Recruitment of dendritic cells and enhanced antigen-specific immune reactivity in cancer patients treated with hr-GM-CSF (Molgramostim) and hr-IL-2: results from a phase Ib clinical trial
Introduction
The antitumour activity of subcutaneous (s.c.) low-dose human recombinant interleukin-2 (hr-IL-2), administered alone or in combination with other cytokines, has been demonstrated in patients with renal cell carcinoma 1, 2. Interest in the chronic subcutaneous (s.c.) administration of hr-IL-2 has increased as a result of various biological observations concerning the modulation of specific cytotoxic T lymphocytes (CTL), CD4+ T cell populations and cytokine profiles in cancer patients [3]. On the basis of the results of numerous trials, cancer immunotherapy with hr-IL-2 is currently used in Europe in an outpatient setting and has practically no toxicity [4].
It is widely accepted that a T lymphocyte response to tumour associated antigens (TAA) is essential for obtaining efficient and prolonged tumour rejection in vivo1, 2. T lymphocytes recognise tumour and viral protein antigens as small peptides (the products of intracellular degradation) bound to MHC molecules on target cells [5]. Tumour cells express major histocompatibility complex (MHC)-bound tumour antigen peptides and can thus be recognised and killed by activated cytotoxic T lymphocytes, but they cannot start a demonstrable CTL immune reaction since they lack the expression of costimulatory molecules such as B.1 (CD80) and B7.2 (CD86), which are indispensable for the activation of CTL precursors [5]. However, these molecules are expressed by professional antigen presenting cells (APC) such as dendritic cells (DCs), which play a central role in initiating an antigen-specific immune reaction as a result of their ability to uptake, process and present the antigen proteins released by the tumour or virally-infected cells 6, 7.
DCs have been extensively studied over the last 5 years, and various authors have described protocols for their in vitro generation from human peripheral blood mononuclear cells (PBMCs) or bone marrow stimulated with granulocyte-macrophage monocyte-colony stimulating factor (GM-CSF) combined with IL-4 or tumour necrosis factor (TNF)-α, respectively 8, 9. These protocols have made it possible to develop new immunotherapeutic strategies using DCs as a living immune-adjuvant for therapeutic anticancer vaccines [9].
hr-GM-CSF is the key agent in the promotion of both in vitro and in vivo DC proliferation and differentiation [10], and also regulates the proliferation and differentiation of granulocyte, eosinophil, and macrophage progenitors 11, 12. The clinical antitumour activity of hrGM-CSF (Molgramostim) has been tested in patients with renal cell carcinoma, and been found to have less antitumour activity than hr-GM-CSF and an acceptable degree of toxicity 13, 14. More recent in vitro studies have shown that hr-GM-CSF interacts with hrIL-2 to generate human prostate-specific antigen PSA-specific CTL lines [15].
On the basis of these observations, we performed a clinical trial in which s.c. hr-GM-CSF and s.c. hr-IL-2 were sequentially administered to patients with advanced cancer in order to verify the hypothesis that hr-GM-CSF promotes the proliferation and differentiation of APCs such as DCs, monocytes and macrophages, which may initiate a tumour-specific immune reaction that is subsequently sustained and amplified by hr-IL-2.
The primary aim of the study was to evaluate the toxicity profile and biomodulatory potential of this new treatment schedule; the secondary aim was to make a preliminary investigation of its antitumour activity.
Section snippets
Patient eligibility
Between August 1998 and July 2000, we enrolled 25 patients (14 females and 11 males) with a median age of 69.5 years (range 58–75 years) and histologically confirmed diagnoses of renal cell carcinoma (11), colorectal carcinoma (8), soft tissue sarcoma (2), non small-cell lung carcinoma (1), pancreas carcinoma (1), prostate carcinoma (1) and malignant melanoma (1). All of the patients had to have advanced disease, an Eastern Cooperative Oncology Group (ECOG) performance status of ⩽2, a life
Treatment response
19 of the 25 patients entering the study had received at least one line of previous treatment. A final 3 patients (nos. 23–25) enrolled in July 2000 were administered what appeared to be the most biologically and clinically active dose of hr-IL-2 (1 MIU/day), and were evaluated only for clinical response and toxicity.
One patient with prostate cancer voluntarily decided to discontinue the treatment at the end of the first cycle and was lost to follow-up, and 2 patients stopped the therapy
Discussion
The clinical results of the trial suggest that the treatment was well tolerated, and indicate that it has promising anti-tumour activity, as shown by the three partial remissions and 13 disease stabilisations observed in patients with very advanced disease. In comparison with other studies of hr-GM-CSF or hr-IL-2 alone or in combination, the side-effects recorded during the present study were much less frequent and severe 2, 3, 13, 14, 23, 24, 25, 26. Four studies have recently reported the
Acknowledgments
The authors wish to thank Professor Manlio Ferrarini, I.S.T., Genoa, Italy and Dr Carol Nieroda, N.C.I., Bethesda, MD, USA for their suggestions. We also thank the paramedic personnel of the Medical Oncology Division, University of Siena for their critical help in patient assistance, management, and care. This study was supported by grants from the Italian Ministry of University, Research and Technological Development (MURST, Progetto inter-universitario ex-40%, 1998–2000) and from the Italian
References (32)
- et al.
Home therapy with recombinant interleukin-2 and interferon-α2b in advanced human malignancies
Lancet
(1990) - et al.
Costimulation, tolerance and ignorance of cytolytic T lymphocytes in immune responses to tumor antigens
Life Sciences
(1997) - et al.
Dendritic cells
Adv. Immunol.
(1999) - et al.
Dendritic cells as initiators of tumor immune responses: a possible strategy for tumor immunotherapy?
Immunol. Today
(1995) - et al.
An improved method for dendritic cell isolation with special regard to clinical applicability
J. Immunol. Methods
(1996) - et al.
Production of interleukin-1 alpha, interleukin-1 beta and tumor necrosis factor by human mononuclear cells stimulated with granulocyte-macrophage colony stimulating factor
Blood
(1988) - et al.
Graphic representation of pain
Pain
(1976) - et al.
Biological indices predictive of survival in 519 Italian terminally ill cancer patients
J. Pain and Symptom. Manag.
(1997) Interleukin 2
Biol. Ther. Cancer Updates
(1994)- et al.
The immunobiological effects of interleukin-2 in vivo
Cancer Immunol. Immun.
(1994)