A phase 1 study with dose expansion of the CDK inhibitor dinaciclib (SCH 727965) in combination with epirubicin in patients with metastatic triple negative breast cancer

PURPOSE

Low molecular weight cyclin E (LMW-E) isoforms, overexpressed in a majority (~70 %) of triple-negative breast cancers (TNBC), were found in preclinical models to mediate tumorigenesis through binding and activation of CDK2. CDK1/CDK2 inhibitors, such as dinaciclib, combined with anthracyclines, were synergistic in decreasing viability of TNBC cell lines. Based on this data, a phase 1 study was conducted to determine the maximum tolerated dose of dinaciclib in combination with epirubicin in patients with metastatic TNBC.

METHODS

Cohorts of at least 2 patients were treated with escalating doses of dinaciclib given on day 1 followed by standard dose of epirubicin given on day 2 of a 21 day cycle. No intra-patient dose escalation was allowed. An adaptive accrual design based upon toxicity during cycle 1 determined entry into therapy cohorts. The target acceptable dose limiting toxicity (DLT) to advance to the next treatment level was 30 %.

RESULTS

Between 9/18/2012 and 7/18/2013, 9 patients were enrolled and treated at MD Anderson Cancer Center. DLTs included febrile neutropenia (grade 3, n = 2), syncope (grade 3, n = 2) and vomiting (grade 3, n = 1). Dose escalation did not proceed past the second cohort due to toxicity. After further accrual, the first dose level was also found to be too toxic. No treatment responses were noted, median time to progression was 5.5 weeks (range 3-12 weeks). Thus, accrual was stopped rather than explore the -1 dose level.

CONCLUSION

The combination of dinaciclib and epirubicin is associated with substantial toxicities and does not appear to be an effective treatment option for TNBC.

Clinical study of the novel cyclin-dependent kinase inhibitor dinaciclib in combination with rituximab in relapsed/refractory chronic lymphocytic leukemia patients

PURPOSE

Dinaciclib is a novel selective inhibitor of cyclin-dependent kinase (CDK)1, CDK2, CDK5, and CDK9. We conducted a phase I study to investigate the effects of dinaciclib when administered with rituximab.

METHODS

In this phase I nonrandomized dose-escalation 3 + 3 trial, patients with relapsed/refractory chronic lymphocytic leukemia (CLL) were treated with dinaciclib and rituximab. Dinaciclib was administered intravenously (IV) over 2 h on days 1, 8 and 15 in cycles 2-13 (28-day cycles). Rituximab 375 mg/m(2) was administered IV on days 1, 8, 15 and 22 in cycle 1 (28-day cycle) and on day 1 during cycle 3-13. Rituximab was not administered in cycle 2. Rituximab and dinaciclib were given alone in cycles 1 and 2, respectively, and in combination in cycles 3-13. Primary objectives included determination of the recommended phase II dose of dinaciclib and evaluation of pharmacokinetics (PK) when administered with rituximab.

RESULTS

Five patients completed the study due to early termination. All presented with drug-related adverse events (AEs), but no dose-limiting toxicities were observed. The most commonly observed toxicities included hematological, digestive and metabolic AEs. However, no tumor lysis syndrome has been reported in the study. Four patients achieved stable disease, and one patient achieved complete response according to 2008 iwCLL criteria at cycle 3. PK samples were collected from 5 patients, and no obvious interaction between dinaciclib and rituximab was observed.

CONCLUSIONS

Limited data from this study shows dinaciclib in combination with rituximab was well tolerated and revealed encouraging clinical activity in relapsed/refractory CLL patients.

Dinaciclib for the treatment of breast cancer

INTRODUCTION

Cyclin-dependent kinases (CDK) represent attractive targets in oncology due to their key role in controlling gene transcription and cell cycle progression. Dinaciclib (MK-7965, formerly SCH727965) is a relatively novel CDK 1/2/5/9 inhibitor that has shown promising results in preclinical studies and an acceptable safety profile in Phase I clinical trials. It is currently under clinical evaluation for the treatment of hematological and solid malignancies, including breast cancer.

AREAS COVERED

This review summarizes the current understanding of CDK's role in physiology and cancer, and the therapeutic value of blocking their pathways in breast cancer. Particularly, the article reviews the preclinical and clinical data for dinaciclib in its use for the treatment of breast cancer.

EXPERT OPINION

A better understanding of the molecular mechanisms underlying cell cycle dysregulation in cancer is needed in order to develop novel CDK inhibitors. Additionally, further efforts are needed to identify potential biomarkers of dinaciclib efficacy, which could allow a better selection of patients enrolled in clinical trials. Moreover, combination therapies with dinaciclib or other CDK and chemotherapy, endocrine therapy or targeted therapies might be further evaluated in breast cancer patients.

Randomized phase 2 study of the cyclin-dependent kinase inhibitor dinaciclib (MK-7965) versus erlotinib in patients with non-small cell lung cancer

OBJECTIVES

Dinaciclib (MK-7965, formerly SCH 727965), a novel, small-molecule inhibitor of cyclin-dependent kinases, has been shown to induce apoptosis in preclinical studies of human tumor cell lines, including non-small cell lung cancer (NSCLC) cells. Erlotinib, an epidermal growth factor receptor inhibitor, is approved for the treatment of advanced NSCLC as second- or third-line therapy. This phase 2, randomized, multicenter, open-label study compared dinaciclib with erlotinib in patients with previously treated NSCLC.

MATERIALS AND METHODS

The study was comprised of 2 parts: in part 1, patients were randomized to either intravenous (IV) dinaciclib (50 mg/m2) or oral erlotinib (150 mg) using an adaptive Bayesian design that adjusted the randomization ratio in favor of the more active arm, and in part 2, patients who had progressed on erlotinib were permitted to cross over to receive dinaciclib at the same dosage as in part 1. Patients were followed until disease progression or death, initiation of nonstudy cancer treatment, discontinuation, or withdrawal of consent. The primary efficacy end point was time-to-progression (TTP) in part 1 and objective response rate (ORR) in part 2.

RESULTS

Based on Kaplan-Meier estimates, the median TTP was 1.49 months (95% confidence interval [CI]: 1.31, 2.63) following initial treatment with dinaciclib, compared with 1.58 months (95% CI: 1.38, 2.83) with erlotinib. No objective responses were observed following initial treatment with dinaciclib. Common severe (grade 3 or 4) drug-related adverse effects included neutropenia, leukopenia, vomiting, and diarrhea.

CONCLUSIONS

Dinaciclib, administered IV, was well tolerated at the 50 mg/m2 dose, but does not have activity as monotherapy in previously treated NSCLC. Evaluation of dinaciclib in combination with other agents for other indications including breast cancer and multiple myeloma is in progress.

Randomized phase II trial of the cyclin-dependent kinase inhibitor dinaciclib (MK-7965) versus capecitabine in patients with advanced breast cancer

INTRODUCTION

Effective therapies after failure of treatment with anthracyclines and taxanes are needed for patients with metastatic breast cancer. Dinaciclib (MK-7965, formerly SCH727965), a small-molecule cyclin-dependent kinase inhibitor, has demonstrated antitumor activity in phase I studies with solid-tumor patients. This phase II trial was designed to assess the efficacy and safety of dinaciclib compared with that of capecitabine in women with previously treated advanced breast cancer.

PATIENTS AND METHODS

Patients were randomized to receive either dinaciclib at 50 mg/m(2), administered as a 2-hour infusion every 21 days, or 1250 mg/m(2) capecitabine, administered orally twice daily in 21-day cycles.

RESULTS

An unplanned interim analysis showed that the time to disease progression was inferior with dinaciclib treatment compared with capecitabine treatment; therefore, the trial was stopped after 30 patients were randomized. Dinaciclib treatment demonstrated antitumor activity in 2 of 7 patients with estrogen receptor-positive and human epidermal growth factor receptor 2-negative metastatic breast cancer (1 confirmed and 1 unconfirmed partial response), as well as acceptable safety and tolerability. Grade 3 or 4 treatment-related adverse events were common and included neutropenia, leukopenia, increase in aspartate aminotransferase, and febrile neutropenia. Population pharmacokinetic model-predicted mean dinaciclib exposure (area under the concentration-time curve extrapolated to infinity [AUC[I]]) at 50 mg/m(2) was similar to that observed in a previous phase I trial, and no drug accumulation was observed after multiple-dose administration.

CONCLUSION

Although dinaciclib monotherapy demonstrated some antitumor activity and was generally tolerated, efficacy was not superior to capecitabine. Future studies may be considered to evaluate dinaciclib in select patient populations with metastatic breast cancer and in combination with other agents.

Clinical and laboratory studies of the novel cyclin-dependent kinase inhibitor dinaciclib (SCH 727965) in acute leukemias

Purpose

Dinaciclib inhibits cyclin-dependent kinases 1, 2, 5, and 9 with a better therapeutic index than flavopiridol in preclinical studies. This study assessed the activity of dinaciclib in acute leukemia both in the clinic and in vitro.

Methods

Adults with relapsed/refractory acute myeloid leukemia (n = 14) and acute lymphoid leukemia (n = 6) were treated with dinaciclib 50 mg/m² given as a 2-h infusion every 21 days.

Results

Most patients had dramatic but transient reduction in circulating blasts; however, no remissions were achieved on this schedule. The most common toxicities were gastrointestinal, fatigue, transaminitis, and clinical and laboratory manifestations of tumor lysis syndrome, including one patient who died of acute renal failure. Dinaciclib pharmacokinetics showed rapid (2 h) achievement of maximum concentration and a short elimination/distribution phase. Pharmacodynamic studies demonstrated in vivo inhibition of Mcl-1 expression and induction of PARP cleavage in patients’ peripheral blood mononuclear cells 4 h after dinaciclib infusion, but the effects were lost by 24 h and did not correlate with clinical outcome. Correlative in vitro studies showed that prolonged exposures to dinaciclib, at clinically attainable concentrations, result in improved leukemia cell kill.

Conclusions

While dinaciclib given as a 2-h bolus did not exhibit durable clinical activity, pharmacokinetic and pharmacodynamic data support the exploration of prolonged infusion schedules in future trials in patients with acute leukemias.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-013-2249-z) contains supplementary material, which is available to authorized users.

Emerging drug profile: cyclin-dependent kinase inhibitors

Abstract As the rational application of targeted therapies in cancer supplants traditional cytotoxic chemotherapy, there is an ever-greater need for a thorough understanding of the complex machinery of the cell and an application of this knowledge to the development of novel therapeutics and combinations of agents. Here, we review the current state of knowledge of the class of targeted agents known as cyclin-dependent kinase (CDK) inhibitors, with a focus on chronic lymphocytic leukemia (CLL). Flavopiridol (alvocidib) is the best studied of the CDK inhibitors, producing a dramatic cytotoxic effect in vitro and in vivo, with the principal limiting factor of acute tumor lysis. Unfortunately, flavopiridol has a narrow therapeutic window and is relatively non-selective with several off-target (i.e. non-CDK) effects, which prompted development of the second-generation CDK inhibitor dinaciclib. Dinaciclib appears to be both more potent and selective than flavopiridol, with at least an order of magnitude greater therapeutic index, and is currently in phase III clinical trials. In additional to flavopiridol and dinaciclib, we also review the current status of other members of this class, and provide commentary as to the future direction of combination therapy including CDK inhibitors.

Targeting triple negative breast cancer: is p53 the answer?

Triple negative breast cancers, which are defined by lack of expression of estrogen, progesterone, or HER2 receptors, represent approximately 15% of all breast cancers, although they account for a much higher proportional of breast cancer mortality. This is due both to their innate aggressive biological characteristics, but also to lack of effective therapies. Conventional chemotherapy is currently the only treatment option, thus there is a critical need to find new and effective targeted therapies in this disease. While investigation of agents such as poly (ADP-ribose) polymerase (PARP) inhibitors and EGFR inhibitors continues, results from recent clinical trials indicate that these therapies are not as active in sporadic triple negative breast cancers as initially hoped. It is important therefore to consider other emerging therapeutic agents. Mutation in p53 is found in the vast majority of triple negative breast cancers, and as such is a target of particular interest. Within this review, several agents with potential activity against aberrant p53 signaling have been considered, as a novel approach to finding an effective targeted therapy for this aggressive breast cancer subtype.