Grifols has completed patient follow-up in its Phase 3 SPARTA study of Prolastin-C in people with alpha-1 antitrypsin deficiency and emphysema.

SPARTA reaches final patient milestone

Grifols has announced the last patient last visit in SPARTA, a Phase 3 study investigating whether Prolastin-C can slow lung tissue loss in people with emphysema caused by alpha-1 antitrypsin deficiency.

The milestone means all 345 participants enrolled in the study have completed follow-up. Topline results are expected by the end of 2026.

SPARTA is a randomised, double-blind, placebo-controlled study comparing two weekly doses of Prolastin-C, 60 mg/kg and 120 mg/kg, with placebo over a three-year treatment period.

The study was conducted at 37 sites across 16 countries and uses whole-lung computed tomography (CT) densitometry as its primary efficacy endpoint.

ClinicalTrials.gov lists the study as Phase 3 and confirms that the primary outcome is the change from baseline in whole-lung PD15, a CT-based measure of lung density assessed during the treatment period.

Eduardo Herrero, Grifols’ executive vice president of biopharma industrial and scientific innovation, said: “The completion of patient follow-up in SPARTA marks a significant milestone for Grifols and the alpha-1 community.”

He added that the company was grateful to the patients, investigators and study teams involved in the trial.

Study tests unresolved question

Alpha-1 antitrypsin deficiency, also known as alpha-1, is an inherited condition caused by changes in the SERPINA1 gene that can result in low levels of alpha-1 antitrypsin, a protein that helps protect lung tissue.

People with severe deficiency can develop emphysema and other forms of chronic lung disease, sometimes at a younger age than people with typical COPD.

Prolastin-C is an intravenous alpha1-proteinase inhibitor used as augmentation therapy in adults with clinical evidence of emphysema caused by severe hereditary alpha1-proteinase inhibitor deficiency. The FDA-approved prescribing information states that it is administered at a dose of 60 mg/kg once a week.

However, an important question remains over whether augmentation therapy can slow the underlying progression of emphysema.

The FDA prescribing information states that the effect of augmentation therapy with alpha1-proteinase inhibitor products, including Prolastin-C, on the progression of emphysema has not been conclusively demonstrated in randomised controlled clinical trials.

That makes the SPARTA results potentially important for the field. Rather than simply measuring whether treatment raises alpha-1 antitrypsin levels, the study is designed to assess changes in lung tissue over three years.

CT densitometry is being used to measure changes in lung density, with additional study measures including lung function, quality of life, adverse events and severe COPD exacerbations.

Results could inform alpha-1 treatment

The study is testing both the currently established 60 mg/kg weekly dose and a higher 120 mg/kg dose against placebo.

ClinicalTrials.gov shows that participants received treatment for 156 weeks, followed by an end-of-study visit, with the study designed to assess both efficacy and safety.

Grifols said SPARTA is the largest randomised, double-blind, placebo-controlled study of augmentation therapy in alpha-1-related emphysema to date.

The company has also recently started the SWIFT-SC Phase 3 trial, which is evaluating a weekly subcutaneous alpha1-proteinase inhibitor for people with alpha-1 antitrypsin deficiency.

The immediate focus, however, will be on SPARTA’s topline results. Until those data are available, it remains unclear whether either Prolastin-C dose will demonstrate a benefit on the study’s primary measure of lung tissue loss.

If positive, the findings could provide clinical evidence addressing one of the key unanswered questions around augmentation therapy for alpha-1-related emphysema.