Phase 1 Study of ABT-348, A Dual Aurora/VEGF-Receptor Kinase Inhibitor, in Patients with Advanced Hematologic Malignancies.

ABT-348 is a potent, novel, adenosine triphospate competitive inhibitor of Aurora A, B and C kinases. ABT-348 is also a potent inhibitor of all members of the vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) receptor tyrosine kinase (RTK) families. ABT-348 has demonstrated strong antitumor activity in a variety of preclinical cancer cell line models, in vitro and in vivo, including leukemias as monotherapy and in combination with the DNA methyltransferase inhibitor, azacitidine.

The primary objectives of this study are to determine the safety and pharmacokinetics (PK) of orally and IV administered ABT-348 as monotherapy or in combination with azacitidine in patients (pts) with advanced hematologic malignancies. Secondary objectives include determination of the maximum tolerated dose (MTD) and exploration of biomarkers associated with ABT-348 activity.

This phase 1 dose-escalation study of ABT-348 utilizes a modified continual reassessment method in pts with advanced hematologic malignancies: acute myelogenous leukemia (AML), acute lymphoblastic leukemia, chronic myelogenous leukemia (CML), chronic lymphocytic leukemia and myelodysplasia (MDS). Adult pts with histological or cytological confirmed disease, ECOG status 0–2, adequate hematological, renal and hepatic function and without significant hypertension or proteinuria are eligible. This study has four arms consisting of ABT-348 administered on a 28-day (D) cycle. Pts receive ABT-348 monotherapy once daily (QD, Arm A) or twice daily (BID; Arm B) on Days (D) 1, 8, and 15 of a 28-day cycle under fasting conditions. In Arm C, ABT-348 is given on the same schedule as Arm A in combination with azacitidine (75 mg/m²) administered IV or SC on Days 1 – 7 of each 28-day cycle. In Arm D, pts receive ABT-348 monotherapy on the same schedule as Arm A, but via IV administration. Samples are collected for PK and biomarker analyses. Pts are treated until progressive disease (PD) or unacceptable toxicity. Adverse event (AE) severity is graded using NCI-CTCAE v4.0.

39 pts (median age, 66 y [45–86]) have enrolled (Arm A, n=32; Arm B, n=4; Arm C, n=3). Of these pts, 27 had AML, 11 had MDS and 1 had CML. Pts received a median of 4 prior therapies (range, 1 – 8). Best response to last prior therapy was: complete or partial response in 3 pts, stable disease in 11 pts, PD in 24, and not determined in 1. Dose escalation is shown in the table. The first dose-limiting toxicity (DLT) of grade 3 pancreatitis was observed at 640 mg in Arm A. Due to this DLT, along with a second case of grade 3 pancreatitis, further enrollment in Arm A was held and Arms B and C were opened. A DLT of grade 4 acute kidney injury was seen at 440 mg in Arm C. ABT-348-related AEs in greater than 2 pts were proteinuria (23%), nausea (21%), diarrhea (18%), hypertension (13%), vomiting (10%) and fatigue (8%). Grade 3/4 ABT-348-related AEs were hypertension (13%), pancreatitis (5%), acute kidney injury (3%) and diarrhea (3%). One patient in Arm A achieved a CRi (640 mg). Five of 32 pts in Arm A were treated for ≥4 cycles, including 2 of 7 pts at ABT-348 doses ≥ 640 mg. Based on preliminary PK analyses, Cmax and AUC of ABT-348 were approximately dose proportional in the dose range studied (10–690 mg); co-administration of azacitidine had no apparent effect on ABT-348 PK. Evidence of dual aurora/VEGF receptor kinase inhibition has been demonstrated by induction of polyploidy and PlGF, respectively. 33 pts have discontinued and 6 remain on study.

ABT-348 has demonstrated on-target biomarker and clinical activity in pts with advanced hematologic magnancies, and was well tolerated at doses below 640 mg in Arm A. PK appears to be dose-proportional. Dose escalation is ongoing in Arms B and C (with azacitidine); an IV formulation of ABT-348 will also be evaluated.

Off Label Use: Clofarabine in AML. Tibes:Abbott: Research Funding. Chiu:Abbott: Employment, Owns stocks Other. Xiong:Abbott: Employment, own Abbott stock Other. Qin:Abbott: Employment. Ansell:Abbott: Employment, own Abbott stock Other. Albert:Abbott: Employment, own Abbott stock Other. Tse:Abbott: Employment, own Abbott stock Other. Oliver:Abbott: Employment, own Abbott stock Other. Sajwani:Abbott: Employment, own Abbott stocks and participated in study design, data collection, analysis, interpretation and reviewing approving study documents related to ABT-348 programs. Other. McKee:Abbott: Employment, own Abbott stocks Other. Ricker:Abbott: Employment, own Abbott stocks Other.