Phase I Study of Triciribine Phosphate Monohydrate, a Specific Inhibitor of AKt Phosphorylation, in Adult Patients with Advanced Hematologic Malignancies.

Activation of Akt, a serine/thronine protein kinase downstream of PI3 kinase, promotes cell survival through phosphorylation of Bad as well as activation of IKKa-NFkB pathway. Aberrant activation of Akt, by its amplification and overexpression, as well as through the loss of the upstream tumor suppressor PTEN, has been reported in many human cancers and is associated with poor prognosis, resistance to chemotherapy and shortened survival; disruption of Akt pathways inhibits tumor cell growth, angiogenesis and metastasis, and induces apoptosis. Through high through put screening of a library of small molecules, it has been determined that Triciribine Phosphate Monohydrate (TCN-PM), a nucleoside analog, is an inhibitor of Akt activation, and inhibition of Akt activation may be one of its antiproliferative mechanisms. We have conducted a phase I study of TCN-PM in patients with advanced hematological malignancies. Cohorts of 3 patients receive escalating doses of TCN-PM at 15, 25, 35, and 45 mg/m² administered IV on days 1, 8, and 15 of a 28 day cycle. Twenty four (19M, 5F) patients have been enrolled in 2 institutions and have received a median of 1 cycle (range, 1 – 3) of TCN-PM including 4 in cohort I, 4 in cohort II and 16 in cohort III. Median age of the patients is 60 (range, 30 – 79). Twenty two patients had AML, 1 CLL, and 1 MDS. Median number of prior therapy before inclusion in the study was 3 (range, 1 – 7). Ten patients were inevaluable including 1 in cohort I, 1 in cohort II, and 8 in cohort III due to disease progression (in 7) and other (in 3). Dose limiting toxicity of mucositis was observed in a patient on the third cohort resulting in expansion of that cohort. No further incidences of mucositis were seen in the expanded cohort. No other severe adverse events related to treatment have been observed. 2 patients have achieved major improvements in platelet count lasting 7 and 36 days. One patient achieved a minor improvement in platelet count. Four patients have achieved major improvements in neutrophil count lasting a median of 19 (range, 8 – 40) days while on therapy. Cell death, measured by annexin-5 staining was examined in pre and post treatment samples in 14 patients; in 2 patients there was a significant increase in apoptosis to 25% and 27% after TCN-PM but this did not correlate with response. Pharmacodynamic studies evaluating inhibition of Akt phosphorylation as well as pharmacokinetic data will be presented. Accrual to higher dose levels is continuing.