Safety, tolerability, pharmacokinetics, and antitumor activity of adavosertib in Japanese patients with advanced solid tumors: A phase I, open-label study

INTRODUCTION

We aimed to assess the safety, pharmacokinetic profile, and antitumor activity of adavosertib monotherapy in Japanese patients with advanced solid tumors.

MATERIALS AND METHODS

This was a single-center, open-label, phase I study with two consecutive cohorts (250 mg and 200 mg cohorts). Patients received adavosertib at 250 mg or 200 mg, orally once daily for 5 days on and 2 days off for Weeks 1 and 2 of a 21-day cycle.

RESULTS

Dose-limiting toxicities (Grade 3 febrile neutropenia) occurred in 2/6 patients in the 250 mg cohort. None of the three patients in the 200 mg cohort developed dose-limiting toxicities. The most frequent treatment-emergent adverse event was nausea (250 mg: 83.3 %; 200 mg: 100.0 %). Median time to peak drug concentration was 4.03 and 2.08 h after the first dose and 2.82 and 1.90 h after multiple dosing in the 250 and 200 mg cohorts, respectively; respective mean terminal elimination half-lives were 7.36 and 7.30 h (first dose) and 10.55 and 8.88 h (multiple dosing). Systemic exposure increased in a slightly more than dose-proportional manner. No RECIST v1.1 response was observed. Disease control rate was 0 % and 33.3 % in the 250 and 200 mg cohorts, respectively. One patient (33.3 %) in the 200 mg cohort showed a best overall response of stable disease at ≥ 8 weeks; the rest showed progressive disease.

CONCLUSIONS

Adavosertib 200 mg once daily was well tolerated in this patient population and no safety concerns were raised. Exposure increased in a slightly more than dose-proportional manner and limited antitumor activity was shown.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04462952.

The Development of p53-Targeted Therapies for Human Cancers

p53 plays a critical role in tumor suppression and is the most frequently mutated gene in human cancers. Most p53 mutants (mutp53) are missense mutations and are thus expressed in human cancers. In human cancers that retain wtp53, the wtp53 activities are downregulated through multiple mechanisms. For example, the overexpression of the negative regulators of p53, MDM2/MDMX, can also efficiently destabilize and inactivate wtp53. Therefore, both wtp53 and mutp53 have become promising and intensively explored therapeutic targets for cancer treatment. Current efforts include the development of small molecule compounds to disrupt the interaction between wtp53 and MDM2/MDMX in human cancers expressing wtp53 and to restore wtp53-like activity to p53 mutants in human cancers expressing mutp53. In addition, a synthetic lethality approach has been applied to identify signaling pathways affected by p53 dysfunction, which, when targeted, can lead to cell death. While an intensive search for p53-targeted cancer therapy has produced potential candidates with encouraging preclinical efficacy data, it remains challenging to develop such drugs with good efficacy and safety profiles. A more in-depth understanding of the mechanisms of action of these p53-targeting drugs will help to overcome these challenges.

Adavosertib (AZD1775) does not prolong the QTc interval in patients with advanced solid tumors: a phase I open-label study

PURPOSE

Adavosertib is a small-molecule, ATP-competitive inhibitor of Wee1 kinase. Molecularly targeted oncology agents have the potential to increase the risk of cardiovascular events, including prolongation of QT interval and associated cardiac arrhythmias. This study investigated the effect of adavosertib on the QTc interval in patients with advanced solid tumors.

METHODS

Eligible patients were ≥ 18 years of age with advanced solid tumors for which no standard therapy existed. Patients received adavosertib 225 mg twice daily on days 1-2 at 12-h intervals and once on day 3. Patients underwent digital 12-lead electrocardiogram and pharmacokinetic assessments pre-administration and time-matched assessments during the drug administration period. The relationship between maximum plasma drug concentration (C_max) and baseline-adjusted corrected QT interval by Fridericia (QTcF) was estimated using a prespecified linear mixed-effects model.

RESULTS

Twenty-one patients received adavosertib. Concentration-QT modeling of ΔQTcF and the upper limit of the 90% confidence interval corresponding to the geometric mean of C_max observed on days 1 and 3 were below the threshold for regulatory concern (not > 10 ms). No significant relationship between ΔQTcF (vs baseline) and adavosertib concentration was identified (P = 0.27). Pharmacokinetics and the adverse event (AE) profile were consistent with previous studies at this dose. Eleven (52.4%) patients experienced 17 treatment-related AEs in total, including diarrhea and nausea (both reported in six [28.6%] patients), vomiting (reported in two [9.5%] patients), anemia, decreased appetite, and constipation (all reported in one [4.8%] patient).

CONCLUSION

Adavosertib does not have a clinically important effect on QTc prolongation.

CLINICALTRIALS

GOV: NCT03333824.

Disparity in the era of personalized medicine for epithelial ovarian cancer

The treatment of high-grade serous ovarian cancer and high-grade endometrioid ovarian cancer has seen significant improvements in recent years, with BRCA1/2 and homologous recombination status guiding a personalized approach which has resulted in improved patient outcomes. However, for other epithelial ovarian cancer subtypes, first-line treatment remains unchanged from the platinum-paclitaxel trials of the early 2000s. In this review, we explore novel therapeutic approaches being adopted in the treatment of clear cell, mucinous, carcinosarcoma and low-grade serous ovarian cancer and the biological rational behind them. We discuss why such disparities exist, the challenges faced in conducting dedicated trials in these rarer histologies and look towards new approaches being adopted to overcome them.

Evolving DNA repair synthetic lethality targets in cancer

DNA damage signaling response and repair (DDR) is a critical defense mechanism against genomic instability. Impaired DNA repair capacity is an important risk factor for cancer development. On the other hand, up-regulation of DDR mechanisms is a feature of cancer chemotherapy and radiotherapy resistance. Advances in our understanding of DDR and its complex role in cancer has led to several translational DNA repair-targeted investigations culminating in clinically viable precision oncology strategy using poly(ADP-ribose) polymerase (PARP) inhibitors in breast, ovarian, pancreatic, and prostate cancers. While PARP directed synthetic lethality has improved outcomes for many patients, the lack of sustained clinical response and the development of resistance pose significant clinical challenges. Therefore, the search for additional DDR-directed drug targets and novel synthetic lethality approaches is highly desirable and is an area of intense preclinical and clinical investigation. Here, we provide an overview of the mammalian DNA repair pathways and then focus on current state of PARP inhibitors (PARPi) and other emerging DNA repair inhibitors for synthetic lethality in cancer.

WEE1 Inhibitor: Clinical Development

Purpose of Review

WEE1 inhibitor has been shown to potential chemotherapy or radiotherapy sensitivity in preclinical models, particularly in p53-mutated or deficient cancer cells although not exclusively. Here, we review the clinical development of WEE1 inhibitor in combination with chemotherapy or radiotherapy with concurrent chemotherapy as well as its combination with different novel agents.

Recent Findings

Although several clinical trials have shown that WEE1 inhibitor can be safely combined with different chemotherapy agents as well as radiotherapy with concurrent chemotherapy, its clinical development has been hampered by the higher rate of grade 3 toxicities when added to standard treatments. A few clinical trials had also been conducted to test WEE1 inhibitor using TP53 mutation as a predictive biomarker. However, TP53 mutation has not been shown to be the most reliable predictive biomarker and the benefit of adding WEE1 inhibitor to chemotherapy has been modest, even in TP53 biomarker-driven studies.

Summary

There are ongoing clinical trials testing WEE1 inhibitor with novel agents such as ATR and PAPR inhibitors as well as anti-PDL1 immunotherapy, which may better define the role of WEE1 inhibitor in the future if any of the novel treatment combination will show superior anti-tumor efficacy with a good safety profile compared to monotherapy and/or standard treatment.

Safety, Antitumor Activity, and Biomarker Analysis in a Phase I Trial of the Once-daily Wee1 Inhibitor Adavosertib (AZD1775) in Patients with Advanced Solid Tumors

PURPOSE

The Wee1 kinase inhibitor adavosertib abrogates cell-cycle arrest, leading to cell death. Prior testing of twice-daily adavosertib in patients with advanced solid tumors determined the recommended phase II dose (RPh2D). Here, we report results for once-daily adavosertib.

PATIENTS AND METHODS

A 3 + 3 dose-escalation design was used, with adavosertib given once daily on days 1 to 5 and 8 to 12 in 21-day cycles. Molecular biomarkers of Wee1 activity, including tyrosine 15-phosphorylated Cdk1/2 (pY15-Cdk), were assessed in paired tumor biopsies. Whole-exome sequencing and RNA sequencing of remaining tumor tissue identified potential predictive biomarkers.

RESULTS

Among the 42 patients enrolled, the most common toxicities were gastrointestinal and hematologic; dose-limiting toxicities were grade 4 hematologic toxicity and grade 3 fatigue. The once-daily RPh2D was 300 mg. Six patients (14%) had confirmed partial responses: four ovarian, two endometrial. Adavosertib plasma exposures were similar to those from twice-daily dosing. On cycle 1 day 8 (pre-dose), tumor pY15-Cdk levels were higher than baseline in four of eight patients, suggesting target rebound during the day 5 to 8 dosing break. One patient who progressed rapidly had a tumor WEE1 mutation and potentially compensatory PKMYT1 overexpression. Baseline CCNE1 overexpression occurred in both of two responding patients, only one of whom had CCNE1 amplification, and in zero of three nonresponding patients.

CONCLUSIONS

We determined the once-daily adavosertib RPh2D and observed activity in patients with ovarian or endometrial carcinoma, including two with baseline CCNE1 mRNA overexpression. Future studies will determine whether CCNE1 overexpression is a predictive biomarker for adavosertib.

Phase II Study of the WEE1 Inhibitor Adavosertib in Recurrent Uterine Serous Carcinoma

PURPOSE

Uterine serous carcinoma (USC) is a distinct histologic subtype of endometrial cancer, with molecular characteristics suggesting frequent cell-cycle dysregulation paired with a high level of oncogene-driven replication stress. Adavosertib is a potent and selective oral inhibitor of the WEE1 kinase, a key regulator of the G2/M and S phase cell-cycle checkpoints. Because cells with impaired cell-cycle regulation and high replication stress may be vulnerable to WEE1 inhibition, we conducted this study to assess the activity of adavosertib monotherapy in women with recurrent USC.

PATIENTS AND METHODS

This was a single-arm two-stage phase II study with coprimary end points of objective response rate (ORR) and rate of progression-free survival at 6 months (PFS6). Women with recurrent USC were treated with adavosertib monotherapy at a starting dose of 300 mg orally once daily days 1 through 5 and 8 through 12 of a 21-day cycle until disease progression.

RESULTS

In 34 evaluable patients, 10 total responses (one confirmed complete response, eight confirmed partial responses, and one unconfirmed partial response) were observed with adavosertib monotherapy, for an ORR of 29.4% (95% CI, 15.1 to 47.5). Sixteen patients were progression-free at 6 months, for a PFS6 rate of 47.1% (95% CI, 29.8 to 64.9). Median PFS was 6.1 months, and median duration of response was 9.0 months. Frequent treatment-related adverse events (AEs) included diarrhea (76.5%), fatigue (64.7%), nausea (61.8%), and hematologic AEs. No clear correlation of clinical activity with specific molecular alterations was observed in an exploratory biomarker analysis.

CONCLUSION

Adavosertib monotherapy demonstrated encouraging and durable evidence of activity in women with USC, and further investigation of this agent in this cancer and biomarkers of activity are indicated.

The Challenge of Combining Chemo- and Radiotherapy with Checkpoint Kinase Inhibitors

Preclinical models of cancer have demonstrated enhanced efficacy of cell-cycle checkpoint kinase inhibitors when used in combination with genotoxic agents. This combination therapy is predicted to be exquisitely toxic to cells with a deficient G1-S checkpoint or cells with a genetic predisposition leading to intrinsic DNA replication stress, as these cancer cells become fully dependent on the intra-S and G2-M checkpoints for DNA repair and cellular survival. Therefore, abolishing remaining cell-cycle checkpoints after damage leads to increased cell death in a tumor cell-specific fashion. However, the preclinical success of these drug combinations is not consistently replicated in clinical trials. Here, we provide a perspective on the translation of preclinical studies into rationally designed clinical studies. We will discuss successes and failures of current treatment combinations and drug regimens and provide a detailed overview of all clinical trials using ATR, CHK1, or WEE1 inhibitors in combination with genotoxic agents. This highlights the need for revised patient stratification and the use of appropriate pharmacodynamic biomarkers to improve the success rate of clinical trials.

Genomic profiling of platinum-resistant ovarian cancer: The road into druggable targets

Ovarian cancer is the most lethal gynecologic cancer. High-grade serous carcinoma (HGSC) is the most frequent histologic subtype and while it is a highly platinum-sensitive cancer at initial treatment, nearly 90 % of stage IIIC patients recur in 5 years and eventually become resistant to platinum treatment. Historically, the definition of platinum-resistant disease is based on the time interval between last platinum therapy and recurrence shorter than 6 months. Nowadays the use of sophisticated imaging techniques and serum markers to detect recurrence makes the accuracy of this clinical definition less clear and even more debatable as we begin to better understand the molecular landscape of HGSC and markers of platinum resistance and sensitivity. HGSC is characterized by a low frequency of recurrent mutations, great genomic instability with widespread copy number variations, universal TP53 mutations, and homologous recombination deficiency in more than 50 % of cases. Platinum agents form DNA adducts and intra- and inter-strand cross-links in the DNA. Most of DNA repair pathways are involved at some point in the repair of platinum induced DNA damaging, most notably homologous recombination, Fanconi Anemia, and nucleotide excision repair pathways. Mechanisms of platinum resistance are related mostly to the limitation of platinum-DNA adduct formation by changing cellular pharmacology, and to the prevention of cell death after DNA damage due to alterations in DNA repair pathways and cell cycle regulation. Understanding these mechanisms of sensitivity and resistance may help to define the utility of platinum re-challenge in each situation and guide new therapeutic opportunities. Moreover, the discovery of mechanisms of synthetic lethality related to alterations in DNA repair and cell cycle regulation pathways has opened up a new avenue for drug therapy in the last decade. In the present article, we review pathways involved in platinum-induced DNA damage repair and their relationship with genomic alterations present in HGSC. Moreover, we report new treatment strategies that are underway to target these alterations.

A WEE1 family business: regulation of mitosis, cancer progression, and therapeutic target

The inhibition of the DNA damage response (DDR) pathway in the treatment of cancer has recently gained interest, and different DDR inhibitors have been developed. Among them, the most promising ones target the WEE1 kinase family, which has a crucial role in cell cycle regulation and DNA damage identification and repair in both nonmalignant and cancer cells. This review recapitulates and discusses the most recent findings on the biological function of WEE1/PKMYT1 during the cell cycle and in the DNA damage repair, with a focus on their dual role as tumor suppressors in nonmalignant cells and pseudo-oncogenes in cancer cells. We here report the available data on the molecular and functional alterations of WEE1/PKMYT1 kinases in both hematological and solid tumors. Moreover, we summarize the preclinical information on 36 chemo/radiotherapy agents, and in particular their effect on cell cycle checkpoints and on the cellular WEE1/PKMYT1-dependent response. Finally, this review outlines the most important pre-clinical and clinical data available on the efficacy of WEE1/PKMYT1 inhibitors in monotherapy and in combination with chemo/radiotherapy agents or with other selective inhibitors currently used or under evaluation for the treatment of cancer patients.

Exploiting replicative stress in gynecological cancers as a therapeutic strategy

Elevated levels of replicative stress in gynecological cancers arising from uncontrolled oncogenic activation, loss of key tumor suppressors, and frequent defects in the DNA repair machinery are an intrinsic vulnerability for therapeutic exploitation. The presence of replication stress activates the DNA damage response and downstream checkpoint proteins including ataxia telangiectasia and Rad3 related kinase (ATR), checkpoint kinase 1 (CHK1), and WEE1-like protein kinase (WEE1), which trigger cell cycle arrest while protecting and restoring stalled replication forks. Strategies that increase replicative stress while lowering cell cycle checkpoint thresholds may allow unrepaired DNA damage to be inappropriately carried forward in replicating cells, leading to mitotic catastrophe and cell death. Moreover, the identification of fork protection as a key mechanism of resistance to chemo- and poly (ADP-ribose) polymerase inhibitor therapy in ovarian cancer further increases the priority that should be accorded to the development of strategies targeting replicative stress. Small molecule inhibitors designed to target the DNA damage sensors, such as inhibitors of ataxia telangiectasia-mutated (ATM), ATR, CHK1 and WEE1, impair smooth cell cycle modulation and disrupt efficient DNA repair, or a combination of the above, have demonstrated interesting monotherapy and combinatorial activity, including the potential to reverse drug resistance and have entered developmental pipelines. Yet unresolved challenges lie in balancing the toxicity profile of these drugs in order to achieve a suitable therapeutic index while maintaining clinical efficacy, and selective biomarkers are urgently required. Here we describe the premise for targeting of replicative stress in gynecological cancers and discuss the clinical advancement of this strategy.

Effect of food on the pharmacokinetics of the WEE1 inhibitor adavosertib (AZD1775) in patients with advanced solid tumors

PURPOSE

To support future dosing recommendations, the effect of food on the pharmacokinetics of adavosertib, a first-in-class, small-molecule reversible inhibitor of WEE1 kinase, was assessed in patients with advanced solid tumors.

METHODS

In this Phase I, open-label, randomized, two-period, two-sequence crossover study, the pharmacokinetics of a single 300 mg adavosertib dose were investigated in fed versus fasted states.

RESULTS

Compared with the fasted state, a high-fat, high-calorie meal (fed state) decreased adavosertib maximum plasma concentration (Cmax) by 16% and systemic exposure (area under the plasma concentration-time curve [AUC]) by 6%; AUC0-t decreased by 7% and time to maximum plasma concentration was delayed by 1.97 h (P = 0.0009). The 90% confidence interval of the geometric least-squares mean treatment ratio for AUC and AUC0-t was contained within the no-effect limits (0.8-1.25), while that of Cmax crossed the lower bound of the no-effect limits. Adverse events (AEs) related to adavosertib treatment were reported by 20 (64.5%) of the 31 patients treated in this study. Grade ≥ 3 AEs were reported by four (12.9%) patients (one in the fed state, three in the fasted state); two of these AEs were considered treatment-related by the investigator. Three serious AEs were reported in three (9.7%) patients; these were not considered treatment-related. No patients discontinued because of treatment-related AEs, and no new safety signals were reported.

CONCLUSION

A high-fat meal did not have a clinically relevant effect on the systemic exposure of adavosertib, suggesting that adavosertib can be administered without regard to meals.

CA-125 ELIMination Rate Constant K (KELIM) Is a Marker of Chemosensitivity in Patients with Ovarian Cancer: Results from the Phase II CHIVA Trial

PURPOSE

In patients with ovarian cancer receiving neoadjuvant chemotherapy, the first-line treatment success will depend on both the tumor-primary chemosensitivity and the completeness of interval debulking surgery (IDS). The modeled CA-125 ELIMination rate constant K (KELIM), calculated with the CA-125 longitudinal kinetics during the first 100 chemotherapy days, is a validated early marker of tumor chemosensitivity. The objective was to investigate the role of the chemosensitivity relative to the success of first-line medical-surgical treatment.

EXPERIMENTAL DESIGN

The CA-125 concentrations were prospectively measured in the randomized phase II trial CHIVA (NCT01583322, carboplatin-paclitaxel regimen ± nintedanib, and IDS, n = 188 patients). The KELIM predictive value regarding the tumor response rate, likelihood of complete IDS, risk of subsequent platinum-resistant relapse (PtRR), progression-free survival (PFS), and overall survival (OS) was assessed using univariate and multivariate tests.

RESULTS

The data from 134 patients were analyzed. KELIM was an independent and major predictor of subsequent PtRR risk, and of survivals. The final logistic regression model, including KELIM [OR = 0.13; 95% confidence interval (CI), 0.03-0.49] and complete IDS (no vs. yes, OR = 0.30; 95% CI, 0.11-0.76) highlights the preponderant role of chemosensitivity on the success of the first-line treatment. In patients with highly chemosensitive diseases, the patient prognosis was driven more by the chemotherapy-induced antitumor effects than by the surgery.

CONCLUSIONS

The tumor-primary chemosensitivity, assessed by the modeled CA-125 KELIM calculated during neoadjuvant chemotherapy (http://www.biomarker-kinetics.org/CA-125-neo), may be a major parameter to consider for decision-making regarding IDS attempt, and selecting patients for treatments meant to reverse the primary chemoresistance.See related commentary by May and Oza, p. 4432.

Safety, Pharmacokinetics, and Clinical Activity of Adavosertib in Combination with Chemotherapy in Asian Patients with Advanced Solid Tumors: Phase Ib Study

BACKGROUND

The WEE1 inhibitor adavosertib (AZD1775) has been investigated in Western patients.

OBJECTIVE

This open-label Phase Ib study (NCT02341456) investigated the safety, pharmacokinetics, and clinical activity of adavosertib in combination with carboplatin alone or paclitaxel plus carboplatin in Asian patients with advanced solid tumors and defined the recommended Phase II dose.

PATIENTS AND METHODS

Nineteen patients received adavosertib 175 mg twice daily (bid) for 2.5 days (five doses) in combination with carboplatin (AUC 5) alone or paclitaxel (175 mg/m²) plus carboplatin, or adavosertib 225 mg bid for 2.5 days in combination with paclitaxel plus carboplatin in 21-day cycles. Preliminary safety and dose-limiting toxicity analyses were performed and dose escalation/de-escalation conducted as appropriate.

RESULTS

Adavosertib 175 mg bid for 2.5 days with carboplatin alone or paclitaxel plus carboplatin was considered tolerable. Two patients receiving adavosertib 225 mg bid in combination with paclitaxel plus carboplatin experienced dose-limiting toxicities (grade 4 sepsis; grade 5 acute respiratory distress syndrome); this regimen was not considered tolerable. Grade ≥ 3 adverse events reported most commonly in any cohort included: anemia; decreased white blood cell count; decreased neutrophil count; neutropenia; decreased platelet count; thrombocytopenia; and febrile neutropenia. Exposure to adavosertib, as determined by pharmacokinetic analysis, in Asian patients was higher than that previously seen in Western patients. A partial response occurred in 2/12 evaluable patients (16.7%) at the recommended Phase II dose.

CONCLUSIONS

Adavosertib 175 mg bid for 2.5 days was chosen as the recommended Phase II dose in combination with paclitaxel and carboplatin in Asian patients.