Lung Cancer: Promising News on Light Therapy

Researchers sucessfully used near infrared photoimmunotherapy (NIR-PIT) to prevent early metastases of lung cancer in mice, without damaging surrounding normal lung tissue. Kazuhide Sato, PhD, of the National Cancer Institute in Bethesda, Maryland, and several colleagues completed the the study, which was published in Oncotarget, volume 6, number 23.

Targeted light therapy has been an established concept for over 30 years, but side effects due to a lack of “sufficient selectivity” made it a an undesirable treatment, the team noted. NIR-PIT is a newer, and much more targeted therapy which is “a potential therapy to prevent further growth of early lung metastases,” they wrote.

The researchers performed tests in in vitro 2D culture, in vitro 3D culture, and in vivo.

Although the number of times cells were exposed to NIR-PIT varied, in all three types of tests, the metastases stopped. For the in vivo tests, the researchers used fluorescence and bioluminescence reporters, along with multimodal imaging to evaluate the effects of NIR-PIT. Only the left lung received the therapy so that researchers could observe the effects of NIR-PIT.

When metastases happen, there are several, predictable steps: the cell loses adhesion and becomes invasive, it gets into the circulatory system, moves to a new location, adheres to a “distant organ vessel walls”, it begins to move from the blood vessels into the surrounding tissue, and finally, colonization begins. NIR-PIT prevented the last three steps in the lungs of mice.

Lungs are especially optimal for the transmission of light, but the researchers also believe that NIR-PIT could be a beneficial treatment during or after surgery to get rid of any residual or remaining cancer cells, or to treat circulating tumor cells (CTCs) in the arteries and veins near the skin. Certain types of malignancies seem to metastasize to the lungs, and NIR-PIT could become a “method for preventing pulmonary metastases.”

In the study, NIR-PIT was administered transcutaneously, but in humans it would have to be bronchoscopically or thoracoscopically. Both techniques are far less invasive than surgery, and could be done multiple times if necessary without harm. However, the researchers note that “metastases outside the lungs would not be affected by NIR-PIT,” and that this particular study did not determine “the long-term durability of response and side effects of NIR-PIT.”