded 95%. The addition of IC to treatment for patients with SR-average disease did not improve CCR or OS, even in patients with higher MRD, in whom it might have been predicted to provide more value. The EFS and OS rates are excellent for this group of patients with SR ALL, with particularly good outcomes for those with SR-high disease.

Preclinical efficacy of daratumumab in T-cell acute lymphoblastic leukemia.

As a consequence of acquired or intrinsic disease resistance, the prognosis for patients with relapsed or refractory T-cell acute lymphoblastic leukemia (T-ALL) is dismal. Novel, less toxic drugs are clearly needed. One of the most promising emerging therapeutic strategies for cancer treatment is targeted immunotherapy. Immune therapies have improved outcomes for patients with other hematologic malignancies including B-cell ALL; however no immune therapy has been successfully developed for T-ALL. We hypothesize targeting CD38 will be effective against T-ALL. We demonstrate that blasts from patients with T-ALL have robust surface CD38 surface expression and that this expression remains stable after exposure to multiagent chemotherapy. CD38 is expressed at very low levels on normal lymphoid and myeloid cells and on a few tissues of nonhematopoietic origin, suggesting that CD38 may be an ideal target. Daratumumab is a human immunoglobulin G1κ monoclonal antibody that binds CD38, and has been demonstrated to be safe and effective in patients with refractory multiple myeloma. We tested daratumumab in a large panel of T-ALL patient-derived xenografts (PDX) and found striking efficacy in 14 of 15 different PDX. These data suggest that daratumumab is a promising novel therapy for pediatric T-ALL patients.

Philadelphia chromosome-like acute lymphoblastic leukemia.

Philadelphia chromosome (Ph)-like acute lymphoblastic leukemia (ALL), also referred to as BCR-ABL1-like ALL, is a high-risk subset with a gene expression profile that shares significant overlap with that of Ph-positive (Ph+) ALL and is suggestive of activated kinase signaling. Although Ph+ ALL is defined by BCR-ABL1 fusion, Ph-like ALL cases contain a variety of genomic alterations that activate kinase and cytokine receptor signaling. These alterations can be grouped into major subclasses that include ABL-class fusions involving ABL1, ABL2, CSF1R, and PDGFRB that phenocopy BCR-ABL1 and alterations of CRLF2, JAK2, and EPOR that activate JAK/STAT signaling. Additional genomic alterations in Ph-like ALL activate other kinases, including BLNK, DGKH, FGFR1, IL2RB, LYN, NTRK3, PDGFRA, PTK2B, TYK2, and the RAS signaling pathway. Recent studies have helped to define the genomic landscape of Ph-like ALL and how it varies across the age spectrum, associated clinical features and outcomes, and genetic risk factors. Preclinical studies and anecdotal reports show that targeted inhibitors of relevant signaling pathways are active in specific Ph-like ALL subsets, and precision medicine trials have been initiated for this high-risk ALL subset.

Potent efficacy of combined PI3K/mTOR and JAK or ABL inhibition in murine xenograft models of Ph-like acute lymphoblastic leukemia.

Philadelphia chromosome (Ph)-like B-cell acute lymphoblastic leukemia (Ph-like ALL) is associated with activated JAK/STAT, Abelson kinase (ABL), and/or phosphatidylinositol 3-kinase (PI3K) signaling and poor clinical outcomes. PI3K pathway signaling inhibitors have been minimally investigated in Ph-like ALL. We hypothesized that targeted inhibition of PI3Kα, PI3Kδ, PI3K/mTOR, or target of rapamycin complex 1/2 (TORC1/TORC2) would decrease leukemia proliferation and abrogate aberrant kinase signaling and that combined PI3K pathway and JAK inhibition or PI3K pathway and SRC/ABL inhibition would have superior efficacy compared to inhibitor monotherapy. We treated 10 childhood ALL patient-derived xenograft models harboring various Ph-like genomic alterations with 4 discrete PI3K pathway protein inhibitors and observed marked leukemia reduction and in vivo signaling inhibition in all models. Treatment with dual PI3K/mTOR inhibitor gedatolisib resulted in near eradication of ALL in cytokine receptor-like factor 2 (CRLF2)/JAK-mutant models with mean 92.2% (range, 86.0%-99.4%) reduction vs vehicle controls (P < .0001) and in prolonged animal survival. Gedatolisib also inhibited ALL proliferation in ABL/platelet-derived growth factor receptor (PDGFR)-mutant models with mean 66.9% (range, 42.0%-87.6%) reduction vs vehicle (P < .0001). Combined gedatolisib and ruxolitinib treatment of CRLF2/JAK-mutant models more effectively inhibited ALL proliferation than either inhibitor alone (P < .001) and further enhanced survival. Similarly, superior efficacy of combined gedatolisib and dasatinib was observed in ABL/PDGFR-mutant models (P < .001). Overall, PI3K/mTOR inhibition potently decreased ALL burden in vivo; antileukemia activity was further enhanced with combination inhibitor therapy. Clinical trials testing combinations of kinase inhibitors in Ph-like ALL patients are indicated.