A phase I study of local treatment of liver metastases with recombinant tumour necrosis factor

Radiocurability by targeting tumor necrosis factor-alpha using a bispecific antibody in carcinoembryonic antigen transgenic mice

PURPOSE

Tumor necrosis factor-alpha (TNF-alpha) enhances radiotherapy (RT) killing of tumor cells in vitro and in vivo. To overcome systemic side effects, we used a bispecific antibody (BsAb) directed against carcinoembryonic antigen (CEA) and TNF-alpha to target this cytokine in a CEA-expressing colon carcinoma. We report the evaluation of this strategy in immunocompetent CEA-transgenic mice.

METHODS AND MATERIALS

The murine CEA-transfected colon carcinoma MC-38 was used for all experiments. In vitro, clonogenic assays were performed after RT alone, TNF-alpha alone, and RT plus TNF-alpha. In vivo, the mice were randomly assigned to treatment groups: control, TNF-alpha, BsAb, BsAb plus TNF-alpha, RT, RT plus TNF-alpha, and RT plus BsAb plus TNF-alpha. Measurements of endogenous TNF-alpha mRNA levels and evaluation of necrosis (histologic evaluation) were assessed per treatment group.

RESULTS

In vitro, combined RT plus TNF-alpha resulted in a significant decrease in the survival fraction at 2 Gy compared with RT alone (p < 0.00001). In vivo, we observed a complete response in 5 (50%) of 10, 2 (20%) of 10, 2 (18.2%) of 11, and 0 (0%) of 12 treated mice in the RT plus BsAb plus TNF-alpha, RT plus TNF-alpha, RT alone, and control groups, respectively. This difference was statistically significant when TNF-alpha was targeted with the BsAb (p = 0.03). The addition of exogenous TNF-alpha to RT significantly increased the endogenous TNF-alpha mRNA level, particularly when TNF-alpha was targeted with BsAb (p < 0.01). The percentages of necrotic area were significantly augmented in the RT plus BsAb plus TNF-alpha group.

CONCLUSION

These results suggest that targeting TNF-alpha with the BsAb provokes RT curability in a CEA-expressing digestive tumor syngenic model and could be considered as a solid rationale for clinical trials.

Functionalization of Tumor Necrosis Factor-α Using Phage Display Technique and PEGylation Improves Its Antitumor Therapeutic Window

PURPOSE

In this study, the optimization of antitumor therapy with tumor necrosis factor-alpha (TNF-alpha) was attempted.

EXPERIMENTAL DESIGN

Using the phage display technique, we created a lysine-deficient mutant TNF-alpha (mTNF-K90R). This mutant had higher affinities to both TNF receptors, despite reports that certain lysine residues play important roles in trimer formation and receptor binding.

RESULTS

The mTNF-K90R showed an in vivo therapeutic window that was 13-fold higher than that of the wild-type TNF-alpha (wTNF-alpha). This was due to the synergistic effect of its 6-fold stronger in vitro bioactivity and its 2-fold longer plasma half-life derived from its surface negative potential. The reason why the mTNF-K90R showed a higher bioactivity was understood by a molecular modeling analysis of the complex between the wTNF-alpha and TNF receptor-I. The mTNF-K90R, which was site-specifically mono-PEGylated at the NH2 terminus (sp-PEG-mTNF-K90R), had a higher in vitro bioactivity and considerably longer plasma half-life than the wTNF-alpha, whereas the randomly mono-PEGylated wTNF-alpha had 6% of the bioactivity of the wTNF-alpha. With regard to effectiveness and safety, the in vivo antitumor therapeutic window of the sp-PEG-mTNF-K90R was 60-fold wider than that of the wTNF-alpha.

CONCLUSIONS

These results indicated that this functionalized TNF-alpha may be useful not only as an antitumor agent but also as a selective enhancer of vascular permeability in tumors for improving antitumor chemotherapy.

A bispecific antibody to enhance radiotherapy by tumor necrosis factor-alpha in human CEA-expressing digestive tumors

Tumor necrosis factor-alpha (TNF-alpha) enhances X-ray killing of human tumor cells in vitro and enhances tumor control when combined with radiotherapy (RT) in animal tumor models. In multiple Phase I studies, intravenous injection of TNF-alpha appeared to have severe systemic side effects. To overcome these limitations, we used a bispecific antibody (BAb) directed against carcinoembryonic antigen and human TNF-alpha to target this cytokine in human digestive carcinoma treated with simultaneous RT. We used human digestive carcinoma cell lines (colon cancer, LS174T, and pancreatic cancer, BxPC-3) to determine the interaction of TNF-alpha and RT on clonogenic cytotoxicity. Isobolograms were established to confirm additive or supra-additive effects between both treatments. LS174T and BxPC-3 cells were grafted subcutaneously at Day 0 into female nude mice (7-8 weeks old). When the tumors reached a volume of about 80 mm(3), the mice were randomly assigned to treatment: Group 1, normal saline i.v. injection (control group); Group 2, TNF-alpha at 1 microg/i.v. injection; Group 3, BAb at 25 microg/i.v. injection; Group 4, BAb plus TNF-alpha (ratio 25 microg to 1 microg) i.v. injection; Group 5, local RT plus normal saline (0.5 Gy. min(-1)) at a total dose of 30 Gy delivered in five fractions; Group 6, local RT plus TNF-alpha injections 3 h before RT; Group 7, local RT plus BAb plus TNF-alpha co-injected 24 h before RT. Tumor growth delay was used as the end point for all groups. In the LS174T experiments, TNF-alpha added 12 h before RT showed a statistically significant decrease in the survival fraction at 2 Gy compared with RT alone (0.23 vs. 0.42 Gy, p = 0.0017). These results were largely confirmed with the BxPC-3 cell lines (0.29 vs. 0.72, p <0.00001). Isobolograms confirmed the additivity between TNF-alpha and RT in both cell lines. At 50% survival, the data points were within the envelope of additivity. In the LS174T and BxPC-3 xenografts, RT as a single agent (Group 5) slowed tumor progression compared with Group 1 (p <0.027 and p = 0.00001, respectively). TNF-alpha alone, BAb alone, or BAb plus TNF-alpha (Groups 2, 3, and 4) had no effect. In the LS174T model, TNF-alpha plus RT enhanced the delay to reach 2000 mm(3) compared with RT alone but without statistical significance. This delay was significantly longer when BAb was added (p = 0.0033, for Group 6 vs. Group 7). In the BxPC-3 experiments, the median delay to reach 2000 mm(3) was similar between the RT and TNF-alpha plus RT groups (93 days). The use of our BAb in combination with TNF-alpha and RT dramatically enhanced this median delay (177 days, p = 0.0013). No body weight loss was observed in any group. Our data could be used as a solid preclinical rationale on which to base a clinical study of locally advanced pancreatic or rectal cancers in the near future.

Optimal site-specific PEGylation of mutant TNF-α improves its antitumor potency

Recently, we created a lysine-deficient mutant tumor necrosis factor-alpha [mTNF-alpha-Lys(-)] with full bioactivity in vitro compared with wild-type TNF-alpha (wTNF-alpha), and site-specific PEGylation of mTNF-alpha-Lys(-) was found to selectively enhance its in vivo antitumor activity. In this study, we attempted to optimize this PEGylation of mTNF-alpha-Lys(-) to further improve its therapeutic potency. mTNF-alpha-Lys(-) was site-specifically modified at its N-terminus with linear polyethylene glycol (LPEG) or branched PEG (BPEG). While randomly mono-PEGylated wTNF-alpha (ran-LPEG5K-wTNF-alpha) with 5 kDa of LPEG (LPEG5K) had about only 4% in vitro bioactivity of wTNF-alpha, mono-PEGylated mTNF-alpha-Lys(-) [sp-PEG-mTNF-alpha-Lys(-)] with LPEG5K, LPEG20K, BPEG10K, and BPEG40K had 82%, 58%, 93%, and 65% bioactivities of mTNF-alpha-Lys(-), respectively. sp-LPEG-mTNF-alpha-Lys(-) and sp-BPEG10K-mTNF-alpha-Lys(-) had much superior antitumor activity to those of both unmodified TNF-alphas and ran-LPEG5K-wTNF-alpha, though sp-BPEG40K-mTNF-alpha-Lys(-) did not show in vivo antitumor activity. Thus, the molecular shape and weight of PEG may strongly influence the in vivo antitumor activity of sp-PEG-mTNF-alpha-Lys(-).

Potentiation of ionising radiation by targeting tumour necrosis factor alpha using a bispecific antibody in human pancreatic cancer

The aim of this study was to treat carcinoembryonic antigen (CEA)-expressing pancreatic carcinoma cells with tumour necrosis factor alpha (TNFα) and simultaneous radiation therapy (RT), using a bispecific antibody (BAb) anti-TNFα/anti-CEA. TNFα used alone produced a dose-dependent inhibition of the clonogenic capacity of the cultured cells. Flow cytometry analysis of cell cycle progression confirmed the accumulation of cells in G₁ phase after exposure to TNFα. When TNFα was added 12 h before RT, the surviving fraction at 2 Gy was 60% lower than that obtained with irradiation alone (0.29 vs 0.73, respectively, P<0.00001). In combination treatment, cell cycle analysis demonstrated that TNFα reduced the number of cells in radiation-induced G₂ arrest, blocked irreversibly the cells in G₁ phase, and showed an additive decrease of the number of cells in S phase. In mice, RT as a single agent slowed tumour progression as compared with the control group (P<0.00001). BAb+TNFα+RT combination enhanced the delay for the tumour to reach 1500 mm³ as compared with RT alone or with RT+TNFα (P=0.0011). Median delays were 90, 93, and 142 days for RT alone, RT+TNFα, and RT+BAb+TNFα groups, respectively. These results suggest that TNFα in combination with BAb and RT may be beneficial for the treatment of pancreatic cancer in locally advanced or adjuvant settings.

Enhancement of radiation therapy by tumor necrosis factor alpha in human colon cancer using a bispecific antibody

PURPOSE

To overcome the systemic side effects of tumor necrosis factor alpha (TNFalpha) injected i.v., we used a bispecific antibody (BAb) directed against carcinoembryonic antigen (CEA) and TNFalpha to target this cytokine in human CEA-expressing colorectal carcinoma treated simultaneously with radiation therapy (RT).

METHODS, MATERIALS AND RESULTS

LS174T cell line was used to study the interaction of TNFalpha and radiation on clonogenic cytotoxicity. When TNFalpha (2500 U/mL) was added 12 h before RT, the surviving fraction at 2 Gy was 54% lower than that obtained with irradiation alone (0.23 vs. 0.42, respectively, p = 0.001). At 20%, 50%, or 70% survival, data points were within the envelope of additivity. Concerning in vivo experiments, RT as a single agent slowed tumor progression as compared with the control group (p = 0.027), whereas TNFalpha, BAb, or BAb + TNFalpha had no effect. BAb + TNFalpha + RT combination enhanced the delay for the tumor to reach 2000 mm(3) as compared with RT alone (p = 0.033, for BAb + TNFalpha + RT group vs. RT group).

CONCLUSION

These results suggest that TNFalpha in combination with BAb and RT may be beneficial for the treatment of locally advanced colorectal cancer.

Radiation-induced tumour necrosis factor-alpha expression: clinical application of transcriptional and physical targeting of gene therapy

Promising data are emerging on a new anticancer agent, Ad.EGR-TNF, an adenoviral vector, which contains radio-inducible DNA sequences from the early growth response (EGR1) gene promoter and cDNA for the gene encoding human tumour necrosis factor-alpha. Ad.EGR-TNF combines the well-documented broad-spectrum anticancer activity of TNFalpha with the proven clinical usefulness of radiotherapy. Systemic delivery of the TNFalpha protein has had limited success clinically because of severe dose-limiting toxic effects. This limitation has been overcome by the use of a gene delivery approach, combined with a radiation-inducible promoter to express the TNFalpha protein in the irradiated tumour tissue. Preclinical and early phase I clinical testing indicates that effective concentrations of TNFalpha can be delivered to the tumour site without significant systemic exposure or toxic effects. The combination of radiation and TNFalpha gene delivery has produced striking antitumour effects in model systems in animals. In the clinical setting, potent anticancer activity has been observed with a high rate of complete and partial objective tumour responses. A novel mechanism of destruction of the tumour vasculature seems to be central to this distinct antitumour activity. This review summarises the rationale, mechanistic basis, preclinical data, and preliminary clinical findings for this new treatment model.

Alternative techniques for the treatment of colon carcinoma metastases in the liver: current status in The Netherlands

BACKGROUND

Review of current treatment modalities for liver metastases resulting from colorectal cancer.

METHODS

Literature review.

RESULTS

An increasing number of techniques are available for the treatment of colorectal liver metastases. When it is not possible to use the current gold standard, radical surgical resection, many patients can be treated with alternative techniques. Chemotherapy in its present form must be considered as purely palliative, perhaps with the exclusion of isolated liver perfusion: however, this therapy should still be considered as experimental. Most other possible treatments focus on local destruction of the metastases. This can be achieved using either immuno-guided techniques (tumor antibodies which carry a local active agent), direct local application of a toxic agent (injection) or thermo therapy, which has been applied in patients on a large scale. Thermo therapy involves either localized heating, by means or laser photocoagulation or radiofrequency or microwave ablation, or localized freezing using cryo probes.

CONCLUSIONS

Local destruction of liver metastases, especially by means of thermo therapy, is feasible and safe. Currently, cryotherapy is most frequently used in patients. New treatment modalities, such as radiofrequency ablation, arc very promising but their true clinical value should be determined in a randomized clinical trial.

The safety of electrolytically induced hepatic necrosis in a pig model

BACKGROUND

Electrolysis fulfils the criteria for an ideal treatment of patients with unresectable liver tumours. Previous studies in the rat and pig have shown that controlled necrosis can be safely produced by inserting platinum electrodes into normal liver' parenchyma and liver tumours. As with any new treatment it is mandatory to investigate the 'worst-case scenario' of inadvertent intravascular electrode placement in a large animal model before progressing to clinical trials.

METHODS

Under ultrasound control in six pigs, electrodes were inserted into, or immediately adjacent to, an hepatic vein. An electrolytic 'dose' of 100 C was then administered and the evolution of the lesion was monitored using ultrasound. Venous blood was collected before and during the electrolysis to evaluate potential acid/base disturbances and animals were closely monitored during electrolysis and during their recovery until a full autopsy was performed 4-7 days after treatment.

RESULTS

Gas bubbles were seen to enter the hepatic veins or interior vena cava during treatment in five of the six animals. There were no major complications as a consequence and all animals recovered and remained in a healthy state until they were killed. At autopsy one animal had complete thrombotic occlusion of the left hepatic vein. Otherwise, findings were normal.

CONCLUSION

In the clinical setting, due to the use of ultrasound to guide electrode placement into the centre of a tumour, the electrodes should rarely juxtapose an hepatic vein. Nevertheless, in this extreme situation, electrolysis is surprisingly safe with only one major vascular occlusion and no morbidity or mortality.

Experimental study of electrolysis-induced hepatic necrosis

BACKGROUND

One of the most promising but unexplored methods for treating patients with irresectable liver tumours is electrolysis. This study examined the effect of increasing 'current dose' on the volume of the lesion induced in normal rat liver.

METHODS

A direct current generator, connected to platinum electrodes implanted in the rat liver, was used to examine the effect of (1) varying current doses from 1 to 5 coulombs and (2) electrode separation (2 or 20 mm), on the volume of liver necrosis.

RESULTS

There was a significant correlation (P < 0.001) between the current dose and the volume of necrosis produced for each electrode separation. Placing the electrodes 2 mm apart resulted in smaller total volumes of necrosis than placing them 20 mm apart when anode lesions were significantly larger than cathode lesions (P< 0.05). Liver enzymes (aspartate aminotransferase, alanine aminotransferase) were significantly raised 1 day after treatment (P < 0.001) and predicted the total volume of hepatic necrosis (P < 0.001).

CONCLUSION

Predictable and reproducible areas of liver necrosis are produced with electrolysis. If these results extrapolate to larger animal models, this technique has potential for patients with irresectable primary and secondary liver tumours.

Isolated hepatic perfusion in the pig with TNF-alpha with and without melphalan

Isolated limb perfusion with tumour necrosis factor alpha (TNF-alpha) and melphalan is well tolerated and highly effective in irresectable sarcoma and melanoma. No data are available on isolated hepatic perfusion (IHP) with these drugs for irresectable hepatic malignancies. This study was undertaken to assess the feasibility of such an approach by analysing hepatic and systemic toxicity of IHP with TNF-alpha with and without melphalan in pigs. Ten healthy pigs underwent IHP. After vascular isolation of the liver, inflow catheters were placed in the hepatic artery and portal vein, and an outflow catheter was placed in the inferior vena cava (IVC). An extracorporeal veno-venous bypass was used to shunt blood from the lower body and intestines to the heart. The liver was perfused for 60 min with (1) 50 microg kg(-1) TNF-alpha (n = 5), (2) 50 microg kg(-1) TNF-alpha plus 1 mg kg(-1) melphalan (n = 3) or (3) no drugs (n = 2). The liver was washed with macrodex before restoring vascular continuity. All but one pigs tolerated the procedure well. Stable perfusion was achieved in all animals with median perfusate TNF-alpha levels of 5.1 +/- 0.78 x 10(6) pg ml(-1) (+/- s.e.m). Systemic leakage of TNF-alpha from the perfusate was consistently < 0.02%. Following IHP, a transient elevation of systemic TNF-alpha levels was observed in groups 1 and 2 with a median peak level of 23 +/- 3 x 10(3) pg ml(-1) at 10 min after washout, which normalized within 6 h. No significant systemic toxicity was observed. Mild transient hepatotoxicity was seen to a similar extent in all animals, including controls. IHP with TNF-alpha with(out) melphalan in pigs is technically feasible, results in minimal systemic drug exposure and causes minor transient disturbances of liver biochemistry and histology.

Thermal enhancement of both tumour necrosis factor alpha-induced systemic toxicity and tumour cure in rats

In vitro and in vivo studies have suggested synergistic anti-tumour activity of combined hyperthermia and tumour necrosis factor alpha (TNF-alpha). However, some studies indicated an increased systemic toxicity of TNF by additional hyperthermia. The aim of this study was to obtain starting dosages for a clinical phase I study on the application of deep local hyperthermia and systemic TNF. We investigated the effect of local hyperthermia on the toxicity and efficacy of systemic TNF. Rats (Wag/Rij) carrying a subcutaneously transplanted osteosarcoma in the hind leg received a single intravenous dose of recombinant human (rh) TNF-alpha, either at normothermia or at hyperthermia, by positioning the tumour bearing hind leg in a water bath of 43 degrees C. Dose-effect curves for lethality and tumour cure were established and LD50 and TCD50 values were calculated. Systemic toxicity was increased by local hyperthermia. The LD50 values (+/- s.e.) were 1088 (+/- 61) micrograms kg-1 at normothermia and 205 (+/- 23) micrograms kg-1 at hyperthermia, resulting in a thermal enhancement ratio (TER) of 5.3. Following normothermia, tumour cures were observed at TNF concentrations of 1000-1300 micrograms kg-1, while this was observed at doses of 50-300 micrograms kg-1 when combined with hyperthermia (TCD50 values of 1211 and 188 micrograms kg-1 respectively), resulting in a TER of 6.4. Systemic toxicity and anti-tumour activity of TNF are both increased by local hyperthermia. A safe starting dose for the combined clinical treatment would be 10% of the dose of TNF-alpha that has been recommended for phase II studies on intravenous bolus administration of TNF-alpha at normothermia. In view of the large variability in tumour sensitivity for TNF-alpha, the clinical usefulness of this combined treatment modality has to be determined.

Tumour growth stimulation after partial hepatectomy can be reduced by treatment with tumour necrosis factor alpha

This study investigated whether partial hepatectomy enhances the growth of experimental liver metastases of colonic carcinoma in rats and whether treatment with recombinant human tumour necrosis factor (TNF) alpha can reduce this increased growth. Resection of 35 or 70 per cent of the liver was performed in inbred WAG rats, with sham-operated controls (five to eight animals per group). Immediately after surgery 5 x 10(5) CC531 colonic tumour cells were injected into the portal vein. After 28 days the animals were killed and the number of liver metastases counted. A 35 per cent hepatectomy induced a significant increase in the median number of liver metastases (28 versus 3 in controls), whereas a 70 per cent resection provoked excessive growth, consistently leading to more than 100 liver metastases and a significantly increased wet liver weight in all animals. TNF-alpha was given intravenously to rats following 70 per cent hepatectomy or sham operation in a dose of 160 micrograms/kg three times per week. This had only a marginal effect on tumour development in sham-operated rats but was very effective following partial hepatectomy (median 45 liver metastases). These observations confirm previous findings that surgical metastasectomy may act as a 'double-edged sword' by provoking outgrowth of dormant tumour cells and suggest that adjuvant treatment with TNF-alpha may be of benefit in patients undergoing resection of metastases.

The role of tumor necrosis factor receptors in cell signaling and the significance of soluble form levels in the serum

Two types of tumor necrosis factor membrane receptors (TNF-R) have been identified, namely 55 and 75 kDa TNF-R. Soluble forms of these receptors are present in the human serum. Recent findings on the role of these two TNF-R in biological cell signaling and the clinical significance of the serum levels of soluble TNF-R (sTNF-R) were reviewed. It is not the uptake of TNF molecules into cells but rather the molecular capping of TNF-R on the cell membrane that initiates the biological activity of TNF. The 55 kDa TNF-R mediates major bioactivities of TNF, while the significance of 75 kDa TNF-R remains unclear. We herein suggest a new concept of the role of these two TNF-R: The 75 kDa TNF-R signal appeared to enhance that of 55 kDa TNF-R in the induction of ICAM-1 expression on HL-60 human promyelocytic leukemic cells. High serum levels of sTNF-R are reported in patients with malignancy, endotoxin shock, pneumonia, and autoimmune diseases. However, the source of elevated serum sTNF-R remains unclear. Studies on the clinical usefulness of serum sTNF-R levels as cancer and inflammation markers are now being carried out.

Tumor necrosis factor activities and cancer therapy--a perspective

Tumor necrosis factor (TNF) is a multifunctional cytokine which has excited and fascinated numerous investigators and commercial entities due to its promise as a therapeutic agent against cancer and as a target for drugs treating septic shock. TNF is a protein having cytotoxic, cytostatic, immunomodulatory as well as several other activities and is also involved in septic shock. This review covers the structure of TNF and its receptors, various in vitro activities and in vivo activities based on studies in animal model systems. The role of TNF as an anticancer therapeutic agent, based on various phase I and phase II clinical studies, has also been considered. The review concludes with several considerations for increasing the therapeutic utility of TNF in terms of targeting, toxicity and half-life.