Phase II study of ceralasertib (AZD6738) in combination with durvalumab in patients with advanced gastric cancer

4045

Background: Alterations in DNA damage response (DDR) and repair are associated with genomic instability and increased somatic tumor mutational burden, and modulating DNA repair using specific inhibitors is a promising strategy to boost the efficacy of cancer immunotherapy. Ceralasertib is an oral inhibitor of the serine/threonine protein kinase Ataxia Telangiectasia and Rad3 Related (ATR), which is crucial to the cell’s response to replication stress. Methods: This phase 2 trial was designed to evaluate the efficacy and safety of ceralasertib in combination with durvalumab in patients with advanced gastric cancer (AGC). The study drug regimen was ceralasertib 240 mg BD days 15 to 28 in a 28-day cycle in combination with durvalumab at 1500 mg day 1 every 4 weeks. The primary end point was overall response rate (ORR) by RECIST (v1.1). Exploratory biomarker analysis was performed using fresh tumor biopsies in all enrolled patients. Results: 31 patients (median no. of prior lines, 2; range, 2-5) were enrolled between Jul 2019 and Mar 2020. All enrolled patients had confirmed microsatellite stable tumors, 5 patients were EBV positive, and 24 patients were PD-L1 positive (CPS≥1). Two patients had received prior anti-PD-1 treatment. At the time of data cut-off (Dec 2020), 30 patients were evaluable for response: 7 partial responses (one patient with prior anti-PD-1 treatment), 11 stable disease, and 12 disease progression were observed. The ORR was 22.6%, DCR 58.1 %, median PFS 3.0 months (95% confidence interval (CI), 2.1-3.9), median duration of response 5.7 months (95% CI, 4.9-6.5), and median OS was 6.7 months (95% CI, 3.8-9.6). A subgroup of patients (n = 11) who with loss of ATM expression and/or high proportion of mutational signature attributable to homologous repair deficiency (sig. HRD) demonstrated significantly longer PFS than those (n = 12) who had intact ATM and low sig. HRD (5.60 vs 1.65 months, hazard ratio 0.13, 95% CI 0.045-0.39, long-rank P < 0.001). The most common adverse events of any grade were fatigue (n = 22, 71.0%), nausea (n = 20, 64.5%) and anorexia (n = 19, 61.3%), and the most common adverse events of grade 3 or more were anemia and thrombocytopenia (n = 11, 35.5% each). Conclusions: Ceralasertib in combination with durvalumab demonstrated promising anti-tumor activity with durable responses in refractory AGC. Clinical trial information: NCT03780608.

A Phase I Study Investigating AZD8186, a Potent and Selective Inhibitor of PI3Kβ/δ, in Patients with Advanced Solid Tumors

PURPOSE

To characterize safety and tolerability of the selective PI3Kβ inhibitor AZD8186, identify a recommended phase II dose (RP2D), and assess preliminary efficacy in combination with abiraterone acetate or vistusertib.

PATIENTS AND METHODS

This phase I open-label study included patients with advanced solid tumors, particularly prostate cancer, triple-negative breast cancer, and squamous non-small cell lung cancer. The study comprised four arms: (i) AZD8186 monotherapy dose finding; (ii) monotherapy dose expansion; (iii) AZD8186/abiraterone acetate (with prednisone); and (iv) AZD8186/vistusertib. The primary endpoints were safety, tolerability, and identification of the RP2D of AZD8186 monotherapy and in combination. Secondary endpoints included pharmacokinetics (PK), pharmacodynamics, and tumor and prostate-specific antigen (PSA) responses.

RESULTS

In total, 161 patients were enrolled. AZD8186 was well tolerated across all study arms, the most common adverse events being gastrointestinal symptoms. In the monotherapy dose-finding arm, four patients experienced dose-limiting toxicities (mainly rash). AZD8186 doses of 60-mg twice daily [BID; 5 days on, 2 days off (5:2)] and 120-mg BID (continuous and 5:2 dosing) were taken into subsequent arms. The PKs of AZD8186 were dose proportional, without interactions with abiraterone acetate or vistusertib, and target inhibition was observed in plasma and tumor tissue. Monotherapy and combination therapy showed preliminary evidence of limited antitumor activity by imaging and, in prostate cancer, PSA reduction.

CONCLUSIONS

AZD8186 monotherapy had an acceptable safety and tolerability profile, and combination with abiraterone acetate/prednisone or vistusertib was also tolerated. There was preliminary evidence of antitumor activity, meriting further exploration of AZD8186 in subsequent studies in PI3Kβ pathway-dependent cancers.

The clinical efficacy of olaparib monotherapy or combination with ceralasertib (AZD6738) in relapsed small cell lung cancer

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Background: The molecular profiling of small cell lung cancer (SCLC) has demonstrated a high incidence of genomic alterations in cell cycle-related genes and DNA damage and response (DDR) pathways, which correlates with devastating clinical outcomes of SCLC. Using two small molecules targeting the DNA repair pathway, olaparib (PARP inhibitor) and ceralasertib (ATR inhibitor), we evaluated their clinical efficacy in monotherapy or in combination, in relapsed SCLC. Methods: As part of the phase II biomarker-driven umbrella study in SCLC (SUKSES), patients who failed prior platinum-based regimen were enrolled and allocated based on their genomic alterations. Patients with mutations harboring HR pathway gene mutation not limited to BRCA 1 or 2, ATM deficiency or MRE11A mutations were allocated to the olaparib monotherapy (SUKSES-B, NCT03009682). As an biomarker non-matched arm, biomarker unselected patients were also allowed to receive olaparib and ceralasertib arm (SUKSES-N2, NCT0328607). The primary endpoint was objective response rate (ORR), and two-stage Simon’s design was used. Results: Based on pre-defined protocol criteria, both arms terminated at stage 1. In the olaparib monotherapy arm (SUKSES-B, n = 15), ORR was 6.7%, and disease control rate (DCR) was 26.7%, 1 partial response (PR), and 3 stable diseases (SD). Median progression-free survival (PFS) was 1.25 months (95% confidential interval [CI] 1.18–NA), and median overall survival (OS) was 8.56 months (95% CI, 6.62–NA). Adverse events that led to treatment discontinuation (n = 2 total, 13.3%) were drug related grade 3 renal impairment, thrombocytopenia, and grade 2 anemia. A patient with confirmed PR showed a tumor volume decrease of 37% compared to the baseline, and a splicing site mutation in BRCA2 was identified from deep target sequencing. In the olaparib and ceralasertib treatment arm (SUKSES-N2, n = 26), ORR was 3.8% (n = 1) and DCR was 42.3% (n = 11). Median PFS was 2.75 months (95% CI 1.77–5.44), and OS was 7.18 months (95% CI 5.97-10.79). Three patients discontinued treatment due to drug related grade 5 pneumonia, grade 3 drug-induced pneumonitis and grade 2 anemia. The most common adverse events for the combination were anemia (n = 11, 42.3%), followed by thrombocytopenia (n = 6, 23.1%). A patient with confirmed PR with a 43% decreases in tumor volume compared with baseline had a mutation in TP53. Conclusions: Targeting the DDR pathways with olaparib as single agent or in combination with ceralasertib demonstrated early signal of efficacy in relapsed SCLC patients with a tolerable safety profile. Clinical trial information: NCT03009682, NCT0328607.

Phase II study of ceralasertib (AZD6738), in combination with durvalumab in patients with metastatic melanoma who have failed prior anti-PD-1 therapy

9514

Background: Alterations in DNA damage response (DDR) and repair are associated with genomic instability and increased somatic tumor mutational burden, and modulating DNA repair is a promising strategy to boost the efficacy of cancer immunotherapy. Ceralasertib is an oral inhibitor of the serine/threonine protein kinase Ataxia Telangiectasia and Rad3 Related (ATR), which is crucial to the cell’s response to replication stress. Methods: This phase 2 trial was designed to evaluate the efficacy and safety of ceralasertib in combination with durvalumab in patients with metastatic melanoma (MM) who had failed to anti-PD-1 therapy. The study drug schedule was: ceralasertib at 240 mg BD on days 15 to 28 in combination with durvalumab at 1500 mg on day 1 in a 28-day cycle. The primary end point was overall response rate (ORR) by RECIST (v1.1). To investigate markers predictive of clinical outcome, fresh tumor biopsies were obtained from all enrolled patients before treatment. Results: From August 2019 to May 2020, 30 MM patients (median # of lines, 2; range, 2 - 5) were enrolled. All enrolled patients were exposed to prior anti-PD-1 treatment (immediate failure, n = 23). The ORR was 30.0% (9 PRs, 10 SDs, 10 PDs), DCR 63.3%, median PFS 7.1 months (95% confidence interval (CI), 3.6-10.6), and median OS was 14.2 months (95% CI, 9.3-19.1). Common adverse events of any grade were anemia (n = 23, 76.7%), anorexia (n = 20, 66.7%) and thrombocytopenia (n = 19, 63.3%). Common adverse events of grade 3 or more included anemia (n = 10, 33.3%). One death occurred due to febrile neutropenia in a patient with a pre-existing wound infection. Conclusions: Ceralasertib in combination with durvalumab demonstrated a promising anti-tumor activity, particularly in melanoma patients who failed to standard of care including anti-PD1 treatment. Clinical trial information: NCT03780608.

DNA-damage response-umbrella study of the combination of ceralasertib and olaparib, or ceralasertib and durvalumab in advanced biliary tract cancer: A phase 2 trial-in-progress

TPS4166

Background: Ceralasertib (AZD6738) is a selective ATR inhibitor that causes stalled replication forks to collapse, leading to accumulation of double-strand DNA breaks, which is expected to have synergistic anti-tumor effects with immune checkpoint inhibitors (ICI) or PARP inhibitors. First, accumulation of DNA damage by ceralasertib induces tumor cell death, leads to the release of tumor-specific antigen, changing the tumor microenvironment to promote antigen presentation and enhances the anti-tumor effect of ICI. Second, by simultaneously inhibiting two DNA-damage response (DDR) pathways downstream of PARP and ATR, cancer cells are unable to repair damaged DNA, leading to cell death. Ceralasertib has demonstrated promising anti-tumor activity and manageable toxicity in combination with durvalumab or olaparib in solid tumors in a phase 1 study (NCT02264678). In preclinical studies, ceralasertib has shown potent anti-tumor effects in biliary tract cancer (BTC) as a monotherapy and in combination with chemotherapy (Nam, et al, 2019). Methods: This is an open-label, phase 2 umbrella study assessing the efficacy of ceralasertib in combination with durvalumab or olaparib in patients with advanced BTC. Eligible patients have histologically confirmed BTC (including intrahepatic or extrahepatic cholangiocarcinoma, gallbladder cancer, or ampullary cancer), have failed at least one chemotherapy and have ECOG performance status of 0-1. Patients who have received prior ICI, ATR or PARP inhibitor are excluded. Each cycle consists of 4 weeks. In ceralasertib /durvalumab cohort, 37 patients will receive durvalumab 1.5g on day 1 and ceralasertib 240mg twice daily on days 15-28. In ceralasertib /olaparib cohort, 37 patients receive ceralasertib 160mg once daily on days 1-7 and olaparib 300mg twice daily on days 1-28. The primary endpoint is disease control rate, with key secondary endpoints including overall response rate, progression-free survival, overall survival, and safety. Tissue and blood samples are being collected for translational biomarker studies. Clinical trial information: NCT04298021.

Results from a phase I, open-label study of ceralasertib (AZD6738), a novel DNA damage repair agent, in combination with weekly paclitaxel in refractory cancer (NCT02630199)

3503

Background: Ataxia Telangiectasia and Rad3 Related (ATR) is an apical kinase with a critical role in the DNA-damage response. During normal DNA replication, ATR is recruited at stalled replication forks which can progress to double strand breaks if left unrepaired. AZD6738 is an oral inhibitor of the serine/threonine protein kinase ATR, a member of the phosphoinositide 3-kinase related kinase (PIKK) family. Methods: Eligible patients (pts) with advanced solid tumours were administered AZD6738 in combination with fixed dose paclitaxel 80 mg/m2 D1, D8, D15 in 28-day cycles. The dose of AZD6738 was escalated to reach a maximum tolerated dose (MTD) in a rolling 6 design. The trial evaluated safety, MTD, pharmacokinetics (PK) and pharmacodynamics (PD). Translational studies on plasma samples included cytokine analysis, panel sequencing of ctDNA, as well as IHC and immunofluorescence of immune cell markers. Results: 58 pts (34 melanoma, 15 gastric cancer (GC), 4 sarcoma, 3 colon cancer, 1 neuroendocrine and 1 hepatocellular cancer) were enrolled in 7 dose cohorts ranging 40mg OD to 240 mg BID. One dose-limiting toxicity (DLT) of neutropenic fever occurred in each cohort of n = 6 evaluable pts at AZD6738 160 mg BD and 240 mg BD days 1-14. Per protocol, the maximum tolerated dose of AZD6738 is 240 mg BID days 1-14. The most common toxicities (all causality, all grade) were: anorexia/nausea (n = 15, 26%), leukopenia (n = 11, 19%) and anemia (n = 11, 19%). 51 pts are evaluable for efficacy; we observed 1 complete response (1.9 %, melanoma), 12 confirmed partial responses (23.5%; 2 gastric, 10 melanoma all of which were post-immunotherapy), 18 stable disease (35.3%) and 20 disease progression (39.2%). The overall confirmed response rate from the dose escalation is 25.5%. Genomic analysis of baseline plasma (27 pts) revealed enrichment of NF1 somatic mutations and activating NRAS mutations amongst melanoma pts (6/18 and 4/18, respectively). Cyclical changes in interleukin-12 levels were observed in three pts with disease control which could reflect an immunological component to the mechanism of response. We will present a comprehensive case report of a patient with dramatic and durable response. Conclusions: We conclude that AZD6738 can be safely combined with weekly paclitaxel and propose a recommended phase II dose and schedule. The combination of AZD6738 and paclitaxel demonstrated promising anti-tumor activity with durable responses, especially in melanoma pts after failing anti-PD1 therapy. Clinical trial information: NCT02630199 .

AcSé-ESMART: European Proof of Concept Therapeutic Stratification Trial of Molecular Anomalies in Relapsed or Refractory Tumors in Children and Adolescents–Arm D: Olaparib and irinotecan

10047

Background: AcSé-ESMART is a proof-of-concept, phase I/II, multicenter, prospective basket trial designed to explore targeting agents in a molecularly enriched cancer population; treatment arms with targeted agents as single agent or in combination regimens are explored independently. Arm D explores the PARP inhibitor olaparib (ola) in combination with irinotecan (iri). The design is based on the hypothesis that in pediatric cancer pathogenic BRCA alterations are extremely rare and proliferative capacity is high requiring a chemotherapy sensitisation approach. Preclinical data in pediatric cancer suggest PARP inhibitor activity in other genomic alterations impairing homologous recombination (HR) and demonstrate synergy with iri. We here report the results of the Phase I part of the trial. Methods: Children and adolescents with relapsed/refractory cancer and comprehensive molecular profiling (whole exome and RNA sequencing) at relapse were eligible. Dose-escalation followed a continuous reassessment method design of pre-specified dose combinations of oral ola and iv iri. Plasma for pharmacokinetics (PK) was collected. Results: From Oct 2016 to April 2018, 27 pts (19 sarcomas, 3 brain tumors, 5 other) with a median age of 15 y (range 4;22) were enrolled over 4 dose levels. Dose limiting toxicities occurred in 7 of 24 evaluable pts (gastrointestinal (n = 4), febrile neutropenia (n = 1), thrombocytopenia (n = 2)). The RP2D was defined as ola 90 mg/m2 BID day 1-10 and iri 20 mg/m2 day 4-8. Twenty-three pts evaluable for response received a median of 2 cycles (range 1-27+). Confirmed PRs were seen in one osteosarcoma, one pinealoblastoma and one neuroblastoma; time to progression was 22.4, 50 and 89+ weeks, respectively. Eight pts experienced disease stabilization (median 14.8 weeks, range 9;42.3). PK and biomarker analysis (ie. HR alterations, DNA and gene expression signatures) is ongoing to identify factors associated with clinical benefit and data will be presented. Conclusions: The RP2D of the combination is ola 90 mg/m2 BID day 1-10 and iri 20 mg/m2 day 4-8. Preliminary activity led to the ongoing Phase II part of the arm. Clinical trial information: NCT02813135.

VIKTORY trial: Report on AZD1775/paclitaxel in TP53 mutation (+) GC, selumetinib/paclitaxel in ras aberrant GC, AZD5363/paclitaxel in PIK3CA mt and biomarker negative, savolitinib/docetaxel in met (+), and vistusertib/paclitaxel in RICTOR(+) GC

4024

Background: The VIKTORY trial is a biomarker-based umbrella trial in GC. Methods: See table below. Results: From June 2014 to Jan 2017, 432 metastatic gastric cancer patients were enrolled. 124 (28.7%) were treated on one of the associated study protocols. At January 2017, 25 pts were allocated to selumetinib/paclitaxel arm, 25 to AZD1775/paclitaxel arm, 16 to AZD5363/paclitaxel arm, 16 to vistusertib/paclitaxel arm, 4 to savolitinib monotherapy, 19 to savolitinib/docetaxel arm, 19 to phase I AZD6738/paclitaxel arm. Initial efficacy signals have been seen in several arms (selumetinib/paclitaxel, 6 of 21 evaluable patients in PR). Correlative analyses between molecular signatures and treatment response are ongoing and will be presented at the meeting. For vistusertib/paclitaxel in the biomarker negative arm, we found RICTOR amplification as a promising predictive biomarker for response. Two (of three) GC patients with RICTOR amplification achieved PR to vistusertib/paclitaxel. Conclusions: This is one of the first attempts to undertake a biomarker-driven trial in metastatic GC. 28.7% of the patients were guided to one of the parallel arms based on molecular screening outcomes. We were able to identify potential molecular targets in the biomarker-negative arm, for further assessment in new protocols. Clinical trial information: 02299648. [Table: see text]

A randomized crossover study comparing the efficacy and tolerability of a novel once-daily morphine preparation (MXL capsules) with MST Continus tablets in cancer patients with severe pain

The efficacy, tolerability and 24-h duration of action of MXL capsules, a novel once-daily morphine preparation, were compared with twice-daily morphine tablets (MST Continus tablets) in patients with severe cancer pain. Eighty-five patients were recruited to this randomized, double-blind, double-dummy, crossover study. There was no significant difference between the two treatment groups in the number of occasions that escape medication was required, the pain scores at each of three time points throughout the day, and the number of nights woken due to pain. Both preparations were well tolerated with no significant difference in the number or severity of reported symptoms and side-effects. Sixteen patients withdrew from the study, of whom 13 withdrew for nontreatment-related reasons. There was no difference between the preparations in terms of expressed treatment preference. MXL capsules were shown to provide effective analgesia over the 24-h dosing interval which was comparable to that of MST Continus tablets administered twice daily.

The accumulation of five antibacterial agents in porin-deficient mutants of Escherichia coli

A library of isogenic mutants containing Mud9-induced deletions of the structural and regulatory genes for the porin proteins OmpF and OmpC of Escherichia coli was constructed. The accumulation of norfloxacin, tetracycline, chloramphenicol, cephalothin and cefoxitin was measured with each strain, and shown to be reproducible with low experimental standard deviations, such that the roles of OmpF, OmpC and PhoE in the accumulation of these agents were determined. All data were statistically analysed to determine whether the differences observed between the data for each mutant compared with those for the other mutants and for the wild-type strain were significant. The loss of OmpF reduced accumulation of norfloxacin, tetracycline, cephalothin and cefoxitin by 16-60% compared to the wild-type parent strain, but reduced accumulation of chloramphenicol by < 10%. The loss of OmpC reduced accumulation of cephalothin and cefoxitin by 13 and 34%, respectively, compared to the wild-type parent strain, but had little effect on the accumulation of norfloxacin, chloramphenicol and tetracycline (< 3%). The loss of both OmpF and OmpC (ompR) reduced accumulation of norfloxacin, chloramphenicol, tetracycline, cephalothin and cefoxitin by 36-68%. However, the presence of PhoE in the absence of both OmpF and OmpC, enhanced accumulation to 52-119% of the concentrations of these five agents accumulated by the wild-type strain. These data suggest that OmpF is the preferred route of entry for three of the antibiotics studied, but not for chloramphenicol and tetracycline which utilize both porins equally well. The high levels of accumulation (30-64%) of all five antibiotics in the absence of all major porins suggest that an alternative mechanism(s) of accumulation is available.

A comparison of methods used for measuring the accumulation of quinolones by Enterobacteriaceae, Pseudomonas aeruginosa and Staphylococcus aureus

Accumulation of norfloxacin by Escherichia coli was studied with a range of published procedures that used either radioactively-labelled norfloxacin (14C and 3H) or the natural fluorescence of the quinolone for detection. All methods except bioassay generated comparable data. A method involving the detection of fluorescence was found to be the method of choice. This method was used to study the accumulation kinetics of ciprofloxacin, lomefloxacin, fleroxacin, norfloxacin, and enoxacin by several species of Gram-negative bacteria, and a Staphylococcus aureus strain. Saturation and efflux kinetics were also studied. There was no saturation at a concentration of norfloxacin less than 50 mg/L. Norfloxacin efflux was minimal during the uptake assay as the samples were withdrawn into ice-cold buffer; however, when the cells were sampled into buffer at 37 degrees C, up to 50% of cell-associated quinolone effluxed within 5 min.