Myeloprotective Effects of Trilaciclib Among Patients with Small Cell Lung Cancer at Increased Risk of Chemotherapy-Induced Myelosuppression: Pooled Results from Three Phase 2, Randomized, Double-Blind, Placebo-Controlled Studies

Purpose

Trilaciclib is an intravenous cyclin-dependent kinase 4/6 inhibitor indicated to decrease the incidence of chemotherapy-induced myelosuppression (CIM) by protecting hematopoietic stem and progenitor cells and immune system function from chemotherapy-induced damage (myeloprotection). Here, we investigated the myeloprotective effects of trilaciclib among patients at increased risk of CIM.

Patients and Methods

Data were pooled from three randomized, double-blind, placebo-controlled, phase 2 clinical studies of trilaciclib administered prior to chemotherapy in patients with extensive-stage small cell lung cancer (ES-SCLC). Myeloprotective outcomes were evaluated in patient subgroups based on age (<65 or ≥65 years), risk of chemotherapy-induced febrile neutropenia (FN), and risk of anemia or red blood cell (RBC) transfusions. For the FN and anemia analyses, risk factors were identified from published literature and used to classify patients into FN and anemia risk categories. Subgroup analysis based on age was also performed on patient reported outcome (PRO) measures.

Results

In total, 123 patients received trilaciclib and 119 patients received placebo. Myeloprotective benefits of trilaciclib were observed regardless of age, with greater effects observed among patients aged ≥65 years. Across FN risk factors and categories, trilaciclib had beneficial effects on neutrophil-related endpoints vs placebo, with greater effects observed in patients at higher risk of FN. Effects on RBC-related endpoints favored trilaciclib vs placebo, regardless of anemia risk factors and categories. Improvements in PROs with trilaciclib were observed irrespective of age group, but with greater improvements and less deterioration from baseline observed in older patients.

Conclusion

By both decreasing the incidence of CIM and improving quality of life, trilaciclib has the potential to allow patients receiving chemotherapy for ES-SCLC, including patients who are older or more vulnerable to CIM, to receive chemotherapy on schedule and at standard-of-care doses, and to improve the experience for patients receiving chemotherapy to treat ES-SCLC.

Clinical Trial Numbers

NCT02499770; NCT03041311; NCT02514447.

Trilaciclib prior to chemotherapy and atezolizumab in patients with newly diagnosed extensive-stage small cell lung cancer: A multicentre, randomised, double-blind, placebo-controlled Phase II trial

Trilaciclib is an intravenous CDK4/6 inhibitor administered prior to chemotherapy to preserve haematopoietic stem and progenitor cells and immune system function from chemotherapy-induced damage (myelopreservation). The effects of administering trilaciclib prior to carboplatin, etoposide and atezolizumab (E/P/A) were evaluated in a randomised, double-blind, placebo-controlled Phase II study in patients with newly diagnosed extensive-stage small cell lung cancer (ES-SCLC) (NCT03041311). The primary endpoints were duration of severe neutropenia (SN; defined as absolute neutrophil count <0.5 × 109 cells per L) in Cycle 1 and occurrence of SN during the treatment period. Other endpoints were prespecified to assess the effects of trilaciclib on additional measures of myelopreservation, patient-reported outcomes, antitumour efficacy and safety. Fifty-two patients received trilaciclib prior to E/P/A and 53 patients received placebo. Compared to placebo, administration of trilaciclib resulted in statistically significant decreases in the mean duration of SN in Cycle 1 (0 vs 4 days; P < .0001) and occurrence of SN (1.9% vs 49.1%; P < .0001), with additional improvements in red blood cell and platelet measures and health-related quality of life (HRQoL). Trilaciclib was well tolerated, with fewer grade ≥3 adverse events compared with placebo, primarily due to less high-grade haematological toxicity. Antitumour efficacy outcomes were comparable. Administration of trilaciclib vs placebo generated more newly expanded peripheral T-cell clones (P = .019), with significantly greater expansion among patients with an antitumour response to E/P/A (P = .002). Compared with placebo, trilaciclib administered prior to E/P/A improved patients' experience of receiving treatment for ES-SCLC, as shown by reduced myelosuppression, and improved HRQoL and safety profiles.

Effects of Trilaciclib on Chemotherapy-Induced Myelosuppression and Patient-Reported Outcomes in Patients with Extensive-Stage Small Cell Lung Cancer: Pooled Results from Three Phase II Randomized, Double-Blind, Placebo-Controlled Studies

BACKGROUND

Chemotherapy-induced myelosuppression (CIM) and its sequalae cause significant side effects and harm to quality of life. Trilaciclib is an intravenous CDK4/6 inhibitor that is administered prior to chemotherapy to protect hematopoietic stem and progenitor cells from chemotherapy-induced damage (myeloprotection).

PATIENTS AND METHODS

Data from three randomized, double-blind, placebo-controlled studies (NCT02499770, NCT03041311, and NCT02514447) were pooled to evaluate the effects of trilaciclib administered prior to standard-of-care chemotherapy (first-line etoposide plus carboplatin [E/P], first-line E/P plus atezolizumab, and second-/third-line topotecan) in patients with extensive-stage small cell lung cancer (ES-SCLC). The primary endpoints were duration of severe neutropenia (absolute neutrophil count < 0.5 × 10⁹ cells/L) in cycle 1 and occurrence of severe neutropenia. Additional prespecified endpoints further assessed the effect of trilaciclib on myeloprotection, health-related quality of life (HRQoL), antitumor efficacy, and safety.

RESULTS

Of 242 randomized patients, 123 received trilaciclib and 119 received placebo. Compared with placebo, administration of trilaciclib prior to chemotherapy resulted in significant decreases in most measures of multilineage CIM. The reduction in hematologic toxicity translated into the reduced need for supportive care interventions and hospitalizations due to CIM or sepsis and improvements in HRQoL domains related to the protected cell lineages, including fatigue, physical wellbeing, and functional wellbeing. Antitumor efficacy was similar for patients receiving trilaciclib or placebo.

CONCLUSION

Administering trilaciclib prior to chemotherapy resulted in clinically meaningful reductions in CIM and its consequences and improved patient HRQoL, with no impact on the antitumor efficacy of three individual chemotherapy regimens used in the first- or second-/third-line treatment of ES-SCLC.

Myelopreservation with Trilaciclib in Patients Receiving Topotecan for Small Cell Lung Cancer: Results from a Randomized, Double-Blind, Placebo-Controlled Phase II Study

INTRODUCTION

Multilineage myelosuppression is an acute toxicity of cytotoxic chemotherapy, resulting in serious complications and dose modifications. Current therapies are lineage specific and administered after chemotherapy damage has occurred. Trilaciclib is a cyclin-dependent kinase 4/6 inhibitor that is administered prior to chemotherapy to preserve hematopoietic stem and progenitor cells and immune system function during chemotherapy (myelopreservation).

METHODS

In this randomized, double-blind, placebo-controlled phase II trial, patients with previously treated extensive-stage small cell lung cancer (ES-SCLC) were randomized to receive intravenous trilaciclib 240 mg/m2 or placebo before topotecan 1.5 mg/m2 on days 1-5 of each 21-day cycle. Primary endpoints were duration of severe neutropenia (DSN) in cycle 1 and occurrence of severe neutropenia (SN). Additional endpoints were prespecified to further assess the effect of trilaciclib on myelopreservation, safety, patient-reported outcomes (PROs), and antitumor efficacy.

RESULTS

Thirty-two patients received trilaciclib, and 29 patients received placebo. Compared with placebo, administration of trilaciclib prior to topotecan resulted in statistically significant and clinically meaningful decreases in DSN in cycle 1 (mean [standard deviation] 2 [3.9] versus 7 [6.2] days; adjusted one-sided P < 0.0001) and occurrence of SN (40.6% versus 75.9%; adjusted one-sided P = 0.016), with numerical improvements in additional neutrophil, red blood cell, and platelet measures. Patients receiving trilaciclib had fewer grade ≥ 3 hematologic adverse events than patients receiving placebo, particularly neutropenia (75.0% versus 85.7%) and anemia (28.1% versus 60.7%). Myelopreservation benefits extended to improvements in PROs, specifically in those related to fatigue. Antitumor efficacy was comparable between treatment arms.

CONCLUSIONS

Compared with placebo, the addition of trilaciclib prior to topotecan for the treatment of patients with previously treated ES-SCLC improves the patient experience of receiving chemotherapy, as demonstrated by a reduction in chemotherapy-induced myelosuppression, improved safety profile, improved quality of life and no detrimental effects on antitumor efficacy.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02514447.

Myelopreservation with the CDK4/6 inhibitor trilaciclib in patients with small-cell lung cancer receiving first-line chemotherapy: a phase Ib/randomized phase II trial

BACKGROUND

Chemotherapy-induced damage of hematopoietic stem and progenitor cells (HSPC) causes multi-lineage myelosuppression. Trilaciclib is an intravenous CDK4/6 inhibitor in development to proactively preserve HSPC and immune system function during chemotherapy (myelopreservation). Preclinically, trilaciclib transiently maintains HSPC in G1 arrest and protects them from chemotherapy damage, leading to faster hematopoietic recovery and enhanced antitumor immunity.

PATIENTS AND METHODS

This was a phase Ib (open-label, dose-finding) and phase II (randomized, double-blind placebo-controlled) study of the safety, efficacy and PK of trilaciclib in combination with etoposide/carboplatin (E/P) therapy for treatment-naive extensive-stage small-cell lung cancer patients. Patients received trilaciclib or placebo before E/P on days 1-3 of each cycle. Select end points were prespecified to assess the effect of trilaciclib on myelosuppression and antitumor efficacy.

RESULTS

A total of 122 patients were enrolled, with 19 patients in part 1 and 75 patients in part 2 receiving study drug. Improvements were seen with trilaciclib in neutrophil, RBC (red blood cell) and lymphocyte measures. Safety on trilaciclib+E/P was improved with fewer ≥G3 adverse events (AEs) in trilaciclib (50%) versus placebo (83.8%), primarily due to less hematological toxicity. No trilaciclib-related ≥G3 AEs occurred. Antitumor efficacy assessment for trilaciclib versus placebo, respectively, showed: ORR (66.7% versus 56.8%, P = 0.3831); median PFS [6.2 versus 5.0 m; hazard ratio (HR) 0.71; P = 0.1695]; and OS (10.9 versus 10.6 m; HR 0.87; P = 0.6107).

CONCLUSION

Trilaciclib demonstrated an improvement in the patient's tolerability of chemotherapy as shown by myelopreservation across multiple hematopoietic lineages resulting in fewer supportive care interventions and dose reductions, improved safety profile, and no detriment to antitumor efficacy. These data demonstrate strong proof-of-concept for trilaciclib's myelopreservation benefits.

CLINICAL TRAIL NUMBER

NCT02499770.

Trilaciclib plus chemotherapy versus chemotherapy alone in patients with metastatic triple-negative breast cancer: a multicentre, randomised, open-label, phase 2 trial

BACKGROUND

Trilaciclib is an intravenous cell-cycle inhibitor that transiently maintains immune cells and haemopoietic stem and progenitor cells in G1 arrest. By protecting the immune cells and bone marrow from chemotherapy-induced damage, trilaciclib has the potential to optimise antitumour activity while minimising myelotoxicity. We report safety and activity data for trilaciclib plus gemcitabine and carboplatin chemotherapy in patients with metastatic triple-negative breast cancer.

METHODS

In this randomised, open-label, multicentre, phase 2 study, adult patients (aged ≥18 years) with evaluable, biopsy-confirmed, locally recurrent or metastatic triple-negative breast cancer who had no more than two previous lines of chemotherapy were recruited from 26 sites in the USA, three in Serbia, two in North Macedonia, one in Croatia, and one in Bulgaria; sites were academic and community hospitals. Availability of diagnostic samples of tumour tissue confirming triple-negative breast cancer was a prerequisite for enrolment. Eligible patients were randomly assigned (1:1:1) by an interactive web-response system, stratified by number of previous lines of systemic therapy and the presence of liver metastases, to receive intravenous gemcitabine 1000 mg/m² and intravenous carboplatin (area under the concentration-time curve 2 μg × h/mL) on days 1 and 8 (group 1), gemcitabine and carboplatin plus intravenous trilaciclib 240 mg/m² on days 1 and 8 (group 2), or gemcitabine and carboplatin on days 2 and 9 plus trilaciclib on days 1, 2, 8, and 9 (group 3) of 21-day cycles. Patients continued treatment until disease progression, unacceptable toxicity, withdrawal of consent, or discontinuation by the investigator. The primary objective was to assess the safety and tolerability of combining trilaciclib with gemcitabine and carboplatin chemotherapy. The primary endpoints were duration of severe neutropenia during cycle 1 and the occurrence of severe neutropenia during the treatment period. Overall survival was included as a key secondary endpoint. Analyses were in the intention-to-treat population. Safety was assessed in all patients who received at least one dose of study treatment. This study is registered with EudraCT, 2016-004466-26, and ClinicalTrials.gov, NCT02978716, and is ongoing but closed to accrual.

FINDINGS

Between Feb 7, 2017, and May 15, 2018, 142 patients were assessed for eligibility and 102 were randomly assigned to group 1 (n=34), group 2 (n=33), or group 3 (n=35). Of all patients, 38 (37%) had received one or two lines of previous chemotherapy in the metastatic setting. Median follow-up was 8·4 months (IQR 3·8-13·6) for group 1, 12·7 months (5·5-17·4) for group 2, and 12·9 months (6·7-16·8) for group 3. Data cutoff for myelosuppression endpoints was July 30, 2018, and for antitumour activity endpoints was May 17, 2019. During cycle 1, mean duration of severe neutropenia was 0·8 day (SD 2·4) in group 1, 1·5 days (3·5) in group 2, and 1·0 day (2·6) in group 3 (group 3 vs group 1 one-sided adjusted p=0·70). Severe neutropenia occurred in nine (26%) of 34 patients in group 1, 12 (36%) of 33 patients in group 2, and eight (23%) of 35 patients in group 3 (p=0·70). Overall survival was 12·6 months (IQR 5·8-15·6) in group 1, 20·1 months (9·4-not reached) in group 2, and 17·8 months (8·8-not reached) in group 3 (group 3 vs group 1 two-sided p=0·0023). The most common treatment-emergent adverse events were anaemia (22 [73%] of 34), neutropenia (21 [70%]), and thrombocytopenia (18 [60%]) in group 1; neutropenia (27 [82%] of 33), thrombocytopenia (18 [55%]) and anaemia (17 [52%]) in group 2; and neutropenia (23 [66%] of 35), thrombocytopenia (22 [63%]), and nausea (17 [49%]) in group 3. There were no treatment-related deaths.

INTERPRETATION

No significant differences were observed in myelosuppression endpoints with trilaciclib plus gemcitabine and carboplatin in patients with metastatic triple-negative breast cancer; however, the regimen was generally well tolerated and overall survival results were encouraging. Further studies of trilaciclib in this setting are warranted.

FUNDING

G1 Therapeutics.

Abstract PD1-01: Trilaciclib (T), a CDK4/6 inhibitor, dosed with gemcitabine (G), carboplatin (C) in metastatic triple negative breast cancer (mTNBC) patients: Preliminary phase 2 results

Background: Cytotoxic chemotherapy-induced damage of hematopoietic stem and progenitor cells (HSPCs) results in acute toxicities consisting of multi-lineage myelosuppression, and late onset toxicities consisting of progressive bone marrow suppression with increased incidence of therapy-related myeloid neoplasms. T is an IV CDK4/6 inhibitor in development to preserve HSPC and immune system function during cytotoxic chemotherapy (myelopreservation). Proof of concept for myelopreservation with T was observed in a randomized, placebo-controlled Phase 2 trial in small-cell lung cancer patients receiving 1st-line chemotherapy. This trial in mTNBC patients (NCT02978716) was designed to explore the utility of T in combination with GC.

Methods: This Phase 2, randomized, open-label study enrolled patients in the US and EU with mTNBC who had received 0-2 prior systemic cytotoxic therapies in the locally recurrent or metastatic setting and had no symptomatic brain metastases. Patients were randomized (1:1:1) to GC alone (Group 1) or T plus GC (Group 2) using a standard schedule (D1, 8 every 21 days) or to an alternative schedule (T on D1, 2, 8 and 9 with GC on D2 and 9 every 21 days; Group 3). On those days when both T and GC were scheduled, T was administered iv prior to GC infusion. Prophylactic growth factors were not administered in cycle 1; otherwise supportive care was allowed as needed. Primary objectives were safety and tolerability; tumor response was evaluated using RECIST v1.1 and PFS and OS were assessed. Myelopreservation endpoints reflecting the potential effects of T on multiple cellular lineages include occurrence of Grade 4 neutropenia (primary), RBC and platelet transfusions (primary), and lymphocyte counts with immune profiling (secondary and exploratory). A signature of CDK4/6 independence developed from preclinical data will be used to evaluate archival tumor tissue samples and data analysis is ongoing.

Results: 95 patients were dosed; median age 57 years (range 32,86), ECOG PS 0 (53%) or 1 (47%), 25% had liver metastases at baseline, and approximately 50% had received no systemic therapy in the recurrent/metastatic setting. Fifty-five patients remain on treatment. Disease progression was the most common reason for drug discontinuation (22/40; 55%). Overall the most common (≥ 25%) TEAEs were anemia (47%), nausea (35%), fatigue (34%), neutropenia (32%), platelet count decreased (25%), and vomiting (25%). The most frequent (≥ 15%) Grade 3 or 4 TEAEs were hematologic toxicities, i.e. neutropenia (28%), anemia (21%), neutrophil count decreased (21%) and thrombocytopenia (16%). These were also the most frequent drug-related TEAEs observed. Tumor efficacy data are being evaluated.

Conclusions: This trial, assessing the myelopreservation effects of T when combined with GC in patients with mTNBC, has completed enrollment. Myelopreservation data, immune profiling, as well as ORR and preliminary PFS results will be presented by study arm at the meeting.

Citation Format: O'Shaughnessy J, Wright GS, Thummala AR, Danso MA, Popovic L, Pluard TJ, Cheung E, Han HS, Daniel BR, Vojnovic Z, Vasev N, Ling M, Richards DA, Wilks ST, Milenkovic D, Sorrentino JA, Roberts PJ, Bomar M, Yang Z, Antal JM, Malik RK, Morris SR, Tan A. Trilaciclib (T), a CDK4/6 inhibitor, dosed with gemcitabine (G), carboplatin (C) in metastatic triple negative breast cancer (mTNBC) patients: Preliminary phase 2 results [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD1-01.

A phase I, open-label, two-stage study to investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of the oral AKT inhibitor GSK2141795 in patients with solid tumors

Background We sought to determine the recommended phase II dose (RP2D) and schedule of GSK2141795, an oral pan-AKT kinase inhibitor. Patients and Methods Patients with solid tumors were enrolled in the dose-escalation phase. Pharmacokinetic (PK) analysis after a single dose (Cycle 0) informed dose escalation using accelerated dose titration. Once one grade 2 toxicity or dose-limiting toxicity was observed in Cycle 1, the accelerated dose titration was terminated and a 3 + 3 dose escalation was started. Continuous daily dosing was evaluated along with two intermittent regimens (7 days on/7 days off and 3 times per week). In the expansion phase at RP2D, patients with endometrial or prostate cancer, as well as those with select tumor types with a PIK3CA mutation, AKT mutation or PTEN loss, were enrolled. Patients were evaluated for adverse events (AEs), PK parameters, blood glucose and insulin levels, and tumor response. Results The RP2D of GSK2141795 for once-daily dosing is 75 mg. The most common (>10%) treatment-related AEs included diarrhea, fatigue, vomiting, and decreased appetite. Most AEs were low grade. The frequency of hyperglycemia increased with dose; however, at the RP2D, grade 3 hyperglycemia was only reported in 4% of patients and no grade 4 events were observed. PK characteristics were favorable, with a prolonged half-life and low peak-to-trough ratio. There were two partial responses at the RP2D in patients with either a PIK3CA mutation or PTEN loss. Conclusion GSK2141795 was safe and well-tolerated, with clinical activity seen as monotherapy at the RP2D of 75 mg daily. NCT00920257.

Abstract C132: Effect of hepatic or renal impairment on the pharmacokinetics of casopitant

Introduction: The pharmacokinetics and safety of casopitant, a neurokinin-1 receptor antagonist being developed for the prevention of chemotherapy-induced and post-operative nausea and vomiting, were evaluated in subjects with mild (Child-Pugh score of 5–6) and moderate (Child-Pugh score of 7–9) hepatic impairment; mild (creatinine clearance 50–80 mL/min) and moderate (creatinine clearance 30–49 mL/min) renal impairment; and subjects with normal hepatic and renal function.

Experimental Design: Twenty-six subjects were enrolled in the hepatic impairment study (9 mild, 9 moderate and 8 normal subjects) and 18 subjects in the renal impairment study (6 mild, 6 moderate and 6 normal subjects). Subjects with severe hepatic or renal impairment were excluded. All subjects received a once-daily dose of 100 mg oral casopitant for 5 days. Pharmacokinetics and plasma protein binding of casopitant and its major metabolite, GSK525060, were determined on Days 1 and 5. Safety was continuously assessed.

Results: Subjects with mild or moderate hepatic impairment had an increase in casopitant AUC of 11% and 24%, respectively, on Day 1 compared with normal subjects; a similar increase was observed on Day 5. Casopitant Cmax was variable, but similar across all subjects. GSK525060 AUC was not significantly different between normal subjects and subjects with mild hepatic impairment; however, AUC was reduced 29% and 19% on Days 1 and 5, respectively, in subjects with moderate hepatic impairment. The percent bound of casopitant and GSK525060 was similar in all subjects. Casopitant AUC increased 34% and 22% in subjects with mild or moderate renal impairment on Day 1, respectively, and 28% and 11% on Day 5, respectively, when compared with normal subjects. GSK525060 AUC increased 17% and 24% on Days 1 and 5, respectively, in subjects with mild renal impairment, but did not significantly change in subjects with moderate impairment. Further age-adjusted analysis showed no meaningful effect of renal impairment on casopitant or GSK525060 AUC. Cmax and half-life in renal impaired subjects were similar to normal subjects. The plasma protein-binding of casopitant and GSK525060 was similar in all subjects. Casopitant was well tolerated, with no significant difference in the type or frequency of adverse events (AEs) noted between subjects with mild, moderate or no hepatic or renal impairment. Somnolence, flatulence and nausea were the most frequently reported AEs in the hepatic impairment study; whereas constipation and dyspepsia were the most frequently reported events in the renal impairment study. No AEs were reported in subjects with mild renal impairment.

Conclusion: The pharmacokinetics of casopitant is not altered to a clinically significant extent in subjects with mild or moderate, hepatic or renal impairment. The impact of severe hepatic or renal impairment on the pharmacokinetics and safety of casopitant was not evaluated.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C132.

Amyloid beta and amylin fibrils induce increases in proinflammatory cytokine and chemokine production by THP-1 cells and murine microglia

Activated microglia surrounding amyloid beta-containing senile plaques synthesize interleukin-1, an inflammatory cytokine that has been postulated to contribute to Alzheimer's disease pathology. Studies have demonstrated that amyloid beta treatment causes increased cytokine release in microglia and related cell cultures. The present work evaluates the specificity of this cellular response by comparing the effects of amyloid beta to that of amylin, another amyloidotic peptide. Both lipopolysaccharide-treated THP-1 monocytes and mouse microglia showed significant increases in mature interleukin-1beta release 48 h following amyloid beta or human amylin treatment, whereas nonfibrillar rat amylin had no effect on interleukin-1beta production by THP-1 cells. Lipopolysaccharide-stimulated THP-1 cells treated with amyloid beta or amylin also showed increased release of the proinflammatory cytokines tumor necrosis factor-alpha and interleukin-6, as well as the chemokines interleukin-8 and macrophage inflammatory protein-1alpha and -1beta. THP-1 cells incubated with fibrillar amyloid beta or amylin in the absence of lipopolysaccharide also showed significant increases of both interleukin-1beta and tumor necrosis factor-alpha mRNA. Furthermore, treatment of THP-1 cells with amyloid fibrils resulted in an elevated expression of the immediate-early genes c-fos and junB. These studies provide further evidence that fibrillar amyloid peptides can induce signal transduction pathways that initiate an inflammatory response that is likely to contribute to Alzheimer's disease pathology.

Surfactant suppresses NF-kappa B activation in human monocytic cells

In addition to biophysical properties, pulmonary surfactant has immunomodulatory activity. We previously demonstrated that both synthetic (Exosurf) and modified natural surfactant (Survanta) downregulated endotoxin-stimulated inflammatory c ytokine mRNA levels and protein products (tumor necrosis factor-alpha [TNF], interleukin-1-beta [IL-1], interleukin-6 [IL-6]) in human alveolar macrophages. In this study, we report that both Exosurf and Survanta suppress TNF mRNA and secretion (85 +/- 4% mean percent inhibition +/- SEM by Exosurf; 71 +/- 6% by Survanta) by endotoxin-stimulated THP-1, a human monocytic cell line. Because surfactant downregulated inflammatory cytokine production similarly in both normal human alveolar macrophages and the THP-1 cell line, we used this cell line to investigate whether surfactant affected transcriptional mechanisms. Specifically, we examined nuclear factor-kappa B (NF-kappa B) activation because it is crucial in transcriptional regulation of many inflammatory cytokine genes including TNF, IL-1, and IL-6. Electrophoretic mobility shift assays showed that both surfactants decreased activation of NF-kappa B. The presence of both p65 and p50 NF-kappa B components in LPS-activated THP-1 cells was confirmed by specific antibody induction of supershifts in mobility assays. These results are the first to suggest that surfactant's suppressive effects on inflammatory cytokine production may involve transcriptional regulation through inhibition of NF-kappa B activation.

Surfactant downregulates synthesis of DNA and inflammatory mediators in normal human lung fibroblasts

The initial inflammatory event in the adult respiratory distress syndrome (ARDS) is followed by fibroproliferation and a cascade of fibroblast-derived mediators. Because lung fibroblasts may be exposed to surfactant as well as inflammatory cytokines during ARDS, we hypothesized that surfactant might modulate fibroblast activity. We previously demonstrated that surfactant inhibited production of inflammatory cytokines from endotoxin-stimulated human alveolar macrophages. In the current study the effects of surfactant on normal human lung fibroblast proliferative capacity and mediator production were examined. Both synthetic (Exosurf) and natural (Survanta) surfactant inhibited fibroblast [3H]thymidine incorporation. Examination of pre-S-phase events indicated stimulation of the immediate response gene, c-fos, and no effect on the G1/S cyclin, cyclin D1, suggesting that the surfactant block occurred elsewhere before S phase. The antioxidant N-acetyl-L-cysteine (NAC), like surfactant, inhibited [3H]thymidine incorporation. Furthermore, menadione, a generator of intracellular H2O2, stimulated fibroblast [3H]thymidine incorporation, and this was inhibited by surfactant. Interleukin-1 (IL-1)-stimulated secretion of the inflammatory mediators, IL-6 and prostaglandin E2, was also inhibited by surfactant. These data suggest that surfactant may modify lung fibroblast participation in ARDS sequelae by downregulating DNA synthesis and secondary inflammatory mediator production.

Regulation of human alveolar macrophage inflammatory cytokines by tyloxapol: a component of the synthetic surfactant Exosurf

We previously demonstrated that the synthetic surfactant Exosurf and a modified natural surfactant, Survanta, both down-regulated endotoxin-stimulated production of inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1 beta, interleukin-6) in human alveolar macrophages. To further characterize the source of the inhibitory effect of surfactant, the three individual components of Exosurf were evaluated. Dipalmitoylphosphatidylcholine had no effect on endotoxin-stimulated cytokine secretion. Cetyl alcohol (spreading agent) compromised macrophage function as measured by adherence. However, at concentrations equivalent to those found in the complete surfactant (Exosurf) preparation, tyloxapol (nonionic dispersing agent) was inhibitory in a dose-dependent manner. The viability of alveolar macrophages as assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide cleavage assay was not affected by incubation in Exosurf or any of its individual components. Cytokine secretion and mRNA levels of endotoxin-stimulated alveolar macrophages were decreased by tyloxapol. These data suggest that tyloxapol alone, like Exosurf, has an inhibitory effect on cytokine production which may be pretranslationally mediated.

Characterization of exosurf (surfactant)-mediated suppression of stimulated human alveolar macrophage cytokine responses

Previous studies in our laboratory demonstrated that the synthetic surfactant Exosurf (Burroughs Wellcome Co.) inhibited endotoxin-stimulated cytokine secretion from human alveolar macrophages in vitro. The purpose of the present study was to further characterize the suppressive effects of Exosurf, which consists of dipalmitoylphosphatidylcholine (DPPC), cetyl alcohol (spreading agent), and tyloxapol (nonionic dispersing agent). Suppression was not stimulus specific in that Exosurf also significantly reduced cytokine production elicited by either Staphylococcus aureus or recombinant interleukin-1. Suppression was also mediated by a modified bovine surfactant (Survanta), which, in contrast to Exosurf, contains the surfactant-associated proteins B and C, and several different phospholipids, but no cetyl alcohol or tyloxapol. This suggests that suppression of macrophage cytokines is not specific to Exosurf. Both cell associated and secreted tumor necrosis factor and interleukin-1 were reduced by Exosurf, indicating that Exosurf is not simply blocking cytokine release. At 3 h, cytokine mRNA levels were not different between Exosurf-treated and untreated cells. However, at 8 and 24 h, cytokine mRNA levels were lower in Exosurf-treated cells. The observations that mRNA levels were decreased at 8 and 24 h and that cellular cytokine release was not blocked suggest that Exosurf's effect may in part be pretranslationally mediated. Collectively, these data add to previous work indicating that pulmonary surfactant may play a critical role in reducing inflammatory cytokine production associated with the adult respiratory distress syndrome and similar disorders.

Immunomodulatory effects of recombinant interleukin-3 treatment on human alveolar macrophages and monocytes

The purpose of these studies was to examine the effects of in vivo and in vitro recombinant IL-3 treatment on alveolar macrophage and monocyte activities associated with antitumor and antimicrobial properties. Alveolar macrophages and blood monocytes from 6 patients receiving IL-3 (125-500 micrograms/m2/day) subcutaneously were isolated before therapy and at various times during the 15 days of therapy. Results indicated that tumor necrosis factor-alpha (TNF), interleukin-1 beta (IL-1), and interleukin-6 (IL-6) secretion were enhanced from monocytes of all patients and from alveolar macrophages of patients receiving 500 micrograms/m2/day IL-3. Constitutive cytokine gene expression was present before therapy, but further enhancement was not detectable during therapy, suggesting a rapid time course of cytokine gene transcription and translation. Serum neopterin levels were elevated 2-5 fold in all patient compatible with the presence of augmented monocyte/macrophage activity. Peak levels of neopterin did not coincide with peak levels of cytokine secretion. In vitro studies of IL-3-treated normal alveolar macrophage and monocyte population demonstrated that IL-3 significantly augmented TNF and IL-6 secretion in monocytes, but not in alveolar macrophages. These differences in alveolar macrophage cytokine secretion observed after in vivo and in vitro IL-3 treatment may reflect the involvement of other cell populations in IL-3 modulation of alveolar macrophages in vivo. Monocytes, in contrast were comparably activated by IL-3 whether presented in vitro or in vivo.

Synthetic surfactant (Exosurf) inhibits endotoxin-stimulated cytokine secretion by human alveolar macrophages

Tumor necrosis factor-alpha (TNF), interleukin-1 beta (IL-1), interleukin-6 (IL-6), and interleukin-8 (IL-8) are inflammatory cytokines produced by alveolar macrophages (AMs) and implicated in sepsis-related adult respiratory distress syndrome (ARDS). Preliminary findings from clinical trials suggest that aerosolized delivery of the synthetic surfactant Exosurf (Burroughs Wellcome Co.) reduces mortality in patients with sepsis-induced ARDS. The purpose of the present study was to examine the effect of Exosurf on inflammatory cytokine secretion from AMs in vitro. AMs were obtained from normal nonsmoking adult volunteers. Secreted TNF, IL-1, IL-6, and IL-8 were measured by enzyme-linked immunoassays in 24 h culture fluids of AMs. Exosurf inhibited LPS-stimulated TNF, IL-1, and IL-6 secretion in a dose-dependent fashion. IL-8 secretion was not affected by Exosurf under these conditions. However, if AMs were preincubated for 24 h in media and then LPS-stimulated, IL-8 secretion was inhibited by Exosurf. Regulation of IL-8 production may differ from TNF, IL-1, and IL-6. Unstimulated cytokine secretion was not affected by any of the tested concentrations of Exosurf. The inhibitory effect of Exosurf on endotoxin-induced cytokine secretion by human AMs suggests that Exosurf may modulate inflammatory cytokine production in the lung.

Opsonin-independent phagocytosis of group B streptococci: role of complement receptor type three

The role of complement receptor type 3 (CR3) in nonopsonic recognition of group B streptococci (GBS) by macrophages was investigated. Monoclonal anti-CR3 (anti-Mac-1) inhibited phagocytosis of GBS strains by as much as 50% in serum-free cultures of both mouse peritoneal macrophages and the macrophage cell line PU5-1.8. GBS uptake was unaffected by the presence of anti-C3 or salicylhydroxamate, an inhibitor of the covalent binding reaction of C3. Soluble antibodies to LFA-1 or to the common beta-chain (CD18) of the LFA-1/CR3/p150,95 family of cell adhesion molecules did not inhibit GBS uptake. Down-modulation of surface Mac-1 on macrophages following adherence to anti-Mac-1- or anti-CD18-coated surfaces also inhibited uptake of GBS. Further evidence for GBS interaction with CR3 was demonstrated by reduction of EC3bi rosette formation in macrophages adherent to GBS-coated plates. These studies suggest that GBS can interact with macrophage CR3, promoting phagocytosis in a C3-independent fashion. In the absence of specific immunity in neonates, this recognition mechanism may be a significant virulence determinant for GBS which poorly activate the alternate complement pathway.