This study is a single center open label phase I study of AZD6738, DNA damage repair/novel
cancer agent, in combination with paclitaxel in metastatic cancer patients who have failed
AZD6738 is an orally dosed selective and potent inhibitor of Ataxia Telangiectasis and Rad3
Related (ATR) kinase with good selectivity against other Pi3 kinase family members.
ATR is a serine/threonine protein kinase and member of the phosphatidylinositol 3-kinase
related kinase (PIKK) family. During normal replication, ATR is recruited at stalled
replication forks which can progress to double strand breaks if left unrepaired. ATR is also
recruited to single strand DNA coated with Replication Protein A (RPA) following single
strand DNA damage or the resection of double strand breaks. Recruitment and activation of ATR
leads to cell cycle arrest in the S phase while the DNA is repaired and the stalled
replication fork resolved, or nuclear fragmentation and entry into programmed cell death
In the clinic ATR inhibitors are expected to cause growth inhibition in tumour cells
dependent upon ATR for DNA repair e.g. ATM-deficient tumours. In addition to monotherapy
activity, ATR inhibitors are also predicted to potentiate the activity of cytotoxic DNA
damaging agents and radiotherapy (through inhibition of ATR-dependent DNA repair processes)
when used in combination. While significant enhancement of anti-tumour activity may be
achieved, data with AZD6738 suggest the potential need to reduce the ATR inhibitor dose and
intensity (relative to monotherapy dose) and introduce dosing breaks to allow normal tissue
recovery when used in combination with systemic DNA damaging chemotherapy agents, in order to
maintain tolerable therapeutic margins.
The mechanism of action of AZD6738 suggests the potential to combine it with a number of
anti-cancer treatments, resulting in either synergistic or additive activity. This study is
evaluating the safety, tolerability, pharmacokinetics and anti-tumour activity of AZD6738 at
increasing doses, in combination with paclitaxel as one of standard salvage regimen in
patients with advanced cancer.
The study will consist of two parts, each evaluating the safety and tolerability of a
specific combination agent, paclitaxel with different drug schedules. An oral formulation of
AZD6738 will be used.
The PART A will be in combination with paclitaxel; the starting dose of 40 mg AZD6738 OD will
be escalated to reach a maximum tolerated dose in patients with advanced solid malignancies,
as defined by dose-limiting toxicity. The PART B will be an independent parallel PK expansion
cohort with cycle 0 of AZD6738 on D1, D8~D21 monotherapy followed by combination therapy with
weekly paclitaxel from cycle 1. Investigators will modify to recruit the minimum or maximum
number of patients depending on data generated from other studies using AZD6738.