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Therapeutic cancer vaccines have effectively induced durable regressions of premalignant oncogenic human papilloma virus type 16 (HPV16)-induced anogenital lesions. However, the treatment of HPV16-induced cancers requires appropriate countermeasures to overcome cancer-induced immune suppression. We previously showed that standard-of-care carboplatin/paclitaxel chemotherapy can reduce abnormally high numbers of immunosuppressive myeloid cells in patients, allowing the development of much stronger therapeutic HPV16 vaccine (ISA101)-induced tumor immunity. We now show the clinical effects of ISA101 vaccination during chemotherapy in 77 patients with advanced, recurrent, or metastatic cervical cancer in a dose assessment study of ISA101. Tumor regressions were observed in 43% of 72 evaluable patients. The depletion of myeloid suppressive cells by carboplatin/paclitaxel was associated with detection of low frequency of spontaneous HPV16-specific immunity in 21 of 62 tested patients. Patients mounted type 1 T cell responses to the vaccine across all doses. The group of patients with higher than median vaccine-induced immune responses lived longer, with a flat tail on the survival curve. This demonstrates that chemoimmunotherapy can be exploited to the benefit of patients with advanced cancer based on a defined mode of action.

The therapeutic synthetic long peptide (SLP) vaccine ISA101 selectively enlarges the pool of tumor-specific T cells recognizing the human papillomavirus type 16 (HPV16) antigens E6 and E7. Vaccine monotherapy for HPV16-induced pre-malignant anogenital lesions is effective, inducing durable complete regressions in approximately 50% of treated patients. However, cancer treatment requires appropriate countermeasures to overcome the suppression of T-cell activation, expansion and effector function imposed by suppressive myeloid cell populations, regulatory T cells and co-inhibitory molecule expression. We recently showed that carboplatin/paclitaxel chemotherapy can normalize the abnormally high levels of immune suppressive myeloid cells, allowing the development of much stronger therapeutic ISA101-induced tumor immunity1. Here we show the effects of ISA101 vaccination during chemotherapy in 77 patients with advanced, recurrent or metastatic cervical cancer in a dose assessment study. Study design involved a single arm dose escalation study with four different ISA101 doses (20, 40, 100 and 300 µg per peptide) with or without immunomodulator pegylated interferon alpha (Pegitron), given concomitantly with standard of care chemotherapy (carboplatin, AUC 6; paclitaxel, 175 mg/m2). Objective regressions were observed in 43% of 72 evaluable patients. The depletion of myeloid suppressive cells by carboplatin/paclitaxel was associated with detection of low level spontaneous HPV16-specific immunity in 26 of the 61 tested patients. Patients mounted type 1 T-cell responses to the vaccine across all doses. No significant differences were observed between the different doses and strength of vaccine-induced T cell responses; the results were therefore combined. Patients with an above median HPV16-specific T cell immune response to ISA101, measured by a validated IFNγ-Elispot, displayed a significantly prolonged median overall survival (OS) of 16.8 months compared to those with a lower HPV-specific immune response (OS 11.2 months, logrank p=0.012). Importantly, this effect was not due to differences in general immune status, as measured by T-cell reactivity to unrelated common microbial recall antigens. In conclusion, our study demonstrates that chemo-immunotherapy can be exploited to the benefit of patients with cervical cancer and warrants confirmation of the benefit of this type of chemo-immunotherapy in a randomized controlled study in HPV16-induced cancer patients. 1Welters, M. J. et al. Vaccination during myeloid cell depletion by cancer chemotherapy fosters robust T cell responses. Sci Transl Med 8, 334ra352, doi:10.1126/scitranslmed.aad8307 (2016). Citation Format: Cornelis J M Melief, Marij J. Welters, Ignace Vergote, Judith R. Kroep, Gemma G. Kenter, Nelleke Ottevanger, Wiebren A. Tjalma, Hannelore Denys, Mariette van Poelgeest, Hans W. Nijman, Anna K. Reyners, Thierry Velu, Frederic Goffin, Roy Lalisang, Willem-Jan Krebber, Leon Hooftman, Sonja Visscher, Brent A. Blumenstein, Richard B. Stead, Winald Gerritsen, Sjoerd van der Burg. A strong HPV-specific T-cell response after chemo-immunotherapy for advanced cervical cancer is associated with prolonged survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT002.

Conventional daily administration of filgrastim is effective in reducing the duration of severe neutropenia and enhancing survival following lethal radiation, myelosuppressive cytotoxic therapy or myeloablation and stem cell transplantation. A sustained-duration form of filgrastim, pegfilgrastim has significantly simplified scheduling protocols after chemotherapy-induced neutropenia to a single injection while maintaining the therapeutic effectiveness of daily administration of filgrastim. We examined the ability of a single or double (weekly) administration of pegfilgrastim to significantly improve neutrophil recovery in a rhesus macaque model of severe radiation-induced myelosuppression. Animals were exposed to potentially lethal 6 Gy total-body X radiation. After irradiation all animals received supportive care and were administered either pegfilgrastim at 300 μg/kg on day 1 or day 1 and day 7 post exposure, or filgrastim at 10 μg/kg/day initiated on day 1 post exposure and continued daily through neutrophil recovery. Pharmacokinetic parameters and neutrophil-related values for duration of neutropenia, neutrophil nadir, time to recovery to an absolute neutrophil count ≥500/μL or ≥2000/μL, and days of antibiotic support were determined. Effective plasma concentrations of pegfilgrastim were maintained in neutropenic animals until after the onset of hematopoietic recovery, which is consistent with neutrophil-dependent properties of elimination. Administration of pegfilgrastim at day 1 and day 7 was most effective at improving neutrophil recovery compared to daily administration of filgrastim or a single injection of pegfilgrastim on day 1, after severe, radiation-induced myelosuppression in rhesus macaques.

We investigated whether a novel, synthetic, peptide-based erythropoietin-receptor agonist (Hematide, Affymax) can stimulate erythropoiesis in patients with anemia that is caused by antierythropoietin antibodies.In this open-label, single-group trial, we enrolled patients with chronic kidney disease who had pure red-cell aplasia or hypoplasia due to antierythropoietin antibodies and treated them with a synthetic peptide-based erythropoietin-receptor agonist. The agonist was administered by subcutaneous injection at an initial dose of 0.05 mg per kilogram of body weight every 4 weeks. The primary end point was a hemoglobin concentration above 11 g per deciliter without the need for transfusions.We treated 14 patients with the peptide agonist for a median of 28 months. The median hemoglobin concentration increased from 9.0 g per deciliter (with transfusion support in the case of 12 patients) before treatment to 11.4 g per deciliter at the time of the last administration of the agonist; transfusion requirements diminished within 12 weeks after the first dose, after which 13 of the 14 patients no longer required regular transfusions. Peak reticulocyte counts increased from a median of 10x10(9) per liter before treatment to peak counts of greater than 100x10(9) per liter. The level of antierythropoietin antibodies declined over the course of the study and became undetectable in six patients. One patient who initially responded to treatment had a diminished hematologic response a few months later despite increased doses of the agonist and required transfusions again; this patient was found to have antibodies against the agonist. One patient died 4 months after the last dose of the agonist, and a grade 3 or 4 adverse event occurred in seven other patients during the study period.This novel agonist of the erythropoietin receptor can correct anemia in patients with pure red-cell aplasia caused by antierythropoietin antibodies. (ClinicalTrials.gov number, NCT00314795.).

Peptidic erythropoiesis receptor agonist is a synthetic, PEGylated peptide that can promote red blood cell production upon binding to the erythropoietin receptor. The objective of this study was to characterize the pharmacokinetics and erythropoietic effects of peptidic erythropoiesis receptor agonist in healthy volunteers. Plasma concentrations of peptidic erythropoiesis receptor agonist and pharmacodynamic responses were obtained after single intravenous injections at doses of 0.025, 0.05, and 0.1 mg/kg. Population pharmacokinetic/pharmacodynamic modeling was performed using NONMEM. Peptidic erythropoiesis receptor agonist exhibited nonlinear pharmacokinetics described by a 1-compartment model with parallel elimination by Michaelis-Menten and linear processes. A catenary, life span-based, indirect response model reflecting bone marrow erythroid and blood cells reflected the pharmacodynamics of peptidic erythropoiesis receptor agonist. A modest tolerance and rebound phenomenon in reticulocytes was modeled with negative feedback regulation related to hemoglobin. This pharmacokinetic/pharmacodynamic model well characterized the prolonged disposition, intrinsic pharmacologic parameters, and typical hematological system properties following single doses of peptidic erythropoiesis receptor agonist in normal subjects.

Objective To evaluate the potential of Hematide, a PEGylated, synthetic peptide–based erythropoiesis-stimulating agent that is in clinical development for the treatment of anemia associated with chronic kidney disease and cancer, to correct antierythropoietin antibody–associated pure red cell aplasia (PRCA). Materials and Methods The binding of anti-Hematide antibodies (mouse, rabbit, and monkey) to recombinant human erythropoietin (rHuEPO) and of anti-rHuEPO antibodies (mouse, goat, rat, and human) to Hematide were evaluated. An anti-EPO antibody–mediated anemia rat model was developed by subcutaneously administering rHuEPO to rats three times weekly for 4 weeks. Sixty percent of the animals developed PRCA as characterized by severe anemia, reduced reticulocytes, anti-EPO antibodies, and limited bone marrow erythroid precursors. The effect of Hematide administration on the PRCA rats was evaluated. Results Antibodies to EPO do not cross react with Hematide and, conversely, antibodies to Hematide do not cross react with EPO. Hematide corrected antibody-induced anemia in a rat PRCA model. Conclusions The data support the potential of Hematide to correct anti-EPO antibody–associated PRCA in humans. In addition, the data suggest a negligible risk for development of anti-EPO antibody–induced PRCA secondary to Hematide administration.

Mathematical modeling of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) pharmacokinetics (PK) and pharmacodynamics (PD) suggest that variations in the PEG-rHuMGDF treatment schedule could reduce the severity and duration of thrombocytopenia following myeloablation and bone marrow transplant (BMT). We tested this hypothesis in a rhesus monkey model of autologous (Au) bone marrow-derived mononuclear cell (BM-MNC) transplantation following lethal myeloablation. On day 0, animals were myeloablated by total body exposure to 920 cGy, 250 kVp x-irradiation (TBI). Four cohorts of animals were infused with 1 x 10(8) AuBM-MNC/kg body weight within 2 hours of TBI. The AuBMT-alone cohort received no cytokine, the daily dosage cohort received PEG-rHuMGDF (2.5 micro g/kg/day, s.c.) post TBI and AuBMT, and the pre/post-transplant cohort received PEG-rHuMGDF (2.5 micro g/kg/day, s.c.) pre (day -9 to day -5) and post TBI and AuBMT. The post-transplant PEG-rHuMGDF administration in the above cohorts was begun on day 1 post TBI and continued until platelet counts reached 200,000 micro l (range, 15-31 days). Another group received PEG-rHuMGDF (300 micro g/kg/day, s.c.) on days 1 and 3 only following TBI and AuBMT. The TBI controls received neither AuBMT nor cytokine therapy. In this model of AuBMT, with regard to the PEG-rHuMGDF administration schedule, the daily dosage of the post-transplant cohort did not significantly improve platelet recovery; the pre/post-transplant schedule and an abbreviated high-dosage, post-transplant schedule (days 1 and 3) significantly improved the duration and nadir of thrombocytopenia and platelet recovery. These data confirm predictions from PK/PD modeling of PEG-rHuMGDF that thrombocytopenia is preventable following AuBMT.

5525 Background: Therapeutic vaccination with HPV type 16 synthetic long peptides (HPV16-SLP) results in T cell–mediated regression of HPV16-induced premalignant lesions but fails to install effective immunity in patients with advanced HPV16-positive cervical cancer. We showed that HPV16-SLP vaccination in mice and in patients with advanced cervical cancer patients fosters robust HPV16-specific T cell responses, when combined with chemotherapy (Welters et al. Sci. Transl. Med., 2016). Methods: We have now completed a chemo-immunotherapy study in 70 patients with late stage HPV16+ cervical cancer (clinical trials.gov NCT02128126). Three HPV16-SLP vaccine doses were given 2 weeks after the second, third and fourth cycle of standard chemotherapy (carboplatin, AUC 6; paclitaxel 175 mg/ m2). Cohorts of 12 patients each were vaccinated with each of 4 dose levels (20, 40, 100 and 300 µg/ per peptide) of 13 overlapping HPV16 synthetic long peptides (HPV16-SLP) together covering the length of the 2 E6 and E7 proteins. Two additional cohorts of 6 patients each were vaccinated with the most promising doses of 40 and 100 µg/ peptide. Results: Robust vaccine-induced HPV16-specific T cell responses as assessed by interferon-γ Elispot were observed and were sustained until at least 30 days after the 6th cycle of chemotherapy. In addition the chemotherapy augmented recall responses to microbial antigens. Such robust T cell responses were not noted in previous trials when similar patients were vaccinated without timing of vaccination during chemotherapy. A marked and significant positive correlation was observed between the strength of the vaccine-induced immune response and overall survival. No such correlation was observed between the strength of the T cell response against common recall antigens and survival. In addition a remarkably high proportion of patients survived beyond 2 years after the start of therapy. Conclusions: The results suggest that survival duration is directly related to the strength of the vaccine-induced HPV16-specific T cell response and is not due to generally better immuno-competence. Clinical trial information: NCT 02128126.

140 Background: Therapeutic vaccination with HPV type 16 synthetic long peptides (HPV16-SLP) results in T cell–mediated regression of HPV16-induced premalignant lesions but fails to install effective immunity in patients with advanced HPV16-positive cervical cancer. We showed that HPV16-SLP vaccination in mice and in patients with advanced cervical cancer patients fosters robust HPV16-specific T cell responses, when combined with chemotherapy. In this study we noted that a single dose of vaccine 2 weeks into the 2nd cycle of chemotherapy was optimal, because at this time the immunosuppressive myeloid cells were down. Methods: We now completed a chemo-immunotherapy study in a larger number of patients with late stage HPV16+ cervical cancer. Three HPV16-SLP vaccine doses were given 2 weeks after the second, third, and fourth cycles of standard chemotherapy. Cohorts of 12 patients each were vaccinated with each of 4 dose levels (20, 40, 100, and 300 µg/ per peptide) of 13 overlapping HPV16 synthetic long peptides (HPV16-SLP) together covering the length of the 2 E6 and E7 proteins. Results: Robust vaccine-induced HPV16-specific T cell responses as assessed by interferon-g Elispot were observed and were sustained throughout the cycles of chemotherapy. These T cell responses were substantially increased in all patients who received HPV16-SLP . In addition, the chemotherapy augmented recall responses to microbial antigens. Such robust T cell responses were not noted in previous trials when similar patients were vaccinated without timing of vaccination during chemotherapy. A marked correlation was observed between the strength of the vaccine-induced immune response and longer-term clinical outcomes such as overall survival. No such correlation exists between the strength of the T cell response against common recall antigens and survival. In addition, a remarkably high proportion of patients survived beyond 20 months after the start of therapy. Conclusions: These results indicate that the survival advantage is specifically related to the strength of the vaccine-induced T cell response and is not due to generally better immuno-competence. Clinical trial information: NCT02128126.

Three chimpanzees experimentally infected with human immunodeficiency virus (HIV) developed significant chronic thrombocytopenia after 5, 4, and 2 years, with peripheral platelet counts averaging 64 ± 19 × 103/μL (P = .004 compared with 228 ± 92 × 103/μL in 44 normal control animals), mean platelet volumes of 11.2 ± 1.8 fL (P > .5 compared with 10.9 ± 0.7 fL in normal controls), endogenous thrombopoietin (TPO) levels of 926 ± 364 pg/mL (P < .001 compared with 324 ± 256 pg/mL in normal controls), uniformly elevated platelet anti-glycoprotein (GP) IIIa49-66 antibodies, and corresponding viral loads of 534, 260, and 15 × 103 RNA viral copies/mL. Pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) was administered subcutaneously (25 μg/kg twice weekly for 3 doses) to determine the effects of stimulating platelet production on peripheral platelet concentrations in this cohort of thrombocytopenic HIV-infected chimpanzees. PEG-rHuMGDF therapy increased (1) peripheral platelet counts 10-fold (from 64 ± 19 to 599 ± 260 × 103 platelets/μL;P = .02); (2) marrow megakaryocyte numbers 30-fold (from 11.7 ± 6.5 × 106/kg to 353 ± 255 × 106/kg;P = .04); (3) marrow megakaryocyte progenitor cells fourfold (from a mean of 3.6 ± 0.6 to 14.1 × 103 CFU-Meg/1,000 CD34+ marrow cells); and (4) serum levels of Mpl ligand from 926 ± 364 pg/mL (endogenous TPO) to predosing trough levels of 1,840 ± 353 pg/mL PEG-rHuMGDF (P = .02). The peripheral neutrophil counts were also transiently increased from 5.2 ± 2.6 × 103/μL to 9.9 ± 5.0 × 103/μL (P= .01), but neither the erythrocyte counts nor the reticulocyte counts were altered significantly (P > .1). The serum levels of antiplatelet GPIIIa49-66 antibodies exhibited reciprocal reductions during periods of thrombocytosis (P < .07). PEG-rHuMGDF therapy did not increase viral loads significantly (395, 189, and 53 × 103 RNA viral copies/mL; P > .5 compared with baseline values). The striking increase in peripheral platelet counts produced by PEG-rHuMGDF therapy implies that thrombocytopenia in HIV-infected chimpanzees is attributable to insufficient compensatory expansion in platelet production resulting from HIV-impaired delivery of platelets despite stimulated megakaryocytopoiesis. These data suggest that PEG-rHuMGDF therapy may similarly correct peripheral platelet counts in thrombocytopenic HIV-infected patients.

This report examines the effects on hematopoietic regeneration of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF ) (2.5 μg/kg/d) alone and in combination with recombinant human granulocyte colony stimulating factor (rHu-GCSF ) (10 μg/kg/d) for 21 days in rhesus macaques receiving intense marrow suppression produced by single bolus injections of hepsulfam (1.5 g/m2). In six hepsulfam-only control animals thrombocytopenia (platelet count

Thrombopoietin (TPO) is the physiologic Mpl-ligand regulating platelet production. Pegylated human recombinant megakaryocyte growth and development factor (PEG-rHuMGDF), a truncated polypeptide Mpl-ligand derivitized with poly-(ethylene glycol), induces megakaryocyte endoreduplication and proliferation in vitro and in vivo. In the present study, the dose-response effects of PEG-rHuMGDF on pharmacokinetics, megakaryocytopoiesis, platelet production, and platelet function were characterized for dosing 0.05, 0.10, 0.50, or 2.5 micrograms/kg/d in 22 baboons for 28 days. Daily subcutaneous injections of PEG-rHuMGDF produced linear log-dose responses in (1) steady-state trough plasma levels of PEG-HuMGDF (P < 10(-3)); (2) marrow megakaryocyte volume (P < 10(-3)), ploidy (P .1 in all cases). PEG-rHuMGDF at 0.5 micrograms/kg/d produced similar blood concentrations of Mpl-ligand and platelets as 10 times the dose of rHu-MGDF (5.0 micrograms/kg/d), reflecting the extended plasma half-life achieved through pegylation. Whereas PEG-rHuMGDF did not induce platelet aggregation in vitro, platelet aggregatory responsiveness induced by thrombin receptor agonist peptide (TRAP1–6) and collagen was transiently enhanced ex vivo during the initial few days of PEG-rHuMGDF administration. However, adenosine diphosphate (ADP)-induced platelet aggregation was not enhanced ex vivo by PEG- rHuMGDF therapy. 111In-platelet deposition on segments of homologous endarterectomized aorta (EA) and vascular graft (VG) interposed in arteriovenous femoral shunts increased in direct proportion to the circulating platelet concentration (P < 10(-4) for both EA and VG); 125l-fibrin accumulation was not affected by PEG-rHuMGDF-induced increases in peripheral platelet counts. Changes in platelet production and function produced by PEG-rHuMGDF returned to baseline within 2 weeks after discontinuing treatment. Thus, in nonhuman primates, PEG- rHuMGDF increases platelet production in a linear log-dose-dependent manner by stimulating megakaryocyte endoreduplication and new megakaryocyte formation from marrow hematopoietic progenitors. These findings suggest that appropriate dosing of PEG-rHuMGDF therapy during periods of chemotherapy-induced marrow suppression may maintain hemostatic concentrations of peripheral platelets without increasing the risk of thrombosis.

The primary physiologic regulator of platelet production, Mpl ligand, has recently been cloned and characterized. To define the regulatory role of Mpl ligand on platelet production and function we measured the effects of a recombinant truncated human Mpl ligand, megakaryocyte growth and development factor (rHu-MGDF) on megakaryocytopoiesis, platelet function, and thrombogenesis in nonhuman primates. rHu-MGDF was administered to 10 baboons for 28 days while performing pharmacokinetics and repeated measurements of the following: (1) platelet count, volume, turnover, and function ex vivo and in vitro; (2) marrow megakaryocyte number, volume, and ploidy; and (3) platelet deposition and fibrin accumulation on segments of vascular graft and endarterectomized aorta in vivo. Daily subcutaneous injections of rHu- MGDF (5 microgram/kg/d) attained plasma concentrations averaging 1,300 +/- 300 pg/mL 2 hours after injection with trough levels of 300 +/- 65 pg/mL before the next dose. These levels of rHu-MGDF incrementally increased the peripheral platelet concentration threefold by day 7 and fivefold by day 28 (P < 10(-4)) associated with a reciprocal decrease of 25% in mean platelet volumes (P < 10(-3)). Platelet mass turnover, a steady-state measure of platelet production, increased fivefold (P < 10(-4)). Platelet morphology, life span, and recovery were normal. No significant change occurred in peripheral leukocyte, neutrophil, or erythrocyte counts (P > .1 in all cases). The platelet count gradually returned to baseline within 2 weeks after discontinuing rHu-MGDF infections. Marrow megakaryocyte volume doubled (P < 10(-3)) three days after initiating rHu-MGDF therapy and the modal ploidy shifted from 16N to 64N (P < 10(-4)). Marrow megakaryocyte number increased twofold by day 7, and nearly fourfold by day 28 (P < 10(-4)), resulting in a 6.5- fold increase in marrow megakaryocyte mass (P < 10(-3)). The effects of rHu-MGDF on thrombosis were determined by comparing baseline, day 5, and day 28 rHu-MGDF-treatment measurements of 111In-platelet deposition and 125I-fibrin accumulation on segments of homologous endarterectomized aorta (EA) and vascular graft (VG) interposed in arteriovenous femoral shunts. rHu-MGDF increased 111In-platelet deposition in direct proportion to the circulating concentration of platelets for both EA and VG (r=.98 in both cases), without significant changes in fibrin accumulation (P > .5 in both cases). During the first week of rHu-MGDF treatment ex vivo platelet aggregatory responsiveness was enhanced to physiologic agonists (adenosine diphosphate, collagen, and thrombin receptor agonist peptide, TRAP1–6) (P < .05 in all cases). Although in vitro platelet aggregation was not induced by any concentration of rHu-MGDF tested (P > .5), rHu-MGDF enhanced aggregatory responses to low doses of physiologic agonists, effects that were maximal at 10 ng/mL for baboon platelets and 100 ng/mL for human platelets, and were blocked by excess soluble c-Mpl receptor. Flow cytometric expression of platelet activation epitopes was not increased on resting platelets (ligand-induced binding sites, P- selectin, or Annexin V binding sites; P > .1 in all cases). Megakaryocyte growth and development factor regulates platelet production and function by stimulating endoreduplication and megakaryocyte formation from marrow progenitor cells, and transiently enhancing platelet functional responses ex vivo. rHu-MGDF has the potential for achieving platelet hemostatic protection with minimal thrombo-occlusive risk.

Daily administration of filgrastim decreases the duration of severe neutropenia in the clinical setting. A sustained-duration form of filgrastim, pegfilgrastim, significantly reduces scheduling protocols to a single injection per chemotherapy cycle while maintaining therapeutic efficiency. We examined the ability of a single injection of pegfilgrastim to significantly improve neutrophil recovery following autologous bone marrow transplantation (AuBMT) in rhesus macaques. On day 1, postmyeloablation (920 cGy x-irradiation) and AuBMT, animals received either 0.1% autologous serum for 18 consecutive days (n=13), or single doses of pegfilgrastim via the subcutaneous (s.c.) or intravenous (i.v.) route (300 or 100 micro g/kg), or a single dose of filgrastim at 300 micro g/kg via the s.c. or i.v. route, or filgrastim at 10 micro g/kg via the s.c. route (n=4) on a daily basis (range=days 12-17). Pharmacokinetic parameters and neutrophil recovery were assessed. A single dose of pegfilgrastim via the i.v. or s.c. route was as effective as daily filgrastim administration, resulting in significant improvement of neutrophil recovery after myeloablation and ABuMT. Effective pegfilgrastim plasma concentrations were maintained in neutropenic animals until after the onset of hematopoietic recovery. Enhanced pharmacokinetics in AuBMT cohorts are consistent with self-regulating, neutrophil-mediated clearance.

PORPHYRIA cutanea tarda, which is the most common and readily treated form of porphyria in humans, results from a deficiency of uroporphyrinogen decarboxylase in the liver.1 2 3 It is characterized by cutaneous photosensitivity. The disease is usually classified as sporadic if uroporphyrinogen decarboxylase is deficient only in the liver, and as familial (autosomal dominant) if the enzyme is also deficient in nonhepatic tissues such as erythrocytes.3 4 5 There is also a familial form in which only the hepatic enzyme is deficient.6 Increased iron content in the liver is a major contributing factor in both sporadic and familial porphyria cutanea tarda,7 as are . . .

Thrombopoietin (TPO), the endogenous Mpl ligand, maintains peripheral platelet concentrations at a constant level by modulating megakaryocytopoiesis to compensate for changing peripheral requirements (1–6). TPO promotes platelet production by inducing hemopoietic stem cells to differentiate into megakaryocytes (3,7–9), and stimulating megakaryocyte proliferation and endoreduplication (3,10–16), thereby amplifying formation of the megakaryocyte cytoplasmic substrate destined for fragmentation and release as functional circulating platelets (17–19) (see Chapters 14–17).

Introduction: Hematide™ a novel, synthetic, PEGylated peptidic compound, binds to and activates the erythropoietin receptor. It is in development for treatment of anemia associated with chronic renal failure and cancer. Objective: To assess the subcutaneous (SC) Hematide™ dose required to increase hemoglobin (Hb) by ≥ 1 g/dL in ≥ 50% of anemic cancer patients (pts) on chemotherapy. Safety, pharmacodynamics and pharmacokinetics were also assessed. Method: In a phase 2, open label, multi-center, dose finding study, up to four doses of Hematide™ were given SC every 3 wks (Q3W) to 4 cohorts of fifteen pts at 0.05, 0.10, 0.15 or 0.2 mg/kg each. Entry criteria included confirmed solid tumor malignancy or lymphoma, >9 weeks of chemotherapy, baseline (BL) H ≥ 8 and Results: Sixty patients were enrolled (45% male). Preliminary data show that across cohorts 0.05, 0.10, 0.15 and 0.20 mg/kg, mean (BL) Hb values were 10.1(±1.07), 10.0(±0.89), 9.8(±0.67), 10.1(±0.69); the % of pts completing the study were approximately 79%, 50%, 60%, and 92%. An increase in mean Hb from BL of ≥ 1g/dL in the pharmacodynamic dataset (forty two pts) at Week 7 occurred in approximately 20%, 70%, 55% and 55% of patients. Three pts withdrew due to AEs and six due to SAEs (none attributed to study drug). Three deaths occurred (two disease progression, one renal insufficiency) none attributed to study drug. One SAE, thrombophlebitis, was considered to be possibly/probably related to study drug. Final safety and efficacy data will be provided at the meeting. Conclusion: In this study, HematideTM dosed SC Q3W resulted in an increase from BL of ≥ 1 g/dL of Hgb in ≥ 50% of patients in the 0.10, 0.15 and 0.20 mg/kg cohorts in the pharmacodynamic analysis. HematideTM appeared to be well tolerated at all doses studied.

Hematide is a PEGylated synthetic peptidic ESA that binds to and activates the erythropoietin (EPO) receptor. It has demonstrated potent and sustained dose dependent erythropoietic activity in healthy volunteers (HV). Methods: A randomized double-blind placebo controlled dose escalation study is being conducted to assess safety, pharmacokinetics (PK) and pharmacodynamics (PD) of Hematide administered as a single intravenous (IV) injection in EPO-naïve patients with Chronic Kidney Disease (CKD) pre-dialysis. Cohorts of 9 patients each (7 on Hematide and 2 on placebo) are planned with escalating doses. The results of this study are compared with those of a recently completed Phase 1 dose escalating study of Hematide in 4 cohorts of HV in which the pharmacologically active dose (PAD; i.e., the dose resulting in a statistically and clinically significant increase in hemoglobin) of Hematide was defined. Results: 28 day follow up of the 9 patients in Cohort 1 is complete. As of this date, the study remains blinded and we assume that increases in reticulocytes and hemoglobin (Hgb) are due to Hematide. Injections were well tolerated with no adverse events reported as related to study drug injection. In 7 patients whose reticulocytes increased, counts peaked at 7–10 days with a mean change from baseline of 151.4 ± 18.4 x 109/L before returning within baseline at 21 days post-injection. A Hgb increase was also observed in these 7 patients with a mean difference in change from baseline Hgb between these 7 responding and the 2 non-responding subjects of 0.80 g/dL at Day 10 (p = 0.028) and 1.16 g/dL (p = 0.08) at Day 28 post-injection. The PD profile of these 7 responding patients is comparable to that of the 10 HV receiving a PAD of Hematide. For example, the average maximum Hgb increase from baseline was 1.22 g/dL (SD: 0.37) in patients versus 1.36 g/dL (SD: 0.39) in HV. However, the PAD for CKD patients was half the Hematide dose that was required to obtain a similar Hgb effect in HV. Unblinded results from the complete study, including dose responses, follow-up after 28 days, PK data, additional PD data, EPO levels and iron status assessment will be presented and compared to the results in HV. Conclusion: A single IV injection of Hematide administered to patients with CKD was well tolerated and demonstrated potent and sustained erythropoietic activity of the same magnitude as that observed in HV. The PAD in patients with CKD was half of that observed in HV. These preliminary data suggest that patients with CKD may be more sensitive to Hematide and/or might have a different PK profile compared to HV. The sustained increases in Hgb levels for at least one month following a single dose of Hematide are compatible with anticipated monthly dosing of Hematide to maintain Hgb in target range. This is a reduced frequency of administration compared to that of currently available ESAs. These results serve as a basis to plan studies of repeat doses of Hematide in patients with anemia related to cancer or CKD and this plan will be outlined.

Thromboembolic complications may develop in patients with heparin-associated thrombocytopenia, presumably due to the formation of platelet aggregates. An unexpectedly high incidence of pulmonary embolism following coronary artery bypass surgery occurred during a brief period of time at a single institution, and all of these cases were found to be associated with thrombocytopenia. All patients tested during thrombocytopenia (five of five) had an increase in platelet-associated antibody. Serum samples from all five patients tested caused normal platelets to aggregate in vitro in the presence of one specific lot of beef lung heparin, which was in use in the operating room at the time; none of six other lots of beef lung heparin mediated in vitro platelet aggregation. Heparinase digestion of the heparin abolished the aggregating activity. It is concluded that thrombocytopenia and platelet activation caused by heparin may vary greatly even among different lots of heparin prepared from the same source.