Amelioration of chemotherapy-induced thrombocytopenia by GM-CSF: apparent dose and schedule dependency

The role of platelet growth factors in cancer therapy

The use of myeloid growth factors has markedly reduced the complications of chemotherapy-induced neutropenia, however, abrogation of severe thrombocytopenia remains a major clinical problem. Platelet transfusions remain the standard method of preventing or treating thrombocytopenia but are associated with a variety of complications and are a limited resource. A number of cytokines have been clinically investigated for their thrombopoietic activity, the most promising of which is the recently cloned ligand to the hematopoietic growth factor receptor, c-Mpl. The c-Mpl ligand, also referred to as thrombopoietin, megakaryocyte growth and development factor (MGDF) and megapoietin, is a potent lineage-specific agent that promotes growth and maturation of megakaryocytes and their progenitors. It holds promise for clinical use in the treatment of iatrogenic or disease-associated bone marrow failure states and possibly in syndromes of excessive platelet consumption. Early clinical trials assessing the safety and activity of recombinant human MGDF are now underway.

Phase I trial of etoposide, carboplatin, and GM-CSF in extensive small-cell lung cancer: a Cancer and Leukemia Group B study (CALGB 8832)

The maximum tolerated dose (MTD) of etoposide and carboplatin without growth factor support was previously defined by Cancer and Leukemia Group B (CALGB) as 200 and 125 mg/m2/day x 3, respectively, given every 28 days to previously untreated patients who have extensive, small-cell lung cancer (SCLC). Myelosuppression was dose-limiting. The purpose of this phase I trial was to determine if granulocyte macrophage colony-stimulating factor (GM-CSF) support allows the dosage of the combination of etoposide and carboplatin to be increased above the previously determined MTD. In this CALGB study of 44 evaluable patients with performance status 0-2, cohorts were treated with etoposide and carboplatin given intravenously on days 1-3 followed by GM-CSF (molgramostim) given subcutaneously on days 4-18. Four dose levels of bacteria-derived recombinant GM-CSF (5, 10, 20 microg/kg/day and 5 microg/kg every 12 h), three dose levels of etoposide (200, 250, and 300 mg/m2/day x 3), and two dose levels of carboplatin (125 and 150 mg/m2/day x 3) were evaluated. There was no chemotherapy dose escalation in individual patients. With 5 microg/kg/d GM-CSF, the first etoposide and carboplatin cycle of 300 and 150 mg/m2/day x 3, respectively, could be administered with acceptable toxicity. However, GM-CSF did not allow repeated administration of this dose-escalated regimen every 21 days, since delayed platelet and/or neutrophil recovery was dose limiting in later cycles. These results demonstrate that GM-CSF alone has limited capability to support the repeated administration of high doses of etoposide and carboplatin. CALGB currently is testing the ability of interleukin (IL)-6 given with GM-CSF to ameliorate the cumulative myelosuppression of this intense regimen.

Continuous infusion or subcutaneous injection of granulocyte-macrophage colony-stimulating factor: increased efficacy and reduced toxicity when given subcutaneously

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a haematopoietic growth factor with a wide variety of applications in the clinic. In early phase I studies the continuous intravenous (c.i.) route of administration was often used. Later it was shown that subcutaneous (s.c.) administration was also effective. The optimal route of administration remains, however, poorly defined, and no studies have made a direct comparison between these two routes of administration. We treated patients with advanced breast cancer with moderately high-dose doxorubicin and cylophosphamide and GM-CSF. The first 14 patients received GM-CSF by c.i, while subsequently 47 patients received it s.c. Comparison between the two groups showed that c.i. GM-CSF was more toxic in several respects. There was a higher need for erythrocyte and platelet transfusions and a significant deterioration in the performance status. This study indicates that subcutaneous GM-CSF is the preferred route of administration. Randomised trials are, however, needed to confirm these conclusions.

Effects of interleukin-3 following chemotherapy of non-Hodgkin's lymphoma. A prospective, controlled phase I/II study

The effect of rhIL-3 was investigated in 32 patients with newly diagnosed non-Hodgkin lymphoma in a phase I/II trial. All patients received 6 cycles of standard CHOP chemotherapy, and each patient was his own control where rhIL-3 was given as a daily s.c. injection for 14 days (day 2-15) in cycle 2 and 4, while cycle 1 and 3 were control cycles. Five dose levels were examined (0.5 - 1 - 5 - 7.5 - 10 micrograms/kg). Compared to the other more lineage-specific hemopoietic growth factors G- and GM-CSF, the effect of rhIL-3 on the hemopoiesis was less dramatic and more delayed, i.e. the most apparent effect was observed in the 2 weeks of treatment. Thus, the neutrophil counts from days 15 to 22 following CHOP were significantly raised and the duration of neutropenia was shorter (significantly only at 10 micrograms/kg), while the nadir values were unaffected. Platelet recovery from days 12-22 was significantly increased and nadir values occurred earlier compared to control cycles, but were only increased in some subsets. Other cell populations affected moderately in the recovery period were eosinophils and monocytes. Reticulocytes increased, but no effect on hemoglobin or RBC transfusion requirement was noted. Only moderate adverse reactions occurred such as fever, chills, flushing of the face and flu-like symptoms. There was no evidence of stimulation of tumor growth. Most significant, the rhIL-3 treatment at all but the lowest dose levels led to an improved tolerance to chemotherapy, as indicated by a decline in number of delayed cycles. A conclusion concerning the role of rhIL-3 as post-chemotherapy adjuvant should await studies using rhIL-3 in combination with more lineage-restricted hemopoietic growth factors.

Hemopoietic growth and inhibitory factors in treatment of malignancies. A review

The clinical use of cytokines is still expanding as the knowledge of beneficial effects as adjunct to cancer treatment is increasing. G-CSF and GM-CSF stimulates hemopoietic recovery after myelosuppressive chemotherapy and enhances engraftment after bone marrow transplantation. New cytokines as IL-1, IL-3, IL-4 and IL-6, are studied in clinical trials and combinations of these with stem cell factor seem promising in ex vivo expansion of stem cells. GM-CSF also have antitumor effects. The most recently discovered hemopoietic growth factor is thrombopoietin, from which probably especially patients with leukemia will benefit.

rhGM-CSF ameliorates neutropenia in patients with malignant glioma treated with BCNU

Nitrosoureas are the drugs most effective in the treatment of patients with intracerebral malignant glioma. Their limiting toxicity is delayed myelosuppression. A prospective, randomised crossover study of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) was performed in patients receiving BCNU for relapsed glioblastoma, to investigate whether the resulting haematological toxicity profile could be modified by rhGM-CSF. Adequate data for analysis were obtained in 13 patients. Following BCNU, the nadir neutrophil count was higher in 12 out of 13 patients during the rhGM-CSF-protected cycles compared with the unprotected cycles. The median nadir was also significantly higher (1.79, CI 0.76-3.52, P < 0.005). Five episodes of neutropenia (< 2 x 10(9) l-1) occurred during the unprotected cycles compared with none in the rhGM-CSF-protected cycles (P = 0.076). There was no evidence of any effect on platelets. This result shows that the haematological toxicity profile following therapeutic doses of BCNU can be modified. It suggests that rhGM-CSF and other growth factors should be investigated for clinical efficacy in chemotherapy using nitrosoureas.

GM-CSF, carboplatin, doxorubicin: a phase I study

Dose intensification has the potential to increase the response frequency of chemosensitive tumors to chemotherapy. G-CSF and GM-CSF offer the possibility of dose-intensifying chemotherapy without prohibitive myelosuppression. A phase I study was undertaken to identify the maximum tolerated dose (MTD) of carboplatin that could be administered with a fixed dose of doxorubicin, 60 mg/m2, administered every 28 days. Further escalation of the carboplatin dose was then attempted, with the concomitant addition of GM-CSF 10 mg/kg per day on days 1-21. We had 21 patients, 13 with prior therapy, who were eligible. In all, 60 courses of therapy were delivered, all with doxorubicin and with carboplatin doses of 250 mg/m2, 325 mg/m2 and 400 mg/m2. At carboplatin 400 mg/m2 and doxorubicin 60 mg/m2, thrombocytopenia was dose limiting. The addition of GM-CSF did not allow further escalation. Of the 6 patients treated with carboplatin 400 mg/m2, doxorubicin 60 mg/m2, and GM-CSF, grade 4 granulocytopenia and thrombocytopenia were seen in 4 and 5 patients, respectively. The severity of thrombocytopenia was related to the calculated carboplatin AUC and also to baseline platelet count and prior therapy. In addition, the interaction of GM-CSF and chemotherapy, especially carboplatin-based, may be more complex than originally anticipated.

Failure of granulocyte-macrophage colony-stimulating factor to reduce febrile neutropenia in children with recurrent solid tumors treated with ifosfamide, carboplatin, and etoposide chemotherapy

Ifosfamide, carboplatin, and etoposide (ICE) chemotherapy has promising activity against various solid tumors but produces significant myelotoxicity that might be ameliorated by hematopoietic growth factors. Twelve patients with relapsed solid tumors were treated with ICE chemotherapy. Carboplatin was given on day 1 at a targeted area under the concentration-time curve (AUC) of 8 mg/mL x min (adjusted for each patient's glomerular filtration rate), followed by ifosfamide 2 g/m2 and etoposide 100 mg/m2 on days 2 through 4. Granulocyte-macrophage colony-stimulating factor (GM-CSF), 1,000 micrograms/m2/day, was started 24 hours after each course and given for 17 days or until the absolute neutrophil count (ANC) reached 10 x 10(9)/L. Myelotoxicity and responses in these patients were compared to those of eight patients who received the same therapy without GM-CSF. Patients received a median of three courses (range, 1-8). All 20 patients developed grade 4 neutropenia and grade 3 or 4 thrombocytopenia. The median duration of neutropenia was significantly shorter in patients who received GM-CSF (16.75 vs. 10 days, P = 0.005). However, the two groups did not differ in the proportion of courses associated with hospitalization for febrile neutropenia, the duration of hospitalization, or the median duration of thrombocytopenia. There were two complete, four partial, and three objective responses in the 12 patients treated with ICE plus GM-CSF, and two partial and three objective responses in the 8 patients treated with ICE only. GM-CSF did not reduce the occurrence of febrile neutropenia or the duration of thrombocytopenia associated with ICE chemotherapy. Studies of other hematopoietic growth factors in conjunction with this promising combination are merited.

Growth factors of the future

Hematopoietic growth factors stimulate proliferation and enhance functional activity of hematopoietic cells. Erythropoietin, recombinant human (rh) granulocyte colony stimulating factor (CSF), rh granulocyte macrophage CSF and rh interferon have been proven to be a clinically useful therapy. Several other cytokines with other unique effects are being developed for possible clinical usage. The purpose of this manuscript is to review novel uses of current approved cytokines and potential application of experimental growth factors.

Colony-stimulating factors: a new step in clinical practice. Part I

Haematopoietic colony stimulating factors (CSFs) stimulate the proliferation, differentiation and functional activity of myelocytes. Since approval of the use of these factors in patients with chemotherapy-induced neutropenia, patients undergoing autologous bone marrow transplantation (BMT) and patients with delayed engraftment after BMT, several other potential clinical uses have been described. Current and potential future clinical applications of CSFs will be reviewed.

Granulocyte-macrophage colony-stimulating factor. Preliminary observations on the influences of dose, schedule, and route of administration in patients receiving cyclophosphamide and carboplatin

BACKGROUND

In an attempt to learn how best to administer granulocyte-macrophage colony-stimulating factor (GMCSF), the authors performed a Phase I study of this agent. They were interested in the influences of dose, schedule, and route of administration on the effects of GMCSF in patients receiving standardized 1-day regimens of cyclophosphamide (CYCLO) and carboplatin (CBDCA).

METHODS

Between June 1988 and March 1991, 57 patients with advanced cancer received GMCSF in association with CYCLO 1 g/m2 plus CBDCA 225-700 mg/m2. After the first dose escalation to 300 mg/m2 of CBDCA, patients who had previously received chemotherapy or radiation therapy were excluded. GMCSF was administered in three different doses, five different schedules, and by two different routes. Altogether, 17 different treatment groups were observed. In addition, 24-hour GMCSF serum concentration curves were charted in four patients.

RESULTS

Using four sequential groups of three patients each who had received myelosuppressive treatment, treatment with CYCLO 1 g/m2 and CBDCA 225 mg/m2, the apparent superiority of daily subcutaneous injection over 30-minute daily IV infusion of GMCSF was demonstrated graphically. Subsequently, the authors observed apparent enhancement of GMCSF effects beyond those produced by the initially selected 20-day basic 10 micrograms/kg daily SC regimen beginning 2 days after chemotherapy. When administered SC every 12 hours for 14 days beginning the day after chemotherapy, GMCSF appeared to ameliorate the severity of both leukopenia and thrombocytopenia. These effects permitted escalation of the CBDCA dose to 700 mg/m2 (with 1 g/m2 of CYCLO) before cytotoxic tolerance limits were reached. Graphic small group comparisons suggest that GMCSF given SC in doses of 5 micrograms/kg twice daily may produce comparable leukocyte and platelet support after chemotherapy with lower toxicity than occurs from higher doses. Prechemotherapy priming with GMCSF twice daily for an additional 4 days (days -6 to -3) seems to ameliorate postchemotherapy cytopenias further but at the cose of some increased risk of GMCSF toxicity. Although most of the toxic effects of moderate-dose GMCSF are controlled by antihistamines and ibuprofen, oral glucocorticoids (e.g., prednisone, 10 mg twice daily during the second week of GMCSF administration) may be required in patients with serositis, pulmonary infiltrates, or severe skin eruptions.

CONCLUSIONS

Our observations suggest that GMCSF should be administered SC in doses of approximately 5 micrograms/kg every 12 hours for 10-14 days beginning the day after chemotherapy. Prechemotherapy priming with these same doses for four additional days (days -6 to -3) may additionally ameliorate postchemotherapy leukopenia and thrombocytopenia, but with increased risk of toxicity.

The biology of granulocyte-macrophage colony-stimulating factor: effects on hematopoietic and nonhematopoietic cells

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is one of a family of glycoprotein cytokines that have potent effects in stimulating the proliferation, maturation, and function of hematopoietic cells. Deriving its name from its ability to stimulate the formation of macroscopic colonies containing neutrophils, eosinophils, macrophages, or mixtures of these cell types, GM-CSF stimulates the proliferation and maturation of myeloid progenitors, as well as functionally activating mature neutrophils, eosinophils, and macrophages. As most of the effects observed using GM-CSF in vitro have been shown to occur in vivo either in animal models or in human subjects, it is important to consider that GM-CSF may also exert some biological effects on nonhematopoietic cells. In response to immunologic stimuli, immunologic surveillance cells and cells of the microenvironment are capable of producing GM-CSF. In vitro experiments indicate that GM-CSF production is tightly regulated. In that regard, GM-CSF is not present in measurable quantities in normal serum, but little is known about the in vivo process of GM-CSF production and regulation. The biologic capabilities of GM-CSF have triggered its widespread clinical use in situations where hematopoiesis is compromised. GM-CSF can act as a potent growth factor in vivo, increasing the number and enhancing the function of hematopoietic progenitors and mature cells. However, the precise in vivo effect that GM-CSF may have on normal and neoplastic cells of nonhematopoietic origin remains undefined. The full range of GM-CSF bioactivity is mediated following binding to its receptor. The presence of specific receptors for GM-CSF has been demonstrated in all responsive cells of hematopoietic lineage, as well as in nonhematopoietic cells, both responsive and unresponsive. In conclusion, a large body of work from a number of laboratories has defined the biology of GM-CSF. Currently available reagents and technology will provide additional insights into the biology of this molecule, thereby expanding our present definition and allowing us to explore the mechanisms regulating hematopoiesis.

A phase I/II study of dose and administration of non-glycosylated bacterially synthesized G-M CSF in chemotherapy-induced neutropenia in patients with non-Hodgkin's lymphomas

Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) derived from E. coli was administered to 24 previously untreated patients with non-Hodgkin's lymphoma following the first cycle of CHOP chemotherapy. Four dose levels were examined, 1.5, 3.0, 5.5 and 11 micrograms/kg and patients were randomized to receive the drug either once or twice daily subcutaneously (s.c.). During rhGM-CSF treatment, the leucocyte counts increased up to 3-4 fold in 20/24 patients, reaching a peak 24-48 (mean 35) hours after initiation of rhGM-CSF. The leukopenic period in cycle one of the CHOP chemotherapy with rhGM-CSF, was shorter than after the course of chemotherapy without rhGM-CSF and also shorter when compared to cycle one of CHOP in the 127 historical controls (p < 0.05 and p < 0.001 respectively). Similar results were observed for neutrophil counts. No effect was seen on platelet counts at nadir but a significant, although moderate increase occurred in the recovery period on days 15 and 22 when compared to control cycles and historical controls. When dose levels were compared, there was only a trend to higher WBC counts at the higher dose groups (5.5 and 11 micrograms/kg) when compared to the two lower dose groups (1.5 and 3.0 micrograms/kg). In the overall evaluation there was no statistical significant difference in results between patients treated s.c. once daily versus twice daily. However when only the two highest dose levels (5.5 + 11 micrograms/kg) were compared, s.c. administration of rhGM-CSF twice daily led to higher leucocyte counts than once daily in the recovery period on day 15 (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Infection risk in patients with small cell lung cancer receiving intensive chemotherapy and recombinant human granulocyte-macrophage colony-stimulating factor

The effect of recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) was assessed in 17 patients with small cell lung cancer. GM-CSF was initially given alone by subcutaneous injection for 10 days at 50-500 micrograms/m2 per day. There was a significant rise in neutrophils and eosinophils and to a lesser extent in monocytes at all dose levels. During the next phase, patients received chemotherapy (etoposide, ifosfamide and doxorubicin), and GM-CSF was given on alternate cycles, the patients acting as their own controls, so that the amelioration of chemotherapy could be assessed. Despite partial abrogation of the neutropenia associated with chemotherapy (P = 0.04), GM-CSF failed to reduce the frequency of febrile episodes in association with neutropenia, with six episodes occurring on GM-CSF and seven while patients were not receiving GM-CSF after a total of 66 cycles of chemotherapy. After GM-CSF, there was a reduction in polymorph phagocytic ability and chemotaxis in 6/12 and 9/11 patients, respectively. Timed blood counts after GM-CSF administration showed that peak leucocytosis occurred at 8-12 h and fell to two-thirds of this level at 24 h. Toxicity consisting of lethargy, myalgia and bone pain occurred at all dose levels but was manageable. 2 patients had thromboembolism. This study failed to demonstrate a reduction in the infection risk associated with moderately intensive chemotherapy for small cell lung cancer despite the partial abrogation of neutropenia.

Use of GM-CSF in children after high-dose chemotherapy

The toxicity and efficacy of recombinant human granulocyte-macrophage colony-stimulating factor (rhuGM-CSF) is established in adults, but limited information is available on its use in children. The profound myelotoxicity induced by cisplatin (40 mg/m2 daily x 5) and etoposide (150 mg/m2 daily x 3) provides a model to test the clinical value of recombinant human granulocyte-macrophage colony-stimulating factor in pediatric cancer patients; myelosuppression occurred (absolute neutrophil count [ANC] < 500/microL) during 99 of 118 (84%) courses given to 44 children with refractory solid tumors. Fifty-nine courses (50%) resulted in hospitalizations for fever. Subsequently, rhuGM-CSF was added to this treatment regimen to: (i) determine the dose-limiting toxicity of this agent in children; and (ii) to determine whether it can decrease the duration and severity of neurtropenia and attendant complications. Here we summarize and update our experience with this glycoprotein in children with relapsed solid tumors.

Doxorubicin plus ifosfamide with rhGM-CSF in the treatment of advanced adult soft-tissue sarcomas: preliminary results of a phase II study from the EORTC Soft-Tissue and Bone Sarcoma Group

Doxorubicin and ifosfamide are the two most active agents used in the treatment of advanced inoperable soft-tissue sarcoma, but their use in combination produces dose-limiting myelosuppression. To explore the feasibility of combining optimal doses of both drugs, doxorubicin (75 mg/m2) and ifosfamide (5 g/m2) were given every 3 weeks with recombinant human granulocyte/macrophage-colony-stimulating factor (rhGM-CSF; 250 micrograms m-2 day-1) by subcutaneous injection for up to 14 days after each course. A total of 52 patients with progressive metastatic soft-tissue sarcoma were entered, none having received prior chemotherapy. One patient was ineligible and received no treatment after registration. Preliminary analysis of six cycles of chemotherapy revealed that the full protocol dose intensity had been administered to the majority of patients. Although the median leucocyte and neutrophil counts did not fall with subsequent courses of chemotherapy, the duration of neutropenia increased with each course delivered. Cumulative thrombocytopenia was a major dose-limiting toxicity and was the main reason for any dose modifications that occurred. Although 26 patients experienced infections after one or more courses of treatment, in only 7 was admission required for parenteral antibiotics. One patient died as a result of septicaemia after the first cycle of treatment. To date, there have been 22 responses (43%) with 8% complete remissions. It appears that the administration of rhGM-CSF allows this high-dose regime of chemotherapy to be given safely and the early encouraging response rate adds support to the concept that increasing the dose of doxorubicin improves the outlook for patients with advanced soft-tissue sarcomas.

Differential dose-related haematological effects of GM-CSF in pancytopenia: evidence supporting the advantage of low- over high-dose administration in selected patients

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a multifunctional haematopoietin which can promote production of several blood cell lineages, though the predominant target cells are neutrophils, monocytes, and their precursors. Occasional undesirable clinical effects include eosinophilia, an increase in blasts, or thrombocytopenia. Here, we describe four patients who were treated with GM-CSF, at subcutaneous doses significantly lower than are conventional, and experienced an unusual response pattern. Three patients had severe pancytopenia associated with chronic lymphocytic leukaemia (CLL) or myelodysplastic syndrome (MDS) and exhibited an unexpected switch in the responsive lineage on high- versus very low-dose therapy. The two CLL patients developed marked eosinophilia (up to 10.0 x 10(9) cells/l) without an increase in neutrophils on 125-300 micrograms/m2/d of GM-CSF. In contrast, when the dose was lowered to 10 micrograms/m2/d, the neutrophils rose to physiological levels, without significant eosinophilia. The MDS patient showed a rapid rise in peripheral blasts (baseline level = 0; post-therapy level = 5.0 x 10(9)/l), without a change in other cell types, when receiving 60 micrograms/m2/d of GM-CSF. After GM-CSF was held, blasts returned to baseline levels; reinstituting therapy at the very low dose of 6 micrograms/m2/d was followed by an increase in platelet counts from 50 to 185 x 10(9)/l with only a minor increase in blasts. The fourth patient, who suffered from severe aplastic anaemia complicated by recurrent gastrointestinal haemorrhage, was only treated with the low-dose regimen. He showed a predominant platelet effect with counts rising from 9 to 169 x 10(9)/l. Very low-dose GM-CSF therapy was devoid of constitutional side effects. The biological implications of these GM-CSF responses are discussed. Our results indicate that, in some patients, GM-CSF may stimulate different target cells depending on the dose. Therefore, in contrast to the results of administration of many classical drugs, there may not always be a direct relationship between the amount of GM-CSF given and the optimal effect.

Clinical use of biologic response modifiers in cancer treatment: an overview. Part II. Colony-stimulating factors and interleukin-2

Colony-stimulating factors (CSFs) are hematopoietic growth hormones that stimulate the production, maturation, and function of white blood cells. The best studied are granulocyte-macrophage CSF (GM-CSF) and granulocyte CSF (G-CSF), both of which can be produced by recombinant DNA technology. Clinical indications for these agents include bone marrow failure secondary to administration of chemotherapeutic drugs or radiation, bone marrow transplantation, and a variety of congenital or iatrogenic neutropenias. Toxicity in usual clinical doses is mild, and consists mainly of bone pain and constitutional symptoms such as fever, headache, and myalgias. Interleukin-2 (IL-2) is a lymphokine that stimulates that multiplication of several types of killer cells. These cells can recognize and destroy foreign substances, such as tumors, without destroying normal cells. Major applications of IL-2 include treatment of patients with renal cell carcinoma, in whom the overall objective response rate is 15-30 percent, and malignant melanoma with response rates of about 18 percent. Combination therapy with other biologics and conventional cytotoxic drugs may increase IL-2's efficacy against these tumors. Toxicity is generally severe, but reversible. Hemodynamic toxicity, consisting of hypotension, edema, weight gain, and decreased renal function, is most characteristic. Suggestions are given for pharmacologic management of these and other IL-2 toxicities.