Phase 1 study of the novel vascular disrupting agent plinabulin (NPI-2358) and docetaxel.

BACKGROUND: Plinabulin (NPI-2358) is a vascular disrupting agent (VDA) that destabilizes tumor vascular endothelial cell architecture resulting in selective collapse of established tumor vasculature producing anti-tumor activity alone or in combination with cytotoxic agents. The objective of this study was to assess the recommended Phase 2 dose (RP2D) of plinabulin combined with docetaxel. PATIENTS AND METHODS: Patients received 75 mg/m(2) docetaxel on day 1 and plinabulin on days 1 and 8 intravenously in 21 day cycles. Plinabulin was escalated from the biologically effective dose (BED) of 13.5 mg/m(2) to the standard single agent dose of 30 mg/m(2) using a "3+3" design. RESULTS: Thirteen patients were enrolled. Adverse events were consistent with those of both agents alone. Fatigue, pain, nausea, diarrhea and vomiting were the most common events. One dose limiting toxicity of nausea, vomiting, dehydration and neutropenia occurred. The RP2D was 30 mg/m(2) of plinabulin with 75 mg/m(2) docetaxel. Pharmacokinetics did not indicate drug-drug interactions. Of the 8 patients with NSCLC evaluable for response, 2 achieved a partial response and 4 demonstrated lesser decreases in tumor measurements. CONCLUSIONS: The combination of full doses of plinabulin and docetaxel is tolerable. With encouraging antitumor activity, this supported further development of this combination.

Phase 1 clinical trial of the novel proteasome inhibitor marizomib with the histone deacetylase inhibitor vorinostat in patients with melanoma, pancreatic and lung cancer based on in vitro assessments of the combination.

PURPOSE: Combining proteasome and histone deacetylase (HDAC) inhibition has been seen to provide synergistic anti-tumor activity, with complementary effects on a number of signaling pathways. The novel bi-cyclic structure of marizomib with its unique proteasome inhibition, toxicology and efficacy profiles, suggested utility in combining it with an HDAC inhibitor such as vorinostat. Thus, in this study in vitro studies assessed the potential utility of combining marizomib and vorinostat, followed by a clinical trial with the objectives of assessing the recommended phase 2 dose (RP2D), pharmacokinetics (PK), pharmacodynamics (PD), safety and preliminary anti-tumor activity of the combination in patients. EXPERIMENTAL DESIGN: Combinations of marizomib and vorinostat were assessed in vitro. Subsequently, in a Phase 1 clinical trial patients with melanoma, pancreatic carcinoma or Non-small Cell Lung Cancer (NSCLC) were given escalating doses of weekly marizomib in combination with vorinostat 300 mg daily for 16 days in 28 day cycles. In addition to standard safety studies, proteasome inhibition and pharmacokinetics were assayed. RESULTS: Marked synergy of marizomib and vorinostat was seen in tumor cell lines derived from patients with NSCLC, melanoma and pancreatic carcinoma. In the clinical trial, 22 patients were enrolled. Increased toxicity was not seen with the combination. Co-administration did not appear to affect the PK or PD of either drug in comparison to historical data. Although no responses were demonstrated using RECIST criteria, 61% of evaluable patients demonstrated stable disease with 39% having decreases in tumor measurements. CONCLUSIONS: Treatment of multiple tumor cell lines with marizomib and vorinostat resulted in a highly synergistic antitumor activity. The combination of full dose marizomib with vorinostat is tolerable in patients with safety findings consistent with either drug alone.

Phase I/II study of IV topotecan in combination with whole brain radiation for the treatment of brain metastases.

A phase I/II trial was conducted to determine the toxicities and efficacy (overall response, overall survival, and progression-free survival) of the combination of topotecan and whole brain radiation therapy (XRT) in patients with brain metastases. Patients received 30 Gy XRT given in 10 fractions to the whole brain. In phase I, patients were treated in groups of three at each topotecan dose level; dose escalation proceeded until the maximum tolerated dose (MTD) was identified. The dose-limiting toxicity proved to be grade IV neutropenia at 0.6 mg/m2/d, resulting in an MTD of 0.5 mg/m2/d. One of nine patients showed a response to treatment, and that was partial (OR 11%). Three had stable disease (33%), and four experienced progressive disease (44%). Median progression-free survival was 60 d; median overall survival was 102 d. Intravenous topotecan at 0.5 mg/m2/d concomitant to XRT with 30 Gy in 3-Gy fractions is tolerable in patients with brain metastases. This regimen has the additional advantage of providing systemic treatment to patients with metastases in other locations while whole brain radiation is in progress. Although response and survival outcomes in this small study do not appear higher than expected from historical controls, these were not primary end points, and larger studies on this topic would be useful to elucidate the efficacy of this combination treatment regimen.

HSV-1 amplicon peptide display vector.

There are significant uses for expressing foreign peptide epitopes in viral surface attachment proteins in terms of investigating viral targeting, biology, and immunology. HSV-1 attachment, followed by fusion and entry, is mediated in large part by the binding of viral surface glycoproteins to cell surface receptors, primarily through heparan sulfate (HS) glycosaminoglycan residues. We constructed a HSV-1 amplicon plasmid (pCONGA) carrying the gC primary attachment protein gene with unique restriction sites flanking the HS binding domain (HSBD) (residues 33-176) to allow rapid, high efficiency substitution with foreign peptide domains. To test this system, a His tag with an additional unique restriction site (for selection and assay digests) was recombined into the pCONGA HSBD site to create pCONGAH. Infection of pCONGAH transfected Vero cells with HSV-1 helper virus (gCdelta2-3 or hrR3) produced His-modified gC as demonstrated by western blot analysis with co-localization of anti-gC and anti-His tag antibodies to a protein of appropriate molecular weight (50 kd). As CONGA and CONGAH amplicons carry a GFP transgene and the gCdelta2-3 and hrR3 viruses carry a lacZ transgene, vector stocks produced from 1 x 10(5) Vero cells could be titered for competent vector on cell monolayers and were demonstrated to contain 2 x 10(5) amplicon vector transducing units (t.u.)/ml and 1 x 10(7) virus t.u./ml. As the amplicon plasmids also contain the neomycin resistance gene (neo(r)), long term vector producer cell lines were created using G418 selection. This amplicon system provides means to rapidly and efficiently generate HSV-1 amplicon and viral vector expressing surface attachment proteins modified with different peptide epitopes for investigational and therapeutic uses, with the advantages of an amplicon plasmid that can be used with interchangeable helper virus vectors, is designed specifically for easy manipulation, and carries GFP and neo(r) transgenes for marker and selection functions.

Vascular disrupting agents (VDA) in oncology: advancing towards new therapeutic paradigms in the clinic.

Vascular Disrupting Agents (VDA) are a potential new class of oncology drugs that have garnered attention recently as a number of these agents have entered into Phase 2-3 studies. Currently available data suggest how the subsequent evolution of these agents into clinical practice may proceed, with new therapeutic paradigms based on similarities, differences and interactions with current standard of care agents. In particular, the broadly successful group of agents targeting angiogenesis through the Vascular Endothelial Growth Factor (VEGF) pathway, can be contrasted to the VDAs that principally disrupt established tumor vasculature through a different set of molecular targets. Although the angiogenesis inhibitors may benchmark where other vascularly targeted agents such as VDAs may be successful, the differences in terms of efficacy and safety profiles lead to important differentiation in how VDAs are likely to be used. Although the majority of VDAs bind tubulin, significant differences also exist between VDAs and cytotoxic agents, including tubulin targeted agents such as taxanes and vinca alkyloids. Clinical trial data is now available for several VDAs allowing such assessment. Data of yet has been the strongest in NSCLC, with indications of how these drugs may be developed beneficially in subsets of patients such as those with squamous cell histology or at risk of bleeding events. Other indications being aggressively pursued include prostate carcinoma, ovarian carcinoma, sarcomas and astrocytomas. The field also continues to advance with investigation into how to optimally schedule administration of VDAs and what effects might be class effects and/or markers of efficacy.

Phase 1 first-in-human trial of the vascular disrupting agent plinabulin(NPI-2358) in patients with solid tumors or lymphomas.

PURPOSE: Plinabulin (NPI-2358) is a vascular disrupting agent that elicits tumor vascular endothelial architectural destabilization leading to selective collapse of established tumor vasculature. Preclinical data indicated plinabulin has favorable safety and antitumor activity profiles, leading to initiation of this clinical trial to determine the recommended phase 2 dose (RP2D) and assess the safety, pharmacokinetics, and biologic activity of plinabulin in patients with advanced malignancies. EXPERIMENTAL DESIGN: Patients received a weekly infusion of plinabulin for 3 of every 4 weeks. A dynamic accelerated dose titration method was used to escalate the dose from 2 mg/m² to the RP2D, followed by enrollment of an RP2D cohort. Safety, pharmacokinetic, and cardiovascular assessments were conducted, and Dynamic contrast-enhanced MRI (DCE-MRI) scans were performed to estimate changes in tumor blood flow. RESULTS: Thirty-eight patients were enrolled. A dose of 30 mg/m² was selected as the RP2D based on the adverse events of nausea, vomiting, fatigue, fever, tumor pain, and transient blood pressure elevations, with DCE-MRI indicating decreases in tumor blood flow (Ktrans) from 13.5 mg/m² (defining a biologically effective dose) with a 16% to 82% decrease in patients evaluated at 30 mg/m². Half-life was 6.06 ± 3.03 hours, clearance was 30.50 ± 22.88 L/h, and distributive volume was 211 ± 67.9 L. CONCLUSIONS: At the RP2D of 30 mg/m², plinabulin showed a favorable safety profile, while eliciting biological effects as evidenced by decreases in tumor blood flow, tumor pain, and other mechanistically relevant adverse events. On the basis of these results additional clinical trials were initiated with plinabulin in combination with standard chemotherapy agents.

Focal radiation therapy of brain metastases after complete surgical resection.

Brain metastases are a frequent occurrence in cancer patients and result in significant morbidity and mortality. The three main treatments for brain metastases include surgery, radiation, and/or chemotherapy, alone or in combination. After resection alone, local recurrence rates are high. Whole brain radiation therapy can decrease the probability of recurrence; however, this has some disadvantages. Focal radiation therapy (FRT) may provide many of the same benefits without some of these disadvantages. In this study, we retrospectively analyzed patients with single brain metastases treated with FRT after surgery. Doses ranged from 14 Gy as single dose stereotactic radiosurgery (SRS) to 54 Gy in 27 2-Gy fractions as conformal fractionated radiotherapy. Four of the seven patients had a same-site recurrence, with an average time to recurrence of 115.5 d. Median dose in the patients that had same-site recurrence was 42 Gy. One of these patients is currently living. Two patients did not have recurrence, and one patient had a recurrence at a different site within the brain. The low rate of out-of-field recurrences during the patients life indicates focal radiation may be a reasonable therapeutic alternative. Given the number of patients with same-site recurrences, wide field margins around the tumor volume or higher radiation doses than those typically used in palliative regimens may be useful in post-excisional FRT. Additionally, we found that a longer delay in the initiation of FRT after initial diagnosis may result in a decreased time to same-site recurrence. However, further studies are warranted given the small number of patients in this study.

Temozolomide and radiation for aggressive pediatric central nervous system malignancies.

This study describes the outcomes of children treated with combinations of temozolomide and radiation therapy for various aggressive central nervous system malignancies. Their age at diagnosis ranged from 1 to 15 years. Patients with focal disease were treated with concomitant temozolomide (daily 75 mg/m) and three-dimensional conformal radiotherapy in a dose that ranged from 50 to 54 Gy, followed by temozolomide (200 mg/m/d x 5 days/month in three patients, 150 mg/m x 5 days/ month in one patient). Patients with disseminated disease were treated with craniospinal radiation (39.6 Gy) before conformal boost. One patient received temozolomide (200 mg/m x 5 days/month) before craniospinal radiation, and one patient received temozolomide (daily 95 mg/m) concomitant with craniospinal radiation and a radiosurgical boost, followed by temozolomide (200 mg/m x 5 days/month). Three patients achieved a partial response during treatment, with two of these patients dying of progressive disease after treatment. One patient has no evidence of disease. Three patients achieved stable disease, with one of these patients dying of progressive disease after treatment. Toxicities observed included low-grade neutropenia, thrombocytopenia, and lymphopenia. The combination of temozolomide and radiotherapy appears to be well tolerated in a variety of treatment schemas for aggressive pediatric central nervous system malignancies. This information is of particular use in designing future studies, given the recent positive results in a randomized study examining the use of temozolomide concomitant with radiation in the treatment of adult glioblastoma.