The treatment of cancer via antibody therapeutics that modulate immune responses is the focus of substantial research and development by the biopharmaceutical industry. To date, 6 monoclonal antibodies (mAbs) that function by modulating immune checkpoints have been approved in the US: ipilimumab (anti-cytotoxic T-lymphocyte-associated antigen 4 (CTLA4)); pembrolizumab and nivolumab (anti-programmed death receptor 1 (PD-1)); durvalumab, avelumab, and atezolizumab (anti-programmed death ligand 1 (PD-L1)). Cemiplimab, another anti-PD-1 mAb, is currently undergoing regulatory review. Antibody immune checkpoint modulators can be used to treat many types of cancer,[1] which makes them highly attractive for biopharmaceutical development. For example, the approved products, which target only 3 of the many proteins involved in either stimulating or inhibiting immune responses, are used to treat melanoma, non-small-cell lung cancer, head and neck cancer, Hodgkin’s lymphoma, bladder cancer, gastric/gastroesophageal junction adenocarcinoma, renal cell cancer, hepatocellular cancer, Merkel cell carcinoma and colorectal cancer. [2]

More than 80 antibody immune checkpoint modulators sponsored by commercial firms are in clinical development, and they comprise ~ 24% of the clinical pipeline of antibody therapeutics for cancer. Most are in early development, with 50 and 28 antibody immune checkpoint modulators undergoing evaluation in Phase 1 and Phase 2 clinical studies, respectively. Seven (IBI308, BCD-100, PDR001, tislelizumab, camrelizumab, utomilumab, and tremelimumab) are undergoing evaluation in late-stage studies.[3]

Despite the fact that 5 antibodies targeting the PD-1 pathway are already marketed, PD-1 and PD-L1 remain popular as targets for antibodies in development. Of the antibody immune checkpoint modulators currently in the clinic, 21 molecules target PD-1, including five in late-stage clinical studies, and 9 antibodies target PD-L1. Other popular antigens for antibodies in clinical development include glucocorticoid-induced tumor necrosis factor receptor (GITR; target of 7 antibodies); CD40, LAG-3 and OX40 (each the target of 6 antibodies); as well as T-cell immunoglobulin and mucin-domain-containing molecule (TIM-3), T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT) and CTLA4 (each the target of 4 antibodies). In addition, two bispecific antibodies (anti-PD-1, LAG-3 MGD013; anti-PD-L1, CTLA-4 AK104) targeting these immune checkpoints are in clinical studies; to avoid double counting, these two were excluded from the totals given above.

Over 100 antibody immune checkpoint modulators have entered commercially sponsored clinical studies since 2000, but ~60% of the molecules first entered such studies in the past 3 years. The ultimate fates (approval or termination) for most of the molecules are thus not yet known, but the available data is sufficient to calculate a Phase 1 to 2 transition rate, which is 74%. This rate compares favorably with that for all antibody therapeutics (75%) and anti-cancer antibody therapeutics (69%). The current data suggest that antibody immune checkpoint modulators, as a group, has a notably higher Phase 2 to 3 transition rate compared with all antibody therapeutics. This result, however, is based on outcomes for relatively few molecules. It should be noted that clinical studies may be terminated for business reasons, as well as safety or efficacy issues. For example, although PD-1 and PD-L1 are well-validated targets, the market for anti-PD-1 and anti-PD-L1 antibodies in the future may not be sufficient to justify continued development of all such antibodies in the current pipeline. Termination of molecules at Phase 2 for business reasons would decrease the Phase 2 to 3 transition rate. To date, no antibody immune checkpoint modulators have been terminated during regulatory review; the transition rate at that phase is thus 100%.

The Antibody Society has partnered with Hanson Wade to track trends in the clinical development of innovative cancer therapies, with a focus on immune checkpoint modulators and antibody-drug conjugates. As the date for ICI Boston 2018 (March 19-21) approaches, Hanson Wade has prepared a comprehensive e-book that provides insights into combination strategies involving immune checkpoint inhibitors, which can be downloaded here. Members of The Antibody Society qualify for a 20% discount to ICI Boston 2018. Please contact us at membership@antibodysociety.org for the code.

1. Torphy RJ, Schulick RD, Zhu Y. Newly Emerging Immune Checkpoints: Promises for Future Cancer Therapy. Int J Mol Sci. 2017; 18(12). pii: E2642. doi: 10.3390/ijms18122642.
2. Iwai Y, Hamanishi J, Chamoto K, Honjo T. Cancer immunotherapies targeting the PD-1 signaling pathway. J Biomed Sci 2017; 24:26. doi.org/10.1186/s12929-017-0329-9.
3. Kaplon H, Reichert JM. Antibodies to watch in 2018. MAbs. 2018 Jan 4:1-21. doi: 10.1080/19420862.2018.1415671.

The Antibody Society tracks the progress of commercially sponsored antibody therapeutics in clinical development on a continuous basis. We collect information, including molecular composition (e.g., format, isotype, target), phase of development and indications studied, from publicly available sources (e.g., press releases, company websites, meeting abstracts, published literature, clinicaltrials.gov, regulatory agency websites). Our data are cross-checked against databases generously provided by our corporate partners, including Hanson Wade’s Beacon Targeted Therapies and the Therapeutic Antibody Database. It should be noted that companies may not publicly disclose all information for all molecules in the pipeline, especially those in the early stages of development. The numbers of molecules discussed above should thus be considered minimums, as targets have not been disclosed for all the molecules we are tracking. We look forward to reporting additional trends and metrics for antibody therapeutics development in the future.

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