Radiopharma company $CU6 have this morning announced the latest clinical trial progresss of 64Cu‑SAR‑bisPSMA .

ASX Announcement

The Investigator-Initiatied Co‑PSMA Phase II trial provides statistically significant superiority of 64Cu‑SAR‑bisPSMA over the current Standard of Care, 68Ga‑PSMA‑11 in lesion detection at low PSA levels. This confirms the biological rationale and reinforces earlier data (PROPELLER, COBRA). While the result materially improves confidence in efficacy and diagnostic differentiation, it remains a supportive, not pivotal, dataset.

My Assessment

The NDA path still depends on Phase III outcomes (CLARIFY, AMPLIFY) and CMC readiness. These are in progress and don't report until 2026.

Overall, my "gusesstimate" of NDA probability‑of‑approval is around 66% prior to today's supportive news. While the news slightly de-risks the broader trials, it is not material enough for me to add to my position (2.7% RL). This is mainly due to the incomplete readout of this IIT. For example, it is not clear from the release what accuracy verification / reader-blind data protocols were in place - these details will be important when the FDA consider this additional information. It will be interesting to read the full account of the study when this is available.

So, good news, I expect the market will react positively, however, I'll not be taking any action today as a result.

Disc: Held in RL and SM

It is turning out to be quite the day for my biotechs, with another "non-price sensitive" announcement, this time from radiopharma aspirant $CU6.

ASX Announcement

Even though this is a VERY EARLY PRE-CLINICAL preliminary result, I'm going to go into this one in some detail, because it is an example of why I hold a small $CU6 position. Basically, IF $CU6 can get approval for one or more of their imaging agents currently in Phase 3, and get a first product commercialised, THEN the operating cash flow will drive a material expansion and acceleration of their pipeline to more fully exploit their unique science platform.

It is a big if, and yes entirely speculative at this stage, but in the success case, I believe the payoff might be huge.

OK, So that's the connection to the thesis. Let's now look at the specifics.

What's Today's Announcement About?

$CU6 announced that new preclinical data on its pan-cancer theranostic candidate 64/67Cu-SAR-bisFAP will be presented at the World Molecular Imaging Conference 2025. The compound targets fibroblast activation protein (FAP), highly expressed on cancer-associated fibroblasts (CAFs) in the tumour microenvironment across a wide range of cancers (e.g. breast, colorectal, pancreatic, lung, brain, ovarian), but minimal in normal tissue — making it an attractive target for imaging and therapy

Clarity compared a monomeric product (SAR-FAP) with a dual-targeting version (SAR-bisFAP) and found the latter achieved superior tumour uptake and retention in FAP-positive glioblastoma mouse models.  Therapeutically, 67Cu-SAR-bisFAP doubled median survival (28.5 days) compared to 67Cu-SAR-FAP (14.5 days) and exceeded the performance of an industry benchmark, 177Lu-FAP-2286 (11.5 days).

The company plans to commence a Phase I trial of 64Cu-SAR-bisFAP in 2026, initially focused on diagnostic applications, followed by therapeutic trials with 67Cu-SAR-bisFAP targeting cancers with unmet medical needs. It highlighted the improved retention and efficacy of the bis-structure and the advantages of copper-64/67 pairing with Clarity’s proprietary SAR chelator.

OK - So Why Is This Potentially Significant?

1. Strategic Implications – A Shift Toward Tumour Microenvironment Targeting

This announcement underscores Clarity’s strategic positioning in the emerging FAP-targeted theranostics space, which represents a complementary approach to tumour-cell-directed therapies. Targeting CAFs and the tumour stroma could enable treatments to overcome resistance mechanisms and broaden applicability across tumour types. If translatable to humans, this pan-cancer approach significantly expands the addressable market beyond single-indication radiopharmaceuticals.

2. Preclinical Data – Strong but Preliminary

The doubling of survival compared to both the monomer and a benchmark product is highly encouraging and suggests meaningful biological efficacy. Moreover, the superior tumour retention observed preclinically indicates potential for improved dosing efficiency and therapeutic index. However, these results are based on murine xenograft models, and translation to human efficacy and safety remains uncertain. The leap from preclinical to clinical success in FAP-targeted therapies has historically been challenging. (So this is a major caveat!)

3. Competitive Positioning – Benchmark Outperformance

Beating 177Lu-FAP-2286, a leading FAP-targeted radioligand from Novartis/ITM, is notable. If replicated clinically, Clarity could differentiate itself in a crowded field with a dual-targeting construct and leverage the logistical and dosimetric advantages of the copper-64/67 theranostic pair over lutetium-based agents.

4. Timeline and Development Path – Key Risks Ahead:

A planned Phase I diagnostic trial in 2026 suggests Clarity remains 12–24 months from initial human proof-of-concept, and therapeutic validation will come later still. Regulatory, manufacturing, and clinical-trial execution risks remain substantial. Demonstrating safety, tumour targeting, and dosimetry advantages in humans will be critical inflection points for value creation.

My Overall Assessment

At the time of writing, the SP has ticked up arouind 13% on this announcement. On the basis of this news as a standalone potential future product, that reaction is way, way overdone. But such is the world of speccy biotechs.

However, what I have tried to spell out here is why this is an important confirmation of the thesis. $CU6 has a science platform with the potential to spawn many products.

As we know from the recent Strawman interview with Alan Taylor, $CU6 is being laser focused on getting its first prostate cancer screen diagnostic over the critical Phase 3 hurdle. But that product is just the point edge of a potentially vast portfolio of other products, and today's announcement is providing a glimpse of that potential.

I'll be honest and say that earlier in the year I was a lot more bullish about the likes of $TLX and $CU6 to at least get a high proportion of the diagnotic imaging agents approved. However, the $TLX experience in quick succession with both Zircaix and Pixclara have provided sobering reminders (if we really needed any) that Phase 3 is a real hurdle, and that products do fail to clear it.

And that's why I have a very small $CU6 position. 2.0% in RL. There is no need to put a lot of capital at risk on this one, because in the success case, the payoff could be very substantial indeed. And yes, of course, it could all go to zero!

Disc: Held in RL and SM

So, some of us have been wondering when $CU6 would raise capital - given their royal cash burn resulting from their mutliple-pronged development program. (Personally, I was expecting something mid next year.)

Answer: They've already done it. $203 million at $4.20 per share, so that must be 48 million shares, a dilution of about 15%. And the capital was provided by "a small group of institutional investors who are close to the company".

At last report they were burning $15-16m a quarter, which of course will ramp up as the development programs mature. But now they have a war chest of $288 million. So that should see them through several key milestones over the coming couple of years.

Drug development is not for the faint-hearted!

Disc: Held in RL and SM

@Strawman - a great meeting with Alan.

He's not the first to draw the analogy between pharma and resources. In fact, some of the world largest resource and pharma companies have studied each others' R&D / Exploration and Development processes to gain learning into better capital allocation and decision processes. (As an aside, I find it interesting that 75% of my career has been in either resources or pharma. The reason I prefer healthcare to invest in, is that the IP protection means that prices aren't commoditised when it counts - i.e., the early revenue years!)

In previous straws and posts, I've said I wasn't considering investing in $CU6. However, as a result of my early position in $TLX, I have been doing a lot of research into radiopharma in oncology. Much of what Alan said in the meeting confirmed and added to my understanding. I am now shifting in my thinking.

In the event that CLARIFY and even more importantly SECURE continue their early initial promise, and should NDAs be granted in due course, the pre-existing products in the market are doing the hard work of building the market of clinicians using these products to diagnose and treat. Should clearly superior products become available, then of course switching products in an existing market and associated workflows, is an easier thing. Because of this, should $CU6 get both the Cu64 and Cu67 products approved for prostate, we'd be look as a very different valuation from today, with the potential for very rapid adoption - particularly if there are positive stats in differentials in patient outcomes.

It was interesting to hear about the clinician demand to get more patients on Cu67, and the relative benefits of the longer half-life both in the imaging and therapy modes (Alan's mentioned this before on investor calls and other podcasts). $TLX have tried to spin their very short half-life issue as a benefit around speed of treatment. They have knocked the idea that a patient might be imaged a day after dosing for better S/N due to the inconvenience of have to be in the process for longer. But given what these patients are dealing with in terms of important life decisions, and potentially earlier failed lines of treatment, I'm not so convinced.

$CU6 is still not aligned with my usual risk appetite. After all, an adverse reaction or series of less promising results, could dampen the outlook quite quickly. However, as Alan says, it is all about understanding the probabilities. I'm not far off from concluding that a small speculative investment might be justified for me.

I'm glad we have some companies like these on the ASX to consider. More work to do! But a great meeting.