Update on development of interleukin-11

Oprelvekin (Neumega®)

Objective. Our objective was to review oprelvekin, which is a new thrombopoietic cytokine approved in the United States to prevent severe thrombocytopenia and reduce the number of platelet transfusions after myelosuppressive chemotherapy. This article focuses on oprelvekin’s pharmacology, pharmacokinetics, and place in therapy.

Data Sources. A search of the National Cancer Institute-sponsored Cancerlit database from 1963 to 1999 was completed. Subject mesh headings that were searched included interleukin-11, oprelvekin, breast cancer, chemotherapy dose intensity, and cancer pharmacoeconomics. Data were also collected from the package insert and from Genetics Institute (Cambridge, MA) publications.

Study Selection. Searches were limited to studies with humans, which included clinical trials, news articles, and review articles. After reading all of the human clinical trials, additional pertinent citations were obtained and read.

Data Synthesis. Oprelvekin has been studied in both adults and children, with the bulk of the data coming from the treatment of women with breast cancer. A phase I study in adults evaluated doses of 10, 25, 50, 75, and 100 mg/kg/day and determined the maximum tolerated dose to be 50 mg/kg/day. The toxicity seen with the 75 and 100 mg/kg/day doses includes constitutional symptoms (arthralgias, myalgias, fatigue, nausea, and headache) and a cerebral vascular accident. Phase II and III trials showed that 25-50 mg/kg/day effectively reduced the number of patients requiring platelet transfusions and decreased the number of platelet transfusions after chemotherapy.

Pharmacokinetics performed with the 50 mg/kg/day subcutaneous (s.c.) dose resulted in a maximum sera concentration of 17.4 6 5.4 ng/mL, which occurred at 3.2 6 2.4 hours. The terminal half-life was 6.9 6 1.7 hours. Clearance decreases with increasing age, and pediatric patients have a 1.2- to 1.6-fold higher clearance than adults. These pharmacokinetic parameters led to a dosing recommendation of 75- 100 mg/kg/day in pediatric patients.

Due to the high cost of oprelvekin and the lack of data demonstrating that it affects mortality, its role in current therapies is unclear. It is currently being promoted to maintain dose intensity in patients with breast cancer, testicular cancer, and lymphoma. Depending upon institutional platelet and oprelvekin costs, it may also be useful in patients receiving a large number of platelet transfusions. Thus far, it has not demonstrated efficacy in bone marrow transplant patients.

Conclusion. Oprelvekin can effectively prevent the need for platelet transfusion in nontransplant patients receiving myelosuppressive chemotherapy. Due to its high cost, it will most likely be used to maintain chemotherapy dose intensity, which may translate into a survival advantage.

Synergism between interleukin-11 and bone morphogenetic protein-2 in the healing of segmental bone defects in a rabbit model

Recombinant human interleukin-11 (rHuIL-11) and recombinant human bone morphogenetic protein-2 (rHuBMP-2) have been shown to act synergistically in the induction of osteoblast differentiation. To determine whether these two proteins can be used clinically in fracture healing and reconstructive surgery, we investigated whether rHuIL-11 and rHuBMP-2 act synergistically to heal segmental bone defects in a rabbit model. A 1.5-cm segmental defect was created in the right ulnar diaphysis of 20 Japanese white rabbits. Polylactic-co-glycolic acid (PLGA)-coated gelatin sponges (PGS) permeated with rHuBMP-2 (n = 8), rHuIL-11 plus rHuBMP-2 (n = 8), or rHuIL-11 (n = 4) were implanted into the bone defects. Radiographs were scored by two independent observers for bone formation and union rates after 2, 3, 4, and 8 weeks. Bone formation was higher in rabbits implanted with rHuBMP-2 plus rHuIL-11 than in those implanted with rHuBMP-2 alone, reaching statistical significance after 4 weeks. At early time points, the union rate in rabbits implanted with rHuBMP-2 plus rHuIL-11 was higher than in rabbits implanted with rHuBMP-2. At 2, 4, and 8 weeks, new bone volume was significantly higher in rabbits administered rHuIL-11 plus rHuBMP-2 than in those given rHuBMP-2 alone. In contrast, mechanical testing after 8 weeks showed that bone strength in the two groups of rabbits was equivalent. These findings show that rHuIL-11 and rHuBMP-2 act synergistically to accelerate bone formation without affecting bone strength. Treatment with a combination of rHuIL-11 and rHuBMP-2 may thus be of great benefit in fracture healing and for patients undergoing reconstructive surgery.

Interleukin-11 acts synergistically with bone morphogenetic protein-2 to accelerate bone formation in a rat ectopic model

We previously demonstrated that recombinant human interleukin-11 (rHuIL-11) induced osteoblast differentiation of C3H10T1/2 progenitor cells and also acted synergistically with recombinant human bone morphogenetic protein-2 (rHuBMP-2) in performing the same function. In this study, we investigated the effect of rHuIL-11 and rHuBMP-2 on bone formation in a rat ectopic model. When placed in rats, implants consisting of polymer-coated gelatin sponges containing various concentrations of rHuBMP-2 showed a dose-dependent increase in calcium content. This was confirmed by radiographic analysis of the implants. Although implants containing rHuIL-11 alone did not accumulate calcium, implants containing a combination of rHuBMP-2 and rHuIL-11 had significantly higher calcium levels than those containing rHuBMP-2 alone. This increase was rHuIL-11 dose dependent. The synergistic effect of 20 micrograms rHuIL-11 and 6 micrograms rHuBMP-2 on bone formation was estimated to be 1 week in advance of that of 6 micrograms rHuBMP-2 alone. Histologic examination revealed that the combination of rHuIL-11 and rHuBMP-2 caused spindle cells to accumulate around implants and induced cell infiltration into implants. Bone formation occurred faster in implants with the combination of rHuIL-11 and rHuBMP-2 compared with rHuBMP-2 alone. These results suggest that rHuIL-11 acts synergistically with rHuBMP-2 to more rapidly stimulate bone formation compared with rHuBMP-2 alone. This novel combined therapy may be of great clinical benefit in bone healing.

Interleukin-11 induces osteoblast differentiation and acts synergistically with bone morphogenetic protein-2 in C3H10T1/2 cells

Interleukin-11 (IL-11) is a pleiotropic cytokine that supports various types of hematopoietic cell growth and is involved in bone resorption. We report here the involvement of recombinant human IL-11 (rHuIL-11) in osteoblast differentiation in mouse mesenchymal progenitor cells, C3H10T1/2. rHuIL-11 alone increased alkaline phosphatase (ALP) activity and upregulated expression levels of osteocalcin (OC), bone sialo protein (BSP), and parathyroid hormone receptor (PTHR) mRNA. rHuIL-11 had no effect on expression of type II collagen, peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2), adipocyte fatty acid-binding protein P2 (aP2), and myogenic MyoD protein (MyoD). Recombinant human bone morphogenetic protein (rHuBMP)-2 increased ALP activity and mRNA expression of these genes except for MyoD. The expression patterns of ALP activity and osteoblast-specific or chondrocyte-specific genes suggest that rHuIL-11 may be involved in early differentiation of osteoblasts at a step earlier than that which is affected by rHuBMP-2. In support of this hypothesis, combined treatment with rHuIL-11 and rHuBMP-2 synergistically increased ALP activity and mRNA expression of OC and type II collagen, rHuIL-11 also abrogated the increased levels of PPAR-gamma2, aP2 mRNA caused by rHuBMP-2. Our results suggest that rHuIL-11 alone and in combination with rHuBMP-2 can induce osteoblastic differentiation of progenitor cells and plays an important role in osteogenesis.

Oprelvekin (Neumega), first platelet growth factor for thrombocytopenia

Oprelvekin decreases the need for platelet transfusion in nontransplant patients receiving myelosuppressive chemotherapy. Until pharmacoeconomics studies determine the most cost-effective strategy for use of oprelvekin, it is likely to be used primarily in patients receiving dose-intensive chemotherapy to maintain the high-dose regimen that may provide a survival advantage for the patient with cancer. Additional product information is available at www.ahp.com/products/neumega.htm.

Interleukin-11 improves survival and reduces bacterial translocation and bone marrow suppression in burned mice

PURPOSE

Major burns are associated with a high mortality, an increased rate of bacterial translocation, and bone marrow suppression. This study evaluates the effect of interleukin-11 (IL-11), a bone marrow-derived growth factor on survival, intestinal cytoarchitecture, bacterial translocation, and bone marrow suppression in a highly lethal murine burn model with a lethal dose greater than 50.

METHODS

C3H/HeJ 8 to 10-week-old mice underwent a standardized 32% total body surface area (TBSA) scald burn using a burn template. Mice were divided equally between groups receiving IL-11 (125 micrograms/kg, twice daily, subcutaneously [SC]) and 0.1% same-volume Bovine Serum Albumin (BSA) (0.2 mL, twice daily, sc). Animals were evaluated for mesenteric lymph node bacterial counts, intestinal mucosal villus height, number of mucosal crypt cell mitoses per 100 crypts, and peripheral platelet and total lymphocyte counts. Survival was calculated to 7 days postburn.

RESULTS

At 24 hours postburn, IL-11-treated mice had significantly less enteric bacteria cultured from mesenteric lymph nodes (P < .001), increased intestinal crypt cell mitoses (P = .002) and intestinal villus height (P = .002), increased peripheral platelet (P = .002) and lymphocyte counts (P = .004), and an improved survival compared with BSA controls (P = .003).

CONCLUSION

These data show that IL-11 improves survival, intestinal cytoarchitecture, reduces bacterial translocation, and reduces bone marrow suppression after a 32% TBSA burn in mice. These data imply that IL-11 cytokine therapy may be a useful adjunct in extensive burn injury.

Murine interleukin-11 (IL-11) is expressed at high levels in the hippocampus and expression is developmentally regulated in the testis

IL-11, derived from a bone marrow stromal cell line, has pleiotropic effects on both hematopoietic cells and nonhematopoietic cells. However, no previous studies have systematically addressed expression of IL-11 in primary tissues in vivo and the relationship of IL-11 tissue specific gene expression and function of IL-11 is not clear. In the present study, we examined constitutive IL-11 expression in various murine adult tissues in vivo. IL-11 mRNA is expressed in a wide range of normal tissues (including hematopoietic organs) at levels only detected by RT-PCR. IL-11 protein was detected in brain and testis by Western blot analysis. The in vivo cellular distribution of IL-11 expression was examined by in situ hybridization. In brain, IL-11 message is distributed in granular layer dentate gyrus and pyramidal cell layers of hippocampus. IL-11 is also expressed in anterior horn cells and lateral column neuronal cells of the spinal cord. In testis, IL-11 mRNA is expressed in round spermatids at stage VI-IX seminiferous tubules. IL-11 expression in testis is restricted to developing spermatogonia and is developmentally regulated, since no expression is seen in mice genetically deficient in germ cells and in mice prior to sexual maturation. These expression data correlate with functional data demonstrating that IL-11 stimulates proliferation in vitro of a hippocampus neuronal progenitor cell line and administration of IL-11 in vivo accelerates recovery of spermatogenesis after cytotoxic therapy. These studies suggest that IL-11 may be an important regulator in neural and testicular function.