No abstract

Natural killer (NK) cells are believed to contribute to the clinical efficacy of cancer immunotherapy using recombinant interleukin-2 (rIL·2) in humans. In previous trials of high-dose i.v. rIL-2, however, no correlation has been established between circulating NK cells and treatment response. Between January 1989 and October 1990, we treated a total of 47 outpatients with advanced tumors using low-dose s.c. rIL·2 and interferon-α-2 (rIFN-α). Therapy consisted of a 2-day rIL·2 pulse at 18 million IU/m2/ day, followed by 6 weeks of rIL-2 (3.6 × 10⁶-4.8 × 10⁶ IU/m²/day × 5 days/week) and rIFN-α (5 × 10⁶-6 × 10⁶U/m² × 3/week). Before and after therapy, we phenotypically evaluated circulating lymphocytes and correlated them with clinical response. During 6-week therapy, peripheral blood lymphocytes bearing the CD 5 6 (NK-cell-associated) surface antigen were increased significantly (p < 0.005) in treatment responders [complete response (CR) and partial response (PR), n = 10; 3.8-fold] and stable disease (SD) patients (n = 20; 2.1-fold), while patients with progressive disease (PD, n = 17) exhibited no significant expansion of circulating NK cells (p > 0.1). After one 6-week treatment cycle, CR/PR patients had significantly more peripheral NK cells, when compared with patients in SD (1.6-fold) and PD (1.9-fold) (p < 0.04). The overall number of circulating lymphocytes was also increased upon therapy (1.6-fold; p ≤ 0.001), but remained independent of response (p > 0.4). These data demonstrate that s.c. rIL·2 and s.c. rIFN-α produce a significant increase in peripheral blood NK cells; this expansion correlates significantly with treatment response in advanced tumor patients receiving long-term combination immunotherapy at outpatient doses.

No abstract

High dose interleukin-2 alone or in combination with lymphokine activated killer (LAK) cells has demonstrated antitumor activity in a variety of malignant diseases. The currently formulated recombinant human interleukin-2 (IL-2) has limited solubility and short circulatory half life resulting in limited bioavailability. To improve the bioavailability of IL-2 the protein was covalently bound to activated Polyethylenglycol (PEG). We designed a phase I/II trial to evaluate the bioactivity of PEG-IL-2 in man, given as intravenous (iv) bolus injection every two weeks, and to determine safety, efficacy, and the maximum tolerated dose (MTD) in patients with advanced malignancies. Assessment of cytokine levels, phenotypic analyses and differential blood counts were performed to investigate the effects of PEG-IL-2 in-vivo. To compare in-vitro PEG-IL-2 activity to activities of IL-2 we evaluated proliferation, cytotolytic activity, morphology, and phenotype of cytokine activated lymphocytes. Among seven patients treated with PEG-IL-2, there was no objective remission, three patients exhibited stabilisation of disease. Four patients presented with further disease progression. Treatment-related toxicity was mild to moderate (mainly WHO grades I and II) in patients receiving dose levels up to 10 x 10(6) IU/m2 (maximum tolerated single dose in the outpatient setting). No toxic deaths occurred. In comparison to IL-2, the pharmacokinetic profile of PEG-IL-2 exhibited increased plasma levels and a decreased clearance (alpha and beta half-life estimates of 4 and 14 hours, respectively). The analysis of a variety of immunologic parameters demonstrated that PEG-IL-2 has significant biologic activity both in vitro, and in man.

We treated 17 patients who had progressive metastatic renal carcinoma with a combination of subcutaneous recombinant human interleukin-2 (administered every 12 hours, at 9.0 million IU/m2 on days one and two, followed by 1.8 million IU/m2, five days per week, over six consecutive weeks) and interferon-alpha 2b (given at 5 million U/m2 three times weekly, for six consecutive weeks). Treatment courses were repeated in patients presenting with stable or regressive disease after the six weeks of combination therapy (11 of 14 evaluable). Two and three of 14 evaluable patients achieved complete and partial remissions, respectively. Toxicity of this regimen was moderate, with local inflammation of the injection sites, grade I-II (WHO) fevers, chills, malaise, nausea/vomiting, and anorexia in more than two-thirds of the patients treated.

Systemic administration of interleukin-2 (IL-2) in humans may induce antibodies specific to IL-2. The case is reported of a patient with metastatic rectal carcinoma who was treated with long-term subcutaneous IL-2 and a combination of subcutaneous IL-2 and interferon-alpha 2b (IFN-alpha 2b). This patient developed nonneutralizing and neutralizing anti-IL-2 antibodies recognizing both the recombinant and natural cytokine. Detectable serum levels of neutralizing antibodies were accompanied by the inhibition of immune responsiveness to systemic IL-2 in vivo.

Phenotypic characterization of peripheral blood lymphocytes was performed in patients with advanced metastatic cancer receiving low-dose recombinant interleukin-2 (rIL-2) and recombinant interferon-α (rIFN-α) as subcutaneous home therapy. A total of 31 patients with progressive metastatic renal cell carcinoma, malignant melanoma, colorectal cancer, B-cell lymphoma, and Hodg-kin’s disease, were evaluated. Patients were treated with a combination of low-dose subcutaneous rIL-2 and rIFN-α, consisting of a 2-day rIL-2 pulse at 9.0 million IU/m2 twice daily, followed by 6 weeks of combined low-dose rIL-2 at 1.8 million IU/m2 twice daily, 5 days per week, and rIFN-α at 5.0 million U/m2 3 times per week. This treatment regimen resulted in an overall significant (p < 0.002) increase in peripheral blood lymphocyte subsets expressing CD3, CD8, CD16, CD25, and CD56. Expansion of peripheral blood natural killer (NK) cells was correlated to treatment response. Thus, treatment-related increase in CD56-positive lymphocytes was 1.8-fold higher in complete or partial responders when compared to progressive disease patients (p = 0.0). Increase in NK cells upon low-dose rIL-2 and rIFN-α was associated with a significant expansion (p = 0.0) of peripheral blood eosinophils (r = 0.71). Patient pretreat-ment using rIL-2, rIL-2 and rIFN-α, or chemotherapy abrogated the treatment-induced induction of NK cells and IL-2 receptor- (CD25) positive T lymphocytes, respectively. Peripheral blood NK cells were significantly decreased (p < 0.05) in patients developing neutralizing antibodies specific to rIL-2.

No abstract