Ep103: Ken Song on Targeted Radiopharmaceuticals for Cancer

Episode Summary

Executive Summary: Ken Song traces his path from physician-scientist to biotech CEO and explains why he believes radiopharmaceuticals are being resurrected as a major oncology modality. He argues that better isotopes, targeting biology, manufacturing, and imaging-enabled patient selection now make targeted radiation far more viable than in earlier failed attempts, positioning Raze Bio as a vertically integrated platform company.

Main Topics: Ken Song’s career path and biotech transition (Priority: 5/5): Song describes growing up in Michigan, training at MIT and UCSF, entering consulting and venture capital, then shifting into company-building after a successful run leading Ariosa Diagnostics and later Mediclin. Why radiopharmaceuticals are re-emerging (Priority: 5/5): He explains that older targeted radiation drugs succeeded clinically but failed commercially due to immature infrastructure, manufacturing issues, prescribing friction, and competition from Rituxan; today the field has better awareness and supply. Scientific rationale for targeted radiation (Priority: 5/5): Song contrasts radiopharmaceuticals with ADCs, emphasizing that radiation only needs to reach the tumor zip code, while alpha and beta particles have highly localized killing ranges, enabling potent tumor cell destruction with manageable toxicity. Platform strategy at Raze Bio (Priority: 5/5): Raze is building a multi-program radiopharmaceutical platform spanning target discovery, binder optimization, isotope sourcing, GMP manufacturing, and future commercialization, rather than a single-asset company. Imaging as a precision-medicine advantage (Priority: 4/5): Song highlights the ability to use the same targeting molecule with either a diagnostic isotope or a therapeutic isotope, letting clinicians image uptake first and select patients most likely to benefit. Combination therapy and future market size (Priority: 4/5): He sees radiopharmaceuticals combining well with immunotherapy, especially PD-1 inhibitors, and believes the modality could become as large or larger than ADCs across multiple solid tumors.

Key Arguments: Earlier radiopharmaceuticals failed commercially, not clinically, because infrastructure, manufacturing, logistics, and prescribing pathways were not ready. The current field is different because lutetium-177 supply is now broadly available and actinium-225 supply is expected to scale. Radiopharmaceuticals are conceptually simpler than ADCs because the isotope itself is the payload; once delivered to the right tumor region, it destroys nearby cells without needing intracellular cleavage. Smaller binders such as peptides or small molecules are preferred because they penetrate tumors better and clear faster, reducing systemic radiation exposure compared with antibodies. Target selection matters, but radiopharmaceuticals require less mechanistic biology than many drugs because the key question is whether the target is present and sufficiently homogeneous on tumor cells. Diagnostic and therapeutic versions of the same construct can enable true precision medicine by imaging uptake before treating patients. Raze Bio is intentionally vertically integrated to control discovery, manufacturing, and eventual commercialization, which Song thinks will differentiate the company. Combination with immunotherapy may amplify response by releasing neoantigens and helping the immune system clear residual disease.

Data Points: Year Song joined Venrock: 2007 - He entered venture capital after clinical training and consulting experience. Ariosa commercialization reach: Over 100 countries - He said Ariosa Diagnostics commercialized noninvasive prenatal testing globally before Roche acquired it. Raze Bio launch: August 2020 - Song said the company was launched after his deep dive into the modality. Actinium-225 range of kill: Tens of microns - Used to explain why alpha isotopes can be potent yet localized. Beta particle range of kill: About 1-2 mm - Described in contrast with alpha particles and in support of targeted tissue effect. Lutathera trial hazard ratio: 0.21 - From the NETTER-1 study in neuroendocrine tumors, cited as dramatic efficacy. Risk reduction implied by hazard ratio: About 80% - Interpreter comment in the transcript about Lutathera reducing progression/death risk. Raze Bio employees: 45 full-time employees - Song described company headcount at the time of the interview. Total effective workforce: Nearly 100 people - Includes contractors overseas doing chemistry work. Time horizon for commercialization: Five years - Song hopes to be commercial and generating revenue with a first product within five years. Target list size at earlier discussion: About 10 validated targets - Song referenced the prior interview where he described the initial target set.

Pivotal Quotes: "We are doing massively parallel discovery." — Ken Song: He described Raze Bio’s broad, multi-partner approach to finding and optimizing radiopharmaceutical targets and binders. "With radiopharmaceuticals, you just need to be in the right zip code." — Ken Song: He used this metaphor to contrast radiation payload delivery with the stricter intracellular requirements of ADCs. "I think that radiopharmaceuticals can actually eclipse that of what antibody drug conjugates have done for the field." — Ken Song: He forecasted the modality’s market potential and its possible role as a major oncology platform.

Implications: If Song is right, radiopharmaceuticals could become a mainstream oncology class with companion imaging, better patient selection, and broad solid-tumor applicability. Raze Bio aims to be an early platform leader if isotope supply, manufacturing, and clinical validation continue to improve.