Tag: Radioactive isotopes

Promising New Radioligand Treatment for Men with Metastatic Prostate Cancer Using Lutetium 177 (177Lu)

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Using small molecules, we are able to target not only the known tumors, but can also treat the unknown tumors.

Physicians and researchers at Weill Cornell Medicine have been utilizing prostate specific membrane antigen (PSMA)-directed radioisotope therapy for more than a decade. Over the years, we have shown that we could use this approach to target the vast majority of prostate cancer tumors (“hitting” essentially all known tumors and avoiding normal organs), demonstrated anti-tumor responses when the J591 antibody is linked to a radioactive particle with a large (single) treatment, and then further improved upon this treatment (while simultaneously reducing the side effects) by dose-fractionation (splitting the dose into two).

Following our lead and with the discovery of new small molecules which also specifically bind to PSMA, European physicians have begun using these compounds tagged with the same radioactive particle. The most common molecule has been termed PSMA-617. They have shown some very nice anti-tumor responses with limited side effects. However, because European laws differ from the U.S., many men are able to pay for treatment outside of the setting of rigorous, organized clinical research studies that clearly define appropriate dosing, efficacy and toxicity.

In January 2017, research was published in the Journal of Nuclear Medicine demonstrating that Lutetium 177 combined with PSMA-617 can reduce the amount of tumors in the body and lead to remission of the cancer as measured by PSA level. Twelve German hospitals reviewed their data and compiled a publication of patients with metastatic prostate cancer who received Lutetium-177 linked to PSMA-617 (177Lu-PSMA-617). Over 18 months, 145 men whose cancer grew despite standard treatments (including abiraterone and/or enzalutamide and chemotherapy) and whose tumors “lit up” on PSMA imaging were treated. While not a proper prospective research study, they were able to determine information about both anti-tumor activity and safety. Most patients who had PSA measured before and after treatment had some decline, with 40% having PSA cut at least in half following a single treatment. Blood counts dropped in less than half (usually to moderate degrees) and some developed dry mouth and/or taste changes. Severe toxicity was rare.

It is encouraging to see that there is a treatment that might lead to reduction in cancer without severe side effects, even in men who previously have received many other lines of treatment. However, both rigorous research as well as access for our patients are current issues. Therefore, we are excited to offer a clinical trial that builds upon our prior experience of anti-PSMA radioimmunotherapy while taking into account the available European data.

This study utilizes the most commonly used molecule, 177Lu-PSMA-617, in a prospective manner. Our prior research has shown that higher doses result in significantly better anti-tumor responses, so one purpose of this study is to perform dose-escalation to determine the safest and most-effective dose without increased side effects. In addition, our research demonstrated that dose-fractionation allowed higher doses with less toxicity, so our treatment schedule will deliver the total dose in 2 fractions.

We look forward to advancing science and also making these treatments available to men in the tri-state area and across the U.S., not just those who can afford to fly to Germany for treatment. At Weill Cornell Medicine and NewYork-Presbyterian, we have an excellent, multidisciplinary team that has led the world in PSMA-targeted radionuclide therapy. We will leverage our combined expertise and experience to translate the exciting knowledge base into true clinical gains for prostate cancer patients.

To learn more about the clinical trial or enroll, click here. Call us at 646-962-2072 to make an appointment or schedule a consultation. 

Using Radiation, Radioimmunotherapy and Radioactive Isotopes such as Lutetium 177 to Treat Prostate Cancer

Radiation is a mainstay in the treatment of prostate cancer. In men with localized prostate cancer (confined to the prostate gland), using radiation can help cure the cancer. In men with advanced disease, radiation can improve survival and help to manage pain.

Radiation can be delivered a variety of different ways. For example, there are external beams that can be used to deliver radiation from an external machine into the prostate, radioactive “seeds” that can be implanted, or ways to inject special radioactive isotopes directly into the bloodstream.

In the United States (U.S.), there are older FDA-approved treatments utilizing radioactive isotopes for men with prostate cancer that has spread to the bones to decrease pain, called samarium-153 (brand name Quadramet) and strontium-89 (Metastron). More recently, a bone-targeted alpha particle called radium-223 (brand name Xofigo®) was approved because it leads to longer overall survival in men with symptomatic metastatic castration-resistant bone metastases. These bone-targeted radioisotopes have been useful because prostate cancer commonly spreads to bone. However, those drugs cannot treat other sites of tumors such as in the prostate, lymph nodes, or lung.

We are also able to use parts of the immune system as a way to deliver radioactive particles or other targeted cancer treatments to the prostate cancer. We have engineered very specific monoclonal antibodies and molecules that will bind only to PSMA, leading to the opportunity for “molecularly targeted” radiotherapy for prostate cancer. When we combine immunotherapy with monoclonal antibodies with radioactive isotopes, we call the treatment approach radioimmunotherapy. Radioimmunotherapy involves attaching a radioactive isotope (such as Lutetium 177) to a cancer-targeting antibody or small molecule that binds only to a specific cancer-related molecule on a tumor cell. This is similar to a “lock and key” scenario, where the antibody or molecule serves as a key that will only recognize a very specific lock (the cancer-related molecule). In prostate cancer, nearly all cells have a specific “lock” that lives on the surface of each cell called prostate-specific membrane antigen (PSMA).

j591_psmaFor nearly 15 years, we have been utilizing a monoclonal antibody known as J591, which is a version of a specific key that will only recognize and enter cells with the specific lock PSMA. We successfully utilized this antibody tagged with small radioactive particles to either visualize or treat prostate cancer tumors within the prostate, bone, lymph nodes, and other sites in the body. Our initial studies demonstrated safety and signaled anti-tumor efficacy. In addition, we showed that the antibody went to virtually all sites of tumors (sometimes discovering new ones) and did not target other normal organs (with the exception of the liver which helps clear the drug from the body). Subsequently, our larger studies have shown responses in larger numbers of patients. In Europe, physicians picked up on our results and Lutetium 177 (also known as Lu-177, 177-Lu or 177 Lutetium) has become a very popular radioactive particle that can be directed to prostate cancer via PSMA. It has been used to kill prostate cancer cells and treat hundreds of prostate cancer patients. This commonly-used approach uses a small molecule which recognizes PSMA to deliver Lu-177 to prostate cancer cells (termed radioligand therapy or radioimmunotherapy therapy).

Lutetium-177 PSMA therapy is associated with a good prostate cancer response and many men travel from all over the world to Europe in order to access this treatment. In the U.S. it is only available via clinical trials, and for more than 10 years, Weill Cornell Medicine and NewYork-Presbyterian have been one of the few centers in the U.S. to offer Lutetium 177 and other targeted treatments using radioactive particles.

Learn more about how this treatment works in this video:

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