Ep195: Ken Song on T-cell Engagers for Autoimmune Diseases

What It Covers

Ken Song, CEO of Candid Therapeutics, explains how bispecific T-cell engaging antibodies could deliver CAR-T-like immune resets for autoimmune diseases at scale. The San Diego startup raised $370M, licensed two clinical-stage assets from China, and has now treated over 60 autoimmune patients across 10 disease indications in under 18 months.

Key Questions Answered

• •Asset sourcing timing: Licensing clinical-stage T-cell engager antibodies from Chinese biotechs in early 2024 was significantly cheaper than six to twelve months later, when pharma and biotech rushed to source the same assets. Companies holding these molecules were resource-constrained and motivated to monetize. Waiting even one additional quarter would have made the economics unworkable for a startup. Identifying licensing windows before competitive demand inflates pricing is a repeatable deal-sourcing strategy.
• •Safety differentiation criteria: When evaluating T-cell engager candidates, prioritize cytokine release syndrome rates below 30% with only mild grade events versus the 60-70% CRS rates seen with approved BCMA engagers like teclistamab. Neurotoxicity must be near zero. This safety threshold is the minimum required for rheumatologists and neurologists to prescribe the therapy outside oncology centers, making it the single most critical filter when selecting autoimmune-ready molecules from existing oncology pipelines.
• •Single-cycle dosing signal: Early clinical data from Candid's BCMA T-cell engager, suzutamig, shows that one treatment cycle — four weekly injections administered within 30 days — can produce durable immune reset in autoimmune patients. Watching for this one-and-done response pattern in the first five patients per indication is the signal threshold used to decide whether to advance or abandon each disease program, avoiding prolonged investment in marginal responders.
• •Regulatory arbitrage strategy: FDA's CDER division required Candid to restart dose escalation from scratch despite existing oncology safety data in 40-90 patients, while CBER simultaneously offers streamlined registrational paths for CAR-T in autoimmunity. Recognizing this regulatory asymmetry early, Candid generated phase-one autoimmune data across Europe and China first, then returned to FDA with 60-plus patient dataset in hand to support a global phase-two filing — a sequencing approach that saved roughly 12-18 months of US development time.
• •Speed-over-savings decision rule: When a vendor negotiation saves $20,000 but delays a study start by two weeks, the true cost is millions in daily burn rate, not $20,000. Song applies this calculation explicitly across all operational decisions at Candid, instructing teams to accept vendor terms and start immediately rather than optimize contracts. Compounding dozens of such decisions across a development timeline produces a material lead over competitors who optimize for cost rather than calendar time.
• •Market sizing framework for TCE class: The T-cell engager class in autoimmunity parallels the anti-TNF wave of 25 years ago, when Humira, Enbrel, and Remicade each generated billions annually in a non-winner-take-all market. Song estimates room for three to five approved TCEs targeting BCMA or CD20, with the first-mover capturing roughly 70% of total revenue. In a class projected to reach $30B annually, the market leader could generate $20B, making speed to registration the primary value driver.