2018 in Review: Advancements and Accomplishments

From delivering exceptional care in the clinic, to presenting at scientific conferences and publishing research in high-impact medical journals, our Genitourinary (GU) Oncology Program had an exceptionally busy 2018. We continue to work diligently to develop new and more effective therapies to treat advanced prostate, bladder and kidney cancers, while educating the community about cutting-edge advancements in the field.

As we look back on 2018, we wish to share a brief update of our research and accomplishments. Here’s what our team has been up to over the past year.

New Faces
Most recently, we were proud to welcome Dr. Cora Sternberg, a global thought-leader in the GU oncology space, to our team. Dr. Sternberg will facilitate the continued growth and development of clinical and translational research programs in GU malignancies, as well as serve as Clinical Director of the Englander Institute for Precision Medicine (EIPM) to develop strategies to incorporate genomic sequencing and precision medicine within our Program and across Weill Cornell Medicine and NewYork-Presbyterian.


New Events
More than 200 prostate cancer patients and loved ones attended our inaugural New York City Prostate Cancer Summit, a multi-institutional collaboration between Weill Cornell Medicine, NewYork-Presbyterian Hospital, Columbia University Irving Medical Center and Memorial Sloan Kettering Cancer Center. This educational and advocacy event featured presentations and panel discussions from local medical experts and national advocacy leaders, with topics including nutrition, screening, coping and anxiety, immunotherapy and much more. Our second annual Summit is slated for September 2019 during Prostate Cancer Awareness Month. Stay tuned for details.


New Research Developments

Prostate Cancer

• Based upon our prior work with fractionated dosing of our radiolabeled antibody 177Lu-J591, we performed the world’s first phase 1 dose-escalation trial of 177Lu-PSMA-617 without finding any dose-limiting toxicity (no major side effects despite higher and higher doses), presenting the initial results at the European Society for Medical Oncology (ESMO) 2018 Congress. The phase II portion of the trial is ongoing. We are also leading the first trial combining two different targeting agents (J591 and PSMA-617) designed to deliver more radiation to tumors and less to other organs.

•  Alpha particles are several thousand-fold more potent than beta-emitters such as 177 Lu. We are completing the phase 1 dose-escalation portion of the world’s first-ever clinical trial utilizing a powerful alpha particle (225Ac) directed almost exclusively at prostate cancer cells by linking it with our J591 antibody, which avoids salivary glands.

• As prostate-specific membrane antigen (PSMA) targeting enters “prime time,” the United States Department of Defense (DOD) has recognized our significant contributions to this evolving field with a grant that will allow us to research optimal patient selection for PSMA-targeted radionuclide therapy and assess the treatment’s immune effects.

• Thanks to developing technology utilizing circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA), we are able to draw information about a patient’s tumor via a simple blood test. In our findings published by the American Association for Cancer Research (AACR) Clinical Cancer Research journal, we analyzed the relationship between chemotherapy treatment and expression of androgen receptor (AR) variants in CTCs of men with metastatic prostate cancer.

• We led a phase II clinical trial through the Prostate Cancer Clinical Trials Consortium (PCCTC) and discovered that an aggressive subset of disease called neuroendocrine prostate cancer (NEPC) is driven by a gene with an associated target known as aurora kinase. Further investigation into targeting of the gene may help us to refine therapy for this difficult-to-treat patient population. Our findings were published as a cover story in Clinical Cancer Research. 

• Working with collaborators and funded by the Prostate Cancer Foundation (PCF), we have developed unique genomics sequencing methodology called PCF SELECT that allows us to identify actionable mutations in men with advanced prostate cancer.

Kidney Cancer

• The number of United States Food and Drug Administration (FDA)-approved drugs for patients with advanced kidney cancer continues to grow. Dr. Ana Molina leads our team in offering clinical trials focused on novel targeted agents, combination treatments, and risk-directed therapies for various subtypes of kidney cancer.

• Working together with the Englander Institute for Precision Medicine, we are evaluating genetic signatures from patient tumor specimens and developing organoids that can be used to test novel pathways and tailor treatment to each individual patient.

• Laboratory studies of our in vivo kidney cancer models have resulted in discoveries regarding the metabolism of the disease. Understanding the role of the mitochondria (a cell’s power generator) in kidney cancer is leading us to novel therapeutic approaches to block tumors from growing and spreading.

Bladder Cancer

• Five immune therapies are now FDA-approved for people with advanced bladder cancer. We continue research to improve upon these agents by combining them with targeted therapeutics with the potential to replace chemotherapy. Collaboration with EIPM will help us to identify tumors most likely to benefit from these treatments.

• Dr. Bishoy Faltas and his lab team are focused on understanding the role of a specific family of proteins that cause mutations (genetic errors) that may be the underlying cause of bladder cancer. This research will enable us to develop new treatments to target the newly-identified genes that drive the disease.

• Based upon Dr. Faltas’ prior high-impact Nature Genetics publication that identified the genetic mechanisms by which bladder cancers become resistant to chemotherapy and new drug targets, we are launching an innovative new clinical trial utilizing a targeted drug that inhibits bladder cancer growth, the first time this type of drug is being tested in bladder cancer.

• We are conducting clinical trials of two antibody-drug conjugates (sacituzumab govitecan and enfortumab vedotin) designed to deliver potent chemotherapy-like toxins preferentially to cancer cells. This type of therapy is anticipated to become one of the standard approaches to bladder cancer treatment.

Precision Medicine

• Using samples of patient tumors (drawn via needle biopsy), we can create small 3-D tumor representations known as organoids that mimic the way that cancer cells grow within the body and respond to treatment. Our team has worked to develop this exciting new form of precision medicine, which is especially significant for rare cancers with a lack of preclinical models available for study.

We are moving closer to our ultimate goal of curing genitourinary cancers and look forward to continued progress in the years ahead.

 

Antibodies and Small Molecules: Two Different Tools to Target PSMA

Prostate-specific membrane antigen (PSMA) is a molecular marker present on the surface of virtually all prostate cancer cells. It can be targeted by different molecular agents that bind to PSMA. This enables a targeted approach to find and image or treat prostate cancer cells wherever they are in the body, including the cells that have escaped (metastasized) to other organs.

The most commonly used agents to target PSMA fall into two categories: small molecules (also known as peptides, ligands, or inhibitors) or antibodies (also termed monoclonal antibodies).

Small molecule- and antibody-based molecules that bind to PSMA have different physical characteristics and these have implications on the way the molecules circulate through the body.

For example, peptides and other small molecules that target PSMA are much smaller than antibodies – approximately 100-fold smaller. As a result of their small size, peptides are able to quickly travel through blood vessels and disperse throughout all body tissues – both normal and tumor – and they are also rapidly excreted by the kidney into the urine and bladder.

Conversely, the larger antibodies tend to stay within the circulating blood and flow more selectively through the larger, abnormal blood vessels within tumors than the vessels in normal tissues. Their large size also prevents them from being excreted by the kidneys. Because of these properties, peptides can penetrate tumors, as well as normal tissues, rapidly and then disappear from the body quickly, in minutes to hours; antibodies take longer to travel and enter the tumor, but this is compensated for by the longer amount of time they spend in the body (days to weeks) and their decreased likelihood to penetrate into normal tissues.

Imaging

From a diagnostic imaging perspective, small molecules are typically better, as the rapid excretion of the radiolabeled peptide quickly minimizes the radioactive background “noise” seen on a scan. Additionally, using small molecules means that patients can be injected with imaging agents and then undergo scans quickly thereafter (on the same day within 1-3 hours). Physicians can see good contrast of the cancerous cells compared to other parts of the body with this method. In comparison, patients must return approximately 3-8 days after infusion with a monoclonal antibody for scans. Some of the benefit of using small molecules is offset by the fact that they are excreted via the urine and accumulate in the urinary bladder. This may lead to an intense signal in the urinary bladder area of the scan, adjacent to the prostate gland and lymph nodes in the pelvis, thereby possibly obscuring these potential sites of tumor. On the other hand, some antibodies are taken up by the liver, obscuring visualization of that organ. Antibody fragments such as so-called “mini-bodies” (derived from the whole antibody), are half the size of a normal antibody, but still large enough so as not to be excreted in the urine, and as such, they may provide improved imaging of the prostate and the pelvic area. This is currently under investigation at Weill Cornell Medicine and NewYork-Presbyterian Hospital.

The nuances of these molecular targeting agents aside, it is clear that both peptide-, antibody or mini-body-based agents provide significantly improved targeted molecular imaging of prostate cancer compared with conventional modalities such as bone, CT, and MR scans and also have some advantages over glucose (FDG), sodium fluoride (bone), choline, or fluciclovine (FACBC) PET scans.

Treatment

From a therapeutic perspective, there are theoretical advantages to the faster tumor penetration of the smaller molecule targeting agents, but this may be offset by their quick disappearance and their ability to impact normal tissue. The longer time antibodies spend circulating in the body theoretically provides for a greater amount of the treatment agent to get internalized into the cancer cells, allowing greater uptake of the payload agent (such as a radionuclide) that is being delivered to kill the cancer cells. Additionally, some antibodies may also be engineered to generate an immune response.

Does uptake in different body areas lead to side effects?

The different characteristics of small molecules and antibodies confer advantages and disadvantages when targeting PSMA on cancer cells within the body. Because of their small size, small molecules/peptides can penetrate through the depths of the tumor very quickly, but they also readily target normal tissues that express low levels of PSMA such as the salivary glands, small intestine, and kidneys. When using as a therapeutic delivery vehicle, this might lead to dry mouth, nausea, or delayed kidney damage. Luckily, no significant kidney damage has been seen in humans to date, but the number of patients treated on prospective clinical trials remains small and follow up is short. An antibody, on the other hand, does not target salivary glands or kidneys because its larger size leads to relatively restricted access to those normal sites. However, it circulates in the body for a longer period of time including high flow through the bone marrow. Antibodies tagged with radioactive particles may therefore contribute to non-specific side effects such as temporary decreased blood counts. This is a common (expected) toxicity related to the dose and schedule of the radiolabeled antibody.

Currently, it is not known whether peptide-based or antibody-based targeted PSMA prostate cancer treatments provide better results, but both approaches offer therapeutic benefit to patients. At Weill Cornell Medicine and NewYork-Presbyterian Hospital – where we have almost two decades of experience pioneering prostate cancer imaging and treatment with PSMA-targeted agents – we are the only center in the world currently able to offer both types of imaging and treatment modalities and plan to combine both within individual patients. We hypothesize that will be able to use the favorable properties of each targeting agent at slightly lower than maximal doses to deliver a higher amount of therapeutic payload to tumor with less to normal organs, further improving the tumor kill : side effect ratio and have initiated a clinical trial testing this approach.


References

Phase I Trial of 177lutetium-Labeled J591, a Monoclonal Antibody to Prostate-Specific Membrane Antigen, in Patients with Androgen-Independent Prostate Cancer

Phase II Study of Lutetium-177-Labeled Anti-Prostate-Specific Membrane Antigen Monoclonal Antibody J591 for Metastatic Castration-Resistant Prostate Cancer 

 

Liquid Biopsies in Prostate Cancer: Ready for Prime Time?

Beltran and Lab
(From L to R) Dr. Himisha Beltran, Dr. Raymond Pastore and Dr. Bishoy Faltas

Recent studies in advanced prostate cancer have identified emerging treatment targets and mechanisms of treatment resistance. At the 2017 European Society of Medical Oncology (ESMO) Annual Meeting, Dr. Himisha Beltran chaired and moderated a session evaluating the use of liquid biopsies – blood tests used to glean information about tumors – as a useful clinical tool for prostate cancer management.

While there are no formal guidelines on who, when, how and what to test for in prostate cancer, Dr. Beltran’s expertise provided important guidance to the global oncology community on this topic, as the prospect that a blood test might reveal many insights about the cancer and the tumor makeup has led oncologists to feel excited. Several steps are still needed for broad clinical implementation.

As tumors grow, some of their cells may enter into the bloodstream. These cells are known as circulating tumor cells (CTCs) and travel throughout the body along with fragments of tumor cell DNA known as circulating tumor DNA (ctDNA). Compared with traditional biopsies which extract tissue directly from the tumor, liquid biopsies offer a less invasive way for doctors to detect molecular biomarkers and learn more about what’s going on with someone’s cancer. Liquid biopsies can also better capture tumor heterogeneity, as CTCs and ctDNA can provide a window into the entire tumor (and metastatic sites), compared with a traditional biopsy in which typically only one part of the tumor is sampled. Thus, with a simple blood test, doctors can potentially access a more comprehensive view of an individual’s cancer, which can then help them determine the best treatment for that person. Blood testing can also be more easily repeated throughout the course of treatment in order to monitor disease changes in response to therapy, so liquid biopsy offers ways to detect treatment resistance and resistance mutations early on and throughout the course of the disease.

Red Blood Cells

There is an emerging role for molecular testing in advanced prostate cancer since this information can better inform treatment decisions involving targeted therapies, such as PARP inhibitors, platinum-based chemotherapy, and immunotherapies. Liquid biopsies such as ctDNA may provide information about the genomic alterations present in the cancer, which can be used to help predict how people might respond to certain therapies.

Through liquid biopsies, physicians and researchers can also better detect signs of therapy resistance that may be emerging. For example, if a patient has a gene amplification or mutation detected in ctDNA that involves the androgen receptor (AR) gene, or AR splice variants expressed in CTCs, this may indicate that potent AR-targeted therapies may be less likely to work. This is because the cancer cells may develop various ways to reactivate androgen receptor signaling by acquiring extra copies of the AR gene (gene amplification), activating AR mutations, and/or AR splice variants (such as the AR-V7 variant), all of which result in downstream over-activity of the AR-pathway. Knowing this information up front may spare people from the side effects from a treatment likely to be ineffective. Current research is focused on developing more effective AR pathway inhibitors in this setting. CTCs may also identify other features of the cancer such as localization of the AR in response to taxanes as observed in the TAXYNERGY trial, tumor heterogeneity, and expression of emerging therapeutic targets.

Through a grant from the Prostate Cancer Foundation (PCF), Dr. Beltran and colleagues at WCM are working as part of an international consortium to develop, validate, and implement a ctDNA platform for prostate cancer. This targeted genomic sequencing test, called PCF SELECT, identifies tumor mutations in ctDNA from metastatic prostate cancer patients to guide treatment selection based on precision medicine. It is currently undergoing centralized development, and the long-term goal is that this ctDNA test will be widely used by the clinical prostate cancer community for precision medicine applications.

While liquid biopsies do have promise for these indications and can help guide decisions on the most appropriate treatments for prostate cancer patients, it is important that both patients and clinicians understand the advantages and limitations of available and emerging technologies. Undergoing treatment at a center of excellence that contributes to research on emerging trends allows individuals the opportunity to be among the first to access cutting-edge technologies that may benefit them.