SAN DIEGO – Treatments aimed at patients diagnosed with amyloidosis fail to get to the root of the problem -- improving function of organs damaged by deposits of light-chain amyloid, researchers reported here at the annual meeting of the American Society of Hematology.
One year after treatment to control light-chain amyloid production in the body, improvements were observed in 24% of patients who had heart dysfunction due to amyloid deposits and 19% of patients with kidney dysfunction, said of the University of California San Francisco.
"Those figures are pretty low, considering that most of the people responded to treatment to stop production of light-chain amyloid," she told ľֱ.
She and her colleagues reported that 60% of patients achieved a partial response to therapy and 49% had a very good partial response to first-line therapy, but that did not appear to translate to improved function.
"We saw just a modest impact on kidney function and heart function with treatment," Wong said. "This study highlights the need for better agents that can control amyloid production but can also improve renal and cardiac function. In amyloidosis, we are concerned about light-chain amyloid deposits. These light-chains become aberrant and then deposit as amyloid in organs. Light-chain amyloidosis is most often associated with plasma cell diseases. These are rare diseases."
The study was a retrospective analysis of 80 patients with light-chain amyloidosis who also had renal dysfunction; about half had heart dysfunction as well, caused by the amyloid deposits in that organ as well.
A majority of patients were treated with bortezomib (Velcade), cyclophosphamide, and dexamethasone as first-line treatment, even though there is no established FDA-approved treatment for light-chain amyloidosis, Wong explained. That combination of drugs has become a default treatment for the disease, she added.
About 60% of these patients responded to the therapy. A year after, however, just 19% of the patients had a renal response -- improved renal function. "And only 24% had an improved cardiac response. Those are pretty dismal numbers considering they have already undergone treatment," she said.
"What we are doing is treating light-chain amyloidosis, but we aren't treating the end organs successfully. These therapies treat the plasma cell factory, which makes the light-chains but not the deposits that are already in the organ and causing organ dysfunction."
Wong said the study also found, not surprisingly, that if a patient had amyloidosis and heart involvement, the risk of mortality was greater. Mean overall survival in the study cohort was 67 months; median overall survival for the 46 patients with heart involvement was 37 months. "We observed that even in patients where there is renal involvement, cardiac involvement is also extremely important in overall survival."
Patients who had a hematological response to therapy also did better than those who did not. That confirms what is in the literature, Wong said, adding, though, that those reports are from controlled clinical trials, while her study reflects a "real-world" look at these patients.
Asked for his perspective, of Harvard ľֱ School/Massachusetts General Hospital Cancer Center, said, "What this study shows is that we have the tools to treat light-chain amyloidosis and stop the production of these proteins, but we do not have the tool we need to get rid of these proteins once they have lodged in the organs such as the heart and kidneys."
"We obviously need better medications to do this," he told ľֱ. "This is really a huge unmet need for these patients."
Disclosures
Wong and Yee reported having no relevant relationships with industry. Some study co-authors were employees of Prothena Biosciences.
Primary Source
American Society of Hematology
Wong S, et al "Impact of cardiac stage and hematologic response on AL amyloidosis patients with renal involvement," ASH 2016.