New approaches and imaging tools in cancer therapy

JNI Oncology lectures, Erasmus MC Rotterdam, 25.11.15

Title: Can we cure cancer? New approaches and imaging tools

Speaker: Clemens Löwik (Erasmus MC, Rotterdam, The Netherlands)

Author: Edgar Schönfeld

 

Clemens Löwik’s talk focused on new imaging techniques that are able to augment existing anti-cancer therapies. At the beginning of his talk he raised the question how we can possibly cure cancer. If the original tumor does not have metastasized yet, resection of the tumor cures the patient usually. For metastatic cancers, combination therapy including immunotherapy will most likely result in a cure for many malignancies in the future, according to Löwik. In his talk he introduced three recent developments he was involved in that touch these subjects:

  1. Fluorescent image guided surgery
  2. Photodynamic therapy + immunotherapy
  3. Necrosis as a target for diagnostic imaging & therapy

Fluorescent image guided surgery (FIGS) employs fluorescent dyes to demarcate cancer tissue during an operation. Metastatic cancers are usually treated with a combination of surgery, irradiation and chemotherapy. However, during an operation it can be difficult to distinguish cancerous tissue from healthy tissue. Especially very small metastases can remain undetected. In recent years contrast agents have been developed that fluoresce upon stimulation with near infrared light (NIR), which can penetrate several centimeters through tissue. In the context of an operation, this contrast agent is administered to the patient. A NIR light source is adjusted such that it points onto the surgical area, while a NIR sensitive camera records life images. These life images can be displayed on a monitor or via goggles. Such a system is already in use at the Leiden University Medical Center.

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Figure: Setup for a fluorescent image guided surgery

 

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Video: Point-of-view footage of fluorescent image guided surgery; Left: normal image; Right: augmented image

 

Löwik was also involved in a study in which tumors were eradicated by a combination of photodynamic therapy (PDT) and immunotherapy in mice. A PDT treatment starts by administering a photosensitizing agent to the patient, which stays longer in cancer cells than in healthy tissue. Subsequently the tumor is irradiated with light of a specific wavelength. This triggers the production of reactive oxygen species (ROS) by the photosensitizer, which destroys the tumor cells. The technique is highly selective, does not leave any scars and most importantly, equally affects cancer stem cells. In addition it causes damage to the vasculature in the tumor environment, thereby cutting off the nutrient supply for tumor cells. Above all, PDT in combination with a therapeutic vaccine can cause an immune response which successfully prevents tumor reoccurrence in mice.

Löwik’s favorite subject however is necrosis. He holds a patent for a method that stains necrotic cells. This involves the use of dyes that cannot enter cells, except if the membrane has lost its integrity. Since almost all tumors have a necrotic core, these dyes can be used for diagnostic purposes. Interestingly, Löwik reported that his team recently developed nanoparticles that can enter the necrotic area of tumors. In doing so, they attack the tumor from the inside.

Each of the presented methods is very promising in my eyes. Above all, fluorescent image guided surgery impresses me deeply. This method can greatly decrease the likelihood of overseeing metastases and thereby make a tumor relapse less likely.

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