At the annual American Association for Cancer Research in Washington, DC last week, Dr. Scott Tagawa presented updated combined analysis of 4 Phase I and Phase II studies involving 114 patients treated with ATL101. The analysis demonstrated that PSMA imaging might be used to predict the response to ATL101 radioimmunotherapy.ATL101 is a new targeted radiotherapy experimental drug for treating prostate cancer. ATL101 combines the humanized J591 monoclonal antibody targeting prostate-specific membrane antigen (PSMA) plus the Lutetium-177 radioisotope, creating the first tumor-specific delivery system able to target radiation to radio-sensitive prostate cancer cells wherever they are in the body.
From the sponsor’s press release:
14 patients were evaluable for semi-quantitative analysis of planar gamma images acquired after injection of ATL101 (35 patients from phase I at dose of 10-75 mCi/m²; 47 patients from Phase II at dose of 65-70 mCi/m² and 39 patients from phase I with a fractionated schedule at dose of 40-90 mCi/m²). 22 patients were also evaluable after injection of Indium-111 labeled J591 and treatment by Yttrium-90 labeled J591 at dose of 5-20mCi/m². Patients were sorted into 3 groups: low PSMA expression group included one third of patients, with no uptake (18%) or with weakly positive images (16%); high PSMA expression group included one half of patients, with tumor image as intense (26%) or more intense (24%) than liver. The 16 % remaining patients had intermediate uptake.
Significant correlation was found between higher PSMA expression (high vs. low) and higher response rates (RR) to treatment defined as >30% decline in PSA (RR=32% vs. 12.5%, p=0.01). RR was itself significantly correlated to longer survival. An association between PSMA expression by imaging and reduction in circulating tumor cell counts was also found (p=0.07). Further studies will examine quantitative molecular imaging with anti-PSMA PET/CT as recently published in animal models (Morris et al, 2013 ASCO Genitourinary Cancers Symposium).
Weill Cornell researchers recently published findings from a Phase II study of the lutetium-177-labeled monoclonal antibody J591 (called Lu-J591).
J591 is a man-made monoclonal antibody that is able to recognize a protein antigen (PSMA) expressed on virtually all prostate cancer cells, and more so in men with treatment-resistant metastatic disease. When a tiny tag of radioactive material is attached to the J591 antibody, that specifically targets prostate cancer cells, and delivered systemically this is known as “radioimmunotherapy.” Dr. Scott Tagawa and colleagues at Weill Cornell have been conducting clinical trials of the precision radioimmunotherapeutic J591 to determine its ability to eradicate prostate cancer cells.
In the recently published study, 47 prostate cancer patients with PSA progression after hormonal therapies with or without chemotherapy were treated with Lu-J591. 10.6 percent experienced more than 50% PSA decline, and 36.2% experienced more than 30% decline. Among those treated at the maximum tolerated dose, 46.9% had more than 30% PSA decline. Furthermore, 75% of patients with radiographically measurable disease had some measure of disease control; 67% of those assessed for circulating tumor cells had more than 50% decline in tumor cell counts 4 to 6 weeks after treatment.
The researchers concluded that a single dose of Lu-J591 was well tolerated and they found a measurable response rate. The authors conclude that Lu-J591 is a promising new therapeutic strategy to explore.
Click here to read the published abstract. Click here to read an article about the study and the findings.
The Weill Cornell Urological Oncology Program has recently opened a new clinical trial for for men who have metastatic castration-resistant prostate cancer (mCRPC) and who have not previously been treated with chemotherapy for their cancer. The study is evaluating the benefit of an early switch from docetaxel plus prednisone to cabazitaxel plus prednisone if the PSA level is not reduced by at least 30% after 4 cycles of treatment. The opposite sequence will also be evaluated. The sponsor of the trial is Sanofi, and the principal investigator at Weill Cornell is Dr. Scott Tagawa.
For more information about the study, please call Renee Khan, RN at (212) 746-1851, e-mail Renee at email@example.com.
Metastatic castration-resistant prostate cancer (mCRPC)
Progressive disease while receiving hormonal therapy or after surgical castration
Have not received prior chemotherapy for prostate cancer
Detailed eligibility reviewed when you contact the study team\
The purpose of this study is to evaluate the benefit of an early switch from docetaxel plus prednisone (Treatment A in this study) to cabazitaxel plus prednisone (Treatment B) if the PSA level is not reduced by at least 30% after 4 cycles of treatment. The opposite sequence will also be evaluated.
Cabazitaxel is FDA-approved for treating mCRPC previously treated with the chemotherapy drug docetaxel. However, cabazitaxel is not approved for treating mCRPC that has not been previously treated with chemotherapy, and therefore its use in this study is considered experimental.
Study participants will be randomly assigned to one of two treatment arms:
Treatment A: participants will receive docetaxel via infusion once every 3 weeks plus oral prednisone taken daily. Participants whose PSA level is not reduced by at least 30% after 4 treatment cycles will switch chemotherapy to receive cabazitaxel via infusion once every 3 weeks plus oral prednisone taken daily. Participants who do achieve a 30% or greater PSA reduction will continue taking docetaxel and prednisone.
Treatment B: participants will receive cabazitaxel via infusion once every 3 weeks plus oral prednisone taken daily. Participants whose PSA level is not reduced by at least 30% after 4 treatment cycles will switch chemotherapy to receive docetaxel infusion every 3 weeks plus daily oral prednisone. Those who do achieve a 30% or greater PSA reduction will continue taking cabazitaxel and prednisone.
Participants may continue to receive study treatment as long as they are responding to therapy and not experiencing intolerable side effects. As a key part of the research, investigational biomarkers (blood tests) will be explored to help researchers determine who will (or will not) benefit from each type of chemotherapy. After completing the treatment period, participants will be seen for follow-up every 3 months for the first year and then every 6 months for about 3.5 years.
Click here to view all current prostate cancer clinical trials in the Department of Medicine.