Phase 2 study of intermittent pulse dacomitinib in patients with advanced non-small cell lung cancers

Drug dependence in cancer is exploitable by optimally constructed treatment holidays

Cancers with acquired resistance to targeted therapy can become simultaneously dependent on the presence of the targeted therapy drug for survival, suggesting that intermittent therapy may slow resistance. However, relatively little is known about which tumours are likely to become dependent and how to schedule intermittent therapy optimally. Here we characterized drug dependence across a panel of over 75 MAPK-inhibitor-resistant BRAFV600E mutant melanoma models at the population and single-clone levels. Melanocytic differentiated models exhibited a much greater tendency to give rise to drug-dependent progeny than their dedifferentiated counterparts. Mechanistically, acquired loss of microphthalmia-associated transcription factor in differentiated melanoma models drives ERK-JunB-p21 signalling to enforce drug dependence. We identified the optimal scheduling of 'drug holidays' using simple mathematical models that we validated across short and long timescales. Without detailed knowledge of tumour characteristics, we found that a simple adaptive therapy protocol can produce near-optimal outcomes using only measurements of total population size. Finally, a spatial agent-based model showed that optimal schedules derived from exponentially growing cells in culture remain nearly optimal in the context of tumour cell turnover and limited environmental carrying capacity. These findings may guide the implementation of improved evolution-inspired treatment strategies for drug-dependent cancers.

Plasma exchange treats severe intrahepatic cholestasis caused by dacomitinib: A case report

RATIONALE

Dacomitinib-induced liver injury is often manifested by mild elevations of transaminases and bilirubin, and severe intrahepatic cholestasis caused by dacomitinib for simultaneous taking orally cytochrome P450 2D6 (CYP2D6) competitive substrates has been rarely reported.

PATIENT CONCERNS

The patient was a 69-year-old woman with non-small cell lung cancer (NSCLC) who was prescribed oral dacomitinib for a month; she was given oral loratadine due to "allergic rhinitis" and metoprolol extended action tablets due to "tachycardia" separately for a few days during the course of dacomitinib treatment. The patient developed liver damage, increased fatigue, yellow urine, and pruritus, with significantly elevated serum levels of bilirubin and glutamyltranspetidase.

DIAGNOSIS

Intrahepatic cholestasis, drug-induced liver injury, and NSCLC.

INTERVENTIONS

After admission, the patient was prescribed adenosylmethionine, acetylcysteine, ursodeoxycholic acid capsule, methylprednisolone and fenofibrate for a month, with progressive elevation of liver biochemical parameters. Through drug enzyme gene assays in the liver tissue after percutaneous liver biopsy, we found both CYP2D6*10/*10 and ATP-binding cassette subfamily B member 1 GG variants (rs1045642) positive. After the poor response to the conventional medication, the patient underwent plasma exchange.

OUTCOMES

The patient was discharged after her liver parameters improved; the parameters remained normal at several follow-up visits, and she renewed the NSCLC regimens without dacomitinib after being evaluated by oncologists.

LESSONS

Dacomitinib can induce severe intrahepatic cholestasis. It is considered that patients with intermediate metabolic CYP2D6 are susceptible to drug-induced liver injury caused by dacomitinib; plasma exchange may be an effective treatment.

Updated Insights on EGFR Signaling Pathways in Glioma

Nowadays, due to recent advances in molecular biology, the pathogenesis of glioblastoma is better understood. For the newly diagnosed, the current standard of care is represented by resection followed by radiotherapy and temozolomide administration, but because median overall survival remains poor, new diagnosis and treatment strategies are needed. Due to the quick progression, even with aggressive multimodal treatment, glioblastoma remains almost incurable. It is known that epidermal growth factor receptor (EGFR) amplification is a characteristic of the classical subtype of glioma. However, targeted therapies against this type of receptor have not yet shown a clear clinical benefit. Many factors contribute to resistance, such as ineffective blood-brain barrier penetration, heterogeneity, mutations, as well as compensatory signaling pathways. A better understanding of the EGFR signaling network, and its interrelations with other pathways, are essential to clarify the mechanisms of resistance and create better therapeutic agents.

Continuous versus intermittent BRAF and MEK inhibition in patients with BRAF-mutated melanoma: a randomized phase 2 trial

Preclinical modeling suggests that intermittent BRAF inhibitor therapy may delay acquired resistance when blocking oncogenic BRAFV600 in melanoma1,2. We conducted S1320, a randomized, open-label, phase 2 clinical trial (NCT02196181) evaluating whether intermittent dosing of the BRAF inhibitor dabrafenib and the MEK inhibitor trametinib improves progression-free survival in patients with metastatic and unresectable BRAFV600 melanoma. Patients were enrolled at 68 academic and community sites nationally. All patients received continuous dabrafenib and trametinib during an 8-week lead-in period, after which patients with non-progressing tumors were randomized to either continuous or intermittent dosing of both drugs on a 3-week-off, 5-week-on schedule. The trial has completed accrual and 206 patients with similar baseline characteristics were randomized 1:1 to the two study arms (105 to continuous dosing, 101 to intermittent dosing). Continuous dosing yielded a statistically significant improvement in post-randomization progression-free survival compared with intermittent dosing (median 9.0 months versus 5.5 months, P = 0.064, pre-specified two-sided α = 0.2). Therefore, contrary to the initial hypothesis, intermittent dosing did not improve progression-free survival in patients. There were no differences in the secondary outcomes, including overall survival and the overall incidence of treatment-associated toxicity, between the two groups.

Evaluation of the potential effect of dacomitinib, an EGFR tyrosine kinase inhibitor, on ECG parameters in patients with advanced non-small cell lung cancer

Purpose The study evaluated the potential effect of dacomitinib, a small molecule epidermal growth factor receptor (EGFR) inhibitor, on the electrocardiogram (ECG) parameters in adult patients with advanced non-small cell lung cancer enrolled in a multicenter, open-label, phase 2 study. Methods Patients received dacomitinib for six doses of 45 mg every 12 h in a 7-day lead-in cycle (cycle 0), then 60 mg every 12 h for six doses in a 14-day cycle (cycle 1). Clock time-matched triplicate ECGs were performed at 0, 2, 4, 6, 8 and 10 h on day 1 (baseline) and day 4 of cycle 0, and prior to dose on days 1 and 4 of cycle 1. The QT interval was corrected for heart rate using Fridericia's correction (QTcF) and a study specific correction factor (QTcS). Results Thirty-two patients in the study comprised the QTc-evaluable population. Dacomitinib had no effect on the heart rate. The upper limits of the 95% confidence interval (CI) for the mean change from baseline in QTcF and QTcS were < 10 ms at all time points. A lack of relationship between plasma concentrations of dacomitinib or total active moiety on QTcF and QTcS was evidenced. All upper 90% CIs of the PR intervals were < 200 ms, although a small mean increase from baseline (2.7-6.6 ms) was observed. Conclusions There was a lack of a clinically relevant effect of dacomitinib on ECG parameters at dacomitinib concentrations comparable to those obtained at its highest therapeutic dosing regimen of 45 mg once daily. ClinicalTrials.gov identifier: NCT01858389.

Clinical evaluation of dacomitinib for the treatment of metastatic non-small cell lung cancer (NSCLC): current perspectives

Systemic treatment of advanced non-small cell lung cancer (NSCLC) has undergone remarkable changes in the last decade, with the introduction of targeted therapies and immunotherapy. The identification of activating mutations in the epidermal growth factor receptor (EGFR) gene (deletions in exon 19 [Del19] and point mutation L858R in exon 21) has been the first important step toward molecularly guided precision therapy in lung cancer. Several randomized trials comparing EGFR tyrosine kinase inhibitors (TKIs) (gefitinib, erlotinib, and afatinib) to standard chemotherapy in first-line treatment of advanced EGFR-mutant NSCLC showed significant improvement in progression-free survival (PFS) and in response rate, with lower rates of adverse events (AEs) and better symptom control. However, none of these trials showed significant improvement in overall survival (OS). Despite impressive responses with EGFR-TKI, disease invariably progresses after 9 to 13 months, due to acquired resistance. Dacomitinib is a potent, irreversible, highly selective, second-generation EGFR-TKI, which inhibits the signaling from both heterodimers and homodimers of all the members of the human epidermal growth factor receptor (HER) family. Here, we review the clinical development of dacomitinib from phase I to phase III, with particular attention to its toxicity and on its activity on T790M mutation. Then, we critically examine the results of ARCHER 1050, a study that was crucial for Food and Drug Administration (FDA) approval. ARCHER 1050 was the first randomized phase III study comparing dacomitinib with gefitinib, in first-line treatment of patients with advanced EGFR-mutated NSCLC. Dacomitinib was superior to gefitinib in terms of primary end-point (14.7 vs 9.2 months) and OS (34.1 vs 26.8 months). The incidence of diarrhea, skin rash, mucositis and, consequently, dose reductions was higher with dacomitinib, while hepatic toxicity was higher with gefitinib. Dacomitinib constitutes one of the standard first-line options in patients with advanced EGFR-mutated NSCLC.

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Overcoming EGFRG724S-mediated osimertinib resistance through unique binding characteristics of second-generation EGFR inhibitors

The emergence of acquired resistance against targeted drugs remains a major clinical challenge in lung adenocarcinoma patients. In a subgroup of these patients we identified an association between selection of EGFR^T790M-negative but EGFR^G724S-positive subclones and osimertinib resistance. We demonstrate that EGFR^G724S limits the activity of third-generation EGFR inhibitors both in vitro and in vivo. Structural analyses and computational modeling indicate that EGFR^G724S mutations may induce a conformation of the glycine-rich loop, which is incompatible with the binding of third-generation TKIs. Systematic inhibitor screening and in-depth kinetic profiling validate these findings and show that second-generation EGFR inhibitors retain kinase affinity and overcome EGFR^G724S-mediated resistance. In the case of afatinib this profile translates into a robust reduction of colony formation and tumor growth of EGFR^G724S-driven cells. Our data provide a mechanistic basis for the osimertinib-induced selection of EGFR^G724S-mutant clones and a rationale to treat these patients with clinically approved second-generation EGFR inhibitors.

Acquired resistance to targeted drugs remains a major clinical challenge in lung adenocarcinoma patients. Here, the authors show how the acquired EGFR^G724S mutation induces resistance to third-generation EGFR inhibitors and why the mutant kinase remains susceptible to second-generation inhibitors.

Therapeutic approaches for T790M mutation positive non-small-cell lung cancer

INTRODUCTION

Epidermal growth factor receptor (EGFR) mutation positive non-small cell lung cancer (NSCLC) is a subset of lung cancer with demonstrated response to targeted therapies. However, resistance to the first targeted approach usually occurs within the first year, and it is associated in 50-60% of cases to the T790M resistance mutation. Areas covered: The review provides an overview on the significance of the presence of the T790M mutation, its detection, treatment options and subsequent mechanisms of resistance. Expert commentary: Osimertinib is the current treatment option for T790M mutation positive NSCLC after progression to first or second-generation EGFR TKIs, with activity also on brain metastasis. However, the scenario is in continuous evolution and results from clinical trials are awaited in first-line setting and in combination strategies.

Dacomitinib potentiates the efficacy of conventional chemotherapeutic agents via inhibiting the drug efflux function of ABCG2 in vitro and in vivo

BACKGROUND

ATP-binding cassette subfamily G member 2 (ABCG2), a member of the ABC transporter superfamily proteins, mediates multidrug resistance (MDR) by transporting substrate anticancer drugs out of cancer cells and decreasing their intracellular accumulation. MDR is a major hurdle to successful chemotherapy. A logical approach to overcome MDR is to inhibit the transporter. However, no safe and effective MDR inhibitor has been approved in the clinic.

METHODS

The MTT assay was used to evaluate cell cytotoxicity and MDR reversal effect. Drug efflux and intracellular drug accumulation were measured by flow cytometry. The H460/MX20 cell xenograft model was established to evaluate the enhancement of anticancer efficacy of topotecan by dacomitinib in vivo. To ascertain the interaction of dacomitinib with the substrate binding sites of ABCG2, the competition of dacomitinib for photolabeling of ABCG2 with [¹²⁵I]- iodoarylazidoprazosin (IAAP) was performed. Vanadate-sensitive ATPase activity of ABCG2 was measured in the presence of a range of different concentrations of dacomitinib to evaluate the effect of dacomitinib on ATP hydrolysis as the energy source of the transporter. A flow cytometry-based assay and western blotting were employed to study whether dacomitininb could inhibit the expression level of ABCG2. The mRNA expression levels of ABCG2 were analyzed by real-time quantitative RT-PCR. The protein expression level of AKT, ERK and their phosphorylations were detected by Western blotting.

RESULTS

Here, we found that dacomitinib, an irreversible pan-ErbB tyrosine kinase inhibitor (TKI) in phase III clinical trial, could enhance the efficacy of conventional chemotherapeutic agents specifically in ABCG2-overexpressing MDR cancer cells but not in the parental sensitive cells. Dacomitinib was found to significantly increase the accumulation of ABCG2 probe substrates [doxorubicin (DOX),Rhodamine 123 (Rho 123) and Hoechst 33342] by inhibiting the transporter efflux function. Moreover, dacomitinib stimulated ABCG2 ATPase activity and competed with [¹²⁵I]-IAAP photolabeling of ABCG2 in a concentration-dependent manner. However, dacomitinib did not alter ABCG2 expression at protein and mRNA levels or inhibit ErbB downstream signaling of AKT and ERK. Importantly, dacomitinib significantly enhanced the efficacy of topotecan in ABCG2-overexpressing H460/MX20 cell xenografts in nude mice without incurring additional toxicity.

CONCLUSIONS

These results suggest that dacomitinib reverses ABCG2-mediated MDR by inhibiting ABCG2 efflux function and increasing intracellular accumulation of anticancer agents. Our findings advocate further clinical investigation of combinations of dacomitinib and conventional chemotherapy in cancer patients with ABCG2-overexpressing MDR tumors.