A single agent, phase I pharmacodynamic study of nimotuzumab (TheraCIM-h-R3) in patients with advanced refractory solid tumors

14030

Background: Nimotuzumab (N) is a humanized mAb against the EGFR extracellular ligand binding domain. Although well tolerated when combined with radiotherapy in previous studies and lacking usual toxicities of EGFR-targeting agents, the pharmacodynamics (PD) of N has not been elucidated. This phase I study was designed to evaluate the safety, tolerability and PD of N. Methods: Eligibility criteria included advanced solid tumors refractory to standard therapy and ECOG PS = 0 - 2. IV N was administered weekly x 6 and then every other week (6 weeks = 1 treatment cycle). Tumor, skin and liver biopsies obtained pre- and 2 and 7 weeks post-treatment were evaluated using computer-based, whole mount assessment of immunohistochemical staining. Results: Accrual was completed 21/09/06, 17 patients (11m/6f, median age 63, 13 colorectal cancer, ECOG 0:1:2 = 6:10:1, prior therapy 1:2:3+ = 2:6:9) were registered and 16 patients were treated on 4 dose levels (100, 200, 400 and 800 mg) for a total of 43 treatment cycles (1 patient deemed ineligible after registration did not receive study therapy). Treatment was well tolerated. One dose-limiting toxicity was observed (dose level 1 - grade 3 fatigue possibly attributable to N) . Skin toxicity was mild (Gr 1/2 in 7/1 patients). Confirmed stable disease was seen in 6 patients, a confirmed partial response in 1 patient with prolonged progression-free status observed in 3 patients for 5.8, 14.1 and 18.7 months (the latter two remain on study). Baseline and week 2 biopsies of tumor/skin/liver were evaluable in 12/13/7 pts. Week 7 tumor/skin/liver biopsies in initially responding or stable patients were evaluable in 6/8/6 pts. Post treatment (week 2), EGFR staining decreased in 8/12 matched tumor [mean ratio (post/pre): 0.79 range: (0.37, 1.91)], 8/13 skin [0.96 (0.40, 1.31)] and 5/7 liver [0.88 (0.62, 1.17)] biopsies. No significant relationship was detected between pre/post-treatment EGFR expression with either response or toxicity. Evaluation of downstream targets of EGFR (in tumor, skin and liver) is ongoing and will be presented. Conclusions: Overall nimotuzumab was well tolerated and exhibits mild skin toxicity. Prolonged progression free-survival was observed in 3/16 of these heavily pre-treated patients.

No significant financial relationships to disclose.

Long-term results of concurrent gemcitabine (G) and radiotherapy (GRT) for locally advanced (LA) or high-risk resected (R) pancreatic cancer

4101

Background: G is active against pancreatic carcinoma and is a potent radiosensitizer. We present extended follow up data from a phase I/II study of patients treated with combination GRT. Methods: Eligible patients had either LA or high-risk resected [R] pancreatic cancer [positive nodes or positive margin]. 28 were enrolled in a Phase I study of increasing doses of radiotherapy (35 Gy [n = 7]/43.75 Gy [n = 11]/52.5 Gy [n = 10] given over 4, 5 or 6 weeks, respectively in 1.75 Gy fractions) concurrently with 40 mg/m2 gemcitabine biweekly. Subsequently 35 were treated with induction gemcitabine (G) 1000 mg/m2 7/8 weeks followed by concurrent bi-weekly gemcitabine (40 mg/m2) with 52.5 Gy (30 fractions of 1.75 Gy over 6 weeks). In total there were 63 patients (31 LA and 32 R) treated between March 1999–July 2001. Results: In the LA population the best response observed was CR - 1, PR - 2, SD - 10, PD - 10. GRT was not delivered to 8 patients due to progression on G alone (n = 5) or patient request (n = 3). By intent to treat analysis, the median survival in LA disease was 15.1 months and the 2 year survival was 19%. In the resected population the median time to progression was 14.3 months, the median survival was 17.9 months and the 5 year survival was 19%. The treatment was generally well tolerated during both the induction G and the GRT ( Table ). Conclusion: Survival for both LA and HR patients with this concurrent gemcitabine radiotherapy regimen is promising and warrants further investigation.

[Table: see text]

No significant financial relationships to disclose.

A phase I study of the humanized anti-epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) TheraCIM-h-R3 (nimotuzumab) in patients with advanced solid tumors

13054

Background: Nimotuzumab is a humanized mAb against the extracellular ligand binding domain of EGFR. Although well tolerated when combined with radiotherapy in previous studies, the pharmacodynamics (PD) of nimotuzumab has not been elucidated. This phase I study was designed to evaluate the safety, tolerability and PD of nimotuzumab. Methods: Eligibility criteria included advanced solid tumors refractory to standard therapy and performance status of ECOG 0–2. Nimotuzumab was administered intravenously weekly × 6 and then every other week (6 weeks = 1 treatment cycle). Tumor and skin biopsies were obtained at baseline and after 2 weeks of treatment. Results: To date, 9 patients (7 m/2 f, median age 60, 7 colorectal cancer, ECOG 0:1:2 = 5:3:1, prior therapy 1:2:3+ = 1:3:5) have been treated on the first 2 dose levels (100 mg and 200 mg) for a total of 13 treatment cycles. The most common toxicities, mainly grade 1- 2, were lymphopenia (n = 8 patients), fatigue (n = 8), abnormal liver function tests (n = 7) and anemia (n = 6). Observed grade 3 toxicities include: pain (n = 3), hyponatremia (n = 2), elevated ALP (n = 2), fatigue (n = 1), hyperglycemia (n = 1) and hyperkalemia (n = 1). One patient at the first dose level experienced grade 3 fatigue, at least possibly attributable to nimotuzumab, and thus considered as a dose-limiting toxicity (DLT). No DLT were observed in the expanded cohort and dose level 2. No skin toxicities were observed. Stable disease was seen in 3 patients with colorectal cancer. PD from tumor and skin biopsies will be presented, and may clarify the reason for the lack of skin toxicity. Conclusions: Overall nimotuzumab was well tolerated, with disease stabilization observed in heavily pretreated patients. Accrual continues at dose level 3 (400 mg) with one further planned dose level (800 mg).

[Table: see text]

Heat-directed gene targeting of adenoviral vectors to tumor cells

Targeting therapeutic gene expression to tumor cells represents a major challenge for cancer gene therapy. The strong transcriptional response exhibited by heat shock genes, along with the beneficial therapeutic effects of hyperthermia have led us to develop a heat-directed gene-targeting strategy for cancer treatment. Heat shock gene expression is mediated in large part by the interaction of heat shock factor 1 with specific binding sites (heat shock elements; HSE) found in the promoters of heat-inducible genes. Here we present a quantitative analysis of heat-inducible gene expression mediated by the wild-type hsp70b gene promoter, as well as a modified hsp70b promoter containing additional HSE sequences. Beta-galactosidase (beta-gal) expression was induced between 50- and 800-fold in a panel of human breast cancer cell lines infected with an adenoviral vector containing the wild-type hsp70b promoter (Ad.70b.betag) following treatment at 43 degrees C for 30 minutes. Infection with an adenoviral vector containing the modified hsp70b promoter (Ad.HSE.70b.betag) resulted in a 200- to 950-fold increase in beta-gal expression under the same conditions, and also provided a 1-2 degrees C decrease in the threshold of activation. Significant increases in the heat responsiveness of the Ad.HSE.70b.betag construct were observed in five of six tumor cell lines tested, as well as under thermotolerant conditions. Finally, we demonstrate that localized heating of a HeLa cell xenograft can effectively target beta-gal gene expression following intratumoral injection of Ad.70b.betag. Adenoviral vectors incorporating heat-inducible therapeutic genes may provide useful adjuncts for clinical hyperthermia.

Placental transforming growth factor-beta is a downstream mediator of the growth arrest and apoptotic response of tumor cells to DNA damage and p53 overexpression

The p53 tumor suppressor gene and members of the transforming growth factor-beta (TGF-beta) superfamily play central roles in signaling cell cycle arrest and apoptosis (programmed cell death) in normal development and differentiation, as well as in carcinogenesis. Here we describe a distantly related member of the TGF-beta superfamily, designated placental TGF-beta (PTGF-beta), that is up-regulated in response to both p53-dependent and -independent apoptotic signaling events arising from DNA damage in human breast cancer cells. PTGF-beta is normally expressed in placenta and at lower levels in kidney, lung, pancreas, and muscle but could not be detected in any tumor cell line studied. The PTGF-beta promoter is activated by p53 and contains two p53 binding site motifs. Functional studies demonstrated that one of these p53 binding sites is essential for p53-mediated PTGF-beta promoter induction and specifically binds recombinant p53 in gel mobility shift assays. PTGF-beta overexpression from a recombinant adenoviral vector (AdPTGF-beta) led to an 80% reduction in MDA-MB-468 breast cancer cell viability and a 50-60% reduction in other human breast cancer cell lines studied, including MCF-7 cells, which are resistant to growth inhibition by recombinant wild-type p53. Like p53, PTGF-beta overexpression was seen to induce both G(1) cell cycle arrest and apoptosis in breast tumor cells. These results provide the first evidence for a direct functional link between p53 and the TGF-beta superfamily and implicate PTGF-beta as an important intercellular mediator of p53 function and the cytostatic effects of radiation and chemotherapeutic cancer agents.

Differential chemosensitivity of breast cancer cells to ganciclovir treatment following adenovirus-mediated herpes simplex virus thymidine kinase gene transfer

The development of resistance to radiation and chemotherapeutic agents that cause DNA damage is a major problem for the treatment of breast and other cancers. The p53 tumor suppressor gene plays a direct role in the signaling of cell cycle arrest and apoptosis in response to DNA damage, and p53 gene mutations have been correlated with increased resistance to DNA-damaging agents. Herpes simplex virus thymidine kinase (HSV-tk) gene transfer followed by ganciclovir (GCV) treatment is a novel tumor ablation strategy that has shown good success in a variety of experimental tumor models. However, GCV cytotoxicity is believed to be mediated by DNA damage-induced apoptosis, and the relationship between p53 gene status, p53-mediated apoptosis, and the sensitivity of human tumors to HSV-tk/GCV treatment has not been firmly established. To address this issue, we compared the therapeutic efficacy of adenovirus-mediated HSV-tk gene transfer and GCV treatment in two human breast cancer cell lines: MCF-7 cells, which express wild-type p53, and MDA-MB-468 cells, which express high levels of a mutant p53 (273 Arg-His). Treating MCF-7 cells with AdHSV-tk/GCV led to the predicted increase in endogenous p53 and p21WAF1/CIP1 protein levels, and apoptosis was observed in a significant proportion of the target cell population. However, treating MDA-MB-468 cells under the same conditions resulted in a much stronger apoptotic response in the absence of induction in p21WAF1/CIP1 protein levels. This latter result suggested that HSV-tk/GCV treatment can activate a strong p53-independent apoptotic response in tumor cells that lack functional p53. To confirm this observation, four additional human breast cancer cell lines expressing mutant p53 were examined. Although a significant degree of variability in GCV chemosensitivity was observed in these cell lines, all displayed a greater reduction in cell viability than MCF-7 or normal mammary cells treated under the same conditions. These results suggest that endogenous p53 status does not correlate with chemosensitivity to HSV-tk/GCV treatment. Furthermore, evidence for a p53-independent apoptotic response serves to extend the potential of this therapeutic strategy to tumors that express mutant p53 and that may have developed resistance to conventional genotoxic agents.

PAY4, a gene required for peroxisome assembly in the yeast Yarrowia lipolytica, encodes a novel member of a family of putative ATPases

PAY genes are required for peroxisome assembly in the yeast Yarrowia lipolytica. Here we characterize one mutant, pay4, and describe the cloning and sequencing of the PAY4 gene. The pay4 mutant shows no identifiable peroxisomes by biochemical and morphological criteria. The complementing PAY4 gene encodes a polypeptide, Pay4p, 1025 amino acids in length and having a predicted molecular mass of 112,258 Da. The predicted Pay4p sequence contains two putative ATP-binding domains and shows structural relationships to other potential ATP-binding proteins involved in biological processes as diverse as peroxisome biogenesis, vesicle-mediated protein transport, cell cycle control, and transcriptional regulation. These proteins all share a highly conserved stretch of approximately 175 amino acids that contains a consensus sequence for ATP binding. Pay4p shows sequence conservation with Pas1p and Pas5p, putative ATPases required for peroxisomal assembly in the yeasts Saccharomyces cerevisiae and Pichia pastoris, respectively. Pay4p, Pas1p, and Pas5p are presumably related members of a family of putative ATPases involved in peroxisome biogenesis. Pay4p is synthesized in low amounts in Y. lipolytica cells grown in glucose, and there is a rapid and pronounced increase in the levels of Pay4p upon transfer of the cells to a medium containing oleic acid as the sole carbon source.

Peroxisome biogenesis in yeast

Eukaryotic cells have evolved a complex set of intracellular organelles, each of which possesses a specific complement of enzymes and performs unique metabolic functions. This compartmentalization of cellular functions provides a level of metabolic control not available to prokaryotes. However, it presents the eukaryotic cell with the problem of targeting proteins to their specific location(s). Proteins must be efficiently transported from their site of synthesis in the cytosol to their specific organelle(s). Such a process may require translocation across one or more hydrophobic membrane barriers and/or asymmetric integration into specific membranes. Proteins carry cis-acting amino acid sequences that serve to act as recognition motifs for protein sorting and for the cellular translocation machinery. Sequences that target proteins to the endoplasmic reticulum/secretory pathway, mitochondria, and chloroplasts are often present as cleavable amino-terminal extensions. In contrast, most peroxisomal proteins are synthesized at their mature size and are translocated to the organelle without any post-translational modification. This review will summarize what is known about how yeast solve the problem of specifically importing proteins into peroxisomes and will suggest future directions for investigations into peroxisome biogenesis in yeast.