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I'll give you the bullets and, if this is interesting, you can get into the deep dive below.
Bullets...
* Alpha Darts have been tested in conjunction with Keytruda (Pembrolizumab)
* What? Keytruda is Merck's $32B/year immunotherapy drug.
* When? Results will be announced on Tuesday, July 21st, 2026 at the AHNS cancer conference in Boston
* Who cares? Every oncologist, every solid tumor cancer patient and every DRTS investor
* Why? We may see the first fully documented Abscopal Effect
* What's that? Abscopal Effect is where treating one tumor causes tumors throughout the body to shrink - even though they were never directly treated.
* How? Keytruda can't "see" cold tumors. Cold tumors are its achilles heel. Once Alpha DaRTs "light them up" the tumor turns hot and Keytruda allows your immune system to destroy tumors all over the body.
* Which? All solid tumors: Skin, Breast, Lung, Colorectal, Pancreas, Prostate, Ovarian, Cervical, Head, Oral, Liver, Bladder, Vulvar, etc.
* Which doesn't it treat? The liquid cancers: Leukemia, Lymphoma, Multiple Myeloma
Deep dive due diligence
First, what is Keytruda? Keytruda is an immunotherapy. It's a PD-1 inhibitor and it's on pace to be the best selling (revenue) drug of all time.
Your body has killer T-cells that have a receptor on their surface called PD-1. It's like an "off-switch" to prevent it from destroying everything in a healthy body. PD-L1 is a camouflage shield that cancer uses to "trick" the killer T-cells into passing by the cancer.
When a T-cell approaches a cancer cell to inspect it, the cancer cell pushes the shield (PD-L1) into the T-cell's off-switch (PD-1). By plugging into that receptor, the cancer cell slams the brakes and the T-cell goes to sleep and the cancer continues to grow undetected.
Keytruda is an antibody engineered to fit perfectly on the PD-1 receptor of the immune cell. When a patient receives Keytruda, the drug floods the system and physically caps the PD-1 receptors with the result that the cancer can no longer flip the off-switch. The body's immune system (T-cells) recognize the cancer as hostile and destroy it.
Sounds amazing! It is. But Keytruda has a weakness called "cold tumors."
For Keytruda to be effective, it has to have two things:
1. Killer T-cells must already be inside or surrounding the tumor
2. Those T-cells must be actively trying to fight the cancer but are suppressed (shut off) by the tumor's defense shield.
Cold tumors have no T-cells inside the microenvironment to begin with. Keytruda's job is to "cut the brakes" so that the killer T-Cells don't stop fighting. No T-cells to cut brakes, no reaction to cold tumors.
Alpha Darts can target cold tumors. Using CT and MRI, we (humans) can see the tumors. Both hot and cold tumors will show up and appear as physical, abnormal masses of tissue. You won't be able to tell if the tumor is hot or cold because you can't see if it's crawling with fighting T-cells (hot) or if it's been deserted by the immune system (cold.)
Via advanced imaging (Immuno-PET) a hot tumor will glow brightly because it's packed with T-cells. A cold tumor will remain dim because there are no T-cells for the tracker to stick to.
Identifying and targeting the cold tumor is the key to unlock...
T H E H O L Y G R A I L
A cold tumor is completely invisible to the immune system. There are no T-cells there so drugs like Keytruda are completely useless.
By inserting Alpha DaRT directly into a cold tumor, the localized high LET radiation physically shatters the cancer cells. This forced destruction acts like a giant biological flare gun. It forces the tumor to spill its hidden internal proteins (antigens) directly into the tissue microenvironment.
This "wakes up" the immune system and rushes killer T-cells to the site and effectively turns the cold tumors hot. Once those T-cells are trained on the newly exposed cancer "fingerprints", they can travel through the bloodstream to hunt down other metastatic tumors elsewhere in the body. Keytruda ensures they never hit the brakes.
This is called the Abscopal Effect and it is a major paradigm shift in oncology.
Alpha DaRT's superpower here is its ability to "light up" a cold tumor, creating the exact environment that Keytruda needs to step in, jam the immune brakes open and unleash a full-body abscopal effect.
Historical note: We've seen some evidence of abscopal effect with Alpha Tau in the past. If you remember, we saw an instance during the Pancreatic presentation.
Personal note: My concern with this upcoming event is that we're dealing with elderly head & neck cancer cases. Elderly people already have a diminished immunity system and the recurring head and neck won't help. This Abscopal Effect won't wipe out tumors systemically unless there are T-cells to do battle. And the truth is that this combination therapy wasn't designed to test for Abscopal Effect but there is good news: It was set up with Best Overall Response Rate (ORR) as its primary objective.
RESULTS SO FAR...
The amazing news is that it worked, at least in early efforts.
ORR means the total percentage of patients whose cancer meaningfully shrank or disappeared.
ORR for Keytruda: 19%
ORR for Keytruda + Alpha DaRT: 75% (!)
Complete Response (CR) means all target cancer lesions have completely disappeared.
Complete Response Rate for Keytruda: 5%
Complete Response Rate for Keytruda + Alpha DaRT: 37.5% (!!)
If these numbers hold up in the presentation, this is a massive performance improvement to the biggest selling immune drug on Earth.
How this could play out...
Remember, Alpha DaRTs are a device and not a drug. Sorry to keep stressing that but it's important. With a device, you run a 30-50 person safety/feasibility trial and then you run a 300 person efficacy "pivot" trial.
If you are safe (trial 1) and more effective than the standard of care (trial 2) you get a gold star on your forehead and the FDA calls you certified.
The challenge is that the FDA won't approve Alpha DaRT + Keytruda. That's not how the FDA works. What they'll do is clear the path for Alpha DaRT + Keytruda in head and neck cancers to be approved.
Then, Alpha DaRT + Keytruda in the next solid tumor and the next solid tumor and the next solid tumor.
And each time, Alpha DaRT + Keytruda will be looking not just for ORR and Complete Response rates but they'll be looking for Abscopal effects.
Which cancers tend to be "cold?"
These will be names you recognize from recent, impressive results:
PDAC Pancreatic cancer - This is the quintessential cold tumor. Up to 70% of the tumor mass isn't actually cancer cells, it's a dense, scarring physical wall (desmoplastic stroma) made of collagen and hyaluronic acid (needed AI for that one.)
Glioblastoma (aggressive brain cancer) - GBM populates an environment heavily dominated by immunosuppressive cells rather than T-Cells. Keytruda has struggled here.
Ovarian cancer - some go hot but most are in "cold deserts."
Prostate cancer - Low mutational burden so it looks like normal healthy tissue. Once it becomes resistant to hormone therapy (castration-resistant prostate cancer) it metastasizes to the bone and is incredibly difficult to treat.
Colorectal cancer - 95% of metastatic colorectal cancers are "Microstaellite-Stable (MSS), meaning they have few mutations and are entirely cold. Keytruda is great with the 5% hot tumors here.
Oncology researchers are desperate for bridging technologies like Alpha DaRT. If a local treatment can shatter the dense stromal walls of PanC or force a low-mutation prostate tumor to spill internal antigens, it will act as a mechanical override - forcing these highly fatal "cold fortresses" to turn hot.
COSTS...
Reimbursement: If you have a choice of reimbursing a drug you know (Keytruda) and an outpatient targeted radiation treatment like Alpha DaRT or you could reimburse for Car-T, TIL Therapy or TCR-T therapy plus a required hospital stay, as an insurance provider, you're going with Keytruda every day. Here's why.
Keytruda: $10k to $15k per dose (given every 3 to 6 weeks) A full year costs $150k to $185k.
CAR-T therapy: MFG cost: $375k Total cost (plus hospital) $1M
TIL Therapy: MFG cost: $515k Total cost + hospital: $1M
TCR-T Therapy: MFG cost: $400k Total cost + hospital $1M
The reason these therapies are expensive is because scientists must physically harvest your cells, ship them to a multi-million dollar lab, re-engineer or cultivate them over several weeks and ship them back. This is a one-patient, one batch process. Then, patients must undergo intense chemotherapy to clear out their existing immune system to make room for the new engineered cells. The therapies can trigger life-threatening immune overreactions and patients routinely require days or weeks in ICU to manage the dangerous side effects while the cells adapt.
Compare that to popping a pill like Keytruda and undergoing a biopsy like outpatient procedure with Alpha Tau...
Not only the insurance guy but the oncologist and the patient will all want Keytruda + DaRTs.
CLOSING...
Still reading? Thank you for allowing me to share a double Ted talk. The abscopal effect, if it shows up consistently in conjunction with Keytruda means that we've won a battle. Oncologists have a new weapon, patients have new hope, and we have invested in a multi-billion dollar global platform across all solid tumors and we were there back when it was at a paltry $1B market cap back in mid-2026.