If Astrazeneca still insists that CTLA-4 inhibition is a valid part of an immuno-oncology combination its private stance seems to be somewhat different. The reality has been laid bare by EvaluatePharma Vision’s estimate of the clinical trial costs of Astra’s tremelimumab, suggesting that R&D investment in this CTLA-4 MAb peaked in 2018 and is now winding down. The estimate is based on enrolment numbers in previous and ongoing trials, and an estimate of the per-patient cost. Tremelimumab is notorious for not recording any resounding clinical wins despite an extensive study programme, and notwithstanding a recent purported success in Astra’s Poseidon study (Poseidon scores, but tremelimumab’s role is still unclear, October 29, 2019). One of the biggest ongoing bets on CTLA-4 inhibition is by Yervoy’s owner, Bristol-Myers Squibb, which is additionally pursuing the afucosylated MAb BMS-986218, and BMS-986249, a CTLA-4 probody licensed from Cytomx, through the clinic. A definitive picture might not emerge until Merck & Co’s Keynote-598 trial combining Keytruda with Yervoy reads out in 2023, and should this be positive Merck has its own CTLA-4 MAb, MK-1308, waiting in the wings.
*EvaluatePharma Vision’s R&D model estimates the cost of individual clinical programmes using real-world data, combining disclosed product-level spend and clinical trial subject numbers.