Luca Giliberto, MD, PhD, and Cristina d’Abramo, PhD, share more than a marriage: After years of research, their combined efforts to develop a passive immunotherapy for Alzheimer disease have earned them a $2 million grant from the National Institutes of Health.
Cristina d’Abramo, PhD
THE SUCCESSFUL TREATMENT of Alzheimer disease (AD) has eluded scientists and physicians for decades, with efforts to develop disease-modifying therapies for the complex neurodegenerative disease culminating mostly in failures. Despite this, much of the field remains highly motivated on the overall quest to provide patients with options that can quell the devastation of AD’s progression. Although those labors have so far fallen short of providing effective therapies, they have led to a better understanding of the pathogenesis of AD as well as advances in imaging and detection.
Among this group of physician scientists aiming to change the course of AD treatment are a unique pair operating out of Northwell Health’s Feinstein Institutes for Medical Research in Manhasset, New York: Cristina d’Abramo, PhD, an assistant professor at the Litwin-Zucker Center for the Study of Alzheimer's Disease and Memory Disorders in the Institute of Molecular Medicine at Feinstein Institute for Medical Research at Northwell Health System; and Luca Giliberto, MD, PhD, an assistant professor at the Litwin-Zucker Center for the Study of Alzheimer's Disease and Memory Disorders in the Institute of Molecular Medicine at Feinstein Institute for Medical Research, assistant professor at Donald and Barbara Zucker School of Medicine of Hofstra/Northwell, and attending neurologist at the Institute for Neurology and Neurosurgery at Northwell Health System. They were recently awarded a $2 million grant from the National Institutes of Health for their work exploring the potential use of small vectorized single-chain variable fragment (scFv) antibodies in targeting tau pathology observed in AD.
Specifically, they aim to employ an epitope-based dual therapy combining scFv-MC1 with scFv directed against other tau epitopes, and are assessing a dual delivery strategy—intracranial and intramuscular—in order to fulfill both a proof-of-concept and a translational approach to their idea.
D’Abramo and Giliberto are an exceptional pairing both inside and outside the lab. As research partners and a married couple, their clinical conversations about AD often follow them home—all for the betterment of their research. They can often be found running together, sharing the ideas that spring up from the papers they read that day, or discussing translational science at the dinner table.
“It’s a 24-7, 365 proposition. We constantly have ideas and thoughts,” Giliberto told NeurologyLive®. “The good thing is that we can bounce them immediately off of each other. We don’t waste any time waiting or facing the ‘I’ll talk to them next week,’ scenario. We do it right away, and we sit back on the computer, check the literature, and then go on.”
Luca Giliberto, MD, PhD
D’Abramo spends her days in the lab working on basic and translational science research into the role of the immune system in the development of AD, particularly focusing on the interaction between tau and microglia activation, as well as on the generation of tau antibodies and on the development of assays to detect tau in biological fluids. Giliberto, meanwhile, operates both in the clinic and in the lab—roughly 40%, he says, he spends in the clinic and the remaining time in the laboratory. Part of his clinical time is spent with patients taking part in clinical trials for potential AD therapies, offering him additional perspectives for his research.
The varying perspectives they have amassed while at the Feinstein Institutes for Medical Research have allowed for a very complementary professional relationship. D’Abramo explained that while her time is spent in the lab, Giliberto’s clinical work fills in some of the gaps that she does not experience in her own time. Ultimately, their success as scientific partners stems from the respect that they carry for one another and their labors.
“A lot of people say, ‘How can you work together? I could never make that work,’” d’Abramo told NeurologyLive®. “But it is really this deep, professional respect that we have that allows us sometimes to erase arguments that we have at home. We come back to work, and everything goes smoothly, and I would say that’s really because of this respect.”
That respect also allows them to bounce ideas and theories off one another that might be too outlandish to suggest to other colleagues. Giliberto explained that often he’ll see patients in different scenarios who are going through different experiences, and as a result come to d’Abramo with “weird ideas” that she will help to elucidate. These quick chats in the elevator between patient visits have produced a multitude of their research projects. The conversations then carry over from the elevator to the dinner table. As Giliberto put it, “The trick has been to choose to never stop thinking about it.”
“Even in the clinic days [I don’t stop],” he said. “If a patient doesn’t show up, I open the browser and I look for papers and I look at the news. I look for things. That’s the trick. If you stop thinking about it, then you sit back, and you’re done. You’re sucked into the routine, and it doesn’t happen. I never stop thinking about it.”
Originally from Italy, Giliberto and d’Abramo met during residency at the Laboratory of Experimental Medicine at the University of Genova, and their professional relationship blossomed. Giliberto’s interest in AD was piqued during his time in medical school in the late 1990s as he explored the genetic aspects of the disease and apolipoprotein E ε4’s role in its pathology. Originally, Giliberto’s captivation with the brain was rooted in the processes leading to the formation of thoughts and emotions, and specifically, the relationship between the brain and music. In addition to his fascination with the brain, his love of the arts was another trait he would share with d’Abramo.
“When we first met, actually, ballet was the big thing for us, besides looking at the microscope and brains, and we kept going to shows together,” d’Abramo said. “We also kept dancing here in New York when we first came in 2004. Unfortunately, now with COVID, we can’t really go to the city and enjoy any art. But art for sure has been a big, big thing in our life, and it is, still.”
In their years at the University of Genova, d’Abramo’s research was mostly in aging cell biology in collaboration with Massimo Tabaton, MD, exploring the relationships between oxidative stress, activation of kinases, and the metabolism of amyloid precursor protein. Her work in AD stemmed from her interest in neurochemistry and neurobiology, which led to her choosing the lab in Genova. Giliberto, meanwhile, was working on the properties of amyloid-beta peptides as signaling molecules, as well as exploring the pathways involved in the biology of AD and regulation by oxidative stress. This led them to collaborate on a project, with Giliberto instructing d’Abramo on compiling brain immunohistochemistry.
After working together for some time, Giliberto was offered a postdoctoral opportunity at Albert Einstein College of Medicine in New York, and left to work with Luciano D’Adamio, MD, a renowned expert in AD. A few years later, d’Abramo followed with an opportunity to work with acclaimed AD investigator Peter Davies, PhD, who would offer the pair an opportunity to come to the Feinstein Institutes together to work with him. Davies, whose work on antibodies in AD helped lay the foundation for the grant that d’Abramo and Giliberto were awarded, died in 2020 just before the award was announced. According to the couple, he was, ultimately, a cornerstone of their work in the field and played the role of mentor for both of them as they ventured further into research and therapeutic development in AD.
Once in the US, Giliberto needed to redo his residency at North Shore University Hospital, and although d’Abramo had originally planned to stay for only 10 months as part of her PhD program to improve her curriculum vitae, she stayed on. “That’s often the story. You go out of the country for an experience, and then you get sucked in and you stay. That’s it,” Giliberto said.
Their efforts since arriving in the US have, along with several years of applications to and conversations with the NIH, led to this grant. The funding will last for 5 years and will offer them the opportunity to further pursue their hypothesis that takes an approach to AD often used in cancer: passive immunotherapy.
“What we are trying to do is to really develop a novel immunotherapeutic approach, where instead of using the conventional antibodies—the big 150 kilodalton proteins—we are engineering the antibodies and making them smaller,” d’Abramo explained. “We don’t inject the single chains directly in the animals, but we insert the cDNA in an adeno-associated virus [AAV]. We’re using these nonpathogenic, nonreplicating viruses, and we insert the sequence for the scFv in this vector. With 1 injection, you’re going to get your animal—or later, patient—expressing these recombinant antibodies that are, possibly, able to cross the blood-brain barrier and find tau, bind it, and clear it.”
To this point, she said, they have developed a muscle injection with a specific AD serotype that acts as a tropism for muscle cells. Their idea is to generate a muscle niche to continuously release the recombinant antibodies into the circulation. If successful, it would require only a single injection, as opposed to the monthly or quarterly infusions that traditional immunotherapy requires.
“Now, not everyone is going to get the therapy, and not everyone is diagnosed. Many of them are hidden at home—that’s another problem,” Giliberto said. “But you’re talking about, reasonably, 30,000 to 40,000 people [on Long Island, New York, alone] that may be treatable with these options. How do you get them into the clinic every month to infuse them? It’s a long conversation. There are a lot of logistics to it. Certainly, the costs and the logistics of that approach are some of the elements that led us to this process.”
D’Abramo and Giliberto are working with multiple antibodies for this grant project, with the hope of applying different scFv antibodies in various paradigms. One of the goals is to explore if the treatment can clear the existing pathology as well as prevent the development of new pathology. The third aspect is to study the mechanism of the immunotherapy, specifically by investigating the microglia.
Giliberto noted that much of the conversation among his colleagues in 2021 has been centered around Biogen’s controversial AD agent, aducanumab. When such a therapy is granted FDA approval, he explained, it can be disruptive to individual health systems because of patient demand for the treatment. “Are we ready for it? Are we able to infuse patients every month, and then check their MRI and spinal fluid? Having these types of alternative approaches where you get intramuscular injection that lasts for months and maybe you’ll get a boost—that’s probably much better.”
“There is one concern that has been voiced about AAV-mediated therapies, which is how do you turn it off if you don’t need it or if you have a problem? There are ways to do it,” he explained. “There are tetracycline-controlled transcriptional activation systems; there are hormonal responsive promoters. There are a bunch of ways to do it. That should not scare us from pursuing these types of approaches.”
At this point, the pair have published 2 studies from this work. The first was a proof-of-concept study of an intracranial injection of the therapy, published in 2018, which assessed the scFv immunotherapy in adult JNPL3 mice.1 After performing extensive biochemical analysis of soluble, oligomeric, and insoluble tau species in the hippocampus, cortex, and hindbrain, they observed a consistent pattern of tau reduction upon treatment with the recombinant antibody. The results showed a decrease in soluble pThr231 common to the 3 brain areas analyzed upon astrocytic expression of the scFv-MC1 (hippocampus: −35%; cortex: –25%; hindbrain: –33%), without major effects on other soluble tau/phosphorylation residues. Supporting those data, they also observed that pThr231 immunoreactivity in the hippocampus and entorhinal cortex was significantly reduced in the injected mice (hippocampus: −60% circa; entorhinal cortex: −70% circa), consistent with the reduced tau-MC1 immunostaining (hippocampus: −60% circa; EC: −70% circa).
"A lot of people say, ‘How can you work together? I could never make that work.’ But it is really this deep, professional respect that we have that allows us sometimes to erase arguments that we have at home. We come back to work, and everything goes smoothly."
—CRISTINA D'ABRAMO, PHD
Then, in August 2020, they published another study, this time assessing an intramuscular injection with the antibodies in JNPL3 (n = 26) and P301S (n = 12) mice. That work showed a dramatic decrease of cortical insoluble tau in the P301S cohort upon treatment with scFv-MC1, as well as in total tau (−70%; P <.01), pThr231 (−70%; P <.01), pSer202 (−60%; P <.05) and pSer396/404 (−65%; P <.01). Additionally, a similar significant reduction was confirmed in the JNPL3 cohort following a sustained peripheral release of scFv-MC1, both as total tau (− 50%; P <.001) and phosphorylation at Thr231(−65%; P <.001), Ser202 (−50%; P < .001) and Ser396/404 (−60%; P <.0001).2
“In the new study, we have shown that MC1 single chain is absolutely working with significant effect,” d’Abramo said. “You do your intramuscular injection in mice, and you get the antibodies in brain reducing pathology in the cortex, hippocampus, and hindbrain at different levels. We looked at different species of tau— soluble tau and insoluble tau—so it’s more complicated than just, ‘OK, it’s working.’ “There are a lot of regional differences, which is another thing that is really striking because it might bring us back to the idea that microglia are really working in different regions different ways,” she added.
Now that they’ve acquired the grant, they explained, the real work begins. They noted that this is the product of multiple rejections for funding over the years. But for this uncommon pair of research partners, the failure is all part of the process. In fact, for Giliberto, it’s almost symbolic of the field in which they have chosen to work. Research and development in AD have been subjected to uncountable failures, and getting over the proverbial hill requires resilience, innovation, and a willingness to accept that a complex, multipathological disease will likely require a multifaceted, complicated approach.
“By no means have we arrived,” he said. “We have so much work to do. One grant doesn’t mean anything. You have to continue going, but it’s a good testament to the fact of continuing to push and working with an ethical statement in your head to do things right. That’s a common thread here. And we need to keep an open mind. Enough of just focusing on one aspect of the disease. This is a very complex disease. We cannot solve it by looking at one aspect. We need to move forward. We need to have a little bit more inventiveness.”