Phase III GRAPPA trial supports ATLG (Grafalon®) as standard of care in matched unrelated donor stem cell transplantation

Late-breaking data presented at EHA 2026 show that post-transplant cyclophosphamide (PTCy) did not demonstrate non-inferiority to ATLG for overall survival in matched unrelated donor allogeneic haematopoietic cell transplantation (allo-HCT).

Rapperswil-Jona, Switzerland – 9 July 2026. Neovii Pharmaceuticals AG highlights late-breaking results from the Phase III GRAPPA trial (NCT05153226), which was independently funded and conducted by DKMS, and presented by Prof. Johannes Schetelig at EHA 2026 in Stockholm, showing that post-transplant cyclophosphamide (PTCy) did not demonstrate non-inferiority to ATLG for overall survival in matched unrelated donor allogeneic haematopoietic cell transplantation. The findings also showed lower non-relapse mortality and lower infection-related mortality with ATLG, supporting its continued role as standard of care in this setting.

Lower non-relapse mortality with Grafalon:
Two-year non-relapse mortality was lower for Grafalon over PTCy (7% vs 13%; adj. HR 1.86; p=0.02). The higher non-relapse mortality observed in the PTCy group was specifically due to infections that occurred without concomitant severe acute or chronic GVHD.

Frederic Prince, PhD, Chief Executive Officer of Neovii Pharmaceuticals AG, said:

"These late-breaking data reinforce the clinical relevance of ATLG in matched unrelated donor transplantation and highlight the importance of balancing GvHD prevention with overall survival, non-relapse mortality and infection outcomes. We are encouraged to see independent investigators present findings that support the continued role of Grafalon^® in this setting."

About the GRAPPA trial

GRAPPA is a multicenter, independently funded, randomised Phase III trial conducted by the DKMS Clinical Trials Unit. It enrolled 640 patients with non-favorable risk AML, MDS or myeloproliferative neoplasms undergoing allo-HCT from an HLA-matched unrelated donor MUD (8/8 or 7/8 match). Patients were randomised 3:2 to receive either PTCy-100 (n=383; cyclophosphamide 50 mg/kg on days +3 and +4) or ATLG-30 (n=257; Grafalon® 10 mg/kg on days −3, −2 and −1), both in combination with tacrolimus and mycophenolate mofetil. Recruitment ran from March 2022 to December 2024, and protocol compliance was high, with the per-protocol population comprising 98% of the intention-to-treat population.

Key findings reported by the investigators

Primary endpoint – Overall survival

• The GRAPPA trial did not meet its primary endpoint, as the non-inferiority of PTCy versus ATLG-30 for OS was not demonstrated (p=0.85; adjusted hazard ratio 1.34).
• There was a clear numerical trend favoring ATLG-30 over PTCY, with 2-year OS of 75% (95% CI 69–80%) in the ATLG-30 group versus 68% (95% CI 63–73%) in the PTCY-100 group (p = 0.051).

Non-relapse mortality and safety

• ATLG-30 was associated with significantly lower 2-year non-relapse mortality: 7% versus 13% with PTCy-100 (HR 1.86, 95% CI 1.09–3.17; p = 0.02).
• ATLG-30 was also associated with significantly lower infection-related mortality at two years: 3.1% versus 7.7% with PTCy-100 (p = 0.023).
• ATLG-30 was associated with faster neutrophil engraftment (median 17 days with ATLG-30 vs. 21 days with PTCy-100; p < 0.001)
• 4-day shorter hospital stay (22 vs. 26 days; p < 0.001).
• Lower use of G-CSF to stimulate engraftment was reported with ATLG-30 over PTCY (26% ATLG-30 vs 58% PTCY, p<0.001)

GvHD outcomes

• There was no significant difference between treatment arms in acute (Grade III–IV 7% vs 7%, p=0.6) or one-year severe chronic GvHD (6% vs 10%, p=0.1) after PTCy-100 and ATLG-30 respectively

• A higher incidence of acute GVHD grade II–IV (26% ATLG-30, 21% PTCy-100; p=0.03) and of overall chronic GVHD (40% ATLG-30, 24% PTCy-100; p<0.001) was observed with ATLG-30 compared to PTCy.

• The higher rates of GvHD seen with ATLG-30 did not adversely affect overall survival, GvHD-free relapse-free survival (adj. HR 0.85, p=0.16), or relapse risk (HR 0.86, p=0.32).

The investigators concluded that ATLG plus tacrolimus/MMF should remain the standard of care for matched unrelated-donor HCT in countries where ATLG is available. Options to further improve the prevention of GvHD in adults and children should continue to be explored.

References

Stelljes M. et al. GVHD prophylaxis including ATG remains standard of care for HLA-compatible unrelated donor haematopoietic cell transplantation: Results from a large randomized controlled trial comparing ATG and PTCy. Abstract LB5009. European Hematology Association (EHA) 2026 Congress, Stockholm, June 2026. Available at: https://library.ehaweb.org/eha/2026/eha-2026/4217020/...

Schetelig J. GVHD prophylaxis including ATG remains standard of care for HLA-compatible unrelated donor hematopoietic cell transplantation: results from a large randomized controlled trial comparing ATG and PTCy. Oral presentation (abstract LB5009) presented at: European Hematology Association (EHA) 2026 Congress, Stockholm, 13 June 2026. https://pag.virtual-meeting.org/EHA/eha2026/en-GB/pag/session/97483

DKMS press release https://professional.dkms.org/news-events/grappa-study-new-evidence-on-gvhd-prevention-with-atlg-in-stem-cell-transplants-from-unrelated-donors

Schetelig J. EHA 2026 interview: IACH (International Academy for Clinical Hematology). Published June 2026. https://www.youtube.com/watch?v=bTeXU75MM-k

About DKMS

DKMS is an international non-profit organization dedicated to the fight against blood cancer and blood disorders. Through its registry of volunteer stem cell donors, DKMS works to give patients in need of a transplant the best possible chance of finding a matching unrelated donor. Beyond donor recruitment, DKMS advances the science of allogeneic hematopoietic stem cell transplantation through its own research, including investigator-initiated clinical trials run by the DKMS Clinical Trials Unit. (https://idw-online.de/de/news872527)

About Grafalon®

Grafalon® (anti-T-lymphocyte globulin, ATLG) is a polyclonal antibody therapy developed by Neovii and used in organ and stem cell transplantation. The therapy is designed to selectively deplete T lymphocytes and modulate immune responses to help reduce the risk of graft-versus-host disease (GvHD) and graft rejection. Grafalon is approved in multiple countries for transplant-related indications; with approved uses varying by country. These indications include the prevention of acute transplant rejection following solid organ transplantation when used in combination with other immunosuppressive medicines, the treatment of acute steroid-resistant transplant rejection, and the prevention of graft-versus host-disease (GvHD) in patients undergoing allogeneic stem cell transplantation. Grafalon has established clinical use with thousands of patients treated across different transplant settings. Grafalon is an important component of transplant protocols for patients with malignant and non-malignant hematologic diseases. Neovii continues to make Grafalon available in accordance with its approved indications and applicable local regulatory requirements.

About Neovii Pharmaceuticals AG

Neovii Pharmaceuticals AG is a Swiss-based, global, fully integrated, commercial-stage biopharmaceutical company focused on antibody-based immunotherapies. Headquartered in Switzerland, Neovii has more than three decades of experience in the development, manufacturing, and commercialization of polyclonal antibody therapies and operates a dedicated biotech manufacturing facility in the Munich area. The company employs approximately 200 people and commercializes its products in more than 50 countries worldwide. Neovii has established a strong position in specialized stem cell and solid organ transplant centers. Building on its established transplantation franchise, the company is advancing a strategic expansion into immune-mediated diseases, including an ongoing European randomized, double-blind, placebo-controlled Phase 2 study in Type 1 Diabetes.

Legal Disclaimer

The GRAPPA trial is an investigator-initiated, independently funded and conducted Phase III randomized clinical study. The findings reported in this release are based on data presented by the study investigators and should be interpreted within the context of the totality of clinical evidence.

Grafalon® (anti-T-lymphocyte globulin, ATLG) is approved in numerous countries for the prevention of graft-versus-host disease (GvHD) in patients undergoing allogeneic haematopoietic stem cell transplantation, although approved indications, patient populations and prescribing information may differ between jurisdictions. Nothing in this release should be interpreted as promoting the use of Grafalon® for any indication not approved under applicable local regulations.

This press release contains information about an independent clinical trial. The GRAPPA trial was designed, funded and conducted by DKMS independently of Neovii Pharmaceuticals AG. Results presented are those of the trial investigators. Grafalon® is a prescription-only medicine; please refer to the applicable prescribing information.

This press release contains information about an independent clinical trial. The GRAPPA trial was designed, funded and conducted by DKMS independently of Neovii Pharmaceuticals AG. Results presented are those of the trial investigators. Grafalon® is a prescription-only medicine; please refer to the applicable prescribing information.

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