Background of a Killer

There are four new cases of lung cancer reported around the globe every second of every day. The most common cancer worldwide, non-small cell lung cancer (NSCLC) is responsible for some 1.6 million deaths a year. ¹

Since the 1980’s, researchers have made significant strides in understanding NSCLC and how its interactions with the immune system ultimately drive clinical outcome. Much of what they discovered serves as the foundation of the promising new field of immunotherapy.

Among the most significant of their discoveries is the linkage between a patient’s response and the presence, functional state, and composition of the immune cells interacting with the tumor. Known as tumor-infiltrating lymphocytes (TILs), these white cells are predisposed to fight cancer. However, there are many ways that their effectiveness gets mitigated.  Researchers have shown that TILs also play an integral role in tumor development, disease progression, eventual metastasis, and how tumors respond to various therapies. Many immunologists and oncologists now believe that leveraging these new insights will enable a new paradigm in cancer treatment including for NSCLC. ²

The primary reason why the specific role TILs play in cancer progression has remained elusive is the lack of tools to elucidate the specific interactions and signaling between immune, cancer and stromal cells. Traditionally, pathologists quantify TILs in tumors using a standard H&E (hematoxylin and eosin) or immunohistochemistry (hematoxylin and DAB), which is a “single-plex” assay.  These methods “are only semi-quantitative” and are “subject to considerable inter-observer variation” that could lead to conflicting results, a new study by Yale researchers says. When dealing with life-and-death decisions in selecting the most appropriate immunotherapies to fight cancer, there is simply no substitute for a precise diagnosis. ³

Championing a Novel Protocol

Yale researchers wanted something more definitive in their search for treating NSCLC. Using two independent collections of formalin-fixed paraffin embedded (FFPE) tissue samples drawn from more than 550 individuals, the Yale team developed an entirely new procedure to measure TIL activity in tumors. Instead of relying on the traditional single-plexed methodology, Yale pathologists, led by Dr. Kurt A. Schalper, associate research scientist at the Yale School of Medicine and director of the Translational Immuno-oncology Laboratory at Yale, used sequential multiplexed quantitative immunofluorescence, or QIF.

QIF uses a number of special fluorescent reagents from PerkinElmer and others that emit different colored light that indicate several types of TILs in the context of the tumor FFPE tissue. The Yale team analyzed the cohort of samples using a tissue microarray format (TMA), which puts tissue samples for many patients on a single microscope slide, allowing simultaneous analysis of the NSCLC tissue samples under identical, standardized conditions. The researchers then imaged the TMA with a Vectra multispectral imaging system from PerkinElmer.  TIL subpopulations were counted using trainable tissue/cell segmentation algorithms in PerkinElmer’s InForm® image analysis software.  That process allowed the researchers to identify a correlation between clinical response and numbers CD8+ and CD20+TILs. ⁴

“The strength of our method is that it allows simultaneous measurement of different TIL subtypes and removes the subjectivity from the process by using automated scoring,” Schalper told YaleNews.com. “We believe that this method could help determine which patients are more likely to benefit from new immune checkpoint therapies.” ⁵

Results of New Assay Procedure

Results of the new Yale assay suggest that increased levels of TILs are linked to better patient outcomes in NSCLC. What does that mean for the future?

With the ability to measure precisely the properties of anti-tumor immune responses in cancerous lung tissue, the novel procedure could become a valuable new platform for predicting response to immunotherapies. Equally important, the insights this platform will enable could lead to the development of new immunostimulatory therapies, adding successful first entrants, anti CTLA4 (ipilimumab) and PD1/PDL1 (nivolumab), into this drug class.  These drugs have demonstrated remarkable results in clinical trials against different forms of cancer. ⁶

Referencess

1. World Cancer Research Fund International, Worldwide Data. See also, World Health Organization, Cancer Fact Sheet, Number 297, February, 2015.
2. “Changes of tumor infiltrating lymphocyte subtypes before and after neoadjuvant endocrine therapy in estrogen receptor-positive breast cancer patients--an immunohistochemical study of Cd8+ and Foxp3+ using double immunostaining with correlation to the pathobiological response of the patients”, International Journal of Biological Markers, December, 2012.
3. “Objective Measurement and Clinical Significance of TILs in Non–small Cell Lung Cancer”, Journal of the National Cancer Institute, March, 2015.
4. “Multiplexed Quantitative Assessment and Prognostic Value of TIL Subtypes in Non-small Cell Lung Cancer”, presentation, American Association for Cancer Research, Philadelphia, PA, April, 2015.
5. “Research In The News: New Tool Helps Identify Lung Cancer Patients Who Will Respond To Immune Therapies”, YaleNews, February, 2015.
6. “Novel Assay To Identify Effective Immune Therapies In Lung Cancer Patients”, Immuno-Oncology News, February, 2015.