Recombinant interleukin-2 in cancer: basic and clinical aspects

Intralesional granulocyte-monocyte colony-stimulating factor followed by subcutaneous interleukin-2 in metastatic melanoma: a pilot study in elderly patients

AIM AND BACKGROUND

Recent data in the literature indicate that antigen-presenting cells (APC) are inactive in tumour tissue because of local immunosuppression. Tumour-infiltrating lymphocyte (TIL) signal activation transducing mechanisms are also seriously impaired. Administration of granulocyte macrophage-colony stimulating factor (GM-CSF) may lead to APC recovery and interleukin (IL)-2 may restore local TIL activation. Moreover, IL-2 increases the systemic lymphocyte population, an event that seems to correlate with a better prognosis.

STUDY DESIGN

The present phase I-II study was carried out to examine whether intralesional injection of GM-CSF followed by subcutaneous IL-2 would induce a clinical response in advanced, pretreated elderly melanoma patients.

METHODS

Sixteen patients over 60 years of age received intralesional GM-CSF (150 ng per lesion on day 1), generally divided between the two largest cutaneous lesions, followed by perilesional subcutaneous IL-2 (3,000,000 IU) for 5 days (days 3-7 inclusive) every 3 weeks.

RESULTS

Four clinical responses [two partial (PR) and two minimal (MR)] (25%), which also involved lesions that had not been directly treated, and nine cases of stable disease were observed. The response duration for PR and MR was 9, 4, 4 and 2.5 + months, respectively. Stable disease (56%) recorded in the nine patients was short-term (3-6 months). Three patients rapidly progressed after two, two and one therapy cycles, respectively. The patient who reached the best PR had a fairly high absolute lymphocyte count (1600-2400/mm3). The second one, who reached complete remission after subsequent locoregional chemotherapy and hyperthermia, however, had a low absolute lymphocyte count that had doubled by the end of treatment. Blood lymphocyte values in the other patients were too varied to allow any correlation with clinical response. Therapy was well tolerated and only mild fever was observed, with the exception of one patient who had grade 3 fever, with muscle pain and arthralgia.

CONCLUSIONS

Considering the very low toxicity observed, this treatment might be indicated in elderly patients for whom systemic therapy is no longer a viable option. Improved scheduling and timing could result from further studies.

Increased endosomal sorting of ligand to recycling enhances potency of an interleukin-2 analog

An interleukin-2 (IL-2) variant containing adjacent point mutations (L18M/L19S, termed 2D1) displaying binding affinity to the heterotrimeric IL-2 receptor similar to that of wild-type IL-2 (WT) had been previously found to surprisingly exhibit increased bioactivity in a peripheral blood lymphocyte proliferation assay. In order to provide an explanatory mechanism for this unexpected potency enhancement, we hypothesize that altered endocytic trafficking of the 2D1 variant might be responsible by increasing the number of ligand-receptor complexes. We demonstrate here that the internalization kinetics of 2D1 via the high affinity IL-2 receptor are equivalent to those of WT but that a significantly increased fraction of internalized 2D1 is sorted to recycling instead of to lysosomal degradation. We further find a reduced pH sensitivity of binding to IL-2 receptor alpha relative to IL-2 receptor beta compared with WT, which could be responsible for the altered sorting behavior of 2D1 in the acidic endosomal compartment. Accordingly, the 2D1 variant displays a half-life 36 h longer than that of IL-2 in T-lymphocyte culture at concentrations equal to the K(D) of the IL-2 receptor. The extended half-life of intact 2D1 provides enhanced mitogenesis as compared with IL-2. In addition, 2D1 stimulates natural killer cells to a lesser degree than IL-2 at equal concentrations. We conclude that this IL-2 variant provides increased mitogenic stimulation that could not be easily predicted from its cell surface receptor binding affinity while minimizing undesired stimulation of natural killer cells. This concept of altering trafficking dynamics may offer a generalizable approach to generating improvements in the pharmacological efficacy of therapeutic cytokines.

Antitumor effects of 5'-deoxy-5-fluorouridine in combination with recombinant human interleukin 2 on murine colon carcinoma 26

The antitumor activity of recombinant human interleukin 2 (rIL-2) in combination with 5'-deoxy-5-fluorouridine (doxifluridine; 5'-DFUR) against marine colon carcinoma 26 (Colon 26) was studied. BALB/c mice were treated daily for 15 days with 5'-DFUR, rIL-2 or both, beginning on day 7 after subcutaneous transplantation of Colon 26. While mice treated with 5'-DFUR or rIL-2 alone died of tumor growth with pulmonary metastases within 9 weeks posttransplantation, the survival time was significantly prolonged in mice treated with both 5'-DFUR and rIL-2. Most of the combination-treated animals showed the regression of local tumors and the inhibition of pulmonary metastasis. Histopathologically, many tumor cells were degenerated and necrotized, with marked infiltration of mononuclear cells including large granular lymphocytes (LGLs) with periodic acid-Schiff-positive cytoplasmic granules. The cells were positive for CD3 epsilon, asialo GM1 and NK1.1. Spleen cells from the combination-treated mice showed high activities of natural killer (NK) cytotoxicity as well as growth inhibition of Colon 26 and Meth A fibrosarcoma in mice. The results suggest that the combination therapy of 5'-DFUR plus rIL-2 enhanced non-specific cytotoxicity of LGL/NK cells for Colon 26 in tumor-bearing mice and was effective in the inhibition of tumor growth.

Sequential biochemotherapy for metastatic colorectal cancer using fluorouracil, folinic acid, thymopentin and interleukin-2: clinical and immunological effects

BACKGROUND

A phase II study was performed to evaluate the clinical and immunological effects of a regimen of fluorouracil (5-FU) and folinic acid (FA) combined with thymopentin (TP-5) and interleukin-2 (IL-2) in the treatment of patients with metastatic colorectal cancer.

PATIENTS AND METHODS

Forty-five evaluable patients with measurable colorectal cancer and no prior therapy for metastatic disease were treated with 5-FU 400 mg/m2/d and FA 200 mg/m2/d i.v. on days 1-5, TP-5 50 mg s.c. on days 8-11, and IL-2 9 MU/m2 s.c. twice daily on days 12-16. Cycles were repeated at 4-week intervals if toxicity had resolved. Immunological changes were evaluated in 13 patients and compared with a well matched series of 13 patients treated with the same regimen without TP-5.

RESULTS

Two complete responses and 17 partial responses were seen (42%; 95% confidence interval, 28% to 56%). Fifteen patients (33%) had stable disease. The median time to progression was 8.5 months and the median survival 13 months. Treatment was reasonably well tolerated, and there was no overlapping toxicity or interference between chemotherapy and biotherapy. Hematological and immunological changes during treatment were qualitatively similar to those expected with IL-2 +/- chemotherapy. Quantitatively, significant changes (higher levels of IL-2, CD25 and IFN-gamma, and lower levels of sIL-2R) were observed in patients given TP-5.

CONCLUSION

The combination of 5-FU + FA and TP-5 + IL-2 is effective in advanced colorectal cancer with acceptable toxicity. Immunological data suggest that TP-5 may modulate the action of IL-2 in the clinical setting. However, improved treatment approaches are needed, and the interactions between thymic hormones and cytokines should be further explored.