Bakacs T, Mehrishi JN, Szabó M, Moss RW. Interesting possibilities to improve the safety and efficacy of ipilimumab (Yervoy).
Pharmacol Res 2012;
66:192-7. [PMID:
22503629 DOI:
10.1016/j.phrs.2012.03.015]
[Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 03/28/2012] [Accepted: 03/28/2012] [Indexed: 10/28/2022]
Abstract
As predicted, an anti-CTLA-4 mAb (ipilimumab) on binding to T lymphocytes breaks down immune-tolerance. Thereby, it was hoped, tumor-specific-T cells would be freed for a sustained attack on cancer cells. Data on ipilimumab treatment in 1498 patients with advanced melanoma (in 14 phase I-III trials) has shown immune-related adverse events (irAEs) in 64.2% of the patients consistent with tolerance breakdown. However, there is no evidence that the antitumor effects via a CTLA-4 blockade are attributable to T cells specifically targeting tumor cells. In fact, several trials indicate a possible correlation between grade 3 and 4 irAEs with clinical efficacy of ipilimumab; tumor regression may be associated with autoimmunity development. Therefore, we suggest a new treatment paradigm. The non-tumor specific pan-lymphocytic activation should be exploited by a 'pretargeting' approach proven successful in radioimmunodetection and radioimmunotherapy. First, an anti-tumor mAb conjugated with streptavidin (StAv) should be administered to be followed by the delivery of biotin-labeled anti-CTLA-4 mAb. This schedule has the virtue of endowing T cells with the ability to travel to tumor sites without prematurely succumbing to apoptosis, while streptavidin's ultra-high affinity for biotin (K(D), 10⁻¹⁵ M) ensures capturing all T cells binding biotin labeled anti-CTLA-4. Using the law of mass action, we calculated that following administration of ipilimumab at >1 mg/L concentration (∼5 mg per patient ∼70 kgbw), the immense forces of the immune system liberated by the anti-CTLA-4 antibody blockade would then be focused with laser sharp accuracy on tumor cells without collateral damage to normal host cells.
Collapse