The United States Food and Drug Administration (FDA) recently approved brentuximab vedotin in combination with chemotherapy as a first-line treatment for people with advanced-stage classical Hodgkin lymphoma.
Also known as Adcetris, brentuximab vedotin is an antibody drug conjugate that targets the CD30 protein present on lymphoma cells and delivers a toxin designed to promote cancer cell death. The drug has been previously approved to treat systemic anaplastic large cell lymphoma (ALCL) and Hodgkin lymphoma that has returned after prior therapy.
The FDA’s approval follows the encouraging results of the phase III ECHELON-1 clinical trial, presented at the 2017 American Society of Hematology (ASH) Meeting and Exposition and published in the New England Journal of Medicine. The trial, which was open at Weill Cornell Medicine and NewYork-Presbyterian Hospital, compared standard therapy with adriamycin, bleomycin, vinblastine and dacarbazine (ABVD) versus adriamycin, vinblastine and dacarbazine plus brentuximab vedotin (A+AVD).
Of the 1,300+ enrolled patients, those receiving A+AVD were demonstrated to be 23 percent less likely to experience disease progression, a need for additional therapy, or death, as compared to the cohort receiving the standard of care therapy.
“ABVD has been the standard therapy for a couple decades because it works really well, but it’s great to have new treatments available for people with Hodgkin lymphoma,” said Peter Martin, Chief of the Lymphoma Program. “I’m proud that we were able to offer this treatment at Weill Cornell a long time ago through the ECHELON-1 trial. Like any treatment, the A+AVD combination may not be right for everyone and requires consideration of side effects, like infection risk and neuropathy. Decisions between patients and physicians regarding the best treatment should follow an open discussion of the evidence.”
Based on the results of the first in-human clinical trial of ibrutinib in chronic lymphocytic leukemia (CLL) – conducted in 2010 at Weill Cornell Medicine/NewYork-Presbyterian Hospital and other centers – researchers led in part by Dr. Richard Furman moved forward with the first phase II trial of the drug. According to a five-year follow-up study recently published in the American Society of Hematology’s Blood journal, ibrutinib continues to demonstrate excellent efficacy and tolerability as a single agent therapy for people with previously untreated and relapsed or refractory CLL.
CLL is characterized by uncontrolled growth of mature B-cells that accumulate in the blood, bone marrow, lymph nodes and spleen. As CLL cells fill these various organs, they interfere with normal cell functions. Ibrutinib is an oral treatment that inhibits Bruton’s tyrosine kinase (BTK), an enzyme involved in B-cell development that plays a critical role in CLL cell survival.
Prior to the Food and Drug Administration (FDA) approval of ibrutinib for CLL in 2014, chemoimmunotherapy (CIT), typically with fludarabine, cyclophosphamide and rituximab (FCR), was one of the only treatment options available for people with CLL. Chemoimmunotherapy often generates deep responses that last a median of five to six years, but it is associated with significant toxicities. When patients relapse after CIT, their disease becomes more resistant to subsequent treatments, and due to the accumulation of toxicities, many patients are unable to receive further CIT. Given the associated toxicities, the use of CIT is limited in older patients with comorbidities – the cohort that comprises the majority of CLL patients.
The phase II study in which Dr. Furman was involved tested ibrutinib as a single agent in over 100 patients – some of whom received no prior therapy, and others who relapsed following initial treatment. Patients received daily oral doses of ibrutinib until their disease progressed or until the presence of side-effects warranted discontinuation of therapy.
Almost 90 percent of all patient participants demonstrated a response to treatment at the five-year mark, and complete remission rates increased over time with ongoing treatment. Ninety-two percent of treatment-naive patients and 44 percent of relapsed/refractory patients remained free of disease progression five years out from the start of treatment.
Side-effects, including infections, diarrhea, bleeding and low-blood counts, were mild. They did not prevent patients from remaining on treatment long-term and often improved with continued dosing.
“These data demonstrate the excellent long-term outcomes for CLL patients treated with ibrutinib, especially those who receive ibrutinib as their first therapy,” says Dr. Furman.
Studying animal models to enhance the overall understanding of cancer is a longstanding and valuable practice that, until recently, had been fairly uniform. The traditional model, the laboratory mouse, has occupied the oncologic arena since the 1980s, offering researchers a way to observe tumor growth and drug response in a natural environment, as opposed to in a petri dish. This approach, known as comparative medicine, more realistically represents how cancer behaves in humans and yields insight as to how scientists can effectively treat the disease.
It wasn’t until late 2005 that a bigger, potentially better animal model entered the comparative medicine scene. Publication of the canine genome enabled comparison of dogs and humans at a molecular and genetic level, revealing biological similarities in each. In October 2017, the National Institutes of Health (NIH) recognized the untapped potential of the canine model in cancer research with a five-year $2.5 million grant awarded to Weill Cornell Medicine and Tufts University scientists to study new therapeutic strategies in dogs with lymphoma.
“I want to cure cancer in people, and dogs provide a great opportunity for research that can help us move lymphoma therapies to the clinic for humans faster,” says the Lymphoma Program’s Kristy Richards, PhD, MD, who will lead the research as a co-principal investigator.
“We’re using the NIH grant to study immunotherapies and targeted treatment regimens in combinations that haven’t yet been tried in humans. The idea is to get to a therapy that can cure diffuse large B-cell lymphoma (DLBCL) in dogs. If it works well in dogs, we have better rationale to move the therapy forward in people.”
The immune system is the body’s in-house security guard that protects against infection and disease, but some forms of disease, like cancer, have evolved to evade the immune system’s defense mechanisms. Immunotherapies, which harness the power of a patient’s own immune system to fight cancer, rely upon an intact immune system, which lab mice grown in sterile cages and never challenged by sickness do not possess. Dogs, thanks to their propensity to eat, lick and roll around in whatever unsanitary substance they please, have thoroughly educated immune systems, a prime environment for testing immunotherapies.
But that is far from the only advantage of the canine model. “We can do things with the dog model that we can’t do with the mouse model, or even with the human model,” says Dr. Richards.
About two-thirds of human DLBCL patients enter remission following six cycles of standard chemotherapy regimen rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP). Dogs on lower, more frequent doses of the same treatment regimen almost always enter remission – but they also almost always relapse. If they were to receive the human dose intensity, they would suffer significant impairments to quality of life, such as decreases in physical activity and appetite, and vomiting and diarrhea.
Since standard chemotherapy cures nearly 70 percent of humans with DLBCL, current clinical trials of less toxic, non-chemotherapy based regimens are limited to the one-third of people who eventually relapse. Novel treatments used in these trials must be proven effective as single agents before being combined in what would ultimately require extensive (and therefore expensive) study.
The fact that dogs are not cured by standard therapies makes them the perfect candidates for testing of new, targeted therapies with fewer toxic side effects, permitting use of doses similar to those used in humans. Through use of these novel agents, dogs help science to leapfrog ahead of years’ worth of human trialing, while science helps dogs to live longer, happier lives.
Treating people’s pet dogs also encourages a humanistic approach. Much like in human oncology, scientists work to develop therapies that take more into consideration than just killing cancer cells, like quality of life, for example.
In fact, one of Dr. Richard’s favorite aspects about her research is that she gets to help the dogs that she’s studying.
“If we can manage to do something good for human medicine at the same time that we’re helping the model organism that’s helping us to study it, that’s a great thing,” she says.
Dr. Richards says that enlisting the help of the canine model to study lymphoma is a concept that is “arriving, but has not yet arrived.” Support from the NIH, as well as from organizations like Puppy Up and Paws 4 a Cure that raise funds to conduct clinical trials for dogs, plays a major role in validating the benefits of the canine lymphoma model, but further research is required to actually reap those benefits.