Dr. Fahar Merchant reports

MEDICENNA PROVIDES UPDATE ON ITS PRESENTATIONS AT THE 2024 ASCO ANNUAL MEETING

The American Society of Clinical Oncology (ASCO) has decided to reverse its decision and to withdraw Medicenna Therapeutics Corp.'s abstract entitled "Results from Ability-1 Monotherapy Dose Escalation Study with MDNA11, an Engineered Long-acting IL-2 agonist, in patients with advanced solid tumors," which had been initially selected for an oral podium presentation at ASCO's 2024 annual meeting. ASCO advised the company that the reason for this withdrawal was that the program committee had determined that the company had allegedly violated ASCO's prior-publication policy by previously reporting results at the 2024 annual meeting of the American Association of Cancer Research (AACR). No other concerns were raised by the ASCO program committee.

The company disagrees with the ASCO program committee's decision to withdraw the oral podium presentation. In the company's opinion, it did not violate the ASCO prior-publication policy. While the company did present results at the AACR, the AACR abstract explicitly referenced a data cut-off date of Dec. 23, 2023, and only continuing interim monotherapy results were presented, whereas the ASCO abstract specified that the results presented would focus on a complete phase 1 monotherapy data set without a data cut-off date. This complete data set was analyzed and prepared specifically for presentation at ASCO 2024.

"Medicenna is disappointed by ASCO's scientific program committee's decision, as we are now unable to share our ground-breaking results that demonstrate ongoing deep and durable responses in advanced solid tumours as a single agent in the Ability-1 clinical trial of MDNA11 at ASCO," said Dr. Fahar Merchant, president and chief executive officer of Medicenna. "The potential to present data from the Ability-1 trial at ASCO would have been a tremendous honour, reflecting the investment of many patients, their families and investigators in the trial that has demonstrated promising advancement in cancer care, bringing comfort of a potential cure to patients through development of this highly promising molecule. The Ability-1 trial demonstrates robust single-agent activity in tumour types not previously shown to have durable response to IL-2-based [interleukin-2] therapies -- a significant feat. Given the strong interest by many stakeholders in our MDNA11 program, we look forward to sharing the full high-impact data set at a special virtual event to be organized over the next two to four weeks, with more details to be announced shortly."

At the event, clinical data originally planned for the 2024 ASCO annual meeting and that have not previously been presented at any external conference, including AACR (summarized in an attached table), will be presented from the continuing phase 1/2 Ability-1 study evaluating MDNA11, a long-acting "beta-enhanced not-alpha" IL-2 superagonist, as both a monotherapy and in combination with pembrolizumab (Keytruda) in patients with advanced or metastatic solid tumours. The data set to be presented will include the full data from the monotherapy dose-escalation arm, updated data from the monotherapy dose-expansion arm and preliminary data from the combination study.

Notably, the MDNA11 abstract was submitted for presentation at the 2024 annual meeting of ASCO on Feb. 6, 2024. On March 29, 2024, the lead author was notified by the ASCO scientific program committee chair that the submitted abstract was accepted as an oral podium presentation. On April 5, 2024, AACR published the full abstracts for its 2024 annual meeting, including the MDNA11 abstract. On April 24, 2024, 19 days after the publication of the AACR abstracts, ASCO, and subsequently Medicenna, announced the acceptance of MDNA11's abstract as an oral presentation. However, ASCO subsequently decided to withdraw the MDNA11 abstract from the ASCO 2024 program, citing "prior publication policy violation."

Medicenna and the lead author requested ASCO to reconsider its withdrawal, explaining that while the data in the AACR 2024 abstract were time limited and in progress, the ASCO 2024 abstract covered the completed phase 1 portion of the study and a good-faith intent to provide substantially new data never previously presented at any other conference, including AACR 2024 (see an attached table). ASCO continues to maintain its position, and the company believes that it has fully exhausted all available avenues to secure a reversal of the decision by ASCO.

MDNA11 continues to demonstrate its potential to be a best-in-class IL-2 agonist through its compelling single-agent activity and has been differentiated from other IL-2's in clinical development by its deep and durable responses in the Ability-1 study amongst high-dose, phase-2-eligible patients (N equals 14) with advanced solid tumours who have failed checkpoint inhibitor therapies. As of the March 22, 2024, the data cut-off date, MDNA11 has demonstrated a response rate of 29 per cent (four partial responses) and a clinical benefit rate of 50 per cent (four partial responses, and three stable diseases greater than 24 weeks).

The second abstract of the company, offering new data analyses for bizaxofusp (formerly known as MDNA55), a phase-3-ready immunotherapy for recurrent glioblastoma, will be presented as a poster at the 2024 ASCO annual meeting, as previously announced by the company. The full text of the published abstracts can be found on the 2024 ASCO annual meeting.

About Medicenna Therapeutics Corp.

Medicenna is a clinical-stage immunotherapy company focused on developing novel, highly selective versions of IL-2, IL-4 and IL-13 superkines and first-in-class empowered superkines. Medicenna's long-acting IL-2 superkine, MDNA11, is a next-generation IL-2 with superior affinity toward CD122 (IL-2 receptor beta) and no CD25 (IL-2 receptor alpha) binding, thereby preferentially stimulating cancer-killing effector T cells and NK cells. Medicenna's IL-4 empowered superkine, bizaxofusp (formerly MDNA55), has been studied in five clinical trials enrolling over 130 patients, including a phase 2b trial for recurrent GBM, the most common and uniformly fatal form of brain cancer. Bizaxofusp has obtained fast-track and orphan drug status from the United States Food and Drug Administration and the FDA/EMA (European Medicines Agency), respectively. Medicenna's early-stage BiSKITs (bifunctional superkine immunotherapies) and the T-MASK (targeted metalloprotease activated superkine) programs are designed to enhance the ability of superkines to treat immunologically "cold" tumours.

We seek Safe Harbor.