neuroblastoma

‘CAR T cells can eradicate solid tumors,’ study in advanced neuroblastoma shows

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Key takeaways:

  • Nearly two-thirds of trial participants with advanced neuroblastoma responded to an experimental CAR T-cell therapy.
  • Investigators reported no cases of high-grade treatment-related toxicities during the study.

A novel chimeric antigen receptor T-cell therapy induced clinically impactful antitumor responses in 63% of younger patients with relapsed or refractory, high-risk neuroblastoma, results of a phase 1/phase 2 trial showed.

The findings, published in The New England Journal of Medicine, suggest the investigational agent also has a manageable safety profile similar to other CAR T-cell therapies, researchers noted.

Results from phase 1/phase 2 trial of GD2-CART01
Data derived from Del Bufalo F, et al. N Engl J Med. 2023;doi:10.1056/NEJMoa2210859.

Franco Locatelli, MD, PhD

Franco Locatelli

“Our results indicate that CAR T cells can be an effective therapeutic option, not only in patients with hematologic malignancies, but also in patients with solid tumors,” Franco Locatelli, MD, PhD, professor of pediatrics at Catholic University of the Sacred Heart and director of the department of pediatric hematology and oncology at IRCCS Ospedale Pediatrico Bambino Gesù in Rome, told Healio.

Background

Previous study has firmly established that the disialoganglioside GD2 is highly expressed on the surface of neuroblastoma tumor cells, making it an attractive therapeutic target, according to Locatelli.

A team of researchers from Italy developed a third-generation, gene edited, autologous CAR T-cell therapy (GD2-CART01) that targets GD2. The novel agent incorporates two co-stimulatory domains — CD28 and 4-1BB — with the aim of increasing its potency and efficacy, Locatelli noted.

“We also added to the construct the sequence coding for a suicide gene — or safety switch — to improve the safety profile of the approach,” he said. “Indeed, this suicide gene can be activated in case of severe or life-threatening toxicity not controlled by pharmacologic therapies.”

Methodology

Locatelli and colleagues conducted a single-center phase 1/phase 2 dose-escalation study to determine the safety, feasibility and recommended phase 2 dose of GD2-CART01 among patients aged 1 to 25 years with relapsed or refractory, high-risk neuroblastoma.

Twenty-seven patients (median age, 6.7 years; range, 2.7-18.6; 67% male) received a single infusion of GD2-CART01 at one of three dose levels (3 × 106, 6 × 106 or 10 × 106 CAR T cells/kg).

The study included 12 patients with refractory disease, 14 with relapsed disease and one who had a complete response after first-line therapy.

Researchers reported successfully manufacturing CAR T cells for all study participants.

Key findings

Investigators reported no dose-limiting toxicities during the phase 1 portion of the study. They established a recommended phase 2 dose of 10 × 106 CAR T cells/kg.

Twenty patients (74%) experienced cytokine release syndrome, with 95% of cases being either grade 1 or grade 2.

Suicide gene activation occurred for one patient using two infusions of rimiducid, resulting in “rapid elimination of circulating GD2-CART01” cells, the investigators wrote.

Infusion of GD2-CART01 cells resulted in clinical responses in 17 patients, for an overall response rate of 63% — nine complete responses and eight partial responses.

Patients who received the recommended phase 2 dose of GD2-CART01 had a 3-year OS rate of 60% and 3-year EFS rate of 36%.

Clinical implications

“We will work to increase the proportion of patients responding to GD2-CART01 and to prolong the durability of the response,” Locatelli told Healio.

Future studies are also planned to evaluate GD2-CART01 as earlier therapy for patients with neuroblastoma, according to Locatelli.

“We expect that this will translate into even better results,” he said.

Locatelli noted that the treatment development and ensuing clinical trial occurred entirely within the academic setting, without commercial support.

“This observation emphasizes that academic institutions may play a major role in the development of the most advanced and innovative therapies,” he said.

The study results suggest an overall favorable safety profile for GD2-CART01, in addition to encouraging objective response rates and durability for treatment of relapsed or refractory neuroblastoma, Oladapo O. Yeku, MD, PhD, of Mass General Cancer Center, and Dan L. Longo, MD, of Harvard Medical School, wrote in an accompanying editorial.

“As with all solid-tumor cancers, understanding the resistance mechanisms in patients who did not have a response could provide insight for the design of future clinical trials,” they wrote. “[Locatelli] and colleagues found that the tumors in patients who did not have a response retained expression of GD2, a finding that raises the question of whether immunosuppressive cytokines, myeloid-derived suppressor cells, T-regulatory cells or tumor-associated macrophages contribute to a lack of efficacy in these patients.”

References:

For more information:

Franco Locatelli, MD, PhD, can be reached at Department of Pediatric Hematology and Oncology, IRCCS Ospedale Pediatrico Bambino Gesu, Piazza Sant’Onofrio, 4, 00165 Rome, Italy; email: franco.locatelli@opbg.net.

Perspective

Robbie Majzner, MD)

Robbie Majzner, MD

There has long been skepticism about whether CAR T cells could demonstrate the same depth of responses in solid tumors as they have in hematologic malignancies. This exciting study by Locatelli and colleagues stands out as the largest series of CAR T-cell responses in a solid tumor to date.

Approximately 60% of patients experienced an objective response to GD2-directed CAR T cells, with half of those being complete responses. This work clearly and irrefutably demonstrates that CAR T cells can eradicate solid tumors in patients.

The researchers should be congratulated on their success, which builds on previous work engineering and testing GD2-directed CARs at Baylor College of Medicine and Texas Children’s Hospital starting in the 2000s. The first CAR T cell ever tested in a child was a first-generation GD2-directed CAR that demonstrated safety and some clinical efficacy, including complete responses. However, multiple additional GD2-CAR constructs and clinical trials failed to improve on this approach, until now.

The researchers’ success suggests that iterative engineering and testing of CAR constructs in small clinical trials will be key to advancing the field. It is essential to recognize the role of academic physicians and scientists in this process, as all of this work was carried out by pediatric oncologists at academic centers, often funded by grants and philanthropy.

GD2 is expressed on normal peripheral nerves, and anti-GD2 antibodies are associated with severe pain in the clinic. However, GD2-directed CAR T cells did not cause any pain or other on-target neurotoxicities in patients, even when they eradicated GD2-expressing tumors. GD2 is expressed at much higher levels on cancer compared [with] normal nerves. Therefore, CAR T cells — like other cancer drugs — demonstrate a therapeutic window, and some expression of target antigens on normal tissue may be tolerable, opening the door to engineering CARs against a host of antigens that are highly differentially expressed.

This trial has several limitations that should be noted. First, neuroblastoma is a highly heterogeneous cancer that ranges from indolent to aggressive, and results of any single-arm, single-institution trial need to be interpreted carefully. Most durable responses on the trial were seen in patients with low-burden disease, often restricted to the bone or bone marrow. These sites may be more accessible to CAR T cells than bulky tumors, hinting that current CAR designs will be most effective when patients are in a minimal residual disease state. Finally, only half of the population of patients in this trial had received anti-GD2 monoclonal antibodies, with no indication how many received combined anti-GD2 antibody and chemotherapy, considered the de facto standard of care for relapsed and refractory patients in the United States.

Despite these limitations, this is a landmark study that shows that CAR T cells are poised to eventually alter the treatment paradigm for immunologically cold tumors, which includes most pediatric cancers.

Robbie Majzner, MD

Stanford University School of Medicine

Predicting neuroblastoma outcomes with molecular evolution

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A research team led by the German Cancer Research Center in Heidelberg, Germany, has discovered that the genetic sequence of a tumor can be read like a molecular clock, traced back to its most recent common ancestor cell. Extracting the duration of tumor evolution can give an accurate predictor of neuroblastoma outcomes.

In a paper published in Nature Genetics titled “Neuroblastoma arises in early fetal development and its evolutionary duration predicts outcome,” the team details the steps they took in identifying a genomic clock tested against a whole genome sequenced population combined with analysis and mathematical modeling, to identify evolution markers, traceability and a likely origin point of infant neuroblastomas.

Cancer cells start out life as heroic healthy tissues, with the sort of all for one, one for all, throw yourself on a grenade to save your mates–type attitude that is taking place throughout the body every day. At some point, something goes wrong, and a good cell goes bad.

It begins with miscommunication in dividing or an injury to a cell’s DNA, which happens with great regularity throughout the body. Typically this is handled before trouble can start by a repair mechanism. If the repair cannot be made, it is time to engage in apoptosis or cell death.

A healthy cell response to a call for apoptosis is to throw itself on the “grenade” to keep all of the surrounding cells and cell tissues safe. If a cell is not able to hear the call for apoptosis, as can happen with chromosomal damage, it takes no action. Without the conforming behavior to grow or stop growing, a cell becomes a threat to its surroundings, a rogue cell, a cancer cell and—if it proliferates unchecked—a tumor.

A cell on its own, no longer able to communicate with its neighbors because the communication network between cells has been lost, still tries to survive. Within a cell is most of what it needs to continue the mission of life—to grow, to reproduce, and to thrive. But from the outside the perspective is very different. From outside the isolated and injured cell, cancer is growing. Depending on where the cancer is, and how it is constructed, the outcomes can be very different.

In the case of neuroblastoma, the most frequent solid tumor in infants, a wide spectrum of clinical outcomes is possible, ranging from low-risk cases requiring light or no treatment to a high-risk situation that is fatal for about 50% of patients.

In the current study, cohorts of primary and relapsed neuroblastoma tumors were retrospectively analyzed. Whole genome sequencing was applied to 100 neuroblastomas and validated in an independent group of 86. Neutral single-nucleotide variants were selected and tracked as a molecular clock to time key events.

By comparing tumor clone sequences to the molecular clock, researchers found that the density of somatic single-nucleotide variants (SSNVs) in cloned cells was similar for the different copy numbers, essentially a continuation of the molecular clock in the clone, and as a result, traceable back to a most recent common ancestor cell. Compare this to standard tumor sampling that can tell if different tumor cells are related but lacks the time-dependent evolutionary connection, and the importance of this method becomes strikingly clear.

Researchers further discovered that the duration of evolution was found to be an accurate predictor of outcome. Cells that quickly became tumors did so without the ability to sustain growth, while others that more slowly transitioned into tumors built an infrastructure for more prolonged and aggressive tactics for survival. Knowing this, researchers could then identify neuroblastomas with favorable clinical outcomes.

Origin story

Researchers were able to wind back the molecular clock of their model and pinpoint a likely origin of neuroblastomas by combining whole-genome sequencing, molecular clock analysis and population-genetic modeling in a comprehensive cohort covering all subtypes. Tumors across the entire clinical spectrum likely begin to develop via aberrant mitoses as early as the first trimester of pregnancy. This is when the adrenal medulla forms from sympathetic neuroblasts, and the modeling suggests that the initial oncogenic event is limited to this time window. The transcriptomes of neuroblastomas most resemble those of sympathetic neuroblasts that are highly proliferative in the first trimester, which may make them vulnerable to aneuploidy (chromosomal abnormalities).

A tremendous effort is underway now to compile a gene atlas, a document of every cell in the human body, their functions and interconnected communications. Everything that science has revealed, from basic anatomy to the discovery of DNA and the human genome project. From unraveling the ways that DNA is transcribed, spliced, translated, and modified to how epigenetics and gene variants affect health. All of it leads to a platform from which we can understand molecular cellular evolution in predictive enough ways to take proactive, preventative and procedural steps to ensure sustained longevity of human life.

The current study is a window into that future, with a predictive and time-dependent understanding of the molecular evolution of a single tumor cell type. The age of modern miracle medical science is not the age we are living in, but it is the age we are now building.

CHOP Researchers Show Liquid Biopsies Can Catch Disease Progression Early in High-Risk Neuroblastoma

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Neuroblastoma is an aggressive pediatric cancer that develops from early nerve cells and accounts for up to 10% of childhood cancer deaths. Survival rates are low – less than 50% of patients with the disease survive, and less than 5% with relapsed disease overcome it.

One challenge researchers face is monitoring how the cancer mutates in response to treatment, shapeshifting as it resists conventional treatments like chemotherapy, as well as newer targeted treatments. The tumors are often in difficult locations – around the spine, within the bone, or in the brain – so performing a tumor biopsy can be risky and may not capture mutations in tumors located elsewhere in the body. Yet identifying tumor changes early is key to successful treatment.

To circumvent this challenge, researchers at Children’s Hospital of Philadelphia (CHOP) investigated whether a series of “liquid biopsies” performed in partnership with Foundation Medicine could less invasively and more accurately identify tumor changes in patients with high-risk neuroblastoma. Patients with solid tumors like neuroblastoma often have tumor cells and tumor DNA circulating in their blood, and recent technological advances have allowed scientists to characterize this circulating tumor DNA (ctDNA). Serial ctDNA profiling is already used in many adult cancers and is even FDA approved for certain indications, so the CHOP researchers explored whether ctDNA profiling could be clinically useful in neuroblastoma.

Examining the blood from 48 patients with high-risk neuroblastoma, the researchers found 73% of patients had at least one ctDNA sample over the course of their treatment where a mutation was detected. The series of liquid biopsies revealed that some patients’ tumors mutated under the pressure of treatment, which not only correlated with disease progression, but also made them potentially eligible for other targeted therapies. For example, several of the mutations included clinically actionable variants, such as those related to ALK and RAS-MAPK pathways, for which targeted treatments exist.

The researchers also found that most patients who received a variety of ALK inhibitors, which are targeted treatments, experienced genomic evolution of their tumors, as the tumors were put under the weight of therapy. The evolution of these tumors happens just before or at the same time as disease progression, showing that ctDNA profiling can identify clinically relevant genomic evolution perhaps even earlier than current standard disease surveillance methods.

“Based on our observations, we suggest that serial ctDNA profiling should be integrated into clinical practice for children with high-risk neuroblastoma to provide real-time data on genomic evolution and insights into mechanisms of therapy resistance, in addition to potentially identifying clinically targetable mutations,” said Kristopher Bosse, MD, an Assistant Professor of Pediatrics in the Cancer Center at Children’s Hospital of Philadelphia and first and corresponding author of the study describing the research. “Our goal is to implement less invasive and more sensitive tumor surveillance and detection of tumor heterogeneity.”

“In time, ctDNA profiling could allow for decreased use of standard radiographic methods used for disease surveillance, many of which require analgesia along with continued exposure to radiation for children who are already at high risk for development of secondary malignancies,” said senior study author Yael P. Mossé, MD, Professor of Pediatrics in CHOP’s Cancer Center. “We have developed our own pediatric-specific liquid biopsy assay that is now being commercialized such that it can be available for all children with high-risk solid tumors and eventually become part of the standard of care.”

Researcher develops cancer drug in memory of girl who died of neuroblastoma

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Linda H. Malkas, PhD, remembers the day a photograph for a newspaper changed her life.

“I was the Vera Bradley chair for oncology at Indianapolis University School of Medicine, and I was doing breast cancer work,” Malkas, who now serves as dean of translational science and M.T. and B.A. Ahmadinia professor in molecular oncology at City of Hope, told Healio. “I had started out as a biochemist and molecular biologist and was interested in DNA replication and repair. I probably would have kept doing that for the rest of my life. Then I met Steve Healey, who showed up to take my photo for a newspaper article.”

Quote from Linda H. Malkas, PhD

Running a bit late for the photo assignment, Healey explained to Malkas that his daughter, Anna, was at Riley Hospital for Children. At age 8 years, Anna had been living with neuroblastoma for almost half of her life.

“Steve took a beautiful photo of me, and as he packed up his camera and equipment, he said, ‘Dr. Malkas, what is it you do?’ I looked at him and said, ‘Come here,’” Malkas said. “We sat in front of my computer, and for 2 hours, I gave him the only thing I could: my data.”

The two wished each other luck, and that might have been the end of the story. However, Malkas kept tabs on Healey and his family. She learned that Anna died of her disease not long after she and Steve met.

When Healey contacted her sometime later asking to visit Malkas at her laboratory, he wasn’t sure she would remember him.

“I said, ‘Oh, I remember you,’” Malkas said.

From inspiration to execution

Malkas hosted Healey at her laboratory for an afternoon, introducing him to each of her young employees and discussing the group’s work.

“It was a wonderful afternoon,” Malkas recalled. “Each of my employees got up and talked for 5 to 10 minutes about what they do. Then we went down to my lab, and he did something that changed the course of my life.”

Healey handed Malkas a check for $25,000 from himself and his wife, Barbara.

“He said, ‘Dr. Malkas, we know you do all this great work on breast cancer, but if you could do something for neuroblastoma, it would mean the world to Barbara and me,’” she said. “This set the whole thing in motion.”

Malkas spoke with her husband and collaborator, Robert Hickey, PhD, associate professor in City of Hope’s department of cancer and molecular medicine, about what they had learned about DNA replication in cancer cells. The two had identified a protein that is altered in cancer cells and correlates with a change in replication fidelity.

“I asked him, ‘Do you think we could make a drug against this protein, and possibly provide a less toxic treatment to these patients?’ I was completely starry-eyed; I had no training in this. And he said, ‘Sure.’”

Malkas’ next challenge: Find a medicinal chemist to help her make this idea a reality.

She spoke with several laboratories, but none could commit the necessary time and resources. Then she received a phone call from City of Hope, asking to meet with her and discuss the possibility of bringing her to their institution.

“We talked about everything they had done during the prior 8 years,” she said. — “They had set up everything I was looking for — current good manufacturing practices facilities and the people for the regulatory process and drug discovery. They had developed the talent. Everything was there.”

When City of Hope offered Malkas a position as director of translational research, she didn’t hesitate.

“I said yes, and the first people I told were Steve and Barbara Healey,” she said. “When I told Barbara, she started to cry. She said, ‘I know if you go, something wonderful is going to happen.’”

‘I came with a target’

When Malkas began her work at City of Hope in 2011, she did so with a mandate: to develop a molecule that would shut down the protein she and Hickey had identified, proliferating cell nuclear antigen (PCNA).

“I came with a target, one that had never been drugged before,” she said. “This protein interacts with at least 200 partners in the human cell, and those are not just DNA replication repair but apoptosis, transcription and cell cycle regulation. I thought if I could shut down the form of this protein that is expressed in cancer cells, I could block not just one pathway, but a variety of pathways.”

Malkas likened this to an airport hub with multiple planes coming into terminals.

“In Indianapolis, the one way you could shut down U.S. air traffic would be with a good snowstorm,” she said. “I thought if I could make a molecule that was like a snowstorm, I’d be able to block those planes from getting into those terminals.”

Malkas and Hickey developed one molecule that came close but was not successful when put into human serum. All the while, the Healey family was never far from Malkas’ mind.

“All I could think of was that I had made a promise to this family,” she said. “I kept thinking of Anna. I needed to do something.”

When Malkas and Hickey created the molecule, she named it AOH1996, which stands for Anna Olivia Healey, the child’s full name, and 1996, her birth year.

“We sent the molecule to the NIH and when they tested it in their NCI-60 cell line panel, it had activity across the board,” she said. “If I hadn’t come to City of Hope, I don’t think I would have been able to create this drug.”

Anna’s legacy

City of Hope has initiated the phase 1 clinical trial of AOH1996, and the institution has announced that the first patient to receive the drug is doing well.

The trial, which will test the safety of AOH1996 in people with recurring solid tumors, is expected to continue for the next 2 years. Although originally studied for neuroblastoma, the pill has shown efficacy in preclinical studies treating cells from breast, prostate, brain, ovarian, cervical, skin and lung cancers.

Malkas said she and her colleagues are investigating other potential indications for AOH1996, including as a combination treatment for patients who may have difficulty tolerating cisplatin or other chemotherapy drugs.

“A lot of the time, you have to cut back on some of these drugs, because the patients’ systems just can’t take it,” she said. “So, I am thinking that this is probably where the home for this molecule will be — in combination treatment.”

Malkas praised her colleagues at City of Hope, including the trial’s principal investigator, Vincent Chung, MD, who she said brings a “quiet strength” to his role of leading the phase 1 trial, and Daniel Von Hoff, MD, who is serving as an advisor on the trial.

“The day I got the [FDA] approval, which was maybe 2 days before Christmas, I emailed Dr. Von Hoff about it. I thought of it as my Christmas present,” she said. “He emailed me back, saying, ‘I want you to know what you’ve done,’ and he sent me a chart with 350 steps on it, from the naming of the compound to getting the first patient. I was on something like step 348. I said, ‘Dan, I’m so glad I didn’t see this before.’”

Perhaps even more meaningful — the email response Malkas received from the Healey family when she notified them of the approval.

“They sent the most beautiful comments back, “she said. “I was so moved by this family who has suffered such a loss. They said, ‘Now Anna has a legacy.’”