Mr. Ken d'Entremont reports

MEDEXUS HIGHLIGHTS DATA ON TRECONDYV (TREOSULFAN) PRESENTED AT MDS 2023

Medexus Pharmaceuticals Inc. is highlighting positive new data on treosulfan that researchers at Toronto's Princess Margaret Hospital (PMH) recently presented at MDS 2023, the 17th annual International Congress on Myelodysplastic Syndromes, held in Marseille, France. The study, a retrospective analysis of patient outcomes, further confirms Medexus's optimism regarding treosulfan's potential positive impact in both Canada and the United States.

The study found that reduced toxicity conditioning (RTC) with fludarabine-treosulfan (FT) improves transplant outcomes in myeloablative conditioning (MAC) ineligible patients with myelodysplastic syndrome (MDS) who receive graft-versus-host disease (GVHD) prophylaxis with dual T-cell depletion (TCD). Notably, the study found a 30-per-cent improvement (83.2 per cent versus 53.2 per cent) in one-year overall survival for patients treated with treosulfan, among other positive findings.

"We are very encouraged by these new results of PMH's study, which are consistent with previous studies and further demonstrate the potential benefits of treosulfan," said Ken d'Entremont, Medexus's chief executive officer. "We see this latest evidence as yet another important indicator of this product's prospects, including because we view these results as equally relevant to patient communities in the United States market."

"Clinicians should always make the best choice possible for their patients, so we are very pleased with the data we presented at MDS 2023, as it further underscores the clinical and therapeutic utility of treosulfan," added Dr. Ivan Pasic from PMH.

The full abstract, which includes further discussion of the study's design and findings, was published in the Leukemia Research journal and is available on-line.

The MDS 2023 presentation is substantially consistent with the previously published final study results and analysis of the pivotal phase 3 clinical trial of treosulfan, which Medexus announced in June, 2022. Among other things, that earlier study demonstrated clinically relevant superiority of treosulfan over a reduced-intensity conditioning busulfan regimen with regard to event-free survival, that study's primary end point.

"We remain excited about the prospect of a treosulfan approval in the United States and about treosulfan's significant potential in the U.S. market," Mr. d'Entremont concluded. "If approved by the FDA, we expect that treosulfan would have a meaningful impact on Medexus's total revenue. For reference, as one indicator of the potential market opportunity, we estimate that a market-leading product in the United States generated approximately $126-million (U.S.) in peak annual revenue before genericization."

About Trecondyv (treosulfan)

Treosulfan is part of a preparative regimen for allogeneic hematopoietic stem cell transplantation, to be used in combination with fludarabine, used in treating eligible patients with acute myeloid leukemia and myelodysplastic syndromes.

Final study results and analysis of the pivotal phase 3 clinical trial of treosulfan conducted by Medac GmbH, which was published in the American Journal of Hematology, concluded that the study demonstrates clinically relevant superiority of treosulfan over a widely applied "reduced-intensity conditioning" busulfan regimen with regard to its primary end point, event-free survival. The publication also includes favourable conclusions on two key secondary end points, finding that overall survival with treosulfan was superior compared with busulfan and that non-relapse mortality for patients in the treosulfan arm was lower than for patients in the busulfan arm. For more information about the study and the publication, including a link to the full publication, see Medexus's June 6, 2022, press release, available through the investors section of Medexus's corporate website.

During the phase 3 clinical trial of treosulfan, treatment-emergent adverse events (TEAEs) were reported by 92.6 per cent of patients in the treosulfan treatment group. TEAEs were most commonly reported in the system organ classes (SOCs) of gastrointestinal disorders, general disorders and administration site conditions, and musculoskeletal and connective tissue disorders. TEAEs of at least CTCAE (common terminology criteria for adverse events) grade III were reported by 54.8 per cent of patients in the treosulfan treatment group. Severe adverse events were reported by 8.5 per cent of patients in the treosulfan treatment group.

For more information about Trecondyv (treosulfan), including important safety information, see the product monograph, which is available on Health Canada's website.

Treosulfan is approved by Health Canada for sale and use in Canada only and is not intended for export outside Canada. Medexus makes no representation that treosulfan is appropriate for, or authorized for sale to or use by, persons who are not located in Canada. Treosulfan is currently the subject of a regulatory review process with the U.S. Food and Drug Administration. Medexus holds exclusive commercialization rights to treosulfan in Canada and the United States.

About the study

PMH researchers determined that several studies have demonstrated favourable outcomes with FT RTC in MAC-ineligible patients with MDS undergoing allogeneic hematopoietic cell transplantation, but that none of these studies included individuals who received dual TCD for GVHD prophylaxis. The researchers therefore retrospectively analyzed outcomes with FT conditioning in a cohort of MAC-ineligible MDS patients who received dual TCD for GVHD prophylaxis.

The researchers compared transplant outcomes among 29 MDS patients who received FT to a propensity-score-matched cohort of 58 subjects who received conditioning with fludarabine, busulfan and 200 cGy (centigray) of total body irradiation (FBT200). The study concluded that RTC with FT improves transplant outcomes in MAC-ineligible patients with MDS who receive GVHD prophylaxis with dual TCD.

One-year overall survival (OS), relapse-free survival (RFS), GVHD- and relapse-free survival (GRFS), transplant related mortality, and relapse in FT and FBT200 patients were: 83.2 per cent versus 53.2 per cent (p equals 0.003), 76.1 per cent versus 42.7 per cent (p equals 0.005), 72.4 per cent versus 37.9 per cent (p equals 0.003), 8.6 per cent versus 33 per cent (p equals 0.01) and 15.3 per cent versus 24.3 per cent (p equals 0.38). There was no difference in day-100 grade 2 to 4 or grade 3 to 4 acute GVHD, or one-year all-grade chronic GVHD between the two groups: 20.8 per cent versus 15.5 per cent (p equals 0.42), zero per cent versus 8.6 per cent (p equals 0.37) and 17.5 per cent versus 29.8 per cent (p equals 0.24). FT was associated with superior OS, RFS and GRFS in multivariate analysis.

Median follow-up for the whole cohort was 20.5 months (range: 3.1 to 77.4). The groups were well matched: FT subjects included more men (p equals 0.01) and received a lower median CD34 cell dose (p equals 0.03). In both FT and FBT200 groups, dual TCD was the most common form of GVHD prophylaxis: 93.1 per cent and 91.4 per cent (p equals 1.0).

Medexus provided partial support for the research through supply of treosulfan.

About Medexus Pharmaceuticals Inc.

Medexus is a leading specialty pharmaceutical company with a strong North American commercial platform and a growing portfolio of innovative and rare disease treatment solutions. Medexus's current focus is on the therapeutic areas of oncology, hematology, rheumatology, autoimmune diseases, allergy and dermatology.

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