Update on ABILITY Trial; Unconfirmed Partial Response in Pancreatic Cancer Patient
On August 9, 2022, Medicenna Therapeutics Corp. (NASDAQ:MDNA) filed a voluntary supplement with the U.S. SEC that contained an update on the ongoing Phase 1/2 ABILITY Study (A Beta-only IL-2 ImmunoTherapY Study) of MDNA11 in patients with advanced solid tumors (NCT05086692). The update included a report of an unconfirmed partial response in a patient with pancreatic ductal adenocarcinoma. This is the fourth patient out of ten evaluable that had at least one on-treatment imaging scan to achieve tumor control (defined as stable disease, partial response, or complete response as per RECIST 1.1). The following image shows the responses for the 10 evaluable patients, with an additional four patients at the 60 μg/kg dose level anticipated to have 12-week scans in September.
We spoke with management about the pancreatic cancer patient with the unconfirmed partial response and learned that this individual had previously had the Whipple procedure and multiple systemic therapies, including FOLFIRINOX, Abraxane/gemcitabine, and Keytruda (the patient was unable to tolerate either Abraxane/gemcitabine or Keytruda). The patient received a loading dose of 2×30 μg/kg MDNA11 at Day 0 and Day 15 then a 60 μg/kg dose at week 4 onwards. The patient has two liver tumors, both of which had decreased in size at week 12, however it was not enough to be considered a partial response. A second scan at week 16 showed that both tumors had further decreased in size with the sum of diameters of the tumors decreasing by > 30%. According to the protocol and RECIST 1.1 criteria, a second scan ≥ 28 days after the most recent scan is required to confirm a partial response. We expect the patient will have the second scan in the coming weeks.
A melanoma patient that achieved tumor control began the trial in the 10 mg/kg dose cohort and has since been escalated to the 30 μg/kg and 60 μg/kg dose levels. This patient is also expected to receive the first scan next month after administration of the 60 μg/kg dose.
Lastly, there are four additional patients from the 60 μg/kg dose cohort that have yet to receive their first scan at 12 weeks. We anticipate those occurring over the next few weeks.
On August 9, 2022, Medicenna announced the pricing of a US$20 million public offering of approximately 13.3 million units for US$1.50 per unit. Each unit consists of one common share and one common share purchase warrant, with an exercise price of US$1.85 and an expiration date 60 months following the closing of the offering. Following this financing, we estimate that Medicenna now has sufficient capital to fund operations into early 2024, and importantly is sufficiently financed to complete both the monotherapy and combination therapy trials of MDNA11 as well as to perform IND-enabling studies and clinical manufacturing for at least one BiSKIT compound.
The unconfirmed PR in a patient with pancreatic cancer is very encouraging news, particularly since pancreatic cancer has not previously been shown to respond to IL-2 therapy. If additional tumor responses can be shown in patients with pancreatic or other gastrointestinal cancers, the company may be justified in evaluating the potential for MDNA11 in those patient populations. Interestingly, an independent research group previously published on the use of an IL-2 variant (same amino acid modifications as MDNA109 but without albumin fusion) in an oncolytic virus that showed anti-tumor effects in a hamster model of pancreatic cancer (Quixabeira et al., 2021), thus demonstrating that IL-2 variants can show activity against pancreatic cancer in vivo.
We are eagerly awaiting the results of the next scan for the patient with the unconfirmed PR to determine if it is confirmed, along with the scans for the other four patients from dosing level 4. The recently announced financing will help ensure that the company has sufficient capital to finish the Phase 1 monotherapy and combination trials for MDNA11, and should allow them to advance at least one BiSKIT compound to be IND ready. After incorporating the financing into our model, our valuation has decreased slightly to US$7 per share, however we remain very optimistic on the prospects for Medicenna and would view any pullback in the share price as a buying opportunity ahead of the expected data in September 2022.
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