Sequencing of novel agents in relapsed/refractory B-cell acute lymphoblastic leukemia: Blinatumomab and inotuzumab ozogamicin may have comparable efficacy as first or second novel agent therapy in relapsed/refractory acute lymphoblastic leukemia

BACKGROUND

The availability of novel agents (NAs), including blinatumomab and inotuzumab ozogamicin (InO), has improved the outcomes of patients with relapsed/refractory (RR) B-cell acute lymphoblastic leukemia (ALL). Because of the relative effectiveness, it is often a challenge for clinicians to determine how to best sequence these NAs with respect to efficacy and toxicity.

METHODS

In this multicenter, retrospective study of patients with RR ALL treated with blinatumomab, InO, or both, their efficacy as a first or second NA was compared.

RESULTS

Among 276 patients, 221 and 55 received blinatumomab and InO, respectively, as a first NA therapy. The complete remission (CR)/complete remission with incomplete count recovery (CRi) rate was 65% and 67% for the blinatumomab and InO groups, respectively (P = .73). The rate of treatment discontinuation due to adverse events was 4% and 7% in the blinatumomab and InO groups, respectively. Ninety-two patients (43%) in the blinatumomab group and 13 patients (29%) in the InO group proceeded with allogeneic hematopoietic stem cell transplantation. The median overall survival (OS) was 15 and 11.6 months in the blinatumomab and InO groups, respectively. A subset analysis was performed for 61 patients who received both NAs (blinatumomab and then InO [n = 40] or InO and then blinatumomab [n = 21]). The CR/CRi rate was 58% for patients who received InO as the second NA and 52% for patients who received blinatumomab as the second NA. The median OS was 10.5 for patients who received InO as the second NA and 5.9 months for patients who received blinatumomab as the second NA (P = .09).

CONCLUSIONS

Although the limited power of this study to detect a significant difference between subgroups is acknowledged, the data suggest that blinatumomab and InO may have comparable efficacy as a first or second NA therapy in RR ALL.

Venetoclax and hypomethylating agents in FLT3-mutated acute myeloid leukemia

FMS-like tyrosine kinase 3 (FLT3) mutations are prevalent in acute myeloid leukemia (AML), and their presence confers adverse risk. FLT3-mutated (FLT3m) AML is a challenging leukemia to manage, particularly in older and unfit patients as well as patients with relapsed/refractory (r/r) disease. We retrospectively analyzed the outcomes of 50 FLT3m AML patients (17 treatment-naïve, 33 r/r) treated with venetoclax (VEN) and hypomethylating agents (HMA). The overall CR/CRi rate with VEN-HMA was 60% (94% in treatment-naïve AML and 42% in r/r AML). Early (60-days) treatment related mortality was 2%. The r/r AML setting was an independent predictor of lower complete response (OR: 0.08; 95%CI: 0.00-0.60, P = .03). Cytogenetics-molecular risk, concurrent mutations, the type of FLT3 mutation (ITD vs TKD), the ITD allelic ratio, the type of HMA, age, prior exposure to HMA and receipt of prior allogeneic transplant did not independently impact response or leukemia-free survival (LFS). Concurrent IDH mutations were associated with lower CR/CRi (P = .01), while ASXL1 or TET2 mutations showed a non-significant association toward higher CR/CRi (P = .07, for both). However, none of the concurrent mutations were an independent predictor for response when adjusted to AML setting. In conclusion, VEN-HMA is associated with encouraging efficacy in FLT3m AML among both newly diagnosed unfit and r/r patients.

CAR T cells targeting BAFF-R can overcome CD19 antigen loss in B cell malignancies

CAR T cells targeting CD19 provide promising options for treatment of B cell malignancies. However, tumor relapse from antigen loss can limit efficacy. We developed humanized, second-generation CAR T cells against another B cell-specific marker, B cell activating factor receptor (BAFF-R), which demonstrated cytotoxicity against human lymphoma and acute lymphoblastic leukemia (ALL) lines. Adoptively transferred BAFF-R-CAR T cells eradicated 10-day preestablished tumor xenografts after a single treatment and retained efficacy against xenografts deficient in CD19 expression, including CD19-negative variants within a background of CD19-positive lymphoma cells. Four relapsed, primary ALLs with CD19 antigen loss obtained after CD19-directed therapy retained BAFF-R expression and activated BAFF-R-CAR, but not CD19-CAR, T cells. BAFF-R-CAR, but not CD19-CAR, T cells also demonstrated antitumor effects against an additional CD19 antigen loss primary patient-derived xenograft (PDX) in vivo. BAFF-R is amenable to CAR T cell therapy, and its targeting may prevent emergence of CD19 antigen loss variants.

Levocarnitine for pegasparaginase-induced hepatotoxicity in acute lymphoblastic leukemia

Pegasparaginase (PEG-Asp), commonly used in acute lymphoblastic leukemia (ALL), is associated with hyperbilirubinemia and elevated transaminases. Treatment of acute hepatotoxicity is limited to case studies reporting success with levocarnitine (LC). In a retrospective analysis, 25 ALL patients experienced Grade ≥3 hyperbilirubinemia and/or elevated transaminases following a single dose of PEG-Asp where 12 patients received LC compared to 13 patients with no intervention. Median LC dose was 50 mg/kg/day for a median of 11 days. Median values were greater in the LC group: total bilirubin 5.2 mg/dL vs 4.5 mg/dL (p = 0.19), AST 75.5 units/L vs. 30 units/L (p = 0.05), and ALT 263.5 units/L vs 47 units/L (p = 0.003). Time to resolution (TTR) did not significantly differ between LC and control (p = 0.08), however, patients on LC did resume therapy sooner (p = 0.17). Although significant limitations exist in the study, LC did not result in a clinically significant impact when used to treat PEG-Asp-induced hepatotoxicity.

Targeting the alpha subunit of IL-3 receptor (CD123) in patients with acute leukemia

The IL-3 alpha chain receptor (CD123) is a cell surface protein that is widely expressed by various subtypes of acute leukemia, including acute myeloid leukemia (AML), acute lymphoblastic leukemia and blastic plasmacytoid dendritic cell neoplasm. Notably, CD123 is preferentially overexpressed in leukemia stem cells (LSC) in contrast to normal hematopoietic stem cells, and this differential expression allows for the selective eradication of LSC and leukemic blasts through therapeutic targeting of CD123, with less impact on hematopoietic cells. The level of CD123 expression in AML correlates with both treatment response and outcomes. Therefore, targeting CD123 represents a promising universal therapeutic target in advanced acute leukemias irrespective of the individual leukemia phenotype. There are currently 31 ongoing clinical trials examining the utility of CD123-based targeted therapies. Here we focus our review on current efforts to target CD123 in acute leukemia through various therapeutic constructs.

Iron Overload Is Associated with Delayed Engraftment and Increased Nonrelapse Mortality in Recipients of Umbilical Cord Blood Hematopoietic Cell Transplantation

The negative impact of iron overload (IO) on outcomes of allogeneic hematopoietic cell transplantation (HCT) is well recognized, but its impact on umbilical cord blood (UCB) transplant outcome is unknown. We retrospectively analyzed outcomes of 150 patients who received UCB-HCT at our institution, stratified by pre-HCT serum ferritin (SF) level of 2000 ng/mL. Two-year overall survival rate among patients with SF >2000 and ≤2000 ng/mL was 26.1% (95% CI, 10.6% to 44.7%) and 52.1% (95% CI, 40.1% to 62.8%), respectively; hazard ratio (HR) = 2.26 (95% CI, 1.28 to 4.00, P = .005). Two-year nonrelapse mortality rate was higher among patients with SF >2000 ng/mL (56.5%; 95% CI, 33.3% to 74.4%) compared to SF ≤2000 ng/mL (30.1%; 95% CI, 20.0% to 40.9%); HR = 2.18 (95% CI, 1.10 to 4.31, P = .025). Neutrophil engraftment at 42 days was 78.3% (95% CI, 53.5% to 90.8%) in patients with SF >2000 ng/mL versus 91.8% (95% CI, 82.1% to 96.4%) in patients with SF ≤2000 ng/mL; HR = 0.58 (95% CI, 0.35 to 0.96, P = .034). A significant difference in platelet engraftment at 3 months was also observed: 52.2% (95% CI, 29.4% to 70.8%) for SF >2000 ng/mL versus 80.8% (95% CI, 69.5% to 88.3%) for SF ≤2000 ng/mL; HR = 0.48 (95% CI, 0.23 to 0.98, P = .044). In conclusion, IO defined by SF of 2000 ng/mL is a strong adverse prognostic factor for UCB-HCT and should be considered when UCB is chosen as the graft source for patients without a fully matched donor.

Long-Term Outcomes of Allogeneic Hematopoietic Cell Transplant with Fludarabine and Melphalan Conditioning and Tacrolimus/Sirolimus as Graft-versus-Host Disease Prophylaxis in Patients with Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is associated with poor survival in older adults, and allogeneic hematopoietic cell transplant (HCT) with reduced-intensity conditioning (RIC) has been an increasingly used strategy in this population. At City of Hope we conducted a retrospective analysis of 72 patients who underwent allogeneic HCT with fludarabine and melphalan (FluMel) as the conditioning regimen between 2005 and 2018, from either a matched sibling or fully matched unrelated donor while in complete remission. Tacrolimus and sirolimus (T/S) were used as graft-versus-host disease (GVHD) prophylaxis. Overall survival and progression-free survival at 4 years post-HCT were 58% and 44%, respectively. The cumulative incidences of relapse/progression and nonrelapse mortality at 4 years were 34% and 22%, respectively. Patients with Philadelphia chromosome-positive (Ph+) ALL had a significantly lower cumulative incidence of relapse/progression (20% versus 48% for patients with Ph-negative status, P = .007). In conclusion, RIC HCT with FluMel conditioning and T/S GVHD prophylaxis was associated with favorable outcomes in patients with Ph+ ALL and should be considered as a viable consolidative therapy for adult patients with ALL.

Real-World Outcomes of Adult B-Cell Acute Lymphocytic Leukemia Patients Treated With Inotuzumab Ozogamicin

BACKGROUND

Inotuzumab ozogamicin (InO) is an anti-CD22 monoclonal antibody-drug (calicheamicin) conjugate that has shown superior efficacy compared to conventional chemotherapy in relapsed/refractory (RR) B-cell acute lymphocytic leukemia (ALL) patients. We sought to find the safety and efficacy of InO in a real-world setting.

PATIENTS AND METHODS

A multicenter cohort analysis on 84 RR ALL patients who received InO outside of clinical trials was conducted to evaluate response and toxicity.

RESULTS

The median (range) age of patients at InO initiation was 50 (20-87) years. Forty patients (48%) had ≥ 3 therapies and 23 patients (27%) underwent allogeneic hematopoietic stem-cell transplantation (allo-HCT) before InO. The median (range) number of cycles of InO provided was 2 (1-6), and cumulative dose was 3.3 (1.8-9.3) mg/m². Overall response rate (complete remission/complete remission with incomplete count recovery) was 63%; 44% had complete remission with minimal residual disease negativity. Twenty-three patients (27%) with response received allo-HCT. The median duration of response was 11.5 months and when censored at allo-HCT was not reached (51% in remission at 2 years). The median overall survival after InO was 11.6 months and when censored at time of allo-HCT was 13.6 months. The most common grade 3 or higher adverse events observed were transaminitis (16%), hyperbilirubinemia (5%), bleeding (4%), veno-occlusive disease (2%), and hyperglycemia (2%). In multivariate analysis, allo-HCT after InO did not retain favorable significance for duration of response (hazard ratio = 1.27; 95% confidence interval, 0.89-1.61; P = .2) or overall survival (hazard ratio = 1.10; 95% confidence interval, 0.37-3.25; P = .85).

CONCLUSION

InO was well tolerated and had significant efficacy in RR B-cell ALL patients.

Poxvirus Vectored Cytomegalovirus Vaccine to Prevent Cytomegalovirus Viremia in Transplant Recipients: A Phase 2, Randomized Clinical Trial

Background

Triplex vaccine was developed to enhance cytomegalovirus (CMV)-specific T cells and prevent CMV reactivation early after hematopoietic stem cell transplant (HCT).

Objective

To determine the safety and efficacy of Triplex.

Design

First-in-patient, phase 2 trial. (ClinicalTrials.gov: NCT02506933).

Setting

3 U.S. HCT centers.

Participants

102 CMV-seropositive HCT recipients at high risk for CMV reactivation.

Intervention

Intramuscular injections of Triplex or placebo were given on days 28 and 56 after HCT. Triplex is a recombinant attenuated poxvirus (modified vaccinia Ankara) expressing immunodominant CMV antigens.

Measurements

The primary outcomes were CMV events (CMV DNA level ≥1250 IU/mL, CMV viremia requiring antiviral treatment, or end-organ disease), nonrelapse mortality, and severe (grade 3 or 4) graft-versus-host disease (GVHD), all evaluated through 100 days after HCT, and grade 3 or 4 adverse events (AEs) within 2 weeks after vaccination that were probably or definitely attributable to injection.

Results

A total of 102 patients (51 per group) received the first vaccination, and 91 (89.2%) received both vaccinations (46 Triplex and 45 placebo). Reactivation of CMV occurred in 5 Triplex (9.8%) and 10 placebo (19.6%) recipients (hazard ratio, 0.46 [95% CI, 0.16 to 1.4]; P = 0.075). No Triplex recipient died of nonrelapse causes during the first 100 days or had serious AEs, and no grade 3 or 4 AEs related to vaccination were observed within 2 weeks after vaccination. Incidence of severe acute GVHD after injection was similar between groups (hazard ratio, 1.1 [CI, 0.53 to 2.4]; P = 0.23). Levels of long-lasting, pp65-specific T cells with effector memory phenotype were significantly higher in Triplex than placebo recipients.

Limitation

The lower-than-expected incidence of CMV events in the placebo group reduced the power of the trial.

Conclusion

No vaccine-associated safety concerns were identified. Triplex elicited and amplified CMV-specific immune responses, and fewer Triplex-vaccinated patients had CMV viremia.

Primary Funding Source

National Cancer Institute and Helocyte.

Outcomes of Allogeneic Hematopoietic Cell Transplantation after Salvage Therapy with Blinatumomab in Patients with Relapsed/Refractory Acute Lymphoblastic Leukemia

Historically, outcomes of adult patients with relapsed acute lymphoblastic leukemia (ALL) who fail to enter remission with conventional chemotherapy are very poor. Blinatumomab, a bispecific CD3/CD19 antibody, has shown remarkable activity in relapsed/refractory (r/r) ALL. Although allogeneic hematopoietic cell transplant (HCT) is the recommended consolidation therapy for patients with r/r ALL who respond to salvage therapy, HCT and toxicity outcomes for those who received blinatumomab salvage and HCT remain largely unknown. We treated 89 patients with r/r ALL with blinatumomab, of whom 43 patients (48%) achieved remission. Here we describe our single-center experience in the subset of patients who responded to blinatumomab salvage therapy for eradication of either gross (n = 24) or minimal residual disease (n = 11) before HCT. Overall survival at 1 and 2 years after allogeneic HCT was 77% and 52%, respectively. Leukemia-free survival at 1 and 2 years were 65% and 40%, respectively. Additionally, with blinatumomab administration pre-HCT, no unusual toxicities such as delayed neutrophil/platelet engraftment or graft failure were observed. Acute grades II to IV graft-versus-host disease (GVHD) at day +100 post-HCT was at 43% and 2-year chronic GVHD was 36%, both comparable with historic control subjects. Finally, results of our subset analysis based on pre-HCT minimal residual disease (MRD) status indicated no significant difference in survival outcomes among patients undergoing transplant in MRD-negative status and the entire cohort. In conclusion, based on results of this study, blinatumomab may be considered as a safe and effective agent for r/r ALL patients before HCT.

Impact of cytogenetic abnormalities on outcomes of adult Philadelphia-negative acute lymphoblastic leukemia after allogeneic hematopoietic stem cell transplantation: a study by the Acute Leukemia Working Committee of the Center for International Blood and Marrow Transplant Research

Cytogenetic risk stratification at diagnosis has long been one of the most useful tools to assess prognosis in acute lymphoblastic leukemia (ALL). To examine the prognostic impact of cytogenetic abnormalities on outcomes after allogeneic hematopoietic cell transplantation, we studied 1731 adults with Philadelphia-negative ALL in complete remission who underwent myeloablative or reduced intensity/non-myeloablative conditioning transplant from unrelated or matched sibling donors reported to the Center for International Blood and Marrow Transplant Research. A total of 632 patients had abnormal conventional metaphase cytogenetics. The leukemia-free survival and overall survival rates at 5 years after transplantation in patients with abnormal cytogenetics were 40% and 42%, respectively, which were similar to those in patients with a normal karyotype. Of the previously established cytogenetic risk classifications, modified Medical Research Council-Eastern Cooperative Oncology Group score was the only independent prognosticator of leukemia-free survival (P=0.03). In the multivariable analysis, monosomy 7 predicted post-transplant relapse [hazard ratio (HR)=2.11; 95% confidence interval (95% CI): 1.04-4.27] and treatment failure (HR=1.97; 95% CI: 1.20-3.24). Complex karyotype was prognostic for relapse (HR=1.69; 95% CI: 1.06-2.69), whereas t(8;14) predicted treatment failure (HR=2.85; 95% CI: 1.35-6.02) and overall mortality (HR=3.03; 95% CI: 1.44-6.41). This large study suggested a novel transplant-specific cytogenetic scheme with adverse [monosomy 7, complex karyotype, del(7q), t(8;14), t(11;19), del(11q), tetraploidy/near triploidy], intermediate (normal karyotype and all other abnormalities), and favorable (high hyperdiploidy) risks to prognosticate leukemia-free survival (P=0.02). Although some previously established high-risk Philadelphia-negative cytogenetic abnormalities in ALL can be overcome by transplantation, monosomy 7, complex karyotype, and t(8;14) continue to pose significant risks and yield inferior outcomes.

Targeting cell membrane HDM2: A novel therapeutic approach for acute myeloid leukemia

The E3 ligase human double minute 2 (HDM2) regulates the activity of the tumor suppressor protein p53. A p53-independent HDM2 expression has been reported on the membrane of cancer cells but not on that of normal cells. Herein, we first showed that membrane HDM2 (mHDM2) is exclusively expressed on human and mouse AML blasts, including leukemia stem cell (LSC)-enriched subpopulations, but not on normal hematopoietic stem cells (HSCs). Higher mHDM2 levels in AML blasts were associated with leukemia-initiating capacity, quiescence, and chemoresistance. We also showed that a synthetic peptide PNC-27 binds to mHDM2 and enhances the interaction of mHDM2 and E-cadherin on the cell membrane; in turn, E-cadherin ubiquitination and degradation lead to membrane damage and cell death of AML blasts by necrobiosis. PNC-27 treatment in vivo resulted in a significant killing of both AML "bulk" blasts and LSCs, as demonstrated respectively in primary and secondary transplant experiments, using both human and murine AML models. Notably, PNC-27 spares normal HSC activity, as demonstrated in primary and secondary BM transplant experiments of wild-type mice. We concluded that mHDM2 represents a novel and unique therapeutic target, and targeting mHDM2 using PNC-27 selectively kills AML cells, including LSCs, with minimal off-target hematopoietic toxicity.

A phase II study (NCI9775) of sapanisertib (MLN0128/TAK-228) in relapsed and/or refractory acute lymphoblastic leukemia (ALL): Interim analysis

e18506

Background: Sapanisertib (SAP) is an oral small molecule dual mTOR complex 1 and 2 (TORC1/2) inhibitor that showed activity in lymphoid neoplasms. It blocks a feedback loop involving mTORC2 activation when TORC1 is selectively inhibited (Yun S et al, Blood 2016). SAP induces apoptosis of malignant lymphoid cells in vitro and in xenografts, with greatest effects in ALL cell lines. We aim to assess potential efficacy of SAP when used as a single agent in relapsed/refractory ALL. Methods: Adults (age ≥18) with ECOG performance status 0-2 and normal organ function (creatinine/total bilirubin <1.5 upper limit of normal) with relapsed and/or refractory ALL (B- or T-cell) were enrolled. Newly diagnosed patients (pts) unfit for aggressive treatments and BCR-ABL+ ALL were allowed if there was no suitable standard treatment. SAP was given at 3 mg orally daily for 21 days every 28 days. Dose escalation was allowed after 2 cycles. Hydroxyurea and corticosteroids were not allowed after starting SAP. The primary end point was complete remission (CR) or CR with incomplete count recovery (CRi). This is a one stage Simon design study with interim analysis after 11 pts completed treatment. Enrollment was continued until interim analysis was done. Results: A total of 16 pts were enrolled on the study with a median age of 46 years old, 56% being males. 1/16 (6%) was treatment naïve. Median number of prior therapies is 3 (range, 1-9). The mean duration on SAP was 14.7 days (range 1-22). Three pts were able to start cycle 2. Safety was evaluable in 14 pts. All 14 pts had at least one G3 AE, while 10 pts had at least one G4 AE. G3/4 related non-hematological adverse events (AE) included 3 mucositis, 1 hepatic failure, 1 sepsis, 3 hyperglycemia, 1 anorexia, 1 seizure, 1 confusion, and 1 pneumonitis. One pt had G5 AE with malignancy. G3/4 hematological AEs included 2 with lymphopenia, 1 thrombocytopenia, 3 with leukopenia, and 1 with neutropenia. No pt achieved a CR/CRi. Best response was stable disease in 2 (12.5%) pts. Five pts had progressive disease while 9 were not evaluable because of early removal. Conclusions: SAP exhibited the expected safety profile. Although several pts developed cytopenias on drug, there was no evidence of clinically meaningful single-agent activity against ALL. Analysis of paired bone marrow aspirates from this trial is being performed to assess whether mTOR was substantially inhibited at therapeutically achievable drug concentrations. Clinical trial information: NCT02484430.