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