About Inolimomab (LEUKOTAC®)

Formerly called bone marrow transplant, Hematopoietic Stem Cell Transplantation (HSCT) is the last therapeutic option for patients with certain blood cancers or severe immunodeficiency. In practice, the treatment is designed to replace the diseased blood cells of the patient with the hematopoietic stem cells of a matching donor (allograft).

Once grafted, these stem cells will produce new healthy and functional blood cells, including white blood cells that will allow patients to bridge their immune deficiency or to eliminate surviving cancer cells.

If this technique has made considerable progress in 60 years, half of transplant recipients are still victims of complications: side effects of conditioning pretreatment (that aims to prevent transplant rejection), long-term susceptibility to infections and Graft-versus-Host disease (GvHD). In the latter case, the donor’s over-active T-cells «turn against» the patient’s tissues: mucous membranes, skin, gastro-intestinal tract, liver and lungs. The acute form appears just after the transplant, the chronic form occurring several months later (preceded or not by an acute GvHD episode).

Affecting between 30 to 50% of patients, GvHD is the main complication of hematopoietic stem cell transplantation. To halt this disease, physicians use corticosteroids. The fact remains that some 30 to 50% of aGvHD patients are refractory or dependent to the steroid treatment.

To date limited therapeutic options are available for these patients with no standard treatment approved so far in Europe and only one in the US.

Inolimomab is an anti-IL-2 Rα monoclonal antibody active as an immunotherapy product for the treatment of steroid-refractory acute GvHD.

In acute GvHD, activated T cell lymphocytes from the allograft’s donor recognize and attack recipient tissues. T cell lymphocyte activation and proliferation is governed by the key IL-2/IL-2 receptor (IL-2 R) pathway.
By recognizing the subunit α of the IL-2 Receptor complex (IL-2 Rα) which is upregulated on T cells upon activation, inolimomab blocks the binding of the cytokine IL-2 on IL-2 Rα thereby inhibiting IL-2 signalling and donor T cell proliferation.

The efficacy of inolimomab in aGvHD relies on its specific potent immunosuppression on T cell lymphocytes through the blocking of the IL-2/IL-2 Rα pathway triggering the disease.

Considering that patients are currently facing a therapeutic emergency and with the full and benefiting from the support of many clinicians specialized in this pathology who have already administered inolimomab, ELSALYS BIOTECH is actively collecting data on clinical benefit and safety profile through cohort Compassionate Use Program, with the ongoing ATU in France and the planned expansion of similar Programs in other countries.

These data will support the company effort on the filing of marketing authorization applications in Europe and in the U.S.

On December 24, 2019, the French National Agency for the Medicines and Health Products Safety (ANSM) granted a Temporary Authorisation for Use (ATU) so-called cohort ATU (cATU) for LEUKOTAC® (inolimomab) for the treatment of acute cortico-resistant or corticosteroid-dependent Graft-versus-Host disease (grade II-IV) in adults and pediatric patients over 28 days of age (see press release issued January 9, 2020). This ATU has been renewed on December 24, 2020 (see press release issued April 13, 2021).

Inolimomab (LEUKOTAC®) received Orphan Drug Designation in Europe (March 2001) and in the U.S. (October 2002).