Tumor immunotherapy by local injection of interleukin 2 and non-reactive lymphocytes. Experimental and clinical results

ReGel® Polymer-based Delivery of Interleukin-2 as a Cancer Treatment

ReGel is an aqueous, filter sterilizable ABA tri-block polymer consisting of poly-(lactide-co-glycolide) and polyethylene glycol. We tested the suitability of this polymer to provide sustained interleukin-2 (IL-2) delivery for cancer immunotherapy. ReGel/IL-2 is liquid at or below room temperature, and is easily injectable through narrow gauge needles, but undergoes a reversible thermal transition into a bioerodible depot at body temperature. We demonstrated that ReGel/IL-2 releases IL-2 over 72 to 96 hours in vitro, without loss of bioactivity. Pharmacokinetic studies after peritumoral injection of 0.1 mL ReGel/IL-2 in mice demonstrated an early burst of IL-2 release, followed by more sustained release kinetics over 96 hours (T(1/2)beta 48 h). Less than 1.5% of the injected dose was detectable in blood or kidneys during the first 48 hours. A single peritumoral dose of ReGel/IL-2 [1 to 4 million international units (MIU) ReGel/IL-2, split into 4 quadrant injections] was administered to mice bearing subcutaneous RD-995 spindle cell carcinoma. Only the highest dose of ReGel/IL-2 tested (4.0 MIU) resulted in significant hypotension on day 3 after injection. Weekly treatment of Meth A fibrosarcoma and RENCA renal carcinoma with ReGel/IL-2 (2 MIU/dose) induced a significant reduction in tumor growth and improved survival. Reduction in tumor growth at implants remote from treated lesions was also observed, suggesting systemic activation of antitumor immunity. These findings establish that peritumoral injection of ReGel/IL-2 is an effective delivery system for cancer immunotherapy, while decreasing IL-2 toxicity. This polymer delivery system is likely to be broadly applicable for sustained delivery of other cytokines and peptides.

Recombinant vaccinia virus expressing IL-2 generates effective anti-tumor responses in an orthotopic murine model of head and neck carcinoma

We evaluated the efficacy of a replication-competent, attenuated recombinant vaccinia virus (rvv) expressing IL-2 as a tumor vaccine in an immunocompetent murine model of head and neck squamous cell carcinoma. We implanted oral tumors by injection of tumor cells (SCC VII/SF) into the floor of the mouth of the syngeneic C3H/HeJ mice. Previous studies with this model suggested the presence of tumor-induced immune suppression. To circumvent the immune suppression we subcutaneously (s.c.) immunized the mice with irradiated, rvv-infected tumor cells prior to or along with intratumoral (i.t.) vaccination. A single s.c. vaccination invoked tumor-specific T cell proliferation and cytotoxicity. Mice treated by this protocol survived longer compared to those treated with i.t. vaccination alone. Tumor growth was significantly inhibited (P < 0.0002) and tumor regression was observed in all mice. The numbers of CD4(+) and CD8(+) lymphocytes as well as macrophages in the tumor beds and in tumor-draining lymph nodes were significantly increased in the mice treated by s.c. plus i.t. vaccination compared to s.c. or i.t. vaccination alone. These results suggested that s.c. vaccination along with i.t. vaccination increased antitumoral immunity and that CD4(+), CD8(+) lymphocytes as well as macrophages may play an important role in this antitumoral immunity.

Gene therapy for head and neck cancer using vaccinia virus expressing IL-2 in a murine model, with evidence of immune suppression

We evaluated the efficiency of recombinant vaccinia virus expressing interleukin-2 (rvv-IL-2) as a tumor vaccine in an immunocompetent mouse model of head and neck squamous cell carcinoma (SCC VII/SF). Mice with five-day-old tumors in the floor of the mouth were treated with rvv-IL-2 by intratumoral injections. These treated mice survived longer (P <.03) than mice treated with control vaccines. Splenocytes, bone marrow, and lymph node cells from tumor-bearing mice responded poorly to concanavalin A stimulation, suggesting induction of immunosuppression. The rvv-IL-2 virus grew for 7 days in the tumor following intratumoral injection. We did not detect any virus particles in several normal organs following rvv-IL-2 injection. Comparison of expression levels of several potential immune inhibitory mediators between the tumors growing in mice and cultured tumor cells demonstrated higher expression of IL-10, GM-CSF, TGF-beta, and NO synthetase in tumors. These results suggested possible roles for these molecules in immunosuppression. We conclude that rvv-IL-2 has potential as a therapeutic vaccine for head and neck cancer and that it can be more effective provided the immunosuppression is reversed.

Interleukin-2 gene transfer into human transitional cell carcinoma of the urinary bladder

Transitional cell carcinoma of the bladder is one of the human cancers most responsive to immunotherapy, and local interleukin-2 (IL-2) production appears to be an important requirement for immunotherapy to be effective. In this study, we engineered two human bladder cancer cell lines (RT112 and EJ) to constitutively release human IL-2 by retroviral vector-mediated gene transfer. Following infection and selection, stable and consistent production of biologically active IL-2 was demonstrated at both the mRNA and the protein level. Morphology, in vitro growth rate and proliferation, as well as other cytokine gene mRNA or membrane adhesion receptor expression, were not altered in IL-2 transduced cells as compared to their parental or control vector-infected counterparts. Moreover, IL-2 engineered cells lost their tumorigenicity into nu/nu mice and the mechanism of rejection appeared to involve multiple host effector cell populations, among which a prominent role was played by neutrophils and radiosensitive cells. These findings may offer support to the development of an IL-2-based gene therapy approach to human bladder cancer.

Interferons and other cytokines in head and neck cancer

The use of cytokines in head and neck cancer is increasingly under investigation. Clinical trials have tested the interferons, interleukin-2 and other cytokines as single agents and in various combinations. The addition of interferon to the cisplatin and 5-fluorouracil (5-FU) regimens (with and without leucovorin) has been explored. A randomized international trial comparing cisplatin and 5-FU with cisplatin, 5-FU and interferon-alpha 2b is in progress.

Correlation between clinical response and urinary interleukin levels using different doses and intravesical administration schedules of interferon-alpha-2b combined with epirubicin: a pilot study

A total of 62 patients at high risk for recurrence of superficial bladder cancer were selected for a study designed to compare the prophylactic efficacy of different doses and schedules of sequential intravesical instillations of epirubicin and interferon-alpha-2b and to evaluate which sequence could enhance the release of cytokines in the urine. Our investigations showed a significant increase in urinary concentrations of interleukins in patients who received the sequential intravesical administration of epirubicin and interferon-alpha-2b. Higher urinary concentrations of interleukins and a lower recurrence rate were detected in patients who received interferon-alpha-2b 24h after epirubicin instillation.

Intratumoral interleukin-2 immunotherapy: activation of tumor-infiltrating and splenic lymphocytes in vivo

Direct intratumoral injection of interleukin-2 (IL-2) was evaluated in a murine model. Balb/c mice received 5 x 10(4) Line 1 alveolar carcinoma cells (L1C2) by subcutaneous injection. On the third day following tumor implantation, mice received injections of IL-2 (5 x 10(3)-5 x 10(4) units) or diluent twice daily, either by i.p. or intratumoral injection, 5 days/week for 3 weeks. Intratumoral injection of 5 x 10(4) units IL-2 significantly reduced tumor volume (P < 0.05 versus control), increased median survival time (P = 0.0001), and resulted in a 23.5% cure rate (P = 0.008). There were no long-term survivors in the other treatment groups. Both tumor-infiltrating lymphocytes (TIL) and splenic lymphocytes isolated directly from IL-2-treated mice demonstrated enhanced cytolytic activity compared to diluent-treated controls. To determine whether non-T-cell-mediated antitumor responses were active in our model, intratumoral immunotherapy was evaluated in athymic Balb/c nu/nu mice. In order to decrease the recruitment of lymphocyte precursors, nude mice were splenectomized and received cyclophosphamide prior to tumor injection and IL-2 therapy. Intratumoral IL-2 immunotherapy also significantly decreased tumor volume in these immunodeficient mice (P < 0.02), but did not lead to long-term survival. We conclude that both TIL and splenic lymphocytes are activated in vivo in response to intratumoral IL-2 immunotherapy, suggesting that intratumoral therapy with IL-2 activates both local and systemic antitumor responses.

Combination therapy with thymosin alpha 1 potentiates the anti-tumor activity of interleukin-2 with cyclophosphamide in the treatment of the Lewis lung carcinoma in mice

In this study we have investigated the effects of thymosin alpha 1 (T alpha 1) and interleukin-2 (IL-2), singly or in combination with cyclophosphamide (CY), on tumor growth, survival and cytotoxicity in C57Bl/6NCrlBR mice with Lewis lung carcinoma (3LL). Combined administration of T alpha 1 plus IL-2, after CY treatment, was much more effective than use of each biological response modifier (BRM) alone, and induced complete tumor regression in all of the mice studied. Combination immunotherapy alone without CY only slightly reduced the rate of tumor growth, and these results are in accordance with previous studied which showed that the 3LL carcinoma is resistant to cytokines. Combined chemo-immunotherapy also increased the cytotoxicity of spleen cells and markedly enhanced long-term survival in all treated animals. Depletion of immune cells, using either total-body sub-lethal irradiation (400 rads) or antibodies directed against T-cell (anti-CD4 and CD8) or NK-cell (anti-asialo GM1) populations, abolished the positive response to combination therapy. Histological analysis of the tumors obtained from mice treated with combination chemo-immunotherapy revealed a high number of infiltrating lymphoid cells surrounding a well-circumscribed area of necrosis consisting solely of dead cells. Our studies show that T alpha 1 potentiates IL-2-induced cytotoxic activities in vitro as well in vivo, and that these compounds have a powerful anti-tumor action when associated with chemotherapy.

Continuous intra-arterial administration of recombinant interleukin-2 in low-stage bladder cancer. A phase IB study

Toxicity and clinical effects of intra-arterial (IA) continuous infusion of recombinant interleukin-2 (rIL-2) were evaluated in twelve patients with low-stage transitional cell carcinoma (TCC) of the bladder (T1NOMO; G1 to G2). rIL-2 dosages were escalated from 18 x 10(3) to 18 x 10(6) IU/m2/d in four groups of three patients. After two 5-day courses, separated by a 48-hour interval, evaluation of clinical response and transurethral resection (TUR) were carried out. World Health Organization (WHO) Grade 3 toxicity occurred in 2 of 12 patients (hypotension/mental confusion and fever, respectively); all side effects rapidly disappeared after infusion was abandoned. No laboratory toxicity developed in any patient. Two pathologically proven complete responses (CR) were achieved using 18 x 10(4) IU/m2/d, and three partial responses (PR) were achieved using 18 x 10(5) IU/m2/d in two patients and 18 x 10(6) IU/m2/d in one patient, giving an overall response rate of 42%. All objective responses are still ongoing after a mean follow-up time of 23 months (range, 12 to 32 months). Local relapses occurred 3 months after TUR only in two nonresponders.

Induction of tumor regression in experimental model of human head and neck cancer by human A-LAK cells and IL-2

In a nude mouse model of human squamous-cell carcinoma of the head and neck (SCCHN), locoregional therapy with interleukin 2 and human lymphokine-activated killer (LAK) cells resulted in a significant inhibition of growth of 3-day established tumors. The same model was used for therapy of 7-day established tumors with highly enriched populations of human adherent (A)-LAK (CD3- CD56+) cells and IL-2. Peritumoral transfer of 10 x 10(6) A-LAK cells, whose in vitro cytotoxicity against a SCCHN cell line (PCI-I) was not significantly different from that of LAK cells, resulted in complete regression of all 3-day or 7-day human SCCHN in nude mice. An initial inflammatory-type reaction, which appeared within hours of the first peritumoral cell transfer, was accompanied by infiltration initially by granulocytes and plasma cells, and later by mononuclear cells into the tumor stroma. A-LAK cells labelled with a fluorescent dye prior to injection appeared in the tumor stroma within 24 hr and were localized around or in the basal epithelial tumor layer by 48 hr. Histologic sections revealed an increasing epithelial disorganization and progressively decreasing basal epithelial layer, which were proportional to the increasing number of A-LAK cells transferred. Within 4 weeks, the tumors were reduced to amorphous keratinic remnants surrounded by the connective tissue containing abundant mononuclear cells. Local administration of human A-LAK cells and IL-2 to SCCHN tumors growing in nude mice led to accelerated tumor differentiation, keratinization and regression.

Interleukin-2 injected around tumor-draining lymph nodes in head and neck cancer

Twenty patients with recurrent, inoperable head and neck squamous cell carcinoma received perilymphatic injections of natural interleukin-2 (nIL-2) for 10 days. Ten patients received 200 units (U) of nIL-2; five 1,000 U; and five 5,000 U. Irrespective of the location of the recurrence, the injections were always performed 1.5 cm below the insertion of the sternocleidomastoid muscle on the mastoid. When the ipsilateral lymphatic chain was still present, they were performed on the same side as the tumor site, whereas when it had been stripped as a result of previous surgery, they were contralateral. Patients who had undergone bilateral neck dissection were injected on the tumor side. Whenever possible, the treatment was repeated after 45-day intervals. In 13 patients (65%) with bilateral or contralateral lymph nodes, complete or partial disappearance of the lesion was observed. Despite these marked responses, the tumor always relapsed, and subsequent IL-2 courses were poorly effective. There were no systemic disturbances during or after treatment, but only moderate local swelling and pain.

Immunotherapy of cancer using local administration of lymphoid cells transformed by IL-2 cDNA and constitutively producing IL-2

Peritumoral administration of X63-m-IL-2 cells transformed by IL-2 cDNA and constitutively producing large quantities of recombinant IL-2 mediated regression of X63-Ag8.653 plasmocytoma and MC14 sarcoma transplanted in syngeneic mice. Injections of the IL-2-producing cells containing an inserted, modified IL-2 gene effectively inhibited tumour growth also in allogeneic recipients. Activation of murine spleen cells in vitro by co-cultivation with X63-m-IL-2 cells gave rise to lymphokine-activated killer (LAK) cell populations cytotoxic for the X63-Ag8.653 plasmocytoma and MC14 sarcoma. The results suggest that peritumoral administration of lymphoid cells transformed with IL-2 cDNA and constitutively producing IL-2 in the immediate tumour vicinity is sufficient for the effective activation of local IL-2-dependent tumour defence mechanisms and, therefore, can be considered a novel, genetic approach to the immunotherapy of cancer.

Helper strategy in tumor immunology: expansion of helper lymphocytes and utilization of helper lymphokines for experimental and clinical immunotherapy

Two main kinds of immune strategy are possible against neoplasia. The first potentiates a selected effector arm. In vitro culture with exogenous interleukin-2 (IL-2) increases the activity of natural killer cells and leads to the expansion of T cytotoxic lymphocytes. Systemic reinfusion of both of these cells with high doses of IL-2 mediates the regression of a variety of murine and human tumors. In an alternative strategy, a few regulatory lymphocytes turn on immune reactivity by triggering a cascade of interconnected effector functions. The efficacy of this strategy rests on the repertoire of effector mechanisms moved to action. An effective immunoregulatory maneuver is the addition of helper determinants on the surface of tumor cells. Its power can be further increased by the pre-induction of helper T lymphocytes specific to the helper determinants. This approach can be achieved in mice by coupling muramyl dipeptides to tumor cells, along with eliciting T lymphocytes specifically reactive to Bacillus Calmette-Guerin. Noncytotoxic T helper lymphocytes produce factors which recruit nonspecific (macrophages) as well as specific (cytolytic T lymphocytes) anti-tumor attacking cells. In this way protection can be afforded against primary tumors and metastases, as well as leukemia cells. As the activity of helper lymphocytes rests mostly on lymphokine release, the use of molecularly defined lymphokines mimicking T-helper functions has also been attempted. In a few experimental models, the association of low doses of IL-2 with non-reactive lymphocytes from tumor-bearing mice promotes an effective anti-tumor reaction in the host. Moreover, the combination of distinct lymphokines can also build a molecularly defined helper system able to activate in sequence non-specific and specific anti-tumor reactions in vivo. Trials intended to evaluate the clinical impact of these helper approaches in the management of human tumors are being started or are already under way.