Molgramostim – GM-CSF and PAP
Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare disease characterized by progressive surfactant accumulation and hypoxemia. It is caused by disruption of granulocyte–macrophage colony-stimulating factor (GM-CSF) signaling, which pulmonary alveolar macrophages require to clear surfactant. Recently, inhaled GM-CSF was shown to improve the partial pressure of arterial oxygen in patients with aPAP.
In a double-blind, placebo-controlled, three-group trial, we randomly assigned patients with aPAP to receive the recombinant GM-CSF molgramostim (300 μg once daily by inhalation), either continuously or intermittently (every other week), or matching placebo. The 24-week intervention period was followed by an open-label treatment-extension period. The primary end point was the change from baseline in the alveolar–arterial difference in oxygen concentration (A-aDo2) at week 24.
In total, 138 patients underwent randomization; 46 were assigned to receive continuous molgramostim, 45 to receive intermittent molgramostim, and 47 to receive placebo. Invalid A-aDo2data for 4 patients (1 in each molgramostim group and 2 in the placebo group) who received nasal oxygen therapy during arterial blood gas measurement were replaced by means of imputation. For the primary end point — the change from baseline in the A-aDo2 at week 24 — improvement was greater among patients receiving continuous molgramostim than among those receiving placebo (−12.8 mm Hg vs. −6.6 mm Hg; estimated treatment difference, −6.2 mm Hg; P=0.03 by comparison of least-squares means). Patients receiving continuous molgramostim also had greater improvement than those receiving placebo for secondary end points, including the change from baseline in the St. George’s Respiratory Questionnaire total score at week 24 (−12.4 points vs. −5.1 points; estimated treatment difference, −7.4 points; P=0.01 by comparison of least-squares means). For multiple end points, improvement was greater with continuous molgramostim than with intermittent molgramostim. The percentages of patients with adverse events and serious adverse events were similar in the three groups, except for the percentage of patients with chest pain, which was higher in the continuous-molgramostim group.
In patients with aPAP, daily administration of inhaled molgramostim resulted in greater improvements in pulmonary gas transfer and functional health status than placebo, with similar rates of adverse events.
Articles and Abstracts
Inhaled granulocyte/macrophage-colony stimulating factor (GM-CSF) is a promising therapy for pulmonary alveolar proteinosis (PAP) but has not been adequately studied.
To evaluate safety and efficacy of inhaled GM-CSF in patients with unremitting or progressive PAP.
We conducted a national, multicenter, self-controlled, phase II trial at nine pulmonary centers throughout Japan. Patients who had lung biopsy or cytology findings diagnostic of PAP, an elevated serum GM-CSF antibody level, and a Pa(O(2)) of less than 75 mm Hg entered a 12-week observation period. Those who improved (i.e., alveolar-arterial oxygen difference [A-aDO(2)] decreased by 10 mm Hg) during observation were excluded. The rest entered sequential periods of high-dose therapy (250 microg Days 1-8, none Days 9-14; x six cycles; 12 wk); low-dose therapy (125 microg Days 1-4, none Days 5-14; x six cycles; 12 wk), and follow-up (52 wk).
Measurements and Main Results
Fifty patients with PAP were enrolled in the study. During observation, nine improved and two withdrew; all of these were excluded. Of 35 patients completing the high- and low-dose therapy, 24 improved, resulting in an overall response rate of 62% (24/39; intention-to-treat analysis) and reduction in A-aDO(2) of 12.3 mm Hg (95% confidence interval, 8.4-16.2; n = 35, P < 0.001). No serious adverse events occurred, and serum GM-CSF autoantibody levels were unchanged. A treatment-emergent correlation occurred between A-aDO(2) and diffusing capacity of the lung, and high-resolution CT revealed improvement of ground-glass opacity. Twenty-nine of 35 patients remained stable without further therapy for 1 year.
Inhaled GM-CSF therapy is safe, effective, and provides a sustained therapeutic effect in autoimmune PAP.
Autoimmune pulmonary alveolar proteinosis (aPAP) is caused by granulocyte/macrophage-colony stimulating factor (GM-CSF) autoantibodies in the lung. Previously, we reported that GM-CSF inhalation therapy improved alveolar-arterial oxygen difference and serum biomarkers of disease severity in these patients. It is plausible that inhaled GM-CSF improves the dysfunction of alveolar macrophages and promotes the clearance of the surfactant. However, effect of the therapy on components in bronchoalveolar lavage fluid (BALF) remains unclear.
To figure out changes in surfactant clearance during GM-CSF inhalation therapy.
We performed retrospective analyses of BALF obtained under a standardized protocol from the same bronchus in each of 19 aPAP patients before and after GM-CSF inhalation therapy (ISRCTN18931678, JMA-IIA00013; total dose 10.5–21 mg, duration 12–24 weeks). For evaluation, the participants were divided into two groups, high responders with improvement in alveolar-arterial oxygen difference ≥13 mmHg (n = 10) and low responders with that < 13 mmHg (n = 9).
Counts of both total cells and alveolar macrophages in BALF did not increase during the therapy. However, total protein and surfactant protein-A (SP-A) were significantly decreased in high responders, but not in low responders, suggesting that clearance of surfactant materials is correlated with the efficacy of the therapy. Among 94 biomarkers screened in bronchoalveolar lavage fluid, we found that the concentration of interleukin-17 and cancer antigen-125 were significantly increased after GM-CSF inhalation treatment.
GM-CSF inhalation decreased the concentration of total protein and SP-A in BALF, and increase interleukin-17 and cancer antigen-125 in improved lung of autoimmune pulmonary alveolar proteinosis.
Autoimmune pulmonary alveolar proteinosis (aPAP) is a rare pulmonary disease caused by functional deficiency of granulocyte-macrophage colony-stimulating factor (GM-CSF). Administration of GM-CSF represents a potential therapeutic strategy in management of aPAP. Herein, we systematically review the efficacy of GM-CSF therapy in aPAP.
We searched the PubMed and EmBase databases for studies reporting the use of GM-CSF in aPAP. We calculated the proportion with 95% Cl to assess the response and relapse rates of GM-CSF therapy in individual studies and pooled them using a random-effects model. Statistical heterogeneity was assessed using the 12 and Cochran Q tests. Publication bias was analyzed using funnel plot and Egger and Begg-Mazumdar tests.
Our initial searches yielded 1,585 studies. Of these, five observational studies (involving 94 patients) were included for analysis. Three studies used the subcutaneous route, and two studies used the inhalational route for GM-CSF administration. The response rate of GM-CSF varied from 43% to 92%, with the pooled response rate being 58.6% (95% Cl, 42.7-72.9). The relapse rate in GM-CSF responders was 29. 7% (95% Cl, 10.5-60.4). There was no evidence of statistical heterogeneity or publication bias for the outcome of response. GM-CSF therapy was associated with minor complications, such as fever and local complications at the site of administration.
GM-CSF represents a useful approach in the treatment of aPAP. The optimal indication, dose and duration of therapy, and the factors predicting response and relapse need to be defined by future studies.
Treatment of autoimmune pulmonary alveolar proteinosis (aPAP) by subcutaneous injection or inhaled therapy of granulocyte-macrophage colony-stimulating factor (GM-CSF) has been demonstrated to be safe and efficacious in several reports. However, some reports of subcutaneous injection described transient benefit in most instances. The durability of response to inhaled GM-CSF therapy is not well characterized.
To elucidate the risk factors for recurrence of aPAP after GM-CSF inhalation, 35 patients were followed up, monitoring for the use of any additional PAP therapies and disease severity score every 6 months. Physiologic, serologic, and radiologic features of the patients were analyzed for the findings of 30-month observation after the end of inhalation therapy.
During the observation, 23 patients remained free from additional treatments, and twelve patients required additional treatments. There were no significant differences in age, sex, symptoms, oxygenation indexes, or anti-GM-CSF antibody levels at the beginning of treatment between the two groups. Baseline vital capacity (% predicted, %VC) were higher among those who required additional treatment (P < .01). Those patients not requiring additional treatment maintained the improved disease severity score initially achieved. A significant difference in the time to additional treatment between the high %VC group (%VC ≥ 80.5) and the low %VC group wafs seen by a Kaplan-Meier analysis and a log-rank test (P < .0005).
These results demonstrate that inhaled GM-CSF therapy sustained remission of aPAP in more than one-half of cases, and baseline %VC might be a prognostic factor for disease recurrence.
Granulocyte macrophage-colony-stimulating factor (GM-CSF) causes variable improvement in autoimmune pulmonary alveolar proteinosis (aPAP). Upon response to short-term treatment, patients are divided into responders and non-responders. The aim of this study was to test the hypothesis that long-term inhaled GM-CSF (iGM-CSF) is effective in all patients and that attainment of remission permits gradual de-escalation of the dose to the lowest effective safe dose.
Patients were treated with iGM-CSF 250 μg once a day given 4 days on and 4 days off for as long as necessary (the “as far as it takes” protocol). Upon remission, defined as absence of symptoms, oxygen desaturation <4 % at the walking test, and significant radiographic reduction of the infiltrates, or at least two of the above, the iGM-CSF dose was de-escalated. In the case of relapse, the patient was repositioned at the previous effective dose. Patients were investigated at 6-month intervals. To detect hematopoietic effects, blood cell counts, CD34+ cells, granulocyte macrophage progenitor colony-forming-units, and burst-forming-unit erythroid were measured.
Six (five female) patients 43.8 ± 15.7 years of age were treated for 14-65 months and all responded to treatment. Remission was achieved after 25.6 ± 10 months. Three patients maintained remission at their lowest effective dose. Two patients relapsed at de-escalating doses. One patient remains on full-dose treatment. iGM-CSF had no impact on any of the hematological parameters tested.
In aPAP, long-term adherence to the dose schedule permitted remission in all patients. Long-term treatment with iGM-CSF also permitted the definition of lower effective doses, minimizing disease burden and treatment costs safely, since no stimulating activity on hematopoiesis was observed, a fact that is of paramount importance for those aPAP patients needing lifelong treatment.
Pulmonary alveolar proteinosis is a disease characterized by abnormal accumulation of surfactant in the alveoli. Most cases are autoimmune and are associated with an autoantibody against granulocyte-macrophage colony-stimulating factor (GM-CSF) that prevents clearing of pulmonary surfactant by alveolar macrophages. An open-label, phase 2 study showed some therapeutic efficacy of inhaled recombinant human GM-CSF in patients with severe pulmonary alveolar proteinosis; however, the efficacy in patients with mild-to-moderate disease remains unclear.
We conducted a double-blind, placebo-controlled trial of daily inhaled recombinant human GM-CSF (sargramostim), at a dose of 125 μg twice daily for 7 days, every other week for 24 weeks, or placebo in 64 patients with autoimmune pulmonary alveolar proteinosis who had a partial pressure of arterial oxygen (Pao2) while breathing ambient air of less than 70 mm Hg (or <75 mm Hg in symptomatic patients). Patients with severe pulmonary alveolar proteinosis (Pao2 <50 mm Hg) were excluded to avoid possible exacerbation of the disease in patients who were assigned to receive placebo. The primary end point was the change in the alveolar-arterial oxygen gradient between baseline and week 25.
The change in the mean (±SD) alveolar-arterial oxygen gradient was significantly better in the GM-CSF group (33 patients) than in the placebo group (30 patients) (mean change from baseline, -4.50±9.03 mm Hg vs. 0.17±10.50 mm Hg; P = 0.02). The change between baseline and week 25 in the density of the lung field on computed tomography was also better in the GM-CSF group (between-group difference, -36.08 Hounsfield units; 95% confidence interval, -61.58 to -6.99, calculated with the use of the Mann-Whitney U test and the Hodges-Lehmann estimate of confidence intervals for pseudo-medians). Serious adverse events developed in 6 patients in the GM-CSF group and in 3 patients in the placebo group.
In this randomized, controlled trial, inhaled recombinant human GM-CSF was associated with a modest salutary effect on the laboratory outcome of arterial oxygen tension, and no clinical benefits were noted. (Funded by the Japan Agency for Medical Research and Development and the Ministry of Health, Labor, and Welfare of Japan; PAGE ClinicalTrials.gov number, NCT02835742; Japan Medical Association Center for Clinical Trials number, JMA-IIA00205.).