Mumbai native Dr Protul Shrikant's accidental discovery has led to a clinical trial for a cancer vaccine at the Roswell Park Cancer Institute in Buffalo, New York.
After news of the trial was released last week, the institute has been flooded with calls from patients who want to participate in the trial. The institute will take only 18-20 patients suffering from different types of cancers. The medicines needed for the trial are expensive and it may cost about $150,000 for each patient.
Shrikant, immunologist at the institute, expects that it might take up to a decade for the vaccine to appear as a drug for common use.
Early indications seem to suggest the vaccine will not only fight cancer but also spare the patient the side effects of other cancer treatments. The vaccine is designed to both eradicate cancer cells and prevent disease relapse.
"This is only the phase 1 of the trial," Shrikant explained to India Abroad. "It focuses on the possible adverse reactions and toxicity. Phase 2 will be a larger study to make sure the effectiveness of the drug. It will be an exhaustive analysis."
The Food and Drug Administration has approved the clinical trial.
'The study just launched,' the RPCI said in a statement, 'will capitalize on a striking recent scientific discovery by Protul Shrikant, PhD, of the Department of Immunology at RPCI, who found that in low doses, rapamycin confers a previously unknown benefit - it prevents the immune system from using up its cancer-killing T-cells in one quick burst.'
Rapamycin is used to prevent rejection of transplanted organs. Dr Shrikant noted that it produces immune cells that, in a sense, have 'memory' - always remembering that 'cancer cells are bad, and should be attacked and killed.'
'It is kind of serendipitous because we just tested this concept that came from nowhere in a laboratory setting, and it did work. It's hard to imagine,' he said.
'We have shown for the first time that rapamycin has the capacity to produce immune cells that have memory attributes,' explained Dr Kunle Odunsi, director of the RPCI's Center for Immunotherapy and the study's principal investigator. 'The immune cells are trained to live longer and to always remember that cancer cells are bad and should be attacked and killed.'
The clinical research study will enroll patients whose tumors express a specific antigen, known as NY-ESO-1. Apart from the adult male testis, NY-ESO-1 is not expressed in the body's normal tissues, but is expressed in cancers. This may help decrease the risk of side effects from the vaccine, because it should target only the tissues that express NY-ESO-1.
Dr Odunsi, who developed the NY-ESO-1 vaccine, led previous trials evaluating its effectiveness in treating ovarian cancer.
Christine Sable of Lancaster, Pennsylvania, was enrolled on one of those studies in February 2004, after undergoing surgery and chemotherapy for advanced-stage ovarian cancer. Although she faced a 75 to 80 percent chance that the cancer would return, her immune system responded strongly to the vaccine, and she has remained cancer-free in the seven years since then, with no side effects.
The new study is also unique in that it is the first to test a dendritic vaccine given in combination with rapamycin, a compound used to prevent rejection of solid-organ transplant. Dendritic cells are the gatekeepers of the human immune system, defending against invaders like bacteria, viruses and cancer.
The vaccine, produced in a special chamber at Roswell that strictly controls temperature and atmospheric gases, will use a special protein that will 'recruit an army of killer immune cells that seek out and destroy cancer.'
What is remarkable about this discovery is that the vaccine is designed to train the body's defenses to never forget how to kill cancer cells. The ability to stretch out the attack for a long-term, durable response suggests the vaccine may be effective in preventing disease recurrence. The new vaccine is expected to show great promise in patients with bladder, brain, breast, esophageal, gastrointestinal, hepatocellular, kidney, lung, melanoma, ovarian, prostate, sarcoma and uterine tumors.
The NY-ESO-1 vaccine, tailor-made for each patient, will be produced in the RPCI's Therapeutic Cell Production Facility under the direction of Dr Yeong "Christopher" Choi, who noted: 'We believe that our facility's custom-made barrier isolator, the unit in which the vaccines are manufactured, is the first of its kind.'
The potential of therapeutic vaccines is attracting increasing interest in the field of oncology. Last year, the FDA approved the first therapeutic cancer vaccine, Provenge, for men with advanced prostate cancer. The RPCI's Center for Immunotherapy is awaiting the FDA's approval to launch additional cancer vaccine trials, including a vaccine for malignant glioma (a type of brain tumor) and another vaccine for patients with ovarian, fallopian tube, and primary peritoneal cancer.
