The DNA-PK Inhibitor AZD7648 Sensitizes Patient-Derived Ovarian Cancer Xenografts to Pegylated Liposomal Doxorubicin and Olaparib Preventing Abdominal Metastases

Abstract

Ovarian cancer is the deadliest gynecologic cancer, with a 5-year survival rate of 30%, when the disease has spread throughout the peritoneal cavity. We investigated the efficacy to delay disease progression by the DNA-dependent protein kinase (DNA-PK) inhibitor AZD7648, administered in combination with two of the therapeutic options for patient management: either pegylated liposomal doxorubicin (PLD) or the PARP inhibitor olaparib. Patient-derived ovarian cancer xenografts (OC-PDX) were transplanted subcutaneously to evaluate the effect of treatment on tumor growth, or orthotopically in the peritoneal cavity to evaluate the effect on metastatic spread. AZD7648 was administered orally in combination with PLD (dosed intravenously) or with olaparib (orally). To prove the inhibition of DNA-PK in the tumors, we measured pDNA-PKcs, pRPA32, and γH2AX, biomarkers of DNA-PK activity. AZD7648 enhanced the therapeutic efficacy of PLD in all the OC-PDXs tested, regardless of their BRCA status or sensitivity to cisplatin or PLD. The treatment caused disease stabilization, which persisted despite therapy discontinuation for tumors growing subcutaneously, and significantly impaired the abdominal metastatic dissemination, prolonging the lifespan of mice implanted orthotopically. AZD7648 potentiated the efficacy of olaparib in BRCA-deficient OC-PDXs but did not sensitize BRCA-proficient OC-PDXs to olaparib, despite an equivalent inhibition of DNA-PK, suggesting the need of a preexisting olaparib activity to benefit from the addition of AZD7648. This work suggests that AZD7648, an inhibitor of DNA-PK, dosed in combination with PLD or olaparib is an exciting therapeutic option that could benefit patients with ovarian cancer and should be explored in clinical trials.

The PARP1 Inhibitor AZD5305 Impairs Ovarian Adenocarcinoma Progression and Visceral Metastases in Patient-derived Xenografts Alone and in Combination with Carboplatin

“…In addition to affecting tumor growth, AZD5305 as single-agent significantly impaired tumor dissemination (visceral metastasis) and prolonged the lifespan of mice bearing OC-PDXs implanted orthotopically to mimic the progressive disease in patients after debulking surgery ( 25 ). This effect on the metastatic setting, which is responsible for the greatest morbidity and mortality for patients with ovarian cancer, is particularly noteworthy in relation to the potential clinical utility of AZD5305 for this tumor.…”

“…The relative tumor volume was calculated as [TV day n /TV at treatment start (day 0)] and the tumor growth curve generated ( 25 ). The percentage change in tumor volume was calculated for each individual mouse as [(TV day n − TV at day 0)/TV at day 0]*100, and waterfall plots were generated ( 24 ).…”

“…To evaluate metastatic dissemination, the presence of tumor masses in representative organs and anatomic sites such as uterus/ovary, diaphragm, liver, pancreas/omentum, and lymph nodes was rated by two independent scientist using an arbitrary scoring system (0 = no organ infiltration; 1 = small tumor masses; 2 = evident tumor masses; 3 = extensive organ infiltration; 4 = complete organ substitution). The “metastatic score” for each mouse was then calculated as the sum of the rating in all the evaluated organs/anatomic sites ( 25, 27, 28 ). Pictures of the peritoneal cavity organs were taken with a macro-digital imaging system (MacroPATH; Milestone S.r.l.).…”

Optimization of hERG and Pharmacokinetic Properties for Basic Dihydro-8H-purin-8-one Inhibitors of DNA-PK

“…The DNA-PK complex has a critical role in the DNA damage response (DDR), , as it is activated by double-strand DNA breaks and regulates the non-homologous end-joining repair pathway, , and is a target of interest for oncology . The DNA-PK complex consists of the DNA-PK catalytic subunit (DNA-PKcs) together with the Ku70/80 heterodimer, and inhibition of the kinase function of DNA-PKcs represents a tractable approach to inhibit the DNA-PK complex. − Inhibition of DNA-PKcs with compound 1 (AZD7648), a potent and highly selective DNA-PKcs inhibitor, has been reported to give antitumor activity in preclinical models as a monotherapy, in combination with other DDR inhibitors, and in combination with inducers of double-strand breaks. ,− These publications have reported that inhibition of DNA-PK with compound 1 resulted in tumor regression when combined with a poly ADP-ribose polymerase (PARP) inhibitor, olaparib, in an ataxia–telangiectasia mutated kinase (ATM) knockout FaDu xenograft model, and that efficacy was enhanced with schedules that provided prolonged target coverage. Compound 1 has good metabolic stability (human hepatocyte CL int = 0.5 μL/min/10 6 cells), low protein binding (76% free in human plasma), and a moderate predicted volume of distribution, as expected for a neutral compound with a measured logD of 1.3, and it was predicted to have a moderate predicted half-life ( t 1/2 ) in humans.…”

Discovery, Optimization, and Evaluation of Potent and Selective DNA-PK Inhibitors in Combination with Chemotherapy or Radiotherapy for the Treatment of Malignancies

“…Recently, AstraZeneca researchers reported a highly potent, selective, and orally active DNA-PK inhibitory molecule, AZD7648 ( 4 ), which is an efficacious combination partner with a set of DSB-inducing agents, including but not limited to radiation, doxorubicin, and the olaparib in a wide variety of murine xenograft models. This molecule has been evaluated in populations with advanced solid tumors as monotherapy or as a combination partner with doxorubicin or with olaparib in phase I/II clinical trial. − However, the program was terminated owing to strategic reasons. The relatively low plasma exposure and short half-life of AZD7648 illustrated the limitations to achieve sustained DNA-PK inhibition in vivo.…”