Phase 1 study of vibecotamab identifies an optimized dose for treatment of relapsed/refractory acute myeloid leukemia.

Acute myeloid leukemia (AML), an aggressive malignancy with unmet medical need, lacks immunotherapeutic options. CD123, the cellular receptor for interleukin-3, expressed in AML is an attractive target for tumor-specific therapy. Vibecotamab (XmAb14045), a humanized bispecific antibody, monovalently binds both CD3 and CD123 to recruit cytotoxic T cells to kill CD123+ tumor cells. This phase 1 study's primary objectives were safety and tolerability and identification of a maximum tolerated dose/recommended dose for use as monotherapy in patients with relapsed/refractory AML. Identification of a recommended phase 2 vibecotamab dose comprised 3 step-up doses (Week 1), which were noted to reduce cytokine response syndrome (CRS), followed by weekly dosing (1.7 µg/kg, Cohort -1D). In 16 of 120 patients, at least 1 treatment-emergent adverse event was classified as a dose-limiting toxicity. CRS, the most common adverse event (59.2%), managed with premedication, were mostly ≤grade 2. A secondary objective was assessment of efficacy in patients with CD123-expressing leukemias. A total of 10 of 111 (9.0%) efficacy-evaluable patients with AML achieved an overall response of morphologic leukemia-free state or better with an overall objective response rate (ORR) of 9.0%. Response was only observed in patients receiving a target dose of 0.75 µg/kg or higher (n = 87) in which the efficacy-evaluable ORR was 11.5%. Response was associated with lower baseline blast counts in blood and bone marrow (<25%) suggesting potential benefit. This trial was registered at www.clinicaltrials.gov as #NCT02730312.

The role of adjuvant chemotherapy in the management of acute promyelocytic leukemia differentiation syndrome.

Acute Promyelocytic Leukemia (APL) is characterized by the t(15;17) chromosomal translocation resulting in a PML-RARA fusion protein. The all-trans-retinoic acid (ATRA) and Arsenic Trioxide (ATO) only regimens have demonstrated success in treating low- and intermediate-risk patients. However, induction with ATRA/ATO only regimens have been showing increased incidence of differentiation syndrome (DS), a potentially lethal complication, traditionally treated with dexamethasone. We conducted a three-institution retrospective study, aiming to evaluate the role of short-term adjuvant chemotherapy in managing moderate DS for patients with low- or intermediate-risk APL initially treated with ATRA/ATO only protocols. We evaluated the difference in incidence and duration of moderate DS in APL patients who were treated with ATRA/ATO with or without adjuvant chemotherapy. 57 low- or intermediate-risk APL patients were retrospectively identified and included for this study; 36 patients received ATRA/ATO only induction treatment, and 21 patients received ATRA/ATO/adjuvant chemotherapy combination induction therapy. Similar proportions of patients experienced DS in both groups (66.7% vs. 81.0%, P = 0.246). The median duration of DS resolution in patients receiving ATRA/ATO only was 17 days (n = 23), and in patients receiving combination therapy was 8 days (n = 16) (P = 0.0001). The lengths of hospital stay in patients receiving ATRO/ATO only was 38 days (n = 7), and in patients receiving combination therapy was 14 days (n = 17) (P = 0.0007). In conclusion, adding adjuvant chemotherapy to ATRA/ATO only protocol may reduce the duration of DS and the length of hospital stay during APL induction treatment.

KTE-X19 anti-CD19 CAR T-cell therapy in adult relapsed/refractory acute lymphoblastic leukemia: ZUMA-3 phase 1 results.

ZUMA-3 is a phase 1/2 study evaluating KTE-X19, an autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, in adult relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). We report the phase 1 results. After fludarabine-cyclophosphamide lymphodepletion, patients received a single infusion of KTE-X19 at 2 × 106, 1 × 106, or 0.5 × 106 cells per kg. The rate of dose-limiting toxicities (DLTs) within 28 days after KTE-X19 infusion was the primary end point. KTE-X19 was manufactured for 54 enrolled patients and administered to 45 (median age, 46 years; range, 18-77 years). No DLTs occurred in the DLT-evaluable cohort. Grade ≥3 cytokine release syndrome (CRS) and neurologic events (NEs) occurred in 31% and 38% of patients, respectively. To optimize the risk-benefit ratio, revised adverse event (AE) management for CRS and NEs (earlier steroid use for NEs and tocilizumab only for CRS) was evaluated at 1 × 106 cells per kg KTE-X19. In the 9 patients treated under revised AE management, 33% had grade 3 CRS and 11% had grade 3 NEs, with no grade 4 or 5 NEs. The overall complete remission rate correlated with CAR T-cell expansion and was 83% in patients treated with 1 × 106 cells per kg and 69% in all patients. Minimal residual disease was undetectable in all responding patients. At a median follow-up of 22.1 months (range, 7.1-36.1 months), the median duration of remission was 17.6 months (95% confidence interval [CI], 5.8-17.6 months) in patients treated with 1 × 106 cells per kg and 14.5 months (95% CI, 5.8-18.1 months) in all patients. KTE-X19 treatment provided a high response rate and tolerable safety in adults with R/R B-ALL. Phase 2 is ongoing at 1 × 106 cells per kg with revised AE management. This trial is registered at www.clinicaltrials.gov as #NCT02614066.

Phase II study of tosedostat with cytarabine or decitabine in newly diagnosed older patients with acute myeloid leukaemia or high-risk MDS.

Tosedostat, an oral aminopeptidase inhibitor, has synergy with cytarabine and hypomethylating agents. We performed a Phase II trial to determine rates of complete remission (CR) and survival using tosedostat with cytarabine or decitabine in older patients with untreated acute myeloid leukaemia (AML) or high-risk myelodysplastic syndrome (MDS). Thirty-four patients ≥60 years old (median age 70 years; range, 60-83) were randomized to receive tosedostat (120 mg on days 1-21 or 180 mg continuously) with 5 d of either cytarabine (1 g/m2 /d) or decitabine (20 mg/m2 /d) every 35 d. Twenty-nine patients (85%) had AML, including 15 (44%) with secondary AML/MDS, and 5 (15%) had MDS-refractory anaemia with excess blasts type 2. The CR/CR with incomplete count recovery (CRi) rate was 53% [9 in each arm; 14 CR (41%) and 4 CRi (12%)], attained in 6 of 14 patients with adverse cytogenetics and 4 of 7 with FLT3-internal tandem duplication mutations. Median follow-up was 11.2 months (range, 0.5-22.3), and median survival was 11.5 months (95% confidence interval, 5.2-16.7). Twenty-three patients (67.6%) were treated as outpatients and 10 of these patients required hospitalization for febrile neutropenia. No Grade 3-4 non-haematological toxicities required withdrawal from study. Tosedostat with cytarabine or decitabine is tolerated in older patients with untreated AML/MDS, results in a CR/CRi rate of >50%, and warrants further study in larger trials.

Anti-CD45 radioimmunotherapy without TBI before transplantation facilitates persistent haploidentical donor engraftment.

Many patients with hematologic malignancies cannot tolerate hematopoietic cell transplantation (HCT), whereas others may not have a compatible human leukocyte antigen-matched donor. To overcome these limitations, we optimized a conditioning regimen employing anti-CD45 radioimmunotherapy (RIT) replacing total body irradiation (TBI) before haploidentical HCT in a murine model. Mice received 200 to 400 µCi (90)Y-anti-CD45 antibody (30F11), with or without fludarabine (5 days starting day -8), with cyclophosphamide (CY; days -2 and +2) for graft-versus-host disease prophylaxis, and 1.5 × 10(7) haploidentical donor bone marrow cells (day 0). Haploidentical bone marrow transplantation (BMT) with 300 µCi (90)Y-anti-CD45 RIT and CY, without TBI or fludarabine, led to mixed chimeras with 81.3 ± 10.6% mean donor origin CD8(+) cells detected 1 month after BMT, and remained stable (85.5 ± 11% mean donor origin CD8(+) cells) 6 months after haploidentical BMT. High chimerism levels were induced across multiple hematopoietic lineages 28 days after haploidentical BMT with 69.3 ± 14.1%, 75.6 ± 20.2%, and 88.5 ± 11.8% CD3(+) T cells, B220(+) B cells, and CD11b(+) myeloid cells, respectively. Fifty percent of SJL leukemia-bearing mice treated with 400 µCi (90)Y-DOTA-30F11, CY, and haploidentical BMT were cured and lived >200 days. Mice treated with 200 µCi (90)Y-DOTA-30F11 had a median overall survival of 73 days, while untreated leukemic mice had a median overall survival of 34 days (P < .001, Mantel-Cox test). RIT-mediated haploidentical BMT without TBI may increase treatment options for aggressive hematologic malignancies.

A phase I/II study of oral clofarabine plus low-dose cytarabine in previously treated acute myeloid leukaemia and high-risk myelodysplastic syndrome patients at least 60 years of age.

Outcomes for older adults with acute myeloid leukaemia (AML) and myelodysplastic syndrome (MDS) are generally poor, and new effective therapies are needed. We investigated oral clofarabine combined with low-dose cytarabine (LDAC) in patients aged 60 years and above with relapsed or refractory AML or high-risk MDS in a phase I/II trial. A 3 + 3 dose escalation of oral clofarabine was followed by a phase II expansion with the aim of obtaining a complete response (CR) rate ≥30%. We identified 20 mg/d for 5 d as the maximum tolerated dose (MTD) of oral clofarabine. A total of 35 patients, with a median age of 72 years, were treated. Of 26 patients enrolled at the MTD, 4 had treatment-related grade 3-4 non-haematological toxicities, but none died within 28 d. The observed CR rate and median survival were 34% [95% confidence interval (CI), 18-50%] and 6.8 months overall and 38% [95% CI, 19-57%] and 7.2 months at the MTD. The median disease-free survival was 7.4 months. Fifty-two percent (23/44) of cycles administered at the MTD were done without hospital admission. This combination of oral clofarabine and LDAC demonstrated efficacy with a CR rate of >30% and acceptable toxicity in older patients.

Idarubicin, cytarabine, and pravastatin as induction therapy for untreated acute myeloid leukemia and high-risk myelodysplastic syndrome.

Previous studies suggest that idarubicin/cytarabine(ara-C)/pravastatin (IAP) is an active salvage regimen for patients with AML. We therefore investigated this regimen in patients with newly-diagnosed AML or MDS (≥10% blasts). Patients were eligible if the anticipated treatment-related mortality (TRM) was <10%. Patients received pravastatin (1,280 mg/day po; days 1-8), cytarabine (1.5 g/m(2) /day; days 4-7), and idarubicin (12 mg/m(2) /day, days 4-6). Up to 3 cycles of consolidation with a shortened course was permitted. The primary endpoints were "good CR" rate (CR on day 35 without minimal residual disease) and TRM in the first 28 days. The study was to stop if after each cohort of 5 patients (a) the Bayesian posterior probability was < 5% that the true "good CR rate" was ≥ 70% or (b) the posterior probability was >25% that the TRM rate was ≥5%. Twenty-four patients were included. Conventional CR was achieved in 15 (63%) patients but only 12 (50%) achieved "good CR". 4 of 12 (33%) patients with "good CR" relapsed at median of 16 weeks (10.5-19). Five (21%) patients had refractory disease. Survival probability at 1 year was 72% (48.7-64). Two (8.3%) patients died within 28 days from multiorgan failure. The most common grade 3-4 adverse effects were febrile neutropenia (75%) and diarrhea (25%). Based on the stopping rules accrual ceased after entry of these 24 patients. IAP did not meet the predefined efficacy criteria for success. Therefore, we would not recommend this regimen for phase three testing in this patient subset.

Central nervous system relapse in adults with acute lymphoblastic leukemia after allogeneic hematopoietic stem cell transplantation.

Central nervous system (CNS) relapse after allogeneic hematopoietic stem cell transplantation (HSCT) confers a poor prognosis in adult patients with acute lymphoblastic leukemia (ALL). Preventing CNS relapse after HSCT remains a therapeutic challenge, and criteria for post-HSCT CNS prophylaxis have not been addressed. In a 3-center retrospective analysis, we reviewed the data for 457 adult patients with ALL who received a first allogeneic HSCT in first or second complete remission (CR). All patients received CNS prophylaxis as part of their upfront therapy for ALL, but post-transplantation CNS prophylaxis practice varied by institution and was administered to 48% of the patients. Eighteen patients (4%) developed CNS relapse after HSCT (isolated CNS relapse, n = 8; combined bone marrow and CNS relapse, n = 10). Patients with a previous history of CNS involvement with leukemia had a significantly higher rate for CNS relapse (P = .002), and pretransplantation CNS involvement was the only risk factor for post-transplantation CNS relapse found in this study. We failed to find a significant effect of post-transplantation CNS prophylaxis to prevent relapse after transplantation. Furthermore, no benefit for post-transplantation CNS prophylaxis could be detected when a subgroup analysis of patients with (P = .10) and without previous CNS involvement (P = .52) was performed. Finally, we could not find any significant effect for intensity of the transplantation conditioning regimen on CNS relapse after HSCT. In conclusion, CNS relapse is an uncommon event after HSCT for patients with ALL in CR1 or CR2, but with higher risk among patients with CNS involvement before transplantation. Furthermore, neither the use of post-HSCT CNS prophylaxis nor the intensity of the HSCT conditioning regimen made a significant difference in the rate of post-HSCT CNS relapse.

Radiolabeled anti-CD45 antibody with reduced-intensity conditioning and allogeneic transplantation for younger patients with advanced acute myeloid leukemia or myelodysplastic syndrome.

We treated patients under age 50 years with iodine-131 ((131)I)-anti-CD45 antibody combined with fludarabine and 2 Gy total body irradiation to create an improved hematopoietic cell transplantation (HCT) strategy for advanced acute myeloid leukemia or high-risk myelodysplastic syndrome patients. Fifteen patients received 332 to 1561 mCi of (131)I, delivering an average of 27 Gy to bone marrow, 84 Gy to spleen, and 21 Gy to liver. Although a maximum dose of 28 Gy was delivered to the liver, no dose-limiting toxicity was observed. Marrow doses were arbitrarily capped at 43 Gy to avoid radiation-induced stromal damage; however, no graft failure or evidence of stromal damage was observed. Twelve patients (80%) developed grade II graft-versus-host disease (GVHD), 1 patient developed grade III GVHD, and no patients developed grade IV GVHD during the first 100 days after HCT. Of the 12 patients with chronic GVHD data, 10 developed chronic GVHD, generally involving the skin and mouth. Six patients (40%) are surviving after a median of 5.0 years (range, 4.2 to 8.3 years). The estimated survival at 1 year was 73% among the 15 treated patients. Eight patients relapsed, 7 of whom subsequently died. The median time to relapse among these 8 patients was 54 days (range, 26 to 1364 days). No cases of nonrelapse mortality were observed in the first year after transplantation. However, 2 patients died in remission from complications of chronic GVHD and cardiomyopathy, at 18 months and 14 months after transplantation, respectively. This study suggests that patients may tolerate myeloablative doses >28 Gy delivered to the liver using (131)I-anti-CD45 antibody in addition to standard reduced-intensity conditioning. Moreover, the arbitrary limit of 43 Gy to the marrow may be unnecessarily conservative, and continued escalation of targeted radioimmunotherapy doses may be feasible to further reduce relapse.

Outpatient bendamustine and idarubicin for upfront therapy of elderly acute myeloid leukaemia/myelodysplastic syndrome: a phase I/II study using an innovative statistical design.

Combinations of agents may improve outcomes among elderly acute myeloid leukaemia (AML) and high-risk myelodysplastic syndrome (MDS) patients. We performed an adaptive phase I/II trial for newly-diagnosed AML or high-risk MDS patients aged ≥50 years using a Bayesian approach to determine whether 1 of 3 doses of bendamustine (45, 60, 75 mg/m(2) days 1-3), together with idarubicin (12 mg/m(2) days 1-2), might provide a complete response (CR) rate ≥40% with <30% grade 3-4 non-haematological toxicity. We treated 39 patients (34 AML; five MDS with >10% marrow blasts; median age 73 years). None of the three bendamustine doses in combination with idarubicin met the required CR and toxicity rates; the 75 mg/m(2) dose because of excess toxicity (two of three patients) and the 60 mg/m(2) dose because of low efficacy (CR rate 10/33), although no grade 3-4 non-haematological toxicity was seen at this dose. Median survival was 7·2 months. All patients began treatment as outpatients but hospitalization was required in 90% (35/39). Although we did not find a dose of bendamustine combined with idarubicin that would provide a CR rate of >40% with acceptable toxicity, bendamustine may have activity in AML/MDS patients, suggesting its addition to other regimens may be warranted.

Frequency of allogeneic hematopoietic cell transplantation among patients with high- or intermediate-risk acute myeloid leukemia in first complete remission.

PURPOSE: To determine the frequency of allogeneic hematopoietic cell transplantation (HCT) for patients with acute myeloid leukemia (AML) in first complete remission (CR1). PATIENTS AND METHODS: Between January 1, 2008, and March 1, 2011, 212 newly diagnosed patients with AML received treatment at our center. Ninety-five patients age less than 75 years with intermediate- or high-risk AML achieved a complete remission, and 21 patients achieved a morphologic remission with incomplete blood count recovery. RESULTS: Seventy-eight (67%; 95% CI, 58% to 76%) of 116 patients received HCT at a median of 2.8 months (range, 0.5 to 19 months) from their CR1 date. The median age was 57 years in both the HCT patient group (range, 18 to 75 years) and the non-HCT patient group (range, 24 to 70 years; P = .514). Between the HCT patients and the non-HCT patients, the mean Eastern Cooperative Oncology Group performance status was 1.1 compared with 1.5, respectively (P = .005), and the average HCT comorbidity score within 60 days of CR1 was 1.7 and 2.1, respectively (P = .68). Twenty-nine (76%) of 38 non-HCT patients were HLA typed, and matched donors were found for 13 of these 29 patients (34% of all non-HCT patients). The most common causes for patients not receiving transplantation in CR1 were early relapse (within 6 months) in 12 patients (32%), poor performance status in eight patients (21%), and physician decision in five patients (13%). CONCLUSION: HCT can be performed in CR1 in the majority of patients with AML for whom it is currently recommended. The main barriers to HCT were early relapse and poor performance status, highlighting the need for improved therapies for patients with AML of all ages.

Strategies to reduce relapse after allogeneic hematopoietic cell transplantation in acute myeloid leukemia.

The incidence of acute myeloid leukemia (AML) is expected to increase in conjunction with our ageing population. Although it is proving to be a heterogeneous disease process, the only treatment with proven survival benefit for poor risk AML remains allogeneic hematopoietic cell transplant. Although this is presumed to be a curative strategy, many patients relapse after transplant, prompting us to examine various ways that we can improve outcomes. These efforts involve every step of AML diagnostics and therapy, including the intricate processes of conditioning, graft manipulation and immunomodulation. The hope is that improvement in these steps will ultimately improve survival and decrease relapse rates for AML patients after transplant.

Acute myeloid leukemia with normal cytogenetics.

Acute myeloid leukemia (AML) is proving to be a heterogeneous disease process that is driven by various genetic mutations and aberrant protein expression. As our population ages, the incidence of AML is likely to increase, with approximately a third of adult cases categorized with normal cytogenetics. Advances in technology are now allowing us to explore the genetic expression and protein transcription patterns of AML, providing more information that must find its place in the prognosis and the therapeutic algorithm of this disease. As we learn more, we hope to further categorize patients with normal karyotype AML into discrete risk categories that will help in treatment decision making and further elucidate the necessity for hematopoietic cell transplantation. However, at this time, many of the identified mutations and expression patterns are still experimental, requiring further analysis to determine their exact role in AML.