$580 Million Partnership Paves the Way for Phase 3 Trial of Rare Cutaneous Lymphoma Antibody

Whether an antibody for a rare cutaneous lymphoma can advance into a phase 3 trial depends not only on early efficacy, but also on who is willing to shoulder the high cost of late-stage development. Swedish rare disease drugmaker Sobi and French biotech company Innate Pharma have entered into a partnership for lacutamab, with a potential total deal value of up to $580 million, filling a critical gap in a program previously constrained by funding.

Upon completion of the transaction, Innate will receive an upfront payment of $75 million. Together with a near-term milestone payment for Sézary syndrome, the upfront payment is expected to fund the launch of the confirmatory phase 3 TELLOMAK-3 trial and preparations for regulatory filings. The remaining payments are contingent on the achievement of development, regulatory review, and commercial milestones and therefore are not guaranteed revenue; Innate may also receive tiered double-digit royalties based on sales.

Lacutamab is a monoclonal antibody targeting KIR3DL2. This protein is found on the surface of some cutaneous T-cell lymphoma cells, and the drug is designed to recognize cells carrying the target and promote their elimination. Development is focused on Sézary syndrome and mycosis fungoides. The former is an aggressive cutaneous T-cell lymphoma with leukemia-like features that may involve the skin and blood, and should not be confused with common melanoma or skin cancer.

Innate plans to use existing phase 2 TELLOMAK data to seek accelerated approval for Sézary syndrome from the U.S. Food and Drug Administration while advancing TELLOMAK-3. This open-label, randomized comparative trial will enroll patients with Sézary syndrome and mycosis fungoides in separate cohorts to assess progression-free survival; it is intended both to confirm the clinical benefit in the former indication and to establish evidence for full approval in the latter.

Regulatory designations support this pathway: lacutamab has received Fast Track and Breakthrough Therapy designations in the U.S., PRIME support from the European Medicines Agency, and orphan drug designation in both the U.S. and the European Union. However, these designations only indicate that the review may receive closer support; they do not mean that efficacy has been confirmed or that the product has been approved for marketing.

The partnership’s immediate impact is particularly clear. Innate previously said that the phase 3 trial was not included in its existing cash plan and that its launch depended on non-dilutive financing; the upfront payment is expected to extend the company’s cash runway into the third quarter of 2027. The company has also appointed Markus Jensen as chief medical officer effective September 1, 2026, to oversee the upcoming late-stage clinical and regulatory execution.

Uncertainty remains concentrated in three areas: the transaction must first close, regulators will determine whether the phase 2 data can support accelerated approval, and the phase 3 trial has not yet produced confirmatory results. The maximum $580 million reflects a series of conditional future payments; lacutamab’s ultimate position will be determined by whether the randomized trial can demonstrate a benefit in disease control and acceptable safety.