Current Therapeutic Strategies in Adult Acute Lymphoblastic Leukemia

Blinatumomab, a bispecific B-cell and T-cell engaging antibody, in the treatment of B-cell malignancies

Blinatumomab (Blincyto, Amgen), a bi-specific antibody, is a first-in-class, targeted immunotherapy agent for treatment of B-cell malignancies with a novel mechanism of action which involves in-vivo engagement of the patient's T cells with CD19-expressing tumour cells. Clinical trials have demonstrated its efficacy in relapsed B-cell Acute Lymphoblastic Leukaemia (B-ALL) and B-cell Non-Hodgkin's Lymphoma including in patients who are refractory to chemotherapy. This review summarises the development and design of Blinatumomab, the outcome of clinical studies demonstrating its efficacy and how to manage the administration, practically, including relevant toxicities. We compare and contrast it to other emerging agents for treatment of B-cell malignancies.

Comparison between Hyper-CVAD and PETHEMA ALL-93 in Adult Acute Lymphoblastic Leukemia: A Single-Center Study

BACKGROUND

Although cure rates in pediatric acute lymphoblastic leukemia (ALL) are quite high with combined chemotherapy regimens, complete response (CR) and long-term survival rates in adults are 80-90 and 30-40%, respectively. Currently, combined chemotherapy regimens, such as Hyper-CVAD and PETHEMA, are used in patients with adult ALL. However, there has been no study comparing the results of Hyper-CVAD and PETHEMA ALL-93.

METHODS

In this retrospective single-center study, we evaluated the results of Hyper-CVAD and PETHEMA ALL-93 in 51 ALL patients treated between September 2008 and March 2017 at the Department of Hematology, Faculty of Medicine, Karadeniz Technical University.

RESULTS

Thirty-eight patients were treated with Hyper-CVAD and 13 with PETHEMA ALL-93. CR was obtained in 90 and 100% of patients, respectively. Survival estimates were comparable between Hyper-CVAD and PE-THEMA ALL-93, with a median overall survival (OS) and a median disease-free survival (DFS) of 17.5 and 12.1 months, respectively, for Hyper-CVAD and of 18.6 and 12.9 months, respectively, for PETHEMA ALL-93. The 2-year OS rates for Hyper-CVAD and PETHEMA ALL-93 were 30 and 40%, respectively, and the 2-year DFS rates were 28 and 44%, respectively. PETHEMA ALL-93 resulted in more hepatotoxicity, hypofibrinogenemia, aspergillus infection, and skin rash than Hyper-CVAD.

CONCLUSIONS

Although Hyper-CVAD and PE-THEMA ALL-93 showed similar effects, Hyper-CVAD was tolerated better. Age and comorbidities should be taken into account before a chemotherapy regimen is determined for patients with ALL.

Targeting WEE1 to enhance conventional therapies for acute lymphoblastic leukemia

BACKGROUND

Despite the recent progress that has been made in the understanding and treatment of acute lymphoblastic leukemia (ALL), the outcome is still dismal in adult ALL cases. Several studies in solid tumors identified high expression of WEE1 kinase as a poor prognostic factor and reported its role as a cancer-conserving oncogene that protects cancer cells from DNA damage. Therefore, the targeted inhibition of WEE1 kinase has emerged as a rational strategy to sensitize cancer cells to antineoplastic compounds, which we evaluate in this study.

METHODS

The effectiveness of the selective WEE1 inhibitor AZD-1775 as a single agent and in combination with different antineoplastic agents in B and T cell precursor ALL (B/T-ALL) was evaluated in vitro and ex vivo studies. The efficacy of the compound in terms of cytotoxicity, induction of apoptosis, and changes in gene and protein expression was assessed using different B/T-ALL cell lines and confirmed in primary ALL blasts.

RESULTS

We showed that WEE1 was highly expressed in adult primary ALL bone marrow and peripheral blood blasts (n = 58) compared to normal mononuclear cells isolated from the peripheral blood of healthy donors (p = 0.004). Thus, we hypothesized that WEE1 could be a rational target in ALL, and its inhibition could enhance the cytotoxicity of conventional therapies used for ALL. We evaluated the efficacy of AZD-1775 as a single agent and in combination with several antineoplastic agents, and we elucidated its mechanisms of action. AZD-1775 reduced cell viability in B/T-ALL cell lines by disrupting the G2/M checkpoint and inducing apoptosis. These findings were confirmed in human primary ALL bone marrow and peripheral blood blasts (n = 15). In both cell lines and primary leukemic cells, AZD-1775 significantly enhanced the efficacy of several tyrosine kinase inhibitors (TKIs) such as bosutinib, imatinib, and ponatinib, and of chemotherapeutic agents (clofarabine and doxorubicin) in terms of the reduction of cell viability, apoptosis induction, and inhibition of proliferation.

CONCLUSIONS

Our data suggest that WEE1 plays a role in ALL blast's survival and is a bona fide target for therapeutic intervention. These data support the evaluation of the therapeutic potential of AZD-1775 as chemo-sensitizer agent for the treatment of B/T-ALL.

Serum neuron-specific enolase levels are upregulated in patients with acute lymphoblastic leukemia and are predictive of prognosis

We explored the relationship between neuron-specific enolase (NSE) levels and the clinical features of acute lymphoblastic leukemia (ALL). Seventy ALL patients and forty-two healthy controls were enrolled in this study, and their serum NSE levels were measured using an electrochemiluminescence assay. The serum NSE concentration was higher in ALL patients than in healthy controls. In ALL patients, the mean serum NSE level declined after complete remission (CR) but increased with relapse. In addition, the mean serum NSE level was lower in the CR group than in the non-CR group. High NSE levels were associated with poorer progression-free and overall survival than low NSE levels. Serum NSE levels closely correlated with several clinical features, including the immunophenotype, risk stratification and serum lactate dehydrogenase levels. Multivariate analysis revealed that high NSE expression was an independent prognostic factor in adult ALL patients. NSE mRNA levels were also higher in ALL cell lines and bone marrow mononuclear cells from ALL patients than in control cells. These results suggested that NSE could be a clinical prognostic factor and a potential therapeutic target in ALL.

Treatment of Relapsed/Refractory Acute Lymphoblastic Leukemia in Adults

Patients with relapsed and refractory acute lymphoblastic leukemia (ALL) have a dismal prognosis with less than 10 % of patients surviving 5 years. Most such patients cannot be rescued with currently available therapies, whatever the initial treatment they receive. Therefore, there is an urgent need for novel treatment options. Fortunately, over the past several years, an improved understanding of the biology of the disease has allowed the identification of rational molecular targets for therapeutic endeavors and the emergence of novel therapies has sparked great interest. This review will discuss the current treatment landscape for adult patients with relapsed and/or refractory ALL.

Role of Chemotherapy and Allografting in the Treatment of Acute Lymphoblastic Leukemia

We report the clinical outcomes of 83 patients with acute lymphoblastic leukemia (median age, 46 years; range, 18-75 years) treated at our institution between 1999 and 2011. Treatment refers to clinical trials open for accrual at the time of diagnosis or to institutional guidelines. Upfront allografting was considered for younger high-risk patients. Seventy-eight of 83 (94%) patients achieved complete remission after induction, although 53% of them eventually relapsed. Forty of 70 patients younger than 61 years underwent allografting. The median follow-up was 7.4 years (range, 0.2-15.0 years). Overall, the 5-year overall survival (OS) and event-free survival (EFS) were 40% and 39%, respectively. In patients undergoing transplantation, OS and EFS at 5 years were both 53%, whereas in a nontransplantation setting, both OS and EFS were 35% at 5 years (P = .044 for both OS and EFS). By multivariate analysis, the independent predictors of OS and EFS were age and leukocytosis in the overall population and allografting in young patients.

In vitro and in vivo single-agent efficacy of checkpoint kinase inhibition in acute lymphoblastic leukemia

BACKGROUND

Although progress in children, in adults, ALL still carries a dismal outcome. Here, we explored the in vitro and in vivo activity of PF-00477736 (Pfizer), a potent, selective ATP-competitive small-molecule inhibitor of checkpoint kinase 1 (Chk1) and with lower efficacy of checkpoint kinase 2 (Chk2).

METHODS

The effectiveness of PF-00477736 as single agent in B-/T-ALL was evaluated in vitro and in vivo studies as a single agent. The efficacy of the compound in terms of cytotoxicity, induction of apoptosis, and changes in gene and protein expression was assessed using different B-/T-ALL cell lines. Finally, the action of PF-00477736 was assessed in vivo using leukemic mouse generated by a single administration of the tumorigenic agent N-ethyl-N-nitrosourea.

RESULTS

Chk1 and Chk2 are overexpressed concomitant with the presence of genetic damage as suggested by the nuclear labeling for γ-H2A.X (Ser139) in 68 % of ALL patients. In human B- and T-ALL cell lines, inhibition of Chk1/2 as a single treatment strategy efficiently triggered the Chk1-Cdc25-Cdc2 pathway resulting in a dose- and time-dependent cytotoxicity, induction of apoptosis, and increased DNA damage. Moreover, treatment with PF-00477736 showed efficacy ex vivo in primary leukemic blasts separated from 14 adult ALL patients and in vivo in mice transplanted with T-ALL, arguing in favor of its future clinical evaluation in leukemia.

CONCLUSIONS

In vitro, ex vivo, and in vivo results support the inhibition of Chk1 as a new therapeutic strategy in acute lymphoblastic leukemia, and they provide a strong rationale for its future clinical investigation.

Treatment of High-Risk Philadelphia Chromosome–Negative Acute Lymphoblastic Leukemia in Adolescents and Adults According to Early Cytologic Response and Minimal Residual Disease After Consolidation Assessed by Flow Cytometry: Final Results of the PETHEMA ALL-AR-03 Trial

Purpose

Minimal residual disease (MRD) is an important prognostic factor in adults with acute lymphoblastic leukemia (ALL) and may be used for treatment decisions. The Programa Español de Tratamientos en Hematología (PETHEMA) ALL-AR-03 trial (Treatment of High Risk Adult Acute Lymphoblastic Leukemia [LAL-AR/2003]) assigned adolescent and adult patients (age 15 to 60 years) with high-risk ALL (HR-ALL) without the Philadelphia (Ph) chromosome to chemotherapy or to allogeneic hematopoietic stem-cell transplantation (allo-HSCT) according to early cytologic response (day 14) and flow-MRD level after consolidation.

Patients and Methods

Patients with good early cytologic response (< 10% blasts in bone marrow at day 14 of induction) and a flow-MRD level less than 5 × 10−4 at the end of consolidation were assigned to delayed consolidation and maintenance therapy, and allo-HSCT was scheduled in patients with poor early cytologic response or flow-MRD level ≥ 5 × 10−4.

Results

Complete remission was attained in 282 (87%) of 326 patients, and 179 (76%) of 236 patients who completed early consolidation were assigned by intention-to treat to receive allo-HSCT (71) or chemotherapy (108). Five-year disease-free survival (DFS) and overall survival (OS) probabilities were 37% and 35% for the whole series, 32% and 37% for patients assigned to allo-HSCT, and 55% and 59% for those assigned to chemotherapy. Multivariable analysis showed poor MRD clearance (≥ 1 × 10−3 after induction and ≥ 5 × 10−4 after early consolidation) as the only prognostic factor for DFS and OS.

Conclusion

Prognosis for Ph-negative HR-ALL in adolescents and adults with good early response to induction and low flow-MRD levels after consolidation is quite favorable when allo-HSCT is avoided. In this study, the pattern of MRD clearance was the only prognostic factor for DFS and OS.

Recognition of adult and pediatric acute lymphoblastic leukemia blasts by natural killer cells

In this study, we aimed to investigate the pathways of recognition of acute lymphoblastic leukemia blasts by natural killer cells and to verify whether differences in natural killer cell activating receptor ligand expression among groups defined by age of patients, or presence of cytogenetic/molecular aberrations correlate with the susceptibility to recognition and killing. We analyzed 103 newly diagnosed acute lymphoblastic leukemia patients: 46 adults and 57 children. Pediatric blasts showed a significantly higher expression of Nec-2 (P=0.03), ULBP-1 (P=0.01) and ULBP-3 (P=0.04) compared to adult cells. The differential expression of these ligands between adults and children was confined to B-lineage acute lymphoblastic leukemia with no known molecular alterations. Within molecularly defined subgroups of patients, a high surface expression of NKG2D and DNAM1 ligands was found on BCR-ABL(+) blasts, regardless of patient age. Accordingly, BCR-ABL(+) blasts proved to be significantly more susceptible to natural killer-dependent lysis than B-lineage blasts without molecular aberrations (P=0.03). Cytotoxic tests performed in the presence of neutralizing antibodies indicated a pathway of acute lymphoblastic leukemia cell recognition in the setting of the Nec-2/DNAM-1 interaction. These data provide a biological explanation of the different roles played by alloreactive natural killer cells in pediatric versus adult acute lymphoblastic leukemia and suggest that new natural killer-based strategies targeting specific subgroups of patients, particularly those BCR-ABL(+), are worth pursuing further.

Treatment of elderly patients with acute lymphoblastic leukaemia using a paediatric-based protocol

All newly diagnosed patients aged 60-79 years with acute lymphoblastic leukaemia (ALL) receiving induction chemotherapy with a modified paediatric-based regimen over a 7-year period were retrospectively analysed (n = 51, median age 65 years). The treatment regimen consisted of induction, central nervous system prophylaxis, seven cycles of intensification and 24 cycles of maintenance. BCR-ABL1 negative patients received weekly asparaginase during intensification, while BCR-ABL1+ patients received daily imatinib. Post-remission therapy was given in an outpatient setting. The complete response rate was 75%, with an induction mortality of 20%; 6% of patients had resistant disease. 37% of patients who achieved a complete remission relapsed. The estimated 5-year overall survival was 40% for BCR-ABL1 negative and 47% for BCR-ABL1+ patients (P = not significant); the 5-year disease-free survival was 57% and 39%, respectively (P = NS). The post-induction phase was generally well tolerated, with 81% able to complete the intensification phase and proceed to maintenance. In conclusion, administration of this modified paediatric-based protocol is feasible and active for elderly patients with ALL. Survival is superior to most previously reported series in this age group, but remains worse compared to younger patients. Further improvement of the toxicity profile, particularly during induction, is required to improve outcomes.

Leukemia cell-rhabdovirus vaccine: personalized immunotherapy for acute lymphoblastic leukemia

PURPOSE

Acute lymphoblastic leukemia (ALL) remains incurable in most adults. It has been difficult to provide effective immunotherapy to improve outcomes for the majority of patients. Rhabdoviruses induce strong antiviral immune responses. We hypothesized that mice administered ex vivo rhabdovirus-infected ALL cells [immunotherapy by leukemia-oncotropic virus (iLOV)] would develop robust antileukemic immune responses capable of controlling ALL.

EXPERIMENTAL DESIGN

Viral protein production, replication, and cytopathy were measured in human and murine ALL cells exposed to attenuated rhabdovirus. Survival following injection of graded amounts of ALL cells was compared between cohorts of mice administered γ-irradiated rhabdovirus-infected ALL cells (iLOV) or multiple control vaccines to determine key immunotherapeutic components and characteristics. Host immune requirements were assessed in immunodeficient and bone marrow-transplanted mice or by adoptive splenocyte transfer from immunized donors. Antileukemic immune memory was ascertained by second leukemic challenge in long-term survivors.

RESULTS

Human and murine ALL cells were infected and killed by rhabdovirus; this produced a potent antileukemia vaccine. iLOV protected mice from otherwise lethal ALL by developing durable leukemia-specific immune-mediated responses (P < 0.0001), which required an intact CTL compartment. Preexisting antiviral immunity augmented iLOV potency. Splenocytes from iLOV-vaccinated donors protected 60% of naïve recipients from ALL challenge (P = 0.0001). Injecting leukemia cells activated by, or concurrent with, multiple Toll-like receptor agonists could not reproduce the protective effect of iLOV. Similarly, injecting uninfected irradiated viable, apoptotic, or necrotic leukemia cells with/without concurrent rhabdovirus administration was ineffective.

CONCLUSION

Rhabdovirus-infected leukemia cells can be used to produce a vaccine that induces robust specific immunity against aggressive leukemia.

Outcome of patients with acute lymphoblastic leukemia (ALL) following induction therapy with a modified (pulsed dexamethasone rather than continuous prednisone) UKALL XII/ECOG E2993 protocol at Tawam Hospital, United Arab Emirates (UAE)

This retrospective data analysis examined the outcome of 99 acute lymphoblastic leukemia (ALL) patients treated at Tawam Hospital between January 2000 and December 2009. Sixteen patients were treated before June 2002, and 83 patients were treated from June 2002. A modified form of UKALL XII/ECOG E2993 with pulsed dexamethasone in induction phase one (modified UKALL) was the main therapy from June 2002 (71/83). The median age was 28 years. Fifty-eight percent had pre-B ALL where 36 % of them were Philadelphia chromosome-positive (Ph+). Overall, complete remission (CR) rate was 86.7 % which was significantly inferior for patients with white blood cell count 30-100 × 10⁹/l (p = 0.009), therapy before June 2002 (p = 0.02), pregnancy (p = 0.005), CNS leukemia (p = 0.028), and unknown karyotype (p = 0.004). With a median follow-up of 11.8 months (0.49-126 months), the estimated overall survival (OS) and event-free survival (EFS) at 3 years were 50.6 and 28.7 %, respectively. OS and EFS were significantly inferior for patients not in CR after induction, age >20 years, Ph+, unknown karyotype and therapy before June 2002. In addition, CR, OS and EFS were significantly superior (p = 0.004, p < 0.001 and p = 0.001, respectively) for therapy with our modified UKALL protocol compared to Tawam protocol (main therapy before June 2002). In conclusion, the outcome of treatment for ALL at our institute is encouraging with significant improvement in the outcome of older adolescents and young adults when using high-intensity chemotherapy. This suggests that such an approach is feasible in developing countries in spite of some limitations including lack of stem cell transplantation service.

Selective inhibition of cell death in malignant vs normal B-cell precursors: implications for cAMP in development and treatment of BCP-ALL

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is the most commonly occurring pediatric cancer. Despite its relatively good prognosis, there is a steady search for strategies to improve treatment effects and prevent the undesired side effects on normal cells. In the present paper, we demonstrate a differential effect of cyclic adenosine monophosphate (cAMP) signaling between normal BCPs and BCP-ALL blasts, pointing to a potential therapeutic window allowing for manipulation of cAMP signaling in the treatment of BCP-ALL. By studying primary cells collected from pediatric BCP-ALL patients and healthy controls, we found that cAMP profoundly decreased basal and DNA damage-induced p53 levels and cell death in malignant cells, whereas normal BCP counterparts displayed slightly augmented cell death when exposed to cAMP-increasing agents. We did not find evidence for a selection process involving generation of increased basal cAMP levels in BCP-ALL cells, but we demonstrate that paracrine signaling involving prostaglandin E2-induced cAMP generation has the potential to suppress p53 activation and cell death induction. The selective inhibitory effect of cAMP signaling on DNA damage-induced cell death in BCP-ALL cells appears to be an acquired trait associated with malignant transformation, potentially allowing the use of inhibitors of this pathway for directed killing of the malignant blasts.

Has MRD monitoring superseded other prognostic factors in adult ALL?

Significant improvements have been made in the treatment of acute lymphoblastic leukemia (ALL) during the past 2 decades, and measurement of submicroscopic (minimal) levels of residual disease (MRD) is increasingly used to monitor treatment efficacy. For a better comparability of MRD data, there are ongoing efforts to standardize MRD quantification using real-time quantitative PCR of clonal immunoglobulin and T-cell receptor gene rearrangements, real-time quantitative-based detection of fusion gene transcripts or breakpoints, and multiparameter flow cytometric immunophenotyping. Several studies have demonstrated that MRD assessment in childhood and adult ALL significantly correlates with clinical outcome. MRD detection is particularly useful for evaluation of treatment response, but also for early assessment of an impending relapse. Therefore, MRD has gained a prominent position in many ALL treatment studies as a tool for tailoring therapy with growing evidence that MRD supersedes most conventional stratification criteria at least for Ph-negative ALL. Most study protocols on adult ALL follow a 2-step approach with a first classic pretherapeutic and a second MRD-based risk stratification. Here we discuss whether and how MRD is ready to be used as main decisive marker and whether pretherapeutic factors and MRD are really competing or complementary tools to individualize treatment.