Cancer Research Institute Media Room



New Report Charts Dramatic Growth in the Global Clinical Trial Landscape for PD-1/L1 Immune Checkpoint Inhibitors

  • 2,250 clinical trials are evaluating PD-1/L1 immune checkpoint inhibitors, an increase of 748 trials over the past year
  • 1,716 trials are assessing regimens that combine PD-1/L1 immune checkpoints with other cancer therapies
  • 240 drug targets are being evaluated in the current landscape, 75 more targets compared to a year ago
  • Over 380,000 patient volunteers are required to fill all trials, and patient recruitment rate has slowed down sharply in recent years

The Cancer Research Institute (CRI), a nonprofit organization dedicated to the discovery and development of powerful immunotherapies for all cancers, announced today the publication of a report that provides a comprehensive analysis of the current clinical trial landscape of anti PD-1/L1 immune checkpoint inhibitors. Based on data from and CRI’s internal database, this report identifies all active clinical trials evaluating anti-PD-1/L1 immune checkpoint inhibitors, the drug targets tested in the trials, and median patient recruitment rate of some trials in the space. This report also compares the current landscape with the previous one surveyed by CRI one year ago.

This report titled, “The clinical trial landscape for PD1/L1 immune checkpoint inhibitors,” was published online today by Nature Reviews Drug Discovery, a leading academic journal and authoritative source in drug development. This report highlights the major trends in the current PD-1/L1 clinical trial landscape and identifies a potential challenge in patient volunteer recruitment.

“Compared to one year ago, we saw 33 percent increase in the number of active trials and 31 percent increase in new targets of drugs being tested in combination with checkpoint inhibitors, demonstrating continuous growth and enthusiasm in the clinical development of these drugs,” noted Jun Tang, PhD, the corresponding and first author of the report and senior manager of the CRI Anna-Maria Kellen Clinical Accelerator. “We are encouraged not only by the fact that the majority of the trials are evaluating PD-1/L1 combination therapies, but also by the diversity of combinations of PD-1/L1 agents with many types of other cancer therapies targeting 240 different targets,” Tang added.

“Another exciting finding is that almost all cancer types are being studied with PD-1/L1 therapies in clinical trials, including many rare cancers,” said Vanessa Hubbard-Lucey, PhD, director of the CRI Clinical Accelerator. “Promising data from a few clinical trials released recently suggest that the use of PD-1/L1-containing regimens will benefit more patients in the clinic very soon,” added Hubbard-Lucey.

The report’s authors also identify a potential challenge facing patient recruitment for these trials. “Although PD-1/L1 combination trials still recruit patients faster than other cancer trials, recruitment has slowed down by 70 percent in four years,” Tang noted. “This slowdown could be the result of both the rapid changes in the standard of care owing to many recently approved PD-1/L1 regimens and the competition among new trials to recruit patient volunteers from a relatively small, unchanged pool,” Tang added.

“We see an opportunity for the field to address the slowdown in patient recruitment by prioritizing resources and directing them into clinical studies that are based on strong scientific evidence and treat patients with urgent unmet medical needs,” said Jill O’Donnell-Tormey, PhD, chief executive officer and director of scientific affairs at CRI. “On the other hand, industry, healthcare providers, government, and nonprofits should encourage and help patients to participate in clinical trials and therefore enlarge the pool of patient volunteers, which appears to be a major limiting factor in the clinical research of cancer immunotherapies,” O’Donnell-Tormey added.

“This publication is the latest of several landscape reports from the Cancer Research Institute designed to inform the drug development community of the latest advances in immuno-oncology,” said Tang. “CRI has created a series of online interactive charts based on data cited in the publications, and we encourage our colleagues to explore these analyses,” Tang added.

Reference: Tang J. et al. The clinical trial landscape for PD1/PDL1 immune checkpoint inhibitors. Nature Reviews Drug Discovery. 17, pages 854–855 (2018)

About the Cancer Research Institute 
The Cancer Research Institute (CRI), established in 1953, is the world’s leading nonprofit organization dedicated exclusively to transforming cancer patient care by advancing scientific efforts to develop new and effective immune system-based strategies to prevent, diagnose, treat, and eventually cure all cancers. Guided by a world-renowned Scientific Advisory Council that includes four Nobel laureates and 26 members of the National Academy of Sciences, CRI has invested $384 million in support of research conducted by immunologists and tumor immunologists at the world’s leading medical centers and universities, and has contributed to many of the key scientific advances that demonstrate the potential for immunotherapy to change the face of cancer treatment. To learn more, go to

About the Anna-Maria Kellen Clinical Accelerator

CRI’s clinical program, the Anna-Maria Kellen Clinical Accelerator, is a unique academia-nonprofit-industry collaboration model that serves as an “incubator” that delivers multi-center clinical trials for promising new immunotherapy combinations. CRI’s venture philanthropy fund supports clinical trials within this program, which fosters a collaborative environment that enables scientists to advance their most ambitious research ideas, and accelerates studies that one group or company could not do alone. To learn more about the Anna-Maria Kellen Clinical Accelerator, go to

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