Phase I/II Study of the WEE1 Inhibitor Adavosertib (AZD1775) in Combination with Carboplatin in Children with Advanced Malignancies: Arm C of the AcSé-ESMART Trial

PURPOSE

AcSé-ESMART Arm C aimed to define the recommended dose and activity of the WEE1 inhibitor adavosertib in combination with carboplatin in children and young adults with molecularly enriched recurrent/refractory malignancies.

PATIENTS AND METHODS

Adavosertib was administered orally, twice every day on Days 1 to 3 and carboplatin intravenously on Day 1 of a 21-day cycle, starting at 100 mg/m2/dose and AUC 5, respectively. Patients were enriched for molecular alterations in cell cycle and/or homologous recombination (HR).

RESULTS

Twenty patients (median age: 14.0 years; range: 3.4-23.5) were included; 18 received 69 treatment cycles. Dose-limiting toxicities were prolonged grade 4 neutropenia and grade 3/4 thrombocytopenia requiring transfusions, leading to two de-escalations to adavosertib 75 mg/m2/dose and carboplatin AUC 4; no recommended phase II dose was defined. Main treatment-related toxicities were hematologic and gastrointestinal. Adavosertib exposure in children was equivalent to that in adults; both doses achieved the cell kill target. Overall response rate was 11% (95% confidence interval, 0.0-25.6) with partial responses in 2 patients with neuroblastoma. One patient with medulloblastoma experienced unconfirmed partial response and 5 patients had stable disease beyond four cycles. Seven of these eight patients with clinical benefit had alterations in HR, replication stress, and/or RAS pathway genes with or without TP53 alterations, whereas TP53 pathway alterations alone (8/10) or no relevant alterations (2/10) were present in the 10 patients without benefit.

CONCLUSIONS

Adavosertib-carboplatin combination exhibited significant hematologic toxicity. Activity signals and identified potential biomarkers suggest further studies with less hematotoxic DNA-damaging therapy in molecularly enriched pediatric cancers.

A Phase 1 Study to Evaluate Absolute Bioavailability and Absorption, Distribution, Metabolism, and Excretion of Savolitinib in Healthy Male Volunteers

Savolitinib is an oral MET (hepatocyte growth factor receptor) tyrosine kinase inhibitor, with demonstrated preliminary efficacy in several cancer types. Previous pharmacokinetics assessments showed that savolitinib is rapidly absorbed but there are limited data on the absolute bioavailability and absorption, distribution, metabolism, and excretion (ADME) of savolitinib. This open-label, two-part, phase 1 clinical study (NCT04675021) used a radiolabeled micro-tracer approach to evaluate absolute bioavailability and a traditional approach to determine the ADME of savolitinib in healthy male adult volunteers (N = 8). Pharmacokinetics, safety, and metabolic profiling and structural identification from plasma, urine, and fecal samples were also assessed. Volunteers received a single oral savolitinib 600 mg dose followed by intravenous 100 μg of [¹⁴ C]savolitinib in Part 1 and a single oral 300 mg [¹⁴ C]savolitinib dose (≤4.1 MBq [megabecquerel] [¹⁴ C]) in Part 2. Following Part 1, absolute oral bioavailability was 69%, the median time of maximum observed concentration was 3.5 hours, and the mean terminal half-life was 6.1 hours. Following Part 2, 94% of the radioactivity administered was recovered, with 56% and 38% in urine and feces, respectively. Exposure to savolitinib and metabolites M8, M44, M2, and M3 accounted for 22%, 36%, 13%, 7%, and 2%, respectively, of plasma total radioactivity. Approximately 3% of the dose was excreted as unchanged savolitinib in urine. Most savolitinib elimination occurred via metabolism by several different pathways. No new safety signals were observed. Our data show that the oral bioavailability of savolitinib is high and the majority of savolitinib elimination occurs via metabolism and is excreted in the urine.

Abstract LB-105: Plasma exposure-target engagement biomarker analysis for danvatirsen after multiple dosing schedules and route of administrations in patients with advanced solid tumors

Background: Danvatirsen (Da) is a generation 2.5 antisense oligonucleotide targeting STAT3 mRNA under clinical development in combination with Durvalumab (NCT03421353). The recommended Phase II dose is intravenous (IV) 200 mg weekly (QW, A). However, alternative 400 mg IV every two weeks (Q2W, B) and subcutaneous 200 mg QW (C) are also under investigation. The JAK-STAT signaling pathway is involved in immunity, cell division, cell death, and tumor formation. Additionally, activation of hepatic STAT3 results in increased secretion of C-reactive protein (CRP) and fibrinogen into blood. Therefore, target engagement in patients may be better understood by analyzing Da exposure and related biomarkers in the blood/plasma. We investigated Da exposure and subsequent impact on target engagement biomarkers such as CRP, platelets, fibrinogen, neutrophils and STAT3 mRNA levels. Methods: Extensive pharmacokinetics (PK) samples were collected at lead-in monotherapy and at steady state (SS) in combination. Plasma biomarker samples were collected at baseline and every two weeks thereafter. Whole blood samples for the analysis of STAT3 mRNA were collected at baseline, after lead-in monotherapy, and every four weeks thereafter. The PK parameters were estimated by non-compartmental analysis by WinNonlin. The biomarkers were analyzed by standard clinical methods and STAT3 mRNA level was measured by NanoString technology. Results: The area under plasma concentration-time curve of Da at SS within dosing interval (AUC0-τ, ng.h/ml) for A, B, and C were 69110 (24.64%), 101600 (22.11%), and 44600 (30.25%), respectively. Additionally, SS Ctrough (ng/ml) levels for A, B, and C were 28.53 (48.86%), 14.56 (36.14%), and 27.66 (49.22%), respectively. Maximum median % decrease from baseline in CRP levels was observed at week 4; A (-91%), B (-94%), C (-82%). Additionally, maximum median % changes from baseline for fibrinogen were -60%, -40%, -53%, in A, B, and C at week 4, respectively. Maximum % decrease from baseline in platelets was observed at week 8 in A (-42%), B (-41%), and C (-69%). In contrast, maximum % change from baseline in neutrophil count was observed at week 6; -37%, -31%, and -32% in A, B, and C, respectively. Additionally, the median maximum change from baseline for STAT3 mRNA was -42.4% and -33.6% for A and C, respectively. Conclusion: Cumulative AUC in A was very similar to B, whereas, AUC in C was 30% lower as compared to A or B. The SS Ctrough values in A and C were similar, although Ctrough value in B was 50% lower. Maximum % decreases in CRP levels were similar across all the doses. Moreover, route of administration did not appear to impact level of STAT3 knockdown. In summary, a similar degree of changes in pharmacodynamic biomarkers were achieved at all three dose levels regardless of route of administration, despite differences in plasma exposure.

Citation Format: Kowser Miah, Patricia McCoon, Deanna Russell, Patrick Mitchell, Martin Scott, Amy Rosenfeld, Li Zhang, Pablo Martinez Rodriguez, Alicia Savage, Ganesh Mugundu. Plasma exposure-target engagement biomarker analysis for danvatirsen after multiple dosing schedules and route of administrations in patients with advanced solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-105.

Open-label, multicenter, phase I study to assess safety and tolerability of adavosertib plus durvalumab in patients with advanced solid tumors

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Background: Adavosertib (AZD1775; A) is a highly selective inhibitor of WEE1. This Phase I study (NCT02617277) investigated a range of doses and schedules for oral A plus IV durvalumab (DV), a human monoclonal antibody targeting PD-L1, to determine the maximum tolerated dose (MTD) and recommended Phase II dose (RP2D) in patients (pts) with advanced solid tumors. Methods: Four 28-day schedules (Sch) were evaluated with pts receiving DV 1500 mg on day (d) 1 of each schedule (Table). Patients continued treatment if they showed clinical benefit in the absence of any discontinuation criteria. Pts received A monotherapy for PK analysis prior to the start of combination therapy in Sch B, C (d –7 to –5) and D (d –9 to –5). MTD was determined using a 3+3 dose-escalation cohort design. Predefined dose-limiting toxicities (DLTs) were evaluated during the first cycle of study treatment. Results: 54 pts received A (most common primary tumor sites: colon, 19%; lung, 13%; breast, 11%). The most common grade ≥3 AEs were fatigue (15%), diarrhea (11%) and nausea (9%). DLTs were nausea (n = 2) and diarrhea (n = 1). 7 pts (13%) had A-related SAEs, including reversible and confounded drug-induced liver injury (Sch B 125 mg and Sch C; 1 each). Disease control rate (DCR) for the total cohort was 36%. Preliminary PK at 150 mg BID suggests adequate coverage for cell kill activity and no drug–drug interaction. Conclusions: The MTD/RP2D was A 150 mg BID (3 d on, 4 d off; treatment d 15–17, 22–24) with DV 1500 mg (d 1 Q4W); safety profile was considered acceptable. Preliminary evidence of antitumor activity was observed. Clinical trial information: NCT02617277. [Table: see text]

Arrhythmias in patients with acute cerebrovascular disease

Cardiac disease is common in patients with cerebrovascular disease (CVD) and cerebral lesions as such may influence cardiac activity and rhythm. To study the indication for continuous ECG surveillance of patients with CVD, 100 consecutive patients admitted to a medical stroke unit were investigated with 24-hour Holter recordings. The patients' mean age was 73 years and 70% of them had a history of heart disease. Twenty-three patients had chronic atrial fibrillation and 55% of the remainder showed ventricular ectopic activity. Serious ventricular arrhythmias were comparatively rare and mainly seen in association with signs of congestive heart failure and acute myocardial infarction. A prolonged Q-T interval was registered in two-thirds of the patients but there was no significant association between this finding and ventricular ectopic activity. Close observation for cardiac complications is important in patients with CVD and continuous ECG surveillance is indicated in selected high-risk patients.

A study of stroke patients treated in a non-intensive stroke unit or in general medical wards

To study the representativity and outcome of patients admitted to a stroke unit (SU) (n = 269), a comparison was made with all stroke patients treated in general medical wards (GMW) (n = 225) in the same hospital during two years. There was no difference between the patient groups regarding sex, age, previous cardiovascular diseases or neurological deficit on admission. As expected, more diagnostic examinations were performed in the SU than in the GMW where a diagnosis of ill-defined stroke was very frequent. A higher frequency of lumbar puncture with CSF spectrophotometry would have increased considerably the number of specific diagnoses in the GMW. Acute and, particularly, secondary prophylactic treatment was more often given in the SU. There was no difference between the patient groups regarding mortality or length of hospital stay.

Prognosis in acute stroke with special reference to some cardiac factors

Neurological assessments were done regularly during hospitalization in 283 consecutive patients (mean age 73 yr) with acute cerebrovascular disease treated at the Stroke Unit of Serafimerlasarettet. A preplanned investigation program and strict criteria for diagnosis and treatment were followed. Hospital mortality was 18%. Patients with a major cerebral infarction or haemorrhage often died very early during the hospital period and deaths due to complications increased significantly during the second week. Multivariate analysis regarding mortality showed that a low neurological score and heart failure were the most important factors for the short-term prognosis. In those patients with cerebral infarction, ambulatory capacity and ECG-diagnosed bundle branch block added significantly to the prognostic power of the neurological score. Among the 227 patients discharged alive, 1 and 2-yr mortality was 14 and 18% respectively. Here, the most important long-term prognostic factors were age and ST changes on the ECG. Again, considering only patients with cerebral infarction (N = 190), bundle branch block was found to be the single most useful predictive factor. Prognostication in acute ischemic stroke should thus be based not only on neurological findings but on careful evaluation of associated cardiac disease, especially in the long-term perspective.

Accuracy of bedside diagnosis in stroke

The clinical diagnosis of the type of acute cerebrovascular diseases is often considered unreliable, although this has not been validated prospectively in representative patients. The accuracy of bedside diagnostics was, therefore, tested in 206 patients consecutively admitted to the Stroke Unit of the Serafimerlasarettet in Stockholm. Bedside diagnosis turned out to be correct in 69%. In 24% the diagnoses were altered after hospital investigation and in the remaining 7% no defined preliminary and/or final diagnosis could be made. When the diagnoses were considered "fairly certain" they were accurate in 87%, compared to 53% when regarded as only "probable". The diagnostic accuracy improved during the period studied. Sensitivity in identifying hemorrhages was much lower (39%) than for cerebral infarctions (83%). It is suggested that new investigational methods should be compared with what can be accomplished with bedside methods alone.

Lack of effect of theophylline on the outcome of acute cerebral infarction

In patients with acute ischemic stroke, dramatic but often transient improvements have been noticed after theophylline injections. Whether better results could be obtained by continuous infusion of the drug was evaluated in a double-blind study. Out of 46 patients with a mean age of 75 years, 22 got theophylline as aminophylline (bolus dose of 230 mg followed by 0.5 mg/kg/h) and 24 placebo during 3 days. The groups were comparable in all aspects at the outset of the trial. Serum theophylline concentrations were kept within the therapeutic range recommended for patients with asthma. No significant difference in outcome was noticed between the groups during the hospital period when repeated neurological assessments by two different scores and mortality were compared.