Inhaled GM-CSF in a Pulmonary Alveolar Proteinosis Patient Refractory to Plasmapheresis Combined with Multiple Whole Lung Lavages

A autoimmune Pulmonary Alveolar Proteinosis (PAP) patient with persistent disease underwent 3 Whole Lung Lavages (WLLs), 10 plasmapheresis sessions and further 3 WLL, from October 2004 to May 2007. Nevertheless HRTC and pulmonary function test (PFT) showed a persistent residual disease of mild degree. At the beginning of 2010, the patient was admitted to inhaled rGM-CSF (Sargramostim) therapy as compassionate treatment. GM-CSF was administered by Akita 2 nebulizer (Vectura), as follow: 250 mcg/ day every other week for 12 weeks, then 250 mcg/day on 2 consecutive days every 2 weeks for 6 months. Follow up visits were scheduled at 3, 10, 18, 30 months and after that once a year. Functional and HRCT data and PaO2 were collected. Since the start of the inhaled GM-CSF therapy, the patient no more required WLL. Furthermore we found a signifi cant increase in DLCO% (p=0.013) and FVC% (p=0.023) while %FEV1 show a positive trend. No substantial differences in blood gas analysis. The pulmonary involvement at HRCT shows a signifi cant decrease of lung infi ltrates (p=0.039) in terms of pathological segments. These data underscore the utility of inhaled GM-CSF not only in case of progressing disease but also in case of refractory patients with persistent lung infi ltrates, in order to increase the response rate. Case Report Inhaled GM-CSF in a Pulmonary Alveolar Proteinosis Patient Refractory to Plasmapheresis Combined with Multiple Whole Lung Lavages Francesca Mariani1, Elena Paracchini1, Davide Piloni2, Zamir Kadija1, Elena Salvaterra1, Laura Divizia1, Giuseppe Rodi3, Carmine Tinelli4, Federica Meloni1,2 and Ilaria Campo1* 1Pneumology Unit, Fondazione IRCCS Policlinico San Matteo, Italy 2Department of Internal Medicine, Pneumology Unit, University of Pavia, Pavia, Italy 3Department of Anesthesiology and Intensive Care, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy 4Clinical Epidemiology and Biometric Unit, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy Dates: Received: 10 March, 2017; Accepted: 04 April, 2017; Published: 06 April, 2017 *Corresponding author: Ilaria Campo, Pneumology Unit, Fondazione IRCCS Policlinico San Matteo, viale Golgi 19, 27100 Pavia, Italy, Tel: +39 0382 501007; Fax: +39 0382 502269; E-mail:


Introduction
Pulmonary alveolar proteinosis (PAP) is a rare pulmonary disease characterized by the accumulation of surfactant proteins and lipids within the alveoli, which is caused by a defective macrophage catabolism, due to a disruption in surfactant homeostasis [1].
PAP occurs as autoimmune, congenital and secondary forms. The autoimmune form is the most frequent, accounting for more than 90% of PAP cases and is associated to the presence of anti-GM-CSF (Granulocyte-Macrophage-Colony stimulating factor) autoantibodies directed towards the GM-CSF, which lead to a defective maturation of alveolar macrophages and thus impair their function in surfactant clearance [2]. Moreover, the anti GM-CSF autoantibodies impair the microbicidal activity of neutrophils [3], possibly explaining the basis for recurrent infections in PAP. Congenital forms are caused by mutations in genes coding for GM-CSF receptor [4]. Secondary forms are generally associated to hematological malignancies or exposure to inorganic materials or immunosuppressive drugs toxicity.
Clinical manifestations include progressive exertional dyspnea of insidious onset, or dyspnea and cough. Nail clubbing due to gas exchange impairment and changes in the ventilation/perfusion ratio may be present. However a large fraction of autoimmune PAP patients are asymptomatic (up to 31%) [5].
Disease progression is highly variable, ranging from spontaneous resolution to cardiorespiratory failure.
Chest HRTC fi ndings show areas of patchy ground-glass opacities and interlobular thickening whose combination determines the "crazy paving" pattern which is characteristic but not diagnostic of PAP.
Diagnosis is based on bronchoalveolar lavage (BAL), histology and chest HRTC fi ndings and on the presence of anti-GM-CSF autoantibodies for the autoimmune form.
The gold standard of treatment is the whole lung lavage (WLL), even if this procedure is not yet standardized [6,7] and is associated with a very variable response rate [8,9]. WLL physically removes the accumulated surfactant, however in some patients it is ineffective, despite repeated WLL treatments.

Case Report
In At the end of treatment, patient was evaluated by PFT and chest HRCT (Figure 3). We found a signifi cant increase in DLCO% (p=0.013) and FVC% (p=0.023) while %FEV1 showed a positive trend (Figure 4). No substantial differences in blood gas analysis were detected. The pulmonary involvement evaluated by the CT-assisted lung profusion score [14], showed a signifi cant decrease of lung infi ltrates (p=0.039) in terms of pathological segments. Of note, since the start of the inhaled rGM-CSF therapy, the patient did not deteriorate further and no more required WLL. No drug-related adverse effects were reported.

Discussion
This case report describes a relapsing disease not controlled by the standard WLL treatment, even if serially repeated. Although WLL still represents the gold standard for the treatment of PAP, the discovery of neutralizing anti-GM-CSF autoantibodies in the serum of autoimmune PAP patients led to plasmapheresis as a potential treatment option [10]. In this way, an improvement of the surfactant clearance could be gain by restoring the normal surfactant catabolism in alveolar macrophage, through the decrease of anti-GM-CSF autoantibodies serum level.
Nevertheless, even after multiple plasmapheresis, we did not obtain an improvement in clinical conditions nor a reduced need for WLL.
Previous studies have challenged the effi cacy of rGM-CSF supplementation in PAP patients, consequently subcutaneous and inhaled administration were considered. Although WLL is still considered the gold standard for treatment, the discovery of alveolar macrophage involvement and anti GM-CSF neutralizing antibodies led to the use of GM-CSF as a potential therapeutic approach for PAP.
In particular, two papers reported a positive but transient clinical response to subcutaneous administration, however the overall response rate was less than 50% of the patient treated. In the fi rst one, 14 autoimmune PAP patients received subcutaneously administered GM-CSF in escalating doses (5-20 mcg/kg/day) over a 3-month-period [15]. In the second study, 21 autoimmune PAP patients were treated with escalating subcutaneous doses of 5-18 mcg/kg/day for 6-12-months [16].
On the other hands, the overall response rate to inhaled rGM-CSF was about 68%, as reported in Wylam [17] and Tazawa [18], studies, with no drug-related adverse effects reported. The fi rst was a retrospective study including 12 autoimmune PAP patients, treated with a rGM-CSF dosage of 250 mg/day every other week (one patient required dose escalation at 500 mg/day and different treatment length). In the second one, 35 autoimmune PAP patients were treated according to an induction dose (250 mcg on days 1-8 of 14, x 6 cycles) followed by maintenance dose (125 mcg on days 1-4 of 14, x 6 cycles).
Since it is conceivable that in autoimmune PAP the alveolar space is the main site of rGM-CSF signal disruption, with the impairment of surfactant catabolism, then it is reasonable to propose rGM-CSF supplementation by inhalatory route.
Starting from these data and considering the unsuccessful results obtained with the therapeutic approaches tried before, we decided to admit our patient to inhaled rGM-CSF therapy.
From the start of the inhalatory treatment, our patient no more required WLL. Furthermore we found a signifi cant improvement in pulmonary function in terms of FVC% and DLCO%, while a positive trend of %FEV1 was identifi ed. Consistent with pulmonary function test data, the lung infi ltration gradually decreased during the inhaled rGM-CSF treatment.
Our experience demonstrates for the fi rst time how the administration of rGM-CSF by inhalatory route is more effi cacious than standard and unconventional therapy in refractory patients, leading to a signifi cant and persistent improvement which lasted years after the end of the treatment.
In conclusion, our results underscore the utility of inhaled rGM-CSF in case of relapsing and refractory disease, in order to increase the response rate and to avoid the recurrence of WLL.

Author's contribution
FMa, EP and ZK managed the patient during the follow up; ES and LD collected data; GR performed the whole lung lavages; CT analyzed data; IC coordinate the study and wrote the paper; DP wrote the paper; FMe revised the draft.