Tagraxofusp: First Global Approval.

Tagraxofusp (tagraxofusp-erzs) [Elzonris™] is an intravenously administered CD123-directed cytotoxin (composed of human interleukin-3 and a truncated diphtheria toxin payload) that was developed by Stemline Therapeutics, Inc. for the treatment of blastic plasmacytoid dendritic cell neoplasm (BPDCN). In December 2018, tagraxofusp received its first global approval in the USA for the treatment of BPDCN in adults and in paediatric patients aged 2 years and older. A centralized registration application for the use of tagraxofusp in patients with BPDCN is under review in the EU. This article summarizes the milestones in the development of tagraxofusp leading to its first global approval for the treatment of BPDCN.

Activity of SL-401, a targeted therapy directed to interleukin-3 receptor, in blastic plasmacytoid dendritic cell neoplasm patients.

This is the first prospective study of treatment of patients with blastic plasmacytoid dendritic cell neoplasm (BPDCN), an aggressive hematologic malignancy derived from plasmacytoid dendritic cells that typically involves the skin and rapidly progresses to a leukemia phase. Despite being initially responsive to intensive combination chemotherapy, most patients relapse and succumb to their disease. Because BPDCN blasts overexpress the interleukin-3 receptor (IL3R), the activity of SL-401, diptheria toxin (DT)388IL3 composed of the catalytic and translocation domains of DT fused to IL3, was evaluated in BPDCN patients in a phase 1-2 study. Eleven patients were treated with a single course of SL-401 at 12.5 µg/kg intravenously over 15 minutes daily for up to 5 doses; 3 patients who had initial responses to SL-401 received a second course in relapse. The most common adverse events including fever, chills, hypotension, edema, hypoalbuminemia, thrombocytopenia, and transaminasemia were transient. Seven of 9 evaluable (78%) BPDCN patients had major responses including 5 complete responses and 2 partial responses after a single course of SL-401. The median duration of responses was 5 months (range, 1-20+ months). Further studies of SL-401 in BPDCN including those involving multiple sequential courses, alternate schedules, and combinations with other therapeutics are warranted. This trial is registered at clinicaltrials.gov as #NCT00397579.

Characterization of variant diphtheria toxin-interleukin-3 fusion protein, DTIL3K116W, for phase I clinical trials.

We have produced clinical grade of DTIL3K116W, a variant diphtheria toxin-interleukin-3 fusion protein, for treatment of acute myeloid leukemia. The product was filter sterilized, aseptically vialed, and stored at -80 degrees C. It was characterized by Coomassie-stained SDS-PAGE, endotoxin assay, cytotoxicity assay, sterility, mass spectroscopy, receptor binding affinity, ADP-ribosylation, inhibition of normal human CFU-GM, disulfide bond analysis, immunoblots, stability, size exclusion chromatography-HPLC, sequencing, and immunohistochemistry. Vialed product was sterile in 0.25 M NaCl/5 mM Tris, pH 7.9, and had a protein concentration of 1.08 mg/ml. Purity by SDS-PAGE was >99%. Aggregates by HPLC were <1%. Endotoxin levels were 0.296EU/mg. Peptide mapping and mass spectroscopy confirmed its composition and molecular weight. The vialed drug kept reactivity with anti-IL3 and DT antibodies. Potency study revealed a 48-h EC(50) of 0.5 pM on TF1/H-ras cell. Its binding properties were confirmed by competitive experiments showing IC(50) of 1.4 nM. ADP-ribosylation activity was equivalent to DTGM-CSF. Drug did not react with tested frozen human tissue sections by immunohistochemistry. There was no evidence of loss of solubility, proteolysis aggregation, or loss of potency over 6 months at -80 degrees C. Further, the drug was stable at 4 and 25 degrees C in the plastic syringe and administration tubing for 48 h.

Low-dose cytosine arabinoside (LD-AraC) vs LD-AraC plus granulocyte/macrophage colony stimulating factor vs LD-AraC plus Interleukin-3 for myelodysplastic syndrome patients with a high risk of developing acute leukemia: final results of a randomized phase III study (06903) of the EORTC Leukemia Cooperative Group.

In this randomized phase III study of the EORTC Leukemia Cooperative Group, patients with myelodysplastic syndromes (MDS) with 10-30% bone marrow blasts and hematopoietic failure were treated with low-dose cytosine arabinoside (LD-AraC) (2 x 10 mg/m2/day subcutaneously (s.c.) days 1-14) either alone or in combination with rhGM-CSF or interleukin-3 (IL-3) both given s.c. at a dose of 150 microg/day from day 8 to 21. A total of 180 evaluable patients with a median age of 65 years and refractory anemia with an excess of blasts (RAEB, n = 107) or RAEB in transformation (RAEBt, n = 73) were randomized. There were no differences among the three treatment regimens with respect to numbers of courses applied or treatment delays. Hemorrhage occurred in approximately 40% in all arms, whereas infection rates were higher in the granulocyte/macrophage colony stimulating factor (GM-CSF)- or IL3-containing arm. The overall response rate was 38.6% with no statistically significant difference among the three arms. In summary, a substantial proportion of patients had achieved relatively durable responses in all the three arms. No influence of either growth factor was detected on the grade of cytopenia. Thus, the combination of LD-AraC with GM-CSF or IL-3 cannot be recommended for routine use in a high-risk MDS population.

Sequential interleukin 3 and granulocyte-macrophage-colony stimulating factor therapy in patients with bone marrow failure with long-term follow-up of responses.

BACKGROUND: Interleukin-3 (IL-3) and granulocyte-macrophage-colony stimulating factor (GM-CSF) have synergistic, hematopoietic growth-promoting activity in preclinical studies. Because of the paucity of effective therapies for patients with chronic bone marrow failure states, the authors studied the biologic activity of sequential IL-3/GM-CSF in such patients. METHODS: IL-3 was given subcutaneously for 5 days (at escalating doses of 0.15 microg/kg, 0.3 microg/kg, 0.6 microg/kg, 1.2 microg/kg, 2.5 microg/kg, 5.0 microg/kg, 10.0 microg/kg, or 15.0 microg/kg per day), and GM-CSF for was given subcutaneously for 9 days (at a dose of 5 microg/kg per day; Phase I 3 + 3 design) followed by 14 days of rest (total, 2 courses), then maintenance therapy. RESULTS: The majority of 38 evaluable patients had aplastic anemia or myelodysplastic syndrome. Most patients (79%) had neutrophil responses. Ten patients (26%), all of whom were treated with IL-3 doses >/= 1.2 microg/kg per day, had platelet responses, with a median increase of 132 x 10(9)/L (range, 41-180 x 10(9)/L) over baseline in responders. Six patients (16%) had trilineage recovery, which could be durable (the longest ongoing at 6.5 years after therapy completion). The most common toxicities were low-grade fever, headache, and fatigue. The maximum tolerated doses were IL-3 at 10 microg/kg per day and GM-CSF at 5 microg/kg per day. CONCLUSIONS: Sequential IL-3/GM-CSF effectively raised blood counts in some patients with bone marrow failure at doses that were tolerated well. These results indicate that early-acting growth factors can induce durable, multilineage responses in a subset of individuals with bone marrow failure.

Recombinant human interleukin-3 administered concomitantly with chemotherapy in patients with relapsed small cell lung cancer.

Although recombinant human interleukin-3 (rhIL-3) shortens both the duration of chemotherapy-induced neutropenia and thrombocytopenia, its effect on nadir counts is limited. Concurrent administration of rhIL-3 and chemotherapy may enhance this effect. However, simultaneous administration of other hematopoietic growth factors and chemotherapy has resulted in enhanced myelosuppression. We investigated whether concomitant administration of rhIL-3 and chemotherapy would result in enhanced myelosuppression. Twelve patients with relapsed small cell lung cancer received vincristine, ifosfamide, mesna, and carboplatin on day 1 every four weeks. RhIL-3 was administered subcutaneously on days 1-14 during cycle 1 at doses of 4 (three patients) or 8 micrograms/kg/day (nine patients). During cycle 2 patients received only chemotherapy. No significant difference in leukocyte (1.4 +/- 1.0 vs. 0.9 +/- 0.4 x 10(9)/l (mean +/- SD), neutrophil (0.5 +/- 0.6 vs. 0.2 +/- 0.2 x 10(9)/l), and platelet (64 +/- 60 vs. 38 +/- 58 x 10(9)/l) nadir counts were demonstrated. The hemoglobin nadir level was significantly higher during cycle 1 (6.5 +/- 1.1 vs. 5.5 +/- 0.9 mmol/l, P = 0.05). Both leukocyte and platelet recovery were significantly enhanced in the rhIL-3 cycle. There was no significant difference in chemotherapy postponement or platelet transfusions. As a result of severe headaches, rhIL-3 administration was discontinued in one patient at 8 micrograms. RhIL-3 during this chemotherapy regimen for relapsed small cell lung cancer did not enhance myelotoxicity but did improve bone marrow recovery. This observation may increase the application of rhIL-3, for instance in combination with other hematopoietic growth factors.

Comparative effects of three cytokine regimens after high-dose cyclophosphamide: granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor (GM-CSF), and sequential interleukin-3 and GM-CSF.

PURPOSE: To compare the toxicity and effects on hematologic recovery and circulating progenitor cell mobilization of three cytokine regimens administered after high-dose cyclophosphamide (HD-CTX; 6 g/m(2)), given as the first step of a high-dose sequential chemotherapy. PATIENTS AND METHODS: Forty-eight patients with breast cancer or non-Hodgkin's lymphoma were randomized to receive granulocyte colony-stimulating factor (G-CSF) alone (arm 1), granulocyte-macrophage colony-stimulating factor (GM-CSF) alone (arm 2), or sequential interleukin-3 (IL-3) and GM-CSF (arm 3). Cytokines were administered as a single daily subcutaneous injection at a dose of 5 to 6 microg/kg/d. Progenitor cells were evaluated in peripheral blood as well as in apheretic product as both CD34(+) cells and granulocyte-macrophage colony-forming units (CFU-GM). RESULTS: Neutrophil recovery was faster in arm 1 as compared with arms 2 and 3 (P <.0001); no significant differences were observed between arms 2 and 3. In arm 3, a moderate acceleration of platelet recovery was observed, but it was statistically significant only as compared with arm 1 (P =.028). The peak of CD34(+) cells was hastened in a median of 2 days in arm 1 compared with arms 2 and 3 (P =.0002), whereas the median peak value of CD34(+) cells and CFU-GM was similar in the three patient groups. Administration of IL-3 and GM-CSF resulted in more significant toxicity requiring pharmacologic treatment in 90% of patients. CONCLUSION: The three cytokine regimens administered after HD-CTX are comparably effective in reducing hematologic toxicity and mobilizing the hematopoietic progenitor cells. G-CSF accelerates leukocyte recovery and progenitor mobilization. Although G-CSF-treated patients have somewhat slower platelet recovery, they definitely have fewer side effects.

Phase II clinical study on the effects of recombinant human interleukin-3 on thrombocytopenia after chemotherapy for advanced ovarian cancer. SDZ ILE 964 [IL-3] Study Group.

The efficacy, safety, and optimum clinical dose of recombinant human interleukin-3 (rhIL-3) was examined in ovarian cancer patients with thrombocytopenia after cancer chemotherapy. In cases with a platelet count < 75,000/mm3 during the control observation period, rhIL-3 was administered subcutaneously at a dose of 5 or 10 micrograms/kg, once a day for 10 days starting from day 4 of the subsequent chemotherapy course. Comparison between the control observation period and the rhIL-3 administration period showed a significant improvement or a tendency toward improvement in increasing the nadir platelet count and the recovery of the platelet count. The major adverse reactions were pyrexia, fatigue, and headache, which were well controlled by the use of antipyretics, analgesics, and antiinflammatory agents. Adverse reactions were for the most part transient and disappeared quickly during or after rhIL-3 administration. Although severe adverse reactions were not observed, the incidence of grade 2 and 3 adverse reactions according to a World Health Organization (WHO) Toxicity Scale were slightly higher in the 10 micrograms/kg/d group. As a consequence, the 5 micrograms/kg/d dose was considered to have a slightly better safety profile than the 10 micrograms/kg/d dose. Although there was no significant difference in the efficacy (the platelet count) between the two doses, the safety profile of the 5 micrograms/kg/d dose was slightly better than the 10 micrograms/kg/d group. Therefore, the 5 micrograms/kg/d was considered to be the optimum clinical dose.

Interleukin-3 in hematology and oncology: current state of knowledge and future directions.

Interleukin (IL)-3 is a multipotent hematopoietic growth factor produced by activated T cells, monocytes/macrophages and stroma cells. The human IL-3 gene is located on chromosome 5 near segment 5q31. The high-affinity receptor for human IL-3 is composed of alpha and beta subunits. IL-3 shares a common beta subunit with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-5; this subunit has been mapped to chromosome 22q13.1. The biological effects of IL-3 have been studied in human and murine hematopoietic cell lines and normal human marrow cells. Addition of IL-3 to the culture medium induces proliferation, maturation and probably self-renewal of pluripotent hematopoietic stem cells and cells of myeloid, erythroid and megakaryocytic lineages. Human IL-3 was cloned in 1986, and since then various clinical trials have assessed the in vivo potential of recombinant human (rhIL-3). Initial results of phase I/II studies of IL-3 at a dose of 5-10 microg/kg subcutaneously daily for 5-10 days in patients with relapsed lymphomas, small-cell lung cancer, breast cancer and ovarian cancer showed that post-chemotherapy application of IL-3 reduces chemotherapy delays and induces faster regeneration of granulocytes and platelets. However, these results were not confirmed in phase III studies. The role of IL-3 alone in the treatment of myelodysplastic syndromes (MDS), aplastic anemia (AA) and other bone marrow failure disorders have also been disappointing. However, preliminary studies of IL-3 in combination with chemotherapeutic agents and immunosuppression have demonstrated encouraging results in patients with MDS and AA respectively. The therapeutic potential of IL-3 in peripheral blood stem cell (PBSC) harvesting and priming of stem cells before harvest is beginning to be identified. Initial results of IL-3 combination with GM-CSF or later-acting growth factors such as granulocyte colony-stimulating factor (G-CSF) have yielded larger amounts of PBSC during harvesting. In recent years, the availability of synthetic IL-3 receptor (IL-3R) agonists and similar chimeric molecules with greater in vitro biological activity and fewer inflammatory side-effects has extended our options to employ and compare these molecules and rhIL-3 for the prevention of chemotherapy-induced myelosuppression. The role of IL-3 and IL-3R agonists in ex vivo expansion of stem cells, dendritic cell development and gene transfer requires further evaluation. It appears that future application of IL-3 in combination with other cytokines is an attractive way forward in the prevention of treatment-related mortality and morbidity in oncology patients. It also shows prospects for the development of new therapeutic strategies for dose escalation and immune modulation for cancer patients with relapsed and resistant disease.

[Efficiency, safety and tolerability of recombinant human interleukin-3 (rhIL-3) as supportive therapy accompanying dose-intensive carboplatin containing chemotherapy in ovarian cancer with special regard to thrombocytopenia]. / Effizienz, Sicherheit und Verträglichkeit von rekombinantem humanen Interleukin-3 (rhIL-3) als supportive Therapie begleitend zur dosisintensivierten Carboplatin-haltigen Chemotherapie bei Patientinnen mit Ovarialkarzinom unter besonderer Berücksichtigung der Thrombozytopenie.

OBJECTIVE: In a prospective, randomized, placebo-controlled double-blind trial we evaluated to what extent a dose-intensification of adjuvant chemotherapy is possible with the help of Interleukin-3 (rhIL-3). MATERIAL AND METHODS: Following initial surgery, 12 patients with primary ovarian cancer have been treated with Carboplatin and Cyclophosphamide (dosage: AUC 4 according to Calvert). After randomisation, a group of 6 patients prophylacticly received rhIL-3 against myelosuppression on days 3-12 of the cycle, in contrast to a group of 6 patients who received placebo-injections. RESULTS: The patients treated with rhIL-3 showed less hematologic side-effects. Adherence to 4-weekly chemotherapy courses was more frequent in the rhIL-3-group (73% vs. 44%, p = 0.005). An intensification of the chemotherapy with 3-weekly courses did not succeed significantly. Observed side-effects of rhIL-3-therapy were headaches, fever, flu-like symptoms, rashes and blisters at the site of injection which excluded 2 of 6 patients from the study. CONCLUSIONS: Supportive rhIL-3 to adjuvant Carboplatin-based chemotherapy enables a better keeping of 4-weekly courses in contrast to the placebo-group due to faster recovery of hematologic parameters. Due to the side-effects, of IL-3, this cytokine cannot be recommended for routine clinical use.

Abrogation of the hematological and biological activities of the interleukin-3/granulocyte-macrophage colony-stimulating factor fusion protein PIXY321 by neutralizing anti-PIXY321 antibodies in cancer patients receiving high-dose carboplatin.

This dose-escalation study was performed to evaluate the hematologic activity, biological effects, immunogenicity, and toxicity of PIXY321 (an interleukin-3/granulocyte-macrophage colony-stimulating factor fusion protein) administered after high-dose carboplatin (CBDCA) treatment. Patients with advanced cancers received CBDCA at 800 mg/m2 intravenously on day 0 of repeated 28-day cycles. In part A of the study, patients were treated with CBDCA alone during cycle 1 and then received PIXY321 on days 1 through 18 of cycle 2 and later cycles. In part B, patients received 18 days of PIXY321 beginning on day 1 of all CBDCA cycles, including cycle 1. PIXY321 was administered subcutaneously in 2 divided doses. Total doses of 135, 250, 500, 750, and 1,000 micrograms/m2/d were administered to successive cohorts of 3 to 6 patients in part A. In part B, patient groups received PIXY321 doses of 750, 1,000, and 1,250 micrograms/m2/d. The hematologic effects of PIXY321 were assessed in the first 2 cycles of therapy. Anti-PIXY321 antibody formation was assessed by enzyme-linked immunosorbent assay (ELISA) and neutralization assay. Of the 49 patients enrolled, 31 were fully evaluable for hematologic efficacy. When comparing the first B cycle (cycle B-1; with PIXY321) with the first A cycle (cycle A-1; without PIXY321), the fusion protein had no significant effect on platelet nadirs or duration of platelets less than 20,000/microL but was able to speed the time of recovery of platelet counts to 100,000/microL (15 v 20 days; P =.01). Significant improvements in neutrophil nadir and duration of ANC less than 500 were observed in cycles A-2 and B-1 (with PIXY321) as compared with cycle A-1 (without PIXY321). Initial PIXY321 prophylaxis (cycle A-2 and cycle B-1), enhanced the recovery of ANC to greater than 1,500/microL by an average of at least 8 days as compared with cycle A-1 (without PIXY321; P

Randomized trial of recombinant human interleukin-3 versus placebo in prevention of bone marrow depression during first-line chemotherapy for ovarian carcinoma.

PURPOSE: To determine whether recombinant human interleukin-3 (rhIL-3) reduces bone marrow depression and improves chemotherapeutic schedule adherence in ovarian cancer patients receiving first-line combination chemotherapy. PATIENTS AND METHODS: In a randomized multicenter study, 185 patients received carboplatin (dose based on projected area under the concentration-time curve [AUC]=4) and cyclophosphamide (750 mg/m2) day 1, every 3 weeks for six cycles. Patients were randomized to receive rhIL-3 (5 microg/kg) or placebo once daily subcutaneously on days 3 to 12. RESULTS: Adherence to chemotherapeutic regimen, mean chemotherapy cycle length, tumor response rate, and median survival at 24 months did not differ between groups. The number of side effects-primarily allergic reactions, flu-like symptoms and fever-were higher in the rhIL-3 group, which resulted in 21 discontinuations compared with one in the placebo group. Compared with placebo, the rhIL-3 group had higher platelet counts day 1 of cycles 2 to 6. The number of patients with World Health Organization (WHO) grade IV thrombocytopenia or number of platelet transfusions did not differ. Leukocyte counts differed only in cycles 1 and 2 between groups. The leukocyte nadir occurred earlier in the rhIL-3 (day 12) than in the placebo group (day 15, P=.006). Leukocytes and neutrophils were only higher in the rhIL-3 group day 1 of cycle 2. In cycles 4 and 5, more patients with WHO grade IV neutropenia received rhIL-3 (P < .005). Eosinophil counts were higher day 1 of cycles 2 to 6 in the rhIL-3 group (P < .0001). CONCLUSION: rhIL-3 had stimulatory hematopoietic effects. This did not result either in reduction of platelet transfusions or in improvement of chemotherapeutic schedule adherence. There were more side effects in the rhIL-3 group than in the placebo group. rhIL-3 at 5 microg/kg/d is, therefore, not of clinical benefit in this chemotherapeutic regimen.

Interleukin 3 in the treatment of chemotherapy induced thrombocytopenia.

We enrolled 19 cancer patients (11 females, 8 males) with thrombocytopenia after standard dose of chemotherapy to receive IL3 10 mg/kg/day s.c. until hematologic recovery. Therapeutic success was obtained in 69.6% of cycles; a major response in 39.3% and a minor response in 30.3% of cycles. We obtained the best results in case of platelet count <49,000/mm3. The main toxicity was a flu-like syndrome. In two cycles (6%) we registered allergic episodes with flushing and lipothymia. In the 47% of cycles evaluable for toxicity no side effect was registered.

A Phase I study of granulocyte-macrophage-colony stimulating factor/interleukin-3 fusion protein (PIXY321) following ifosfamide, carboplatin, and etoposide therapy for children with recurrent or refractory solid tumors: a report of the Children's Cancer Group.

BACKGROUND: This Phase I trial was developed to determine the safety, biologic activity, and effects on hematopoietic recovery of PIXY321 following ifosfamide, carboplatin, and etoposide chemotherapy for children with recurrent or refractory solid tumors. METHODS: Children (age < 22 years at diagnosis) received ifosfamide 1800 mg/m2/day x 5 days, carboplatin 400 mg/m2/day x 2 days, and etoposide 100 mg/m2/day x 5 days, followed by daily subcutaneous administration of PIXY321. Dose-limiting toxicity was defined as Grade IV toxicity related to PIXY321. Pharmacokinetic and endogenous cytokine production studies were conducted during Course 1, and peripheral blood (PB) progenitor cell and receptor expression studies were conducted during Course 1 when the white blood cell count recovered to > or=1000/mm3. RESULTS: Twenty-four children received ifosfamide, carboplatin, and etoposide chemotherapy plus PIXY321, the latter at doses of 500 /g/m2/day (n=3), 750 microg/m2/day (n=6), 1000 microg/m2/day (n=9), or 500 microg/m2/twice a day (n=6). PIXY321 was well tolerated, with only 1 dose-limiting toxicity (chills, occurring at a dose of 750 microg/m2/day). The maximum tolerated dose was not reached in this study. The median days to absolute neutrophil count recovery (> or =1000/mm3) and platelet recovery (>100,000/mm3) during Course 1 following PIXY321 (1000 microg/ m2/day) were 22 days (range, 5-33 days) and 20 days (range, 5-31 days), respectively. There was a 2500, 5000, 3000, and 390% increase in PB granulocyte-macrophage colony-forming units, erythrocyte blast-forming units, granulocyte erythrocyte macrophage and megakaryocyte colony-forming units, and CD34+ cells, respectively. CONCLUSIONS: In summary, this pediatric Phase I trial demonstrated that PIXY321 was well tolerated by children and resulted in platelet recovery a median of 20 days after ICE chemotherapy and an increase in the number of PB progenitor cells above baseline. However, based on recent negative results with PIXY321 in randomized Phase II/III trials involving adult subjects, PIXY321 is not currently available for future trials involving children.

Clinical effects and pharmacokinetics of the fusion protein PIXY321 in children receiving myelosuppressive chemotherapy.

UNLABELLED: A hemopoietin with the ability to accelerate both platelet and granulocyte recovery after intensive chemotherapy would have great clinical utility. The recombinant fusion protein composed of human granulocyte-macrophage colony-stimulating factor and interleukin-3 (PIXY321), showed some promise in early adult trials. However, studies for pediatric patients are limited, and there are no systematic data on the pharmacokinetics of PIXY321 given over prolonged periods at current dosage levels. PURPOSE: To determine the safety, clinical effects and plasma concentrations of increasing doses of PIXY321 in children treated with myelosuppressive chemotherapy. METHODS: A total of 39 children with relapsed or high-risk solid tumors were enrolled in this phase I/II study. PIXY321 was administered once or twice daily by subcutaneous injection in total doses of 500 to 1000 microg/m2 per day for 14 days after each course of chemotherapy with ifosfamide, carboplatin, and etoposide (ICE). Pharmacokinetic studies were performed on day 1 of the first course in 33 patients and repeated on day 14 in 13 patients (once-daily schedule only). RESULTS: Although mild local skin reactions and fever were frequent, no dose-limiting toxicity was identified at the maximum dose studied (1000 microg/m2 per day). There were no statistically significant differences in chemotherapy-induced hematologic toxicity with increasing doses of PIXY321 or with twice-daily vs once-daily dosing. On day 1, the median PIXY321 clearance was 657 ml/min per m2 (range 77 1804 ml/min per m2) and the median half-life was 3.7 h (range 2.1-20.8 h). On day 14, clearance increased in all patients studied (median increase 63%), with a corresponding decrease in the median 12-h concentration (from 1.2 to 0.25 ng/ml). Maximum concentrations were < 1 ng/ml in 81% of patients, and only two patients had maximum plasma concentrations equivalent to those required for consistent activity in vitro. CONCLUSIONS: The recombinant fusion protein PIXY321 proved safe in children treated with myelosuppressive ICE chemotherapy but had no demonstrable clinical benefits. The pharmacokinetic studies suggest that the observed lack of hematologic benefit may be explained by low plasma concentrations resulting from increased clearance with prolonged administration. Moreover, the significant increase in PIXY321 systemic clearance in the absence of increased circulating myeloid cells suggests that the upregulation of either extravascular compartment hematopoietic progenitor cells or nonhematopoietic cells may play an important role in controlling circulating concentrations of this unique cytokine. These findings highlight the importance of a thorough assessment of the systemic disposition of cytokines when determining the dose and schedule necessary to achieve clinical activity in patients.

Peripheral blood progenitor cell cycle kinetics following priming with pIXY321 in patients treated with the "ICE" regimen.

PURPOSE: Treatment with hematopoietic growth factors increases the percentage of hematopoietic progenitor cells in cell cycle. Following withdrawal of certain growth factors, preclinical data suggest that there is a transient fall in the percentage of progenitor cells in cycle below the baseline, thus providing a window to administer chemotherapy with reduced risk of myelotoxicity. PATIENTS AND METHODS: Patients with histologically confirmed, previously untreated neoplasia, were treated with pIXY321 by subcutaneous injection at a dose of 375 microg/m2 twice daily (total dose 750 microg/m2/day) for seven days (days -8 to -2), followed by a two-day rest (days -1 to 0). Patients received ICE (ifosfamide, carboplatin and etoposide) on days 1 to 3. On day 4, pIXY321 was resumed until hematologic recovery. Peripheral blood was collected on days -8, -2, -1, 1, and cell cycle distribution was determined using flow cytometry. RESULTS: Twenty patients were treated in this study and received a total of 54 cycles. Partial responses were observed in three of 13 patients with non-small cell lung cancer (23 percent) and two of five patients with small cell lung cancer (40 percent). Six of 15 patients had an increased number of cells in S+G2/M on day 1 of ICE following seven days of pIXY321 and two days off (days -1 to 0). The average increase was 63 percent (range 6-253). Seven patients had a decreased number of cells in S+G2/M. The average decrease was 55 percent (range 6.3-78). There were no significant differences among the fifteen patients with regards to the observed toxicity of the chemotherapy. DISCUSSION: pIXY321 in this schedule did not consistently decrease the percentage of cycling progenitor cells in the peripheral blood. Future studies should define whether other growth factors and/or schedules can synchronize progenitor cell cycling and protect the marrow compartment from cycle specific chemotherapy.

In vitro and in vivo biologic effects of interleukin-3 (IL-3) in follicular low-grade lymphoma.

Interleukin-3 (IL-3) is a pleiotropic cytokine which has stimulatory effects on a broad range of hematopoietic progenitor cells. These effects have led to the use of IL-3 in clinical trials for the treatment of aplastic anemia and myelodysplastic syndrome as well as to stimulate bone marrow recovery in patients who have received high-dose therapy and bone marrow/stem cell transplantation. However, because one study suggested that IL-3 may also stimulate the growth of follicular small cleaved cell lymphoma (FSCCL) cells in vitro, it was concerning that the use of IL-3 after bone marrow transplantation in patients with FSCCL may stimulate the growth of undetectable minimal residual tumor cells resulting in early relapsed disease. In contrast to these observations, our own in vitro studies demonstrated that IL-3 inhibited FSCCL cells in short-term culture in a dose-dependent manner. Subsequently, we conducted a phase II clinical trial using single agent IL-3 for the treatment of patients with follicular low grade lymphoma. Our clinical data did not support the hypothesis that IL-3 is a growth stimulator of FSCCL.

Treatment of prolonged chemotherapy induced severe thrombocytopenia with recombinant human interleukin-3--a report on four cases.

Interleukin-3 (IL-3) is a multipotent hematopoietic growth factor, which exhibits stimulatory effects on leucocytes, reticulocytes and platelets. Due to its pronounced induction of megakaryopoiesis, IL-3 is thought to be a cytokine with the potential to prevent and to overcome chemotherapy-induced thrombocytopenia. We report on four cases (two of metastatic breast cancer, one of metastatic ovarian cancer and one of Hodgkin's disease) with prolonged chemotherapy-induced thrombocytopenia in whom rhIL-3 in combination with either recombinant human (rh) granulocyte macrophage colony stimulating factor (GM-CSF) or rh granulocyte colony stimulating factor (G-CSF) was administered. In all cases, a steady and clinically significant increase in platelet counts could be observed. No major side effects, neither due to the application of rhIL-3 nor due to rhGM-CSF or rhG-CSF, occurred; only flu-like symptoms were seen, which could effectively be treated with paracetamol. This report highlights the efficacy of combined treatment with rhIL-3 plus rhGM-CSF or rhG-CSF in chemotherapy-induced thrombocytopenia, where megakaryopoiesis could be stimulated efficiently by rhIL-3. Based on this experience, the authors conclude that established thrombocytopenia as a major side effect of myelosuppressive chemotherapy should be considered as an indication for the use of rhIL-3 in interventional treatment. Further investigations in this area are encouraged.

TNF-alpha release from human peripheral blood mononuclear cells to predict the proinflammatory activity of cytokines and growth factors.

Therapeutic applications of novel growth factors and cytokines can be limited due to the oftentimes severe inflammatory reactions that are encountered in patients following parenteral administration. These inflammatory responses, hallmarked by fever, headache, and chills are mediated by the release of inflammatory cytokines following administration of protein-based therapeutics. TNF-alpha appears to be one of the most potent and pleiotropic inflammatory cytokines released during the early stages of an inflammatory response. In the present study, we have explored the use of an in vitro assay system to determine whether the release of TNF-alpha from human PBMC could be correlated with documented inflammatory activity in humans. The cytokines tested included rhGM-CSF, rhIL-2, rhIL-3, and rhIFN-gamma, rhG-CSF, which has been shown to lack substantial proinflammatory activity in humans, was also tested. The potent macrophage activator and inflammatory agent, LPS, was used as a positive control. Results of this study demonstrate and confirm an association between the inflammatory activity of cytokines observed in patients and the stimulation of TNF-alpha release from PBMC in vitro. This assay system can be used as a predictive tool in determining the inflammatory potential of novel growth factors and cytokines.