By Willie Foerstner

For decades, cancer treatment often meant surgery, chemotherapy, and radiation therapy; approaches that, while lifesaving for many, came with significant side effects and uncertain outcomes. But theranostics, which combines advanced imaging with highly targeted treatment, is changing that. The theranostics market, valued at $6.5–7 billion in 2024, is growing at double-digit rates, fueled by strong adoption of radioligand therapies and 400+ active global trials. Backed by over $10 billion in recent pharma investments, the field is rapidly emerging as one of the fastest-growing segments in precision oncology

While this field has already made its mark with FDA approved Ga-68 and F-18 PSMA diagnostic tracers, and Lu-177 PSMA radionuclide therapies for prostate (Pluvicto) and neuroendocrine cancers (Lutathera), research is rapidly advancing. A new generation of isotopes is entering clinical trials, each designed to strike tumors more precisely while minimizing damage to healthy tissue.
Early promise of next-gen isotopes
Scientists are exploring a diverse set of therapeutic “building blocks.” Each isotope has unique strengths, and when linked to tumor-seeking molecules, they act like guided missiles against cancer cells:

Terbium-161 (Tb-161): A beta emitter that also releases tiny “Auger electrons” for extra impact. Tb-161 may be especially effective at eliminating small clusters of cancer cells (micrometastases).
Astatine-211 (At-211): An alpha emitter with short range but powerful effect. At-211 shows promise in hard-to-treat brain and central nervous system (CNS) cancers, where precision is critical.
Copper-67 (Cu-67): A beta emitter often paired with its imaging partner Cu-64. This dual-use capability allows the same tracer to be used both for scans and for therapy.
Lead-212 (Pb-212): A generator-based alpha therapy that delivers Bi-212 (its daughter particle) directly into tumor cells. Trials are underway in ovarian, pancreatic, and prostate cancers.
Actinium-225 (Ac-225): One of the most advanced alpha emitters in development. Its strong, short-range radiation has already shown remarkable results in advanced prostate cancer, especially in cases resistant to other treatments.
Terbium-149 (Tb-149): Unique because it emits both alpha particles (for treatment) and positrons (for PET imaging). This “two-in-one” capability lets doctors monitor in real time as the therapy destroys cancer cells.

Linking isotopes to targeted molecules
The real power of theranostics lies in coupling isotopes with molecules that “lock onto” cancer:

PSMA ligands (for prostate cancer)
Somatostatin analogs (for neuroendocrine tumors)
HER2 antibodies (for breast and gastric cancers)
Novel peptides and antibodies (for ovarian, pancreatic, and blood cancers)
Tb-149 conjugates (provide both PET imaging and alpha therapy in a single compound)

These targeted therapies act like smart weapons — homing in on cancer cells while sparing most healthy tissue.

Why “early” matters
Most of these therapies are still in clinical trials, but the early results are encouraging:

– Tumors are shrinking more effectively.
– Side effects appear lower than with traditional chemotherapy or radiation.
– Applications are expanding beyond prostate and neuroendocrine cancers.

Most importantly, cancer cells are remarkably adaptive. Over time, many tumors develop resistance to existing treatments such as chemotherapy drugs like docetaxel (for prostate cancer) or temozolomide (TMZ), the frontline treatment for glioblastoma and other brain tumors.

When resistance occurs, cancer cells can activate survival strategies, including mitochondrial transfer, a process in which healthy or stronger cells donate their energy, providing mitochondria to weaker ones. This “battery swap” allows damaged cancer cells to repair themselves and continue growing, even after treatment.

For patients, this means that if even a small number of resistant cells survive, the cancer can regenerate. That is why next-generation theranostic isotopes are so vital:

– They can deliver highly targeted, high-energy radiation directly into resistant cells.
– Some, like Tb-149, let doctors track treatment in real time to ensure no cancer site is missed.
– By eradicating cancer cells at both macroscopic and microscopic levels, the chance of recurrence may be reduced.

The rapid growth in trial enrollment reflects strong belief in this science from doctors, patients, and researchers alike.

Tumor treating fields: Another answer to resistance
Alongside isotopes, another promising therapy is Tumor Treating Fields (TTFields), a noninvasive treatment that uses low-intensity, alternating electric fields to disrupt cancer cell division.

How it works: Cancer cells grow rapidly and rely on precise internal structures to divide. TTFields interfere with these structures, making it harder for tumor cells to multiply.
Why it matters for resistance: When drugs like TMZ fail, glioblastoma cells can still spread unchecked. TTFields physically disrupt division, making it harder for resistant cells to survive or adapt.
Combination potential: Researchers are exploring TTFields alongside theranostics. While isotopes deliver targeted radiation inside tumor cells, TTFields weaken their ability to repair and replicate — attacking resistance from another angle.

For patients with aggressive cancers like glioblastoma, where standard treatments often fall short, TTFields may become an important companion in the theranostic toolkit.

What IS mitochondrial transfer?
Think of mitochondria as the “batteries” of cells — they produce the energy needed for survival and growth.

When cancer cells are damaged by chemotherapy or radiation, they can “borrow” mitochondria from nearby healthy cells or even from other cancer cells. This “battery transfer” recharges damaged cancer cells, giving them the energy to repair and continue dividing.

This explains why, even if most of a tumor is destroyed, a small group of survivors can “bounce back” and regrow the cancer.

Next-generation theranostic treatments aim to stop this cycle by delivering powerful, targeted radiation directly into resistant cells, making it far harder for them to survive, recharge, and return.

Having personally witnessed mitochondrial transfer in vitro in the lab, and how TTFields can eradicate cancer cells under the same conditions, gives real hope that new treatments are on the horizon.

Expanding clinical trials
Clinical trials are no longer confined to rare cancers, they’re moving into common ones:

– Prostate cancer: PSMA-targeted radioligand therapies in late-stage studies are already showing extended survival.
– Neuroendocrine tumors: Trials like NETTER-2 confirm that PRRT (Peptide Receptor Radionuclide Therapy) is becoming a standard of care.
– Emerging frontiers: New trials are expanding into breast, lung, brain, ovarian, and pancreatic cancers — areas where current treatments often fall short.

What this means for patients
The potential benefits are profound:

– Personalized treatment: Doctors can select the isotope-molecule pairing best suited to a patient’s cancer.
– Real-time monitoring: Isotopes like Tb-149 let doctors see exactly where treatment is going.
– Reduced toxicity: By sparing healthy tissue, many patients may experience fewer side effects than with chemotherapy.
– Improved access: As production expands and trials advance, more treatment centers will be able to offer these therapies.

The road forward
There are still hurdles to overcome:

– Manufacturing and supply chains: Producing isotopes requires specialized equipment such as cyclotrons.
– Regulatory approval: Each therapy must pass rigorous safety and efficacy testing.
– Insurance and reimbursement: Payers must adapt to the dual role of diagnostics and therapy in a single treatment.

Yet momentum is strong. If Lu-177 was the proof of concept, these next-generation isotopes may redefine cancer treatment in the coming decade.

The theranostic revolution
Theranostics has moved from niche research to the forefront of oncology. Within the next five years, it is likely that patients across many cancer types will gain access to therapies that not only locate cancer with unmatched precision, but also treat it simultaneously.

For patients and families, this revolution represents not just another treatment option, but a new vision of hope: therapies that are smarter, gentler, and more effective than ever before.

About the author: Willie Foerstner is healthcare correspondent at PMAC Capital Reports. Willie leverages his unique blend of clinical insight and capital expertise to report on how innovation is funded, developed, validated, and delivered to patients. From advanced imaging technologies — including photon-counting CT, PET/MR, and myocardial perfusion imaging — to cyclotron-based isotope production, theranostics, and next-generation radiopharmaceutical trials, he offers perspective that bridges financial strategies, regulatory pathways, and patient outcomes.

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