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Using Clinical Pharmacology Principles to Develop New Anticancer Therapies

William Figg

1 Collaborator(s)

Funding source

National Cancer Institute (NIH)
A successful drug development program requires a complete understanding of the clinical pharmacology of the agents being evaluated. The Clinical Pharmacology Program (CPP) has as its primary interest the use of pharmacokinetic (PK) and pharmacodynamic (PD) concepts in the development of novel anticancer agents. The CPP is directly responsible for the PK/PD analysis of numerous Phase I and II clinical trials conducted within the NCI and also provides direct PK support for many studies performed elsewhere in the extramural community. We utilize compartmental and noncompartmental approaches to define the disposition of agents. We also often characterize the plasma protein binding properties and metabolism of new agents through in vitro techniques. Several of our clinical trials have used adaptive control with a feedback mechanism to target particular plasma concentrations (e.g., suramin, CAI). The drugs with which the CPP has had its greatest experience include: suramin, phenylacetate, phenylbutyrate, TNP-470, CAI, DAB486IL2, IgG-RFB4-SMPT-dgA CD22, IgG-HD37-SMPT-dgA CD19, ormaplatin, UCN-01, docetaxel, flavopiridol, thalidomide, lenalidomide, intraperitoneal cisplatin, intraperitoneal carboplatin, paclitaxel, 17-DMAG, imatinib, sorafenib, nelfinavir, bevacizumab, romidepsin, clopidrogrel, bortezomib, TRC-105, vandetanib, olaparib, topotecan, irinotecan, AZD7451 (tropomyosin-receptor kinase inhibitor), 7-hydroxystaurosporine and fludararbine phosphate. During the FY2015, the CPP provided PK support for several phase I/II clinical studies, including carfilzomib, sorafenib combined with cetuximab, TRC-105, TRC105 and bevacizumab, recombinant human interleukin-15, nelfinavir, daclizumab, bortezomib and alvocidib, belinostat, and perifosine. We provided the PK support for a study evaluating the treatment with carfilzomib-lenalidomide-dexamethasone with lenalidomide extension in patients with smoldering or newly diagnosed multiple myeloma. The PK results include a mean Cmax of 284 ng/mL, AUC of 112 hr*ng/mL, half-life of 0.3 hr, CL of 663 L/hr and VSS of 236 L. Based on carfilzomib clearance, there was significant stratification based on albumin levels, as more albumin (in healthier patients) led to a faster carfilzomib clearance, hence lower albumin (in sicker patients) had a slower clearance, and subsequently better progression-free survival. TRC105 is a chimeric immunoglobulin G1 monoclonal antibody that binds endoglin (CD105). This phase I open-label study evaluated the safety, pharmacokinetics and pharmacodynamics of TRC105 in patients with metastatic castration-resistant prostate cancer. The maximum tolerated dose was 20 mg/kg every 2 weeks. Significant plasma CD105 reduction was observed at the higher dose levels. An exploratory analysis showed a tentative correlation between the reduction of CD105 and a decrease in PSA velocity, suggestive of potential activity of TRC105 in the patients with mCRPC. We conducted the PK analysis for an open-label phase Ib dose-escalation study of TRC105 (anti-endoglin antibody) with bevacizumab in patients with advanced cancer. TRC105 and bevacizumab were well tolerated at their recommended single-agent doses (10 mg/kg) when the initial dose of TRC105 was delayed by one week and divided over 2 days to limit the frequency of headache. The first-in-human clinical trial of recombinant human interleukin-15 was conducted in patients with cancer. IL-15 could be safely administered to patients with metastatic malignancy with the MTD determined at 0.3 ug/kg per day. To reduce toxicity and increase efficacy, alternative dosing strategies have been initiated, including continuous intravenous infusions and subcutaneous IL-15 administration. We provided PK support for a phase 1 trial of the HIV protease inhibitor nelfinavir in adults with solid tumors. The MTD was established at 3125 mg twice daily. Nelfinavir is well tolerated in cancer patients at doses 2.5 times the FDA-approved dose for HIV management and showed preliminary activity in tumors of neuroendocrine origin. Daclizumab a humanized monoclonal antibody blocks IL-2 binding by recognizing the interleukin-2 receptor chain (CD25). We conducted the pharmacokinetics/pharmacodynamics analysis of daclizumab and found that up to 8 mg/kg of daclizumab administered every 3 weeks was well tolerated. High-dose daclizumab would be more effective than low-dose daclizumab in treatment of lymphoid malignancies and autoimmune diseases (e.g., multiple sclerosis) since high-dose daclizumab is required to saturate IL-2R alpha in extravascular sites. We provided the PK support for a phase I study conducted to determine the dose-limiting toxicities (DLT) and MTD for the combination of bortezomib and alvocidib in patients with B-cell malignancies. The MTD was established as 1.3 mg/m(2) for bortezomib and 40 mg/m(2) for alvocidib. Pharmacokinetic findings with the current dosing regimen were consistent with the comparable literature and the hybrid dosing regimen. Pharmacodynamic study results did not correlate with clinical responses. The combination of bortezomib and alvocidib is tolerable, and an MTD has been established for this schedule. The regimen appears to be efficacious in patients with relapsed/refractory multiple myeloma or indolent non-Hodgkin lymphoma. As the nonhybrid regimen is less cumbersome than the previous hybrid dosing schedule regimen, the current schedule is recommended for successor studies. This phase I/II study sought to determine the safety and maximum tolerated dose (MTD) of a novel schedule of belinostat, a histone deacetylase inhibitor (HDAC) administered before and in combination with cisplatin (P), doxorubicin (A), and cyclophosphamide (C) in thymic epithelial tumors (TET). Antitumor activity, pharmacokinetics, and biomarkers of response were also assessed. Twenty-four patients were treated at the MTD of 1,000 mg/m(2) with chemotherapy (P, 50 mg/m(2) on day 2; A, 25 mg/m(2) on days 2 and 3; C, 500 mg/m(2) on day 3). Modulation of pharmacodynamic markers of HDAC inhibition and declines in regulatory T cell (Treg) and exhausted CD8(+) T-cell populations were observed. Decline in Tregs was associated with response (P = 0.0041) and progression-free survival (P = 0.021). Declines in TIM3(+) CD8(+) T cells were larger in responders than nonresponders (P = 0.049). We conducted a phase I and pharmacokinetic study of oral perifosine using different oral loading and maintenance regimens in an effort to avoid gastrointestinal toxicity while seeking maximal sustained plasma concentrations in patients with refractory neoplasms. The MTD and recommended phase II dose was dose level 3B, with a loading dose of 900 mg on day 1 divided into two doses of 450 mg administered 6 h apart and a maintenance dose of 150 mg on day 2 through 21. On subsequent cycles, the loading dose was reduced to 300 mg. Non-gastrointestinal toxicities included three episodes of gout or gout-like syndromes observed at doses above the MTD. The median peak plasma concentration of perifosine achieved at the MTD was approximately 8.3 ug/mL. Four patients had stable disease ranging from 167 to 735 days. Perifosine given according to a loading and maintenance schedule can safely sustain concentrations of drug, approaching concentrations achieved in preclinical models with evidence of anti-tumor effect.

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