Timothy Fong

Comparison of Serum Interleukin-10 (IL-10) Levels Between Normal Volunteers and Patients with Advanced Melanoma

Melanoma is an immunoresponsive malignancy. Interleukin-10 (IL-10) is a potent regulator of immunosuppression. The purpose of this research was to define the relationship of serum IL-10 to survival in patients with metastatic melanoma. Forty-one melanoma patients and 50 normal volunteers were analyzed. The median IL-10 level as determined by enzyme-linked immunosorbent assay (ELISA) in melanoma patients was 8.75 pg/ml compared to <3.0 pg/ml in normal volunteers (p = 0.0001). Survival of melanoma patients with an IL-10 level above 10.0 pg/ml was 365 days compared to 557 days in patients with IL-10 levels less than 10.0 pg/ml (p = 0.0259, Wilcoxon). Elevated IL-10 levels were correlated with poor survival.

Phase I Trial of Interferon gamma Retroviral Vector Administered Intratumorally with Multiple Courses in Patients with Metastatic Melanoma

The purpose of this study was to determine the safety and antitumor activity of IFN-gamma retroviral vector in patients with advanced melanoma. Seventeen patients (9 single courses, 8 multiple courses) received a total of 363 intratumor injections of IFN-gamma retroviral vector (1 x 10(7) PFU/ml administered at 0.3, 0.5, and 1.0 ml per cohort). No grade III/IV adverse events were attributed to study medication. Replication-competent retrovirus was not detected in any of the 17 patients by polymerase chain reaction studies. Eight patients showed elevated anti-tumor antibody responses in comparison with baseline by ELISA. One of nine patients treated with a single course had an optimal response of stable disease, compared with eight of eight multiple-injected patients. Median survival of single-injected patients was 150 days, and patients who received multiple injections have still not achieved median survival duration, with four of eight still living (p = 0.0462, Wilcoxon; p = 0.0273, log rank). We conclude that intratumor injection of IFN-gamma is safe and well tolerated. Evidence of antitumor activity is suggested in patients with advanced malignancy that received multiple injections.

Induction of melanoma-associated antigen systemic immunity upon intratumoral delivery of interferon-gamma retroviral vector in melanoma patients.

A total of 17 patients with metastatic melanoma were treated with intratumoral interferon-γ (IFN-γ) retroviral vector in a phase I clinical trial. A cycle of treatment consisted of five daily injections every 2 weeks. Patients were divided into two treatment arms that involved a single course (one cycle) of treatment (group I; n = 9) and multiple cycles (six cycles) of treatment (group II; n = 8). Patients received intratumoral injections of IFN-γ (107 plaque-forming units/mL administered at 0.3, 0.5, and 1.0 mL per cohort of patients). All patients receiving multiple injections either maintained stable disease (n = 5) or achieved a partial or complete response (n = 3) of the injected lesion, whereas in patients receiving a single cycle of treatment, only one of nine patients had a response. Patients were assessed for immunoglobulin G antibody (Ab) responses to the melanoma-associated antigens (MAA) tyrosinase, gp100, TRP-2, and MAGE-A1 by affinity enzyme-linked immunosorbent assay. Anti-MAGE-A1 and tyrosinase Ab were significantly elevated from baseline (day 0) to week 16 during treatment (P = .005; P = .002, respectively) in patients who received multiple injections. Patients undergoing treatment who had a clinical response (stable disease or better) also had significantly more elevated Ab responses to a greater number of MAA (P = .0004). The induction of systemic Ab responses to multiple MAA also correlated with systemic clinical responses. These studies suggest that multiple anti-MAA Ab responses are associated with clinical responses to IFN-γ retroviral treatment and may be used as surrogate response markers.

Phase I trial of interferon-γ (IFN-γ) retroviral vector administered intratumorally to patients with metastatic melanoma

Background: Interferon-γ (IFN-γ) gene/retroviral vector cell vaccinations have generated protective responses from unmodified tumor cell challenges as well as a regression of established tumors in animal models. The purpose of this trial was to determine the feasibility and safety of a direct intratumoral injection of IFN-γ retroviral vector in advanced melanoma patients.Methods: This was a phase I study, in which 13 patients received a single daily injection of a retroviral vector with the IFN-γ gene for 5 consecutive days (1.5 × 108 colony-forming units total dose); patients subsequently underwent resection of the injected lesion to confirm DNA transduction in situ.Results: No toxicity related to the injected vector was observed. Replication competent retrovirus was not observed in any prepared samples (n = 65). IFN-γ expression was confirmed in 3 of 10 harvested tumor samples; one was equivocal, and DNA transduction was unable to be confirmed by enzyme-linked immunospot assay in six samples.Conclusions: An injection of IFN-γ gene/retroviral vector is well tolerated. DNA transduction was demonstrated in human subjects, confirming the feasibility of the direct injection approach for the gene therapy of solid tumors. Further trials to determine optimal schedule and potential efficacy are indicated.

Ablation of Tumor Cells In Vivo by Direct Injection of HSV‐Thymidine Kinase Retroviral Vector and Ganciclovir Therapy

Abstract: The introduction of therapeutic genes into proliferating tumor cells in vivo by direct intralesional injection of retroviral vectors can provide an effective and valuable approach for the treatment of a variety of solid tumor types. Efficient transduction of tumor cells in situ by direct injection was demonstrated using a retroviral vector containing the β‐galactosidase (β‐gal) gene. Ablation therapy in vivo was demonstrated using a retroviral vector containing the Herpes simplex virus thymidine kinase gene (HSV‐TK) to deliver the TK gene into the murine colorectal tumor cell line CT26. Ablation of CT26 tumor cells in situ was achieved by directly injecting high‐titer HSV‐TK retroviral vector preparations into the site of tumor cell inoculation followed by intraperitoneal (i.p.) delivery of ganciclovir (GCV). This gene therapy strategy demonstrated a markedly lower rate of tumor progression, with several complete regressions, compared to animals in control groups. We also demonstrated that resistance to subsequent challenges with unmodified CT26 cells and an enhanced cellular immune response is associated with tumor regression in immunocompetent animals. Our results demonstrate the feasibility of direct in situ administration of HSV‐TK retroviral vectors for the treatment of cancer and suggest that a cellular immune response may be elicited by this therapy.