Safety and Efficacy of Docetaxel, Bevacizumab, and Everolimus for Castration-resistant Prostate Cancer (CRPC)

BACKGROUND

Previous data suggests that co-targeting mammalian target of rapamycin and angiogenic pathways may potentiate effects of cytotoxic chemotherapy. We studied combining mammalian target of rapamycin and vascular endothelial growth factor inhibition with docetaxel in castrate-resistant prostate cancer (CRPC).

METHODS

Eligible patients had progressive, metastatic, chemotherapy-naive CRPC. Docetaxel and bevacizumab were given intravenously day 1 with everolimus orally daily on a 21-day cycle across 3 dose levels (75:15:2.5, 75:15:5, and 65:15:5; docetaxel mg/m2, mg/kg bevacizumab, and mg everolimus, respectively). Maintenance therapy with bevacizumab/everolimus without docetaxel was allowed after ≥ 6 cycles.

RESULTS

Forty-three subjects were treated across all dose levels. Maximal tolerated doses for the combined therapies observed in the phase 1B portion of the trial were: docetaxel 75 mg/m2, bevacizumab 15 mg/kg, and everolimus 2.5 mg. Maximal prostate-specific antigen decline ≥ 30% and ≥ 50% was achieved in 33 (79%) and 31 (74%) of patients, respectively. Best response by modified Response Evaluation Criteria In Solid Tumors criteria in 25 subjects with measurable disease at baseline included complete or partial response in 20 (80%) patients. The median progression-free and overall survival were 8.9 months (95% confidence interval, 7.4-10.6 months) and 21.9 months (95% confidence interval, 18.4-30.3 months), respectively. Hematologic toxicities were the most common treatment-related grade ≥ 3 adverse events including: febrile neutropenia (12; 28%), lymphopenia (12; 28%), leukocytes (10; 23%), neutrophils (9; 21%), and hemoglobin (2; 5%). Nonhematologic grade ≥ 3 adverse events included: hypertension (8; 19%), fatigue (3; 7%), pneumonia (3; 7%), and mucositis (4; 5%). There was 1 treatment-related death owing to neutropenic fever and pneumonia in a patient treated at dose level 3 despite dose modifications and prophylactic growth factor support.

CONCLUSIONS

Docetaxel, bevacizumab, and everolimus can be safely administered in CRPC and demonstrate a significant level of anticancer activity, meeting the predetermined response criteria. However, any potential benefit of combined therapy must be balanced against increased risk for toxicities. Our results do not support the hypothesis that this combination of agents improves upon the results obtained with docetaxel monotherapy in an unselected population of chemotherapy-naive patients with CRPC.

A phase 1 study of everolimus plus docetaxel plus cisplatin as induction chemotherapy for patients with locally and/or regionally advanced head and neck cancer

BACKGROUND

Activation of the phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway is common in head and neck cancers, and it has been demonstrated that inhibition of mTOR complex 1 sensitizes cell lines to platinum and taxane chemotherapy. The authors conducted a phase 1 study to evaluate the addition of oral everolimus to cisplatin and docetaxel as induction chemotherapy for head and neck cancer.

METHODS

In this single-institution phase 1 study, 3 doses of daily everolimus were explored: 5 mg daily, 7.5 mg daily (administered as 5 mg daily alternating with 10 mg daily), and 10 mg daily of each 21-day cycle. Cisplatin and docetaxel doses were fixed (both were 75 mg/m(2) on day 1 of 21-day cycle) at each dose level with pegfilgrastim support. A standard 3 + 3 dose-escalation plan was used. After induction, patients were removed from protocol.

RESULTS

Eighteen patients were enrolled (15 men, 3 women), and their median Karnofsky performance status was 90. The most common toxicities were hyperglycemia, low hemoglobin, fatigue, and thrombocytopenia. Dose-limiting toxicities (DLTs) were neutropenic fever (1 event at dose level 2, 2 events at dose level 3), and all patients recovered fully from these DLTs. The maximum tolerated dose was exceeded at dose level 3. The progression-free survival rate at 1 year was 87.5% (95% confidence interval, 56.8%-96.7%); and, at 2 years, it was 76.6% (95% confidence interval, 41.2%-92.3%). Activating PI3K catalytic subunit α (PIK3CA) gene mutations were identified in 2 human papillomavirus-associated oropharyngeal cancers.

CONCLUSIONS

The phase 2 recommended dose was 7.5 mg daily for everolimus plus cisplatin and docetaxel (both at 75 mg/m(2) on day 1 of a 21-day cycle) given with pegfilgrastim support.

Differences in the biologic activity of 2 novel MEK inhibitors revealed by 18F-FDG PET: analysis of imaging data from 2 phase I trials

Two mitogen-activated protein kinase kinase (MAPK2, also known as MEK) inhibitors were assessed with (18)F-FDG PET in separate phase I clinical studies, clearly illustrating the potential of metabolic imaging for dose, dosing regimen, and compound selection in early-phase trials and utility for predicting nonresponding patients.

METHODS

(18)F-FDG PET data were collected during 2 independent, phase I, dose-escalation trials of 2 novel MEK inhibitors (RO5126766 and RO4987655). PET acquisition procedures were standardized between the 2 trials, and PET images were analyzed centrally. Imaging was performed at baseline; at cycle 1, day 15; and at cycle 3, day 1. A 10-mm-diameter region of interest was defined for up to 5 lesions, and peak standardized uptake values were determined for each lesion. The relationship between PET response and pharmacokinetic factors (dose and exposure), inhibition of extracellular-signal-regulated kinase (ERK) phosphorylation in peripheral blood mononuclear cells, and anatomic tumor response as measured by Response Evaluation Criteria in Solid Tumors was investigated for both compounds.

RESULTS

Seventy-six patients underwent PET, and 205 individual PET scans were analyzed. Strong evidence of biologic activity was seen as early as cycle 1, day 15, for both compounds. (18)F-FDG PET revealed striking differences between the 2 MEK inhibitors at their recommended dose for phase II investigation. The mean amplitude of the decrease in (18)F-FDG from baseline to cycle 1, day 15, was greater for patients receiving RO4987655 than for those receiving RO5126766 (47% vs. 16%, respectively; P = 0.052). Furthermore, a more pronounced relationship was seen between the change in (18)F-FDG uptake and dose or exposure and phosphorylated ERK inhibition in peripheral blood mononuclear cells in patients receiving RO4987655. For both investigational drugs, PET responses tended to be greatest in patients with melanoma tumors. (18)F-FDG was able to identify early nonresponding patients with a 97% negative predictive value.

CONCLUSION

These data exemplify the role of (18)F-FDG PET for guiding the selection of novel investigational drugs, choosing dose in early-phase clinical development, and predicting nonresponding patients early in treatment.

Castration-resistant prostate cancer: new science and therapeutic prospects

There is a growing number of new therapies targeting different pathways that will revolutionize patient management strategies in castration-resistant prostate cancer (CRPC) patients. Today there are more clinical trial options for CRPC treatment than ever before, and there are many promising agents in late-stage clinical testing. The hypothesis that CRPC frequently remains driven by a ligand-activated androgen receptor (AR) and that CRPC tissues exhibit substantial residual androgen levels despite gonadotropin-releasing hormone therapy, has led to the evaluation of new oral compounds such as abiraterone and MDV 3100. Their results, coupled with promising recent findings in immunotherapy (eg sipuleucel-T) and with agents targeting angiogenesis (while awaiting the final results of the CALGB trial 90401) will most probably impact the management of patients with CRPC in the near future. Other new promising agents need further development. With our increased understanding of the biology of this disease, further trial design should incorporate improved patient selection so that patient populations are those who may be most likely to benefit from treatment.

Emerging therapeutic approaches in the management of metastatic castration-resistant prostate cancer

Although treatment options for men with castration-resistant prostate cancer (CRPC) have improved with the recent and anticipated approvals of novel immunotherapeutic, hormonal, chemotherapeutic and bone-targeted agents, clinical benefit with these systemic therapies is transient and survival times remain unacceptably short. Thus, we devote the second section of this two-part review to discussing emerging therapeutic paradigms and research strategies that are entering phase II and III clinical testing for men with metastatic CRPC. We will discuss a range of emerging hormonal, immunomodulatory, antiangiogenic, epigenetic and cell survival pathway inhibitors in current clinical trials, with an emphasis on how these therapies may complement our existing treatment options.

Clinical activity of mammalian target of rapamycin inhibitors in solid tumors

The phosphatidylinositol 3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) pathway is vital for cell metabolism, growth, and proliferation. mTOR is frequently upregulated in many tumor types and hence has become an important target in cancer treatment. Sirolimus and its derivatives (rapalogs) interact with the intracellular receptor FK506 binding protein 12 (FKBP12), forming a complex with high affinity for mTOR and thus disrupting its activity. Rapalogs are being evaluated extensively in cancer patients with different formulations and schedules. Significant clinical activity has led to their approval for the treatment of kidney cancer, mantle cell lymphoma, and subependymal giant cell astrocytoma; however, despite increasing knowledge about cancer cell biology, their activity in other malignancies is unclear. Further research is needed to identify optimal dosage, administration and targeted combination as well as the subset of patients likely to respond to mTOR/PI3K inhibition. This review focuses on a discussion of the pathway, its implications in cancer biology and results of clinical trials of rapalogs alone or in combination, organizing them by common malignancy type.

Horizon scanning for novel therapeutics for the treatment of prostate cancer

IMPORTANCE OF THE FIELD

Treatment options for patients with advanced prostate cancer (PCa) remain limited. Improved understanding of the underlying molecular drivers of prostate cancer pathogenesis, progression and resistance development has provided the fundamental basis for rational targeted drug design.

AREAS COVERED IN THIS REVIEW

This review will discuss the most recent developments in the field of prostate cancer therapies including key findings such as the identification of ETS gene rearrangements, the dissection of prostate cancer molecular heterogeneity and the discovery that castration-resistant prostate cancer (CRPC) remains androgen-driven despite the androgen-depleted milieu, thus making androgen receptor signaling a continued focus of molecularly targeted treatments. A multitude of new molecularly targeted agents are in clinical development and are highly likely to change the current treatment paradigm.

WHAT THE READER WILL GAIN

This review will outline the current clinical development of molecular targeted treatments in CRPC.

TAKE HOME MESSAGE

Unraveling the complex molecular biology that underpins this heterogeneous disease may pave the way to personalized therapy with a wide range of rationally targeted agents and combination treatments. In conclusion, we can predict that the rational clinical development of new targeted drugs will improve the outcome of men with prostate cancer in the years ahead.

Emerging therapies in castrate-resistant prostate cancer

Prostate cancer is the most common cancer in men in the United States, and despite screening and early treatment, more than 27,000 men are predicted to die of the disease this year, almost all of whom will die of castrate-resistant, metastatic cancers that have progressed despite androgen deprivation therapy, also known as hormonal therapy. In recent years, an increased understanding of molecular mechanisms of prostate cancer progression and castration resistance has led to improved treatment strategies. This review focuses on emerging therapies for the treatment of castrate-resistant prostate cancer, with an emphasis on the importance of the drug targets as well as the state of current clinical trials, including those utilizing hormonal therapies, biological agents, and immunotherapy that are underway or have recently been completed.

Induction chemotherapy in the management of head and neck cancer

The strategy of induction chemotherapy prior to planned definitive local therapy for head and neck squamous cell carcinoma has been studied for over 30 years, and appears to have a role in select clinical situations. Here we review landmark studies regarding induction chemotherapy, both in the pre-taxane era and in the current taxane era, and we address some of the unresolved questions regarding the role of induction chemotherapy in head and neck cancer.

Beyond RECIST: molecular and functional imaging techniques for evaluation of response to targeted therapy

The development of targeted therapies is a major breakthrough in the treatment of cancer. By evoking necrosis and cavitation, evaluation based on tumour size alone, as is done in the RECIST criteria, is no longer an adequate method. New molecular and functional imaging techniques are developed. This review focuses on the use of new imaging modalities for the evaluation of treatment response of pathway based targeted therapies. First, the basic principles of functional and molecular imaging modalities are briefly discussed. Thereafter, their clinical application in targeted therapies is correlated to the underlying biological mechanism. In this way, the best method for response evaluation for a new agent can be identified.