Thalia Therapeutics (AIM: THAT) shares jump 17% as Sanmirna deal adds Phase 1 AML asset

Thalia Therapeutics plc (AIM: THAT) has agreed to acquire Sanmirna Therapeutics Inc. for an initial £3.675 million and up to £13 million of milestone-based deferred consideration, giving the London-listed biotechnology company control of the clinical-stage acute myeloid leukaemia candidate miRisten. The transaction is accompanied by an oversubscribed £2.75 million equity raise at 0.6 pence per share, with the proceeds intended to complete the ongoing Phase 1 trial and advance Thalia Therapeutics’ cardiovascular RNA programme towards United States regulatory filing readiness. Initial miRisten clinical results are expected during the first half of 2027, creating a nearer-term data catalyst than Thalia Therapeutics’ existing preclinical portfolio could previously offer. THAT shares traded around 0.675 pence on June 24, approximately 17% above the previous closing price, as investors weighed the clinical opportunity against substantial immediate and potential future dilution.

Why does the Sanmirna acquisition fundamentally change the Thalia Therapeutics investment case?

Before the proposed Sanmirna Therapeutics acquisition, Thalia Therapeutics was primarily a preclinical RNA therapeutics and drug-delivery company. Its value depended on generating enough laboratory and animal evidence to move internally developed programmes towards clinical trials, partnerships or regulatory filings.

Sanmirna Therapeutics immediately changes that development timetable. Its principal asset, miRisten, is already being tested in a first-in-human Phase 1 trial at City of Hope in Los Angeles for adults with relapsed or refractory acute myeloid leukaemia. Thalia Therapeutics will therefore move from discussing how its technologies might eventually reach patients to managing an active clinical programme with data expected within roughly a year.

That transition can materially alter how investors value the company. Clinical-stage biotechnology assets normally receive greater attention than early research platforms because the path to human evidence is shorter and the upcoming milestones are easier to define. Successful Phase 1 results could support further development, external licensing or a strategic partnership.

The acquisition also diversifies Thalia Therapeutics beyond its Nuvec delivery technology and its internally developed cardiovascular small interfering RNA programme. The enlarged company would hold a clinical oncology asset, a preclinical cardiovascular candidate and a separate delivery platform, reducing dependence on any single scientific approach.

Diversification does not eliminate risk. It creates additional capital requirements and forces management to allocate limited cash across programmes with different timelines, technologies and commercial markets. A micro-cap biotechnology company can own three interesting assets and still lack the resources to develop all three properly.

The strategic question is therefore not simply whether miRisten is scientifically promising. Investors must determine whether Thalia Therapeutics can finance, govern and prioritise the enlarged pipeline without repeatedly issuing shares before the underlying assets have generated decisive value.

How is miRisten designed to address treatment resistance in acute myeloid leukaemia?

Acute myeloid leukaemia is an aggressive blood cancer that can return after treatment because a population of leukaemia stem cells survives conventional therapy. These cells can remain relatively inactive, making them less vulnerable to treatments that primarily attack rapidly dividing cancer cells.

MiRisten is an oligonucleotide therapy designed to inhibit microRNA-126, a biological regulator associated with the survival, self-renewal and treatment resistance of certain leukaemia stem cells. By blocking microRNA-126, the treatment is intended to disrupt the mechanisms that allow those cells to remain protected and contribute to relapse.

Preclinical research has shown that reducing microRNA-126 activity can lower leukaemia burden and leukaemia stem-cell activity in laboratory and animal models. Research has also indicated that miRisten may enhance the activity of existing acute myeloid leukaemia medicines such as venetoclax, creating potential for future combination strategies.

Those findings provide a credible scientific basis for human testing, but they should not be confused with proof of clinical benefit. Many oncology candidates generate persuasive laboratory results and then fail because the required exposure cannot be achieved safely in patients, the target proves less important in human disease, or treatment responses are not sufficiently durable.

The ongoing Phase 1 study is designed primarily to evaluate safety, tolerability, pharmacokinetics and the appropriate biological dose. Any initial signs of anti-leukaemia activity would be encouraging, particularly in heavily treated patients, but the early trial is not structured to provide definitive evidence that miRisten improves survival or outperforms established treatments.

The most important near-term scientific question is whether the drug can inhibit the intended biology in patients at doses that remain tolerable. If the Phase 1 results demonstrate target engagement and a manageable safety profile, Thalia Therapeutics will have a stronger basis for designing a larger efficacy-focused study.

What will investors need to see in the first miRisten clinical data expected in 2027?

The Phase 1 trial is an open-label dose-escalation study involving patients whose acute myeloid leukaemia has returned or failed to respond to previous treatment. This is a medically challenging population in which patients may have received several earlier therapies and can enter trials with significant disease burden.

Safety will be the first test. Investors should examine the nature, frequency and severity of treatment-emergent adverse events, whether toxicities increase with dose and whether patients can remain on treatment long enough to evaluate the drug properly.

Pharmacokinetic data will show how miRisten behaves after administration, including the level and duration of exposure. Pharmacodynamic analysis may provide evidence that the therapy is affecting microRNA-126 or related disease biology as intended.

Any reported reductions in leukaemia cells, improvements in blood counts, complete responses or partial responses will attract attention. However, response claims must be assessed against the number of evaluable patients, prior treatments, dose levels and duration of follow-up. A response in one patient can justify additional research, but it cannot establish a reliable response rate.

Durability will be particularly important. Acute myeloid leukaemia can initially respond and then progress, especially when resistant stem-cell populations remain. If miRisten’s proposed mechanism genuinely affects those cells, investigators will eventually need to demonstrate that responses or disease control persist.

The company expects top-line Phase 1 data during the first half of 2027. Timing risk remains because early-stage oncology trials can be delayed by patient recruitment, dose-escalation decisions, safety reviews and the availability of suitable participants.

Investors should also distinguish between completion of the trial and readiness for a late-stage study. A Phase 1 result may support further dose optimisation, combination cohorts or a Phase 2 study before the programme is prepared for any registration-enabling development.

Is the £3.675 million initial acquisition price attractive for a clinical-stage cancer asset?

Thalia Therapeutics will pay initial consideration of £3.675 million for the entire issued share capital of Sanmirna Therapeutics. Approximately £2.91 million of that value will be satisfied through 485.1 million new Thalia Therapeutics shares issued at the 0.6 pence fundraising price, with the remaining £764,357 represented by an unsecured, interest-free convertible loan note.

On the surface, the initial price appears modest for an asset that has already received regulatory clearance to enter human testing and is progressing through a Phase 1 oncology trial. Thalia Therapeutics is avoiding the years of preclinical work, manufacturing development and regulatory preparation normally required before first patient dosing.

The initial consideration does not represent the transaction’s full potential cost. Sanmirna Therapeutics’ vendors may receive up to another £13 million if miRisten reaches specified clinical, regulatory and commercial milestones.

The largest early deferred payment is £4.1 million following completion of the Phase 1 trial and submission of the clinical study report. A further £3.9 million becomes payable when the third patient is dosed in a Phase 3 or label-enabling study. Additional payments are linked to filing for United States approval, obtaining United States and European Union approvals, and reaching annual net sales above US$250 million.

This structure reduces immediate cash pressure and links much of the purchase price to value-creating progress. Thalia Therapeutics will pay considerably more only if miRisten advances beyond its current stage.

However, the first £4.1 million milestone can become payable after Phase 1 completion, before the programme has demonstrated success in a randomised efficacy trial. Part or all of that amount may be settled through additional shares or convertible debt, creating another potential dilution event close to the first major clinical readout.

Thalia Therapeutics must also reimburse City of Hope for up to US$1.2 million of trial funding over five years, with earlier payment possible following a licensing transaction or later-stage clinical progress. The true economic commitment therefore extends beyond the headline initial consideration.

The deal may prove inexpensive if miRisten produces convincing human data. It may prove costly if Phase 1 completion triggers substantial consideration but the results are insufficient to support an attractive partnership or subsequent development.

How much dilution will existing THAT shareholders face if the transaction completes?

Thalia Therapeutics had approximately 832.3 million shares in issue before the fundraising and acquisition. The £2.75 million financing will add 458.3 million shares, increasing the share count by roughly 55% before consideration shares are included.

The Sanmirna Therapeutics acquisition will add another 485.1 million initial consideration shares. Following full admission of the fundraising and acquisition shares, Thalia Therapeutics is expected to have approximately 1.776 billion shares outstanding.

Existing shareholders would collectively own about 46.9% of the enlarged company, before any conversion of the £764,357 loan note or issuance of future deferred consideration shares. In practical terms, investors who do not participate in the fundraising will see their percentage ownership more than halved.

The convertible loan note could create approximately 127.4 million additional shares if converted at the 0.6 pence fundraising price, subject to restrictions preventing the vendors from exceeding a combined 29.9% holding. Full conversion would lift the share count to approximately 1.9 billion before later milestones, options or other securities.

The dilution must be considered alongside the asset acquired. Shareholders will own a smaller percentage of a company containing an active clinical-stage programme and more cash. The transaction can still create value if miRisten’s contribution exceeds the economic value transferred to new investors and vendors.

The fundraising price was set at a premium to the June 23 closing price, which is more supportive than a deeply discounted rescue placing. Directors and vendors subscribed for approximately £1.29 million, including about £1.12 million from directors, demonstrating significant insider participation.

Insider participation aligns part of the board’s financial interest with outside shareholders, but it does not remove the need to judge the transaction independently. Directors can invest with conviction and still be wrong about clinical outcomes.

The central dilution question is whether the expanded share base creates enough runway to reach a meaningful rerating event. If the company requires another large placing before or immediately after the first miRisten data, the ownership impact could extend well beyond the current transaction.

Does the £2.75 million fundraise provide enough capital to reach the next clinical milestone?

Thalia Therapeutics plans to allocate £1 million of the fundraising proceeds to completing the miRisten Phase 1 study. Approximately £750,000 will support development of its bispecific cardiovascular programme towards investigational new drug readiness, while the remaining £1 million will fund working capital, research expenditure and transaction costs.

Management expects the enlarged work programme to be funded through the first half or middle of 2027. That period covers the expected miRisten top-line results, creating a defined bridge between the financing and a potential clinical value inflection point.

The runway is nevertheless tight. Thalia Therapeutics reported cash of approximately £1.08 million at the end of December 2025 and an operating loss of about £1.17 million for the year. The enlarged company will inherit additional clinical, regulatory, legal and administrative responsibilities beyond the former preclinical organisation.

Clinical costs can also move unpredictably. Recruitment delays, protocol amendments, manufacturing requirements, additional safety monitoring or expanded analysis could increase spending before the study is complete.

Even a successful Phase 1 result would require further capital. A Phase 2 programme, combination study or expansion cohort could cost several times the amount currently allocated to finish Phase 1. The company may seek a licensing partner, strategic investor or another equity financing after the data.

The fundraising should therefore be viewed as milestone financing rather than long-term development capital. It appears sufficient to reach the announced near-term objectives, assuming the programme remains on schedule, but it does not fund miRisten through registration or commercialisation.

Why does the chief executive’s interest in Sanmirna require closer governance scrutiny?

Thalia Therapeutics Chief Executive Officer David Solomon is also the sole director of Sanmirna Therapeutics and will own approximately 19% of the target immediately before completion. He will consequently receive around 19% of the economic consideration payable to Sanmirna Therapeutics’ vendors.

The company disclosed that David Solomon is expected to receive approximately £700,159 through convertible loan notes as part of the initial consideration. He may also receive roughly 19% of future milestone payments if those amounts become payable.

This creates a related-party transaction because the executive responsible for leading the buyer has a financial interest in the seller. Such arrangements are not automatically improper, especially when an executive has helped create or advance an asset that the listed company wishes to acquire.

They do require strong independent governance. The directors not connected with the acquisition stated that they consider the terms fair and reasonable after consultation with the company’s nominated adviser. Shareholder approval will also be required at the annual general meeting scheduled for July 17.

Investors should examine whether the acquisition price, milestone structure and scientific diligence would appear reasonable if the chief executive had no interest in Sanmirna Therapeutics. The answer may still be yes, but the burden of transparency is higher.

The alignment argument also cuts both ways. David Solomon’s continuing exposure to Thalia Therapeutics shares and deferred milestones gives him a direct incentive to advance miRisten successfully. At the same time, the transaction transfers substantial ownership and potential future consideration to a vendor group that includes the company’s chief executive.

Can Thalia Therapeutics manage miRisten, Nuvec and its cardiovascular programme simultaneously?

The enlarged portfolio will contain three distinct value propositions. MiRisten offers the nearest clinical catalyst through the ongoing acute myeloid leukaemia trial. The cardiovascular programme targets PCSK9 and lipoprotein(a), two established contributors to cardiovascular risk. Nuvec remains a proprietary RNA delivery technology that could support internal programmes or external partnerships.

This portfolio can create several routes to value. MiRisten may attract oncology partners if the Phase 1 results are encouraging. The cardiovascular candidate could appeal to larger pharmaceutical companies seeking long-acting RNA medicines. Nuvec may generate collaborations if comparative and targeting studies demonstrate differentiated delivery performance.

The difficulty is resource allocation. Clinical oncology, cardiovascular development and drug-delivery platform research require different scientific, manufacturing and regulatory expertise. Thalia Therapeutics must resist the temptation to advance every asset at maximum speed simply because each has a large theoretical market.

Management has allocated specific fundraising proceeds to miRisten and the cardiovascular candidate, indicating that both programmes will progress in parallel. Nuvec work will continue through research and development resources, although its exact funding priority may become less visible after the acquisition.

The best strategic outcome may involve using miRisten to generate a nearer-term clinical catalyst while seeking partners for one or more other assets. The weakest outcome would involve spreading capital across several programmes without moving any one of them far enough to support a partnership or institutional rerating.

Portfolio breadth is valuable only when accompanied by prioritisation. In small-cap biotechnology, three shots on goal can be reassuring, until shareholders see the bill for three goalkeepers.

What does the THAT share-price reaction reveal about investor sentiment?

Thalia Therapeutics shares traded around 0.675 pence during June 24, up approximately 17% from the previous closing price of 0.575 pence. The shares were also about 17% higher than their level around June 19 and roughly 4% above the 0.65 pence close recorded on May 22.

The stock remains within a 52-week range of approximately 0.35 pence to 1 pence. The current price is nearly twice the annual low but remains around one-third below the 52-week high, showing that investors have recognised the transaction without assigning the enlarged portfolio a fully de-risked valuation.

Using the pre-fundraising share count, a price near 0.675 pence implies a market capitalisation of approximately £5.6 million. Applying the same price to the expected 1.776 billion post-transaction shares would imply an enlarged equity value close to £12 million, before potential conversion shares and future milestone securities.

That comparison explains why the transaction can be both transformational and heavily dilutive. The company is acquiring a clinical-stage asset for an initial price large relative to its existing market capitalisation, principally by issuing equity rather than paying cash.

The positive market reaction suggests investors believe miRisten adds more value than the immediate dilution removes. The relatively modest scale of the rerating also indicates that the market wants clinical evidence before assigning a substantially higher valuation.

There is no broad analyst consensus for THAT shares, and trading liquidity remains limited. Price movements can therefore be amplified by relatively small transactions, fundraising announcements and speculative interest around clinical milestones.

Which milestones will determine whether the Sanmirna acquisition creates lasting value?

The first milestone is shareholder approval at the July 17 annual general meeting. Completion and admission of the consideration shares are expected shortly afterwards, assuming the required resolutions pass.

The second milestone is continued patient recruitment and dose escalation in the miRisten Phase 1 trial. Any delay could shorten the remaining cash runway and push the top-line data beyond the first half of 2027.

The third milestone is the clinical dataset itself. Safety, tolerability, pharmacokinetics, biological activity and any preliminary anti-leukaemia responses will determine whether miRisten can progress into efficacy-focused development.

The fourth milestone is financing or partnering strategy after the readout. A licensing agreement containing upfront cash and funded development would validate the asset while reducing future dilution. Another equity raise without external validation would place greater pressure on the investment case.

Progress towards investigational new drug readiness for the cardiovascular programme will also matter, as will evidence that Nuvec can compete with established RNA delivery approaches. These programmes provide diversification, but they must deliver measurable technical progress rather than remain permanent background optionality.

The Sanmirna Therapeutics acquisition gives Thalia Therapeutics something it previously lacked, a clinical-stage catalyst capable of changing the company’s valuation within a defined period. It also more than doubles the initial share count and introduces milestone obligations that could become significant before commercial success is established.

The transaction will ultimately be judged neither by the size of the acute myeloid leukaemia market nor by the number of assets placed on a corporate slide. It will be judged by whether miRisten generates data strong enough to attract capital on terms better than the dilution shareholders are accepting now.

Key takeaways on the Sanmirna acquisition, miRisten and the THAT investment outlook

• Thalia Therapeutics has agreed to acquire Sanmirna Therapeutics and its Phase 1 acute myeloid leukaemia candidate miRisten.
• The initial consideration is £3.675 million, with up to £13 million of additional payments linked to clinical, regulatory and commercial milestones.
• MiRisten is designed to inhibit microRNA-126, a biological regulator associated with leukaemia stem-cell survival and treatment resistance.
• Top-line Phase 1 data are expected during the first half of 2027, creating Thalia Therapeutics’ nearest major clinical catalyst.
• The £2.75 million fundraising will issue 458.3 million shares at 0.6 pence and is expected to fund the work programme through mid-2027.
• Initial acquisition consideration will include another 485.1 million shares, taking the expected post-transaction share count to approximately 1.776 billion.
• Existing shareholders will own about 46.9% of the enlarged company before convertible loan note conversion or future milestone shares.
• Chief Executive Officer David Solomon’s interest in Sanmirna Therapeutics makes the acquisition a related-party transaction requiring independent oversight and shareholder approval.
• THAT shares traded about 17% higher near 0.675 pence, indicating support for the clinical strategy but continued caution around dilution and execution.
• Clinical data quality, cash runway, future partnering and disciplined portfolio prioritisation will determine whether the acquisition creates sustainable shareholder value.