A phase Ib dose escalation study of oral monotherapy with KX2-391 in elderly patients with acute myeloid leukemia

Poor tolerance to standard therapies and multi-drug resistance complicate treatment of elderly patients with acute myeloid leukemia (AML). It is therefore imperative to explore novel tolerable agents and target alternative pathways. KX2-391 is an oral non-ATP-competitive inhibitor of Src kinase and tubulin polymerization. This multi-center phase Ib open-label safety and activity study involved elderly patients with relapsed or refractory AML, or who declined standard chemotherapy. Twenty-four patients averaging 74 years of age were enrolled. The majority previously received hypomethylating agents. Five doses were tested: 40 mg (n = 1), 80 mg (n = 2), 120 mg (n = 8), 140 mg (n = 12), and 160 mg (n = 1). Seven patients were treated for 12 days or less, nine for 15-29 days, five for 33-58 days, and three for 77-165 days. One patient receiving 120 mg for 165 days had reduced splenomegaly and survived 373 days. Another had no evidence of disease progression for 154 days. One patient receiving 160 mg for 12 days remained treatment-free for about 18 months. Dose-limiting toxicities occurred in eight patients at: 120 mg (transaminitis, hyperbilirubinemia), 140 mg (mucositis, allergic reaction, transaminitis, acute kidney injury), and 160 mg (mucositis). The maximum tolerated dose for KX2-391 was 120 mg once daily. KX2-391 bone marrow concentrations were approximately similar to plasma concentrations. This is the first study to evaluate the safety of KX2-391 in elderly patients with AML. Further studies are warranted, including alternative dosing phase I trials evaluating shorter courses at higher doses and phase II trials. (Clinical Trial Registration:The study was registered at ClinicalTrials.gov: NCT01397799 (July 20, 2011)).

Integrating touchscreen-based geriatric assessment and frailty screening for adults with acute myelogenous leukemia to drive personalized treatment decisions

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Background: AML is a disease of older adults, with median age of 68 years at presentation. NCCN guidelines suggest comprehensive geriatric assessments (GA) be included in clinical practice to guide treatment decisions. Utility of GA in older AML patients in a real-world environment is not yet established. We tested the feasibility of using a modified GA (mGA), administered by patient self-report on a touchscreen computer, real-time use and utility by clinicians and the correlation of mGA results on treatment decision-making. Methods: Sixty-two patients were recruited from three sites to complete a tablet-based mGA screening at a treatment decision-making time point. The mGA consists of the Frailty Index (FI) that includes four domains: age, activities of daily living, instrumental ADLs, and comorbidities. Falls within the past 6 months and patient reported health interference with function are also assessed. Results are displayed for the clinician to inform the treatment discussion. Results: Participants were mean age 73 years (range 61-88), 63% male, and 90% white. Frailty Index result was 32% fit, 40% intermediate, and 28% frail. Providers were asked the fit/frailty status prior to seeing the results of the mGA. Of 53 provider responses, there was 57% (n=30) provider concordance with the mGA result; 9% (n=5) said fit when mGA said intermediate and 17% (n=9) said intermediate when mGA said frail. When asked their goals of care, nearly all (n=60, 97%) patients agreed with the statement “my cancer is curable”, yet 30% (n=19) disagreed the treatment goal was to get rid of all the cancer. Nearly half (n=30) indicated they want to make treatment decisions together with the provider rather than provider or patient making decision alone. 73% (45/62) of patients were satisfied with the ease of using the survey and took an average 16.3 minutes to complete. Patient self-reported presence/severity of eight symptoms at baseline (see Table). Conclusions: A simple electronic tool may provide valuable insight into patient understanding of disease to better tailor patient-provider discussion and treatment decision-making. Providers overestimated fitness 26% of the time. Final results will be presented to include the outcome at 3 months by Frailty Index. [Table: see text]

A phase I trial of palbociclib in combination with dexamethasone in relapsed or refractory adult B-cell acute lymphoblastic leukemia (ALL)

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Background: c-Myb is a DNA-binding transcription factor that is highly expressed in immature hematopoietic cells. c-Myb and its products are essential in regulating normal hematopoiesis and influencing leukemogenesis. Knockdown of c-Myb causes cell cycle arrest and apoptosis in pre-B-ALL cells. The effects of c-Myb depend on transcriptional regulation of CDK6 and Bcl-2. c-Myb-silenced Ph+ ALL cells exhibit Rb-dependent cell cycle arrest and apoptosis, both of which are rescued by ectopic expression of cyclin D3, CDK6, and Bcl-2 expression. Preclinical studies suggest that the cytotoxic activity of dexamethasone in ALL cells may be due to decreased c-Myb expression and reduced Bcl-2 levels. Thus, the novel combination of palbociclib, a small molecule CDK4/6 inhibitor, and dexamethasone is a logical approach for the treatment of B-cell ALL. Methods: This is a single arm, phase I, dose escalation study with a traditional 3+3 design. Adult patients with relapsed or refractory B-cell ALL are eligible. Patients with Ph+ ALL must be refractory to or intolerant of standard tyrosine kinase inhibitor therapy. Patients receive a 1-week lead-in of palbociclib alone followed by induction with 4 weeks of palbociclib and dexamethasone. If an adequate response is seen, patients move to maintenance therapy, which consists of 1 week of palbociclib plus dexamethasone followed by 3 weeks of palbociclib alone. Treatment continues until disease progression, dose limiting toxicity, or availability of an alternative therapy. The primary endpoints are dose limiting toxicity and maximum tolerated dose of palbociclib and dexamethasone. Correlative studies, which are performed on pretreatment, day +1 and day +8 samples, include RB phosphorylation and FOXM1 expression as measures of palbociclib activity; CD19+ cell gene expression profiling of (1) p21 expression as an indicator of cell cycle activity, (2) S-Phase, Annexin V/Caspase 3 activation as indicators of proliferation and apoptosis and (3) Myb and Bcl-2 expression as indicators of dexamethasone sensitivity. Cohort 1 is currently enrolling. Once a maximum tolerated dose is established, an expansion cohort is planned. Clinical trial information: NCT03472573.

A phase 1b dose escalation study to evaluate safety, tolerability and pharmacokinetics of oral monotherapy with KX2-391 in elderly subjects with acute myeloid leukemia who are refractory to or have declined standard induction therapy

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Background: Treatment of elderly AML patients is complicated by poor tolerance to standard therapies and multi-drug resistance. It is imperative to explore novel agents which are tolerable and target alternative pathways. KX2-391 is an oral non-ATP-competitive inhibitor of Src kinase and tubulin polymerase. We conducted a phase I open-label safety and activity study in elderly subjects with AML who were refractory to or declined standard induction chemotherapy. Five dose levels were tested from 40 to 160 mg daily. Methods: 24 subjects were recruited from 3 institutions with an average age of 74 years (range 63-86). The majority had previously received HMAs. 1 subject was treated at 40 mg, 2 at 80 mg, 8 at 120 mg, 12 at 140 mg, and 1 at 160 mg. Of the 24 subjects enrolled, 7 (29%) were on treatment for 12 days or less; 9 (38%) from 15 to 29 days, 5 (21%) from 33 to 58 days and 3 (13%) from 77 to 165 days. One subject treated at 120 mg for 165 days had a reduction in splenomegaly from 16 cm to 4 cm BLCM, and survived 373 days. A second subject was treated at 120 mg for 154 days until disease progression. One subject was dosed at 160 mg for 12 days and remained treatment-free for about 18 months. Results: DLTs occurred in 8 subjects at: 120mg (AST/ALT, elevated bilirubin); 140 mg (Mucositis, Allergic Reaction, 2 elevated LFTs, acute kidney injury) and 160 mg (Mucositis). The most common (≥ 25%) treatment-related adverse events were nausea/vomiting; diarrhea; anorexia; fatigue/weakness; increase ALT/AST; hypokalemia; hypotension; febrile neutropenia; dyspnoea; abdominal pain; constipation; dizziness. The RPTD for KX2-391 is 120 mg given once daily. KX2-391 bone marrow concentrations are similar to the target IC50 of 142 ng/mL. Conclusions: This is the first study conducted to determine whether KX01 can be safely given to this high risk, frail AML patient population. The data from this study support proceeding with further studies including alternative dosing phase 1 studies (higher dose, shorter course followed by drug-free intervals) and phase 2 studies to assess efficacy. Clinical trial information: NCT01397799.

Polo-like kinase and its inhibitors: Ready for the match to start?

Polo-like kinases (Plks) plays a central role in the normal cell cycle and their upregulation has been shown to play a role in the pathogenesis of multiple human cancers. Preclinical work demonstrates that targeting Plk has a significant impact on the treatment of both solid and hematologic malignancies in vitro and in vivo. We review here the basic science and clinical work to date with the Plks as well as future directions with this novel class of mitotic inhibitors.

Single-cell pharmacodynamic monitoring of S6 ribosomal protein phosphorylation in AML blasts during a clinical trial combining the mTOR inhibitor sirolimus and intensive chemotherapy

PURPOSE

Integration of signal transduction inhibitors into chemotherapy regimens generally has generally not led to anticipated increases in response and survival. However, it remains unclear whether this is because of inadequate or inconsistent inhibition of target or other complex biology. The mTOR signaling pathway is frequently activated in acute myelogenous leukemia (AML) and we previously showed the safety of combining the mTOR inhibitor, sirolimus, with mitoxantrone, etoposide, and cytarabine (MEC) chemotherapy. However, we did not reliably determine the extent of mTOR inhibition on that study. Here, we sought to develop an assay that allowed us to serially quantify the activation state of mTOR kinase during therapy.

EXPERIMENTAL DESIGN

To provide evidence of mTOR kinase activation and inhibition, we applied a validated whole blood fixation/permeabilization technique for flow cytometry to serially monitor S6 ribosomal protein (S6) phosphorylation in immunophenotypically identified AML blasts.

RESULTS

With this approach, we show activation of mTOR signaling in 8 of 10 subjects' samples (80%) and conclusively show inhibition of mTOR in the majority of subjects' tumor cell during therapy. Of note, S6 phosphorylation in AML blasts is heterogeneous and, in some cases, intrinsically resistant to rapamycin at clinically achieved concentrations.

CONCLUSIONS

The methodology described is rapid and reproducible. We show the feasibility of real-time, direct pharmacodynamic monitoring by flow cytometry during clinical trials combining intensive chemotherapy and signal transduction inhibitors. This approach greatly clarifies pharmacokinetic/pharmacodynamic relationships and has broad application to preclinical and clinical testing of drugs whose direct or downstream effects disrupt PI3K/AKT/mTOR signaling.

A phase I study of the mammalian target of rapamycin inhibitor sirolimus and MEC chemotherapy in relapsed and refractory acute myelogenous leukemia

PURPOSE

Inhibiting mammalian target of rapamycin (mTOR) signaling in acute myelogenous leukemia (AML) blasts and leukemic stem cells may enhance their sensitivity to cytotoxic agents. We sought to determine the safety and describe the toxicity of this approach by adding the mTOR inhibitor, sirolimus (rapamycin), to intensive AML induction chemotherapy.

EXPERIMENTAL DESIGN

We performed a phase I dose escalation study of sirolimus with the chemotherapy regimen MEC (mitoxantrone, etoposide, and cytarabine) in patients with relapsed, refractory, or untreated secondary AML.

RESULTS

Twenty-nine subjects received sirolimus and MEC across five dose levels. Dose-limiting toxicities were irreversible marrow aplasia and multiorgan failure. The maximum tolerated dose (MTD) of sirolimus was determined to be a 12 mg loading dose on day 1 followed by 4 mg/d on days 2 to 7, concurrent with MEC chemotherapy. Complete or partial remissions occurred in 6 (22%) of the 27 subjects who completed chemotherapy, including 3 (25%) of the 12 subjects treated at the MTD. At the MTD, measured rapamycin trough levels were within the therapeutic range for solid organ transplantation. However, direct measurement of the mTOR target p70 S6 kinase phosphorylation in marrow blasts from these subjects only showed definite target inhibition in one of five evaluable samples.

CONCLUSIONS

Sirolimus and MEC is an active and feasible regimen. However, as administered in this study, the synergy between MEC and sirolimus was not confirmed. Future studies are planned with different schedules to clarify the clinical and biochemical effects of sirolimus in AML and to determine whether target inhibition predicts chemotherapy response.

The diabetes gene Pdx1 regulates the transcriptional network of pancreatic endocrine progenitor cells in mice

Heterozygous mutations in the gene encoding the pancreatic homeodomain transcription factor pancreatic duodenal homeobox 1 (PDX1) are associated with maturity onset diabetes of the young, type 4 (MODY4) and type 2 diabetes. Pdx1 governs the early embryonic development of the pancreas and the later differentiation of the insulin-producing islet beta cells of the endocrine compartment. We derived a Pdx1 hypomorphic allele that reveals a role for Pdx1 in the specification of endocrine progenitors. Mice homozygous for this allele displayed a selective reduction in endocrine lineages associated with decreased numbers of endocrine progenitors and a marked reduction in levels of mRNA encoding the proendocrine transcription factor neurogenin 3 (Ngn3). During development, Pdx1 occupies an evolutionarily conserved enhancer region of Ngn3 and interacts with the transcription factor one cut homeobox 1 (Hnf6) to activate this enhancer. Furthermore, mRNA levels of all 4 members of the transcription factor network that regulates Ngn3 expression, SRY-box containing gene 9 (Sox9), Hnf6, Hnf1b, and forkhead box A2 (Foxa2), were decreased in homozygous mice. Pdx1 also occupied regulatory sequences in Foxa2 and Hnf1b. Thus, Pdx1 contributes to specification of endocrine progenitors both by regulating expression of Ngn3 directly and by participating in a cross-regulatory transcription factor network during early pancreas development. These results provide insights that may be applicable to beta cell replacement strategies involving the guided differentiation of ES cells or other progenitor cell types into the beta cell lineage, and they suggest a molecular mechanism whereby human PDX1 mutations cause diabetes.

Update on the therapy for myelodysplastic syndrome

The myelodysplastic syndromes (MDS) are a diverse group of clonal hematopoietic stem cell disorders characterized by cytopenias. Patients have a risk of developing acute leukemia though most succumb to complications of low blood counts. Over the past decade many novel treatments have been developed and investigation of new agents is ongoing. In this article, we discuss the classification and prognostic systems that are used in MDS, the agents available for treatment of MDS as well as review supportive and palliative care options for patients who are not candidates for, or opt against, newer treatment strategies.

Increased cerebral blood flow after leukapheresis for acute myelogenous leukemia

Leukapheresis is often considered in the management of acute myelogenous leukemia (AML) with hyperleukocytosis and its sequelae, including myocardial infarction, pulmonary complications, and stroke. It is utilized on the assumption that leukapheresis improves blood rheology. We present a woman with AML and a history of meningioma encasing her left internal carotid artery. She presented with hyperleukocytosis and symptoms of ischemia. As her white blood cell continued to rise despite initiation of hydroxyurea therapy, she underwent leukapheresis emergently. Transcranial Doppler ultrasound demonstrated increased flow velocities in the left internal carotid and the right middle cerebral arteries, which normalized after leukapheresis. This is the first documentation that leukapheresis, in combination with hydroxyurea, improves cerebral hemodynamics in a patient with AML.