John Schieszer

New investigations into T-cell signaling may significantly advance the immunotherapy field by leading to the development of more effective chimeric antigen receptor (CAR) T-cell therapies for patients. That’s the finding of several recent clinical studies on CAR T-cell immunotherapy, and the recent approval of a promising new agent targeting T cells in both the United States and the European Union adds to the growing body of evidence supporting their efficacy and the promise these agents hold.

Recent CAR T-Cell Therapy Approvals in the United States and Europe

The European Commission (EC) approved tisagenlecleucel (Kymriah) in late August for the treatment of relapsed or refractory B-cell acute lymphoblastic leukemia (ALL) in pediatric and young adult patients up to age 25, as well as for relapsed or refractory diffuse large B-cell lymphoma (DLBCL) in patients over 18. The decision follows the US Food and Drug Administration’s (FDA’s) approval of tisagenlecleucel in May to treat both B-cell ALL and DLBCL.

According to oncologists from the Children’s Hospital of Philadelphia (CHOP), the latest EU approval marks a milestone in CAR T-cell therapy. The CHOP researchers helped pioneer this immunotherapy (via the 

 trials), and they have now treated more than 250 patients at their institution. Additional clinical trials are underway at CHOP to further improve CAR T-cell therapy and to study their use in more pediatric cancers. The researchers are encouraged by how quickly CAR therapies are making their way into clinical practice.

Additional trials are underway outside of CHOP, too. 

, chair of the children’s oncology group at CHOP, said ClinicalTrials.gov lists 236 studies on CAR therapies as planned or underway. “This is a good estimate for the United States but does not necessarily include all studies,” Adamson told 

, meaning that more may be in progress internationally.

Emerging Research on CAR T-Cell Therapies

Increasing attention to CAR T-cell therapies also prompted researchers at Fred Hutchinson Cancer Research Center in Seattle, to examine the differences between CARs built with the two most commonly used costimulatory domains, CD28 and 4-1BB. Their findings were 

During the study, researchers examined how CD28 and 4-1BB affected T-cell behavior, as well as their effectiveness against human cancer cells in lab dishes and in mice. Study investigator Alex Salter, of Fred Hutchinson Cancer Research Center and the University of Washington, said there has been plenty of interest in targeting the T cells to cancer, but little has been known about the instructions CARs give the T cells­­ until now.

“Scientists who create engineered CAR T-cell therapies often incorporate one of two costimulatory domains, known as CD28 and 4-1BB, into CARs. CD28, for example, is used in the FDA-approved CAR T-cell product axicabtagene ciloleucel (Yescarta), and 4-1BB is used in the other currently approved CAR T-cell product, tisagenlecleucel (Kymriah). Prior work has shown that CD28 CAR T cells and 4-1BB CAR T cells behave differently in the lab and in the clinic,” Salter told 

However, researchers have not known how costimulatory domains impact the identity or quality of the T-cell activating messages delivered by CARs, according to Salter. Using mass spectrometry, the researchers found that both CD28 CARs and 4-1BB CARs delivered highly similar signaling messages. “This was quite surprising because many researchers had assumed that CD28 and 4-1BB CARs used different signaling pathways. Instead, we found differences in the patterns of the signals: CD28 CARs delivered really fast and strong messages, while 4-1BB CARs delivered identical messages, but in a slower and less intense fashion. The faster and stronger CD28 CAR messages led to T cells that were less functional in a mouse model of lymphoma,” explained Salter.

Overall, Salter concluded that these findings challenge an assumption in the field and suggest that the strength of CAR signaling influences how T cells respond. New approaches to fine-tune CAR signaling strength may allow researchers to design new types of safer and more effective CARs.

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Recent studies on CAR T-cell immunotherapy, and the recent approval of a new agent, add to evidence supporting the efficacy of these therapies.

Investigating CAR T-Cell Signals May Lead to New Approaches

New chimeric antigen receptor (CAR) T-cell immunotherapies are offering hope for patients with hematologic malignancies. However, that is not the case with solid tumors. Researchers in Seattle are hoping to change that, having just announced the start of a CAR T-cell immunotherapy trial for children and young adults with relapsed or refractory non–central nervous system, epidermal growth factor receptor (EGFR)-expressing solid tumors. In the phase I STRIvE-01 trial, CAR T cells will target the EGFR protein expressed in many childhood sarcomas, kidney tumors, and neuroblastomas.

“Our CAR is generated using an EGFR antibody that has been shown to effectively target EGFR on tumors while sparing EGFR-expressing normal tissues. We hypothesize that using CD19 as a second target, which is expressed on all normal B cells, will enhance expansion and persistence of the infused CAR T cells,” 

 Katie Albert, MD, of Seattle Children’s Hospital and lead investigator for the STRIvE-01 trial.

Albert said the phase I, open-label, non-randomized study with 36 patients will examine the safety and feasibility of administering autologous peripheral blood–derived T cells that have been genetically modified using a self-inactivating lentiviral vector to express an EGFR-specific CAR alone or in combination with a CD19-specific driver CAR.

Anticipating that it will take a multifaceted approach to overcome solid tumors, STRIvE-01 will include two sequential treatment arms. In the first arm, patients will receive EGFR806 CAR T cells to first evaluate the toxicity and establish the maximum tolerated dose of the experimental therapy. Once the first arm is complete, the second arm will open and patients will receive CAR T cells reprogrammed to target both EGFR and CD19.

“We have made significant advances in CAR T-cell immunotherapy for hematologic malignancies, so much so that it is being incorporated into standard approaches for certain high-risk patients,” Albert told 

. She said there is still a long way to go when it comes to solid tumors in terms of refining the details. Albert also noted it will be a bit of time before there is an available product as a first-line therapy.

According to Albert, the bench-to-bedside pace has been swift overall, especially for the pediatric setting. “However, solid tumors are not at the same place and pose some unique challenges. CAR T cells have to find their way to bulk tumor sites throughout the body and overcome tumor microenvironment defenses.”

Albert said it is important that patients and their families are not given false hope. She noted that we are now in a time when significant advances are occurring in the lab and quickly leading to early-phase clinical trials. “Patients and researchers alike will always be anxious for new therapies to progress more quickly, and solid tumors may require even more innovation for success, but I would not call it false hope. The enthusiasm for CAR T-cell immunotherapy is legitimate,” she said.

The STRIvE-01 study explored the safety of CAR T-cell therapy in children and young adults with relapsed or refractory solid tumors.

New CAR T-Cell Immunotherapy Approaches to Solid Tumors in Children

A team of investigators from the University of California San Diego School of Medicine and the University of Minnesota has concluded, based on a murine study, that it may be possible to engineer natural killer (NK) cells to include chimeric antigen receptors (CARs) and thereby create a less toxic form of CAR immunotherapy. The 

. It showed that similarly modified NK cells derived from human induced pluripotent stem cells (iPSCs) displayed heightened activity against a mouse model of ovarian cancer.

The findings suggest a major advantage over current CAR T-cell–based immunotherapies because NK cells can be safely delivered in an off-the-shelf manner without patient matching. Senior author Dan Kaufman, MD, PhD, who is a professor of medicine in the Division of Regenerative Medicine and director of cell therapy at UC San Diego School of Medicine, San Diego, Calif., said one of the main challenges of immunotherapy has been the clinical manufacture of modified cells.

CAR-T cell–based immunotherapies have garnered considerable attention and investment in recent years. T cells are extracted from a patient’s blood, genetically modified with a chimeric antigen receptor, and then grown in large numbers in a laboratory.   

Kaufman said one batch of iPSC-derived NK cells potentially can be used to treat thousands of patients. This would enable standardized off-the-shelf treatments that could be used in combination with other anticancer therapies. He and his colleagues have shown that it is possible to engineer iPSCs and create chimeric antigen receptor–expressing NK cells to better target refractory cancers that have resisted other treatments.

Kaufman noted that CAR T-cell immunotherapies have been associated with severe toxicities, including unexpected organ damage and death. Previous research that he and others have conducted suggests that NK cells do not trigger similar toxicities, and the latest study reported few adverse effects in mouse models.

In their research, the team tested CAR-NK cells derived from human iPSCs in an ovarian cancer xenograft mouse model. They compared the antitumor activity against other versions of NK cells and CAR T cells. The NK cells demonstrated activity to that of CAR T cells, but with significantly less toxicity. Kaufman said the data indicate that ovarian cancer may be a good first target, but added that other solid tumors (such as breast cancer, brain tumors, and colon cancers) as well as blood cell cancers (such as leukemias) are also likely to be suitable targets of iPSC-derived NK cells.

Renier J. Brentjens, MD, PhD, a medical oncologist at Memorial Sloan Kettering Cancer Center in New York City, said it is common for toxicities to occur in humans even though they were not evident in the animal studies. “Hypothetically, any type of these (approaches) shows promise and should be moved forward to the clinical study. The promise is high. It might work, but whether it is safer or better than CAR T cells will have to be determined with clinical trials,” Dr. Brentjens said in an interview with Cancer Network

Brentjens added that the fact that this could be an off-the-shelf product makes it very attractive in terms of costs and convenience. “With any kind of approach where you can potentially make a one-size-fits-all product that is equally effective or better, you will have an advantage over the current system, which is cumbersome and expensive,” Brentjens said.

A murine study suggests this engineered combination may offer a major advantage over current CAR T-cell–based immunotherapies.

Might CAR-NK–Based Immunotherapy Be More Effective, Less Toxic?

It may be time to adopt a broader approach to tumor and matched normal sequencing in patients with advanced renal cell carcinoma (RCC), according to a large new study. In an 

, researchers report that germline mutations in patients with advanced RCC may be prevalent, and many of these mutations can be used to guide therapy. However, they are not being adequately detected.

Maria I. Carlo, MD, from Memorial Sloan Kettering Cancer Center, New York City, and colleagues assessed 254 patients and found that phenotype-directed or tumor-only testing failed to identify most of the patients with actionable mutations. This suggests that patients with non–clear cell RCC, in particular, may benefit from a broader approach to tumor-normal sequencing.

The researchers noted that identifying patients with hereditary RCC is paramount because it can help guide treatment decisions. However, there have been few investigations into the prevalence of cancer-related germline mutations in patients with advanced RCC. In addition, little is known about the phenotypes associated with some rare mutations.

Carlo and coinvestigators evaluated 254 patients with advanced RCC (American Joint Committee on Cancer stage III or IV disease) who were treated between October 1, 2015 and July 31, 2017. All patients (median age, 56 years) underwent germline sequencing. The patients ranged in age from 13 to 79 years, and 70.5% were male (N = 179).

Germline mutations were identified in 41 patients (16.1%). In this group, 14 patients (5.5%) had mutations in s

Soroush Rais-Bahrami, MD, Assistant Professor of Urology and Radiology at the University of Alabama at Birmingham, believes these findings may be clinically relevant. “It is a very interesting study,” he said in an interview with Cancer Network. “This could lead to more directed treatments and better outcomes.” He said the findings point to a better way of identifying patients with advanced RCC who would benefit most from targeted therapies.

The study found genes not previously associated with RCC risk. Specifically, 

 was overrepresented in patients with RCC compared with the general population (odds ratio, 3.0). Moreover, patients with non–clear cell RCC were significantly more likely to have an RCC-associated gene mutation (9 of 74 patients compared with 3 of 177 patients). 

The investigators reported that among patients with non–clear cell RCC, more than 20% had a germline mutation; further, 50% of those patients could benefit from direct systemic therapy. The researchers concluded that the current referral criteria for genetic testing may fail to identify a substantial proportion of patients with mutations.

“This really highlights how important it is to do genetic and germline testing. We can hone in on the genetic findings and that can make a difference,” said Rais-Bahrami. He added that the study results may lead to important new avenues of preventing advanced disease, and benefiting family members who get adequately screened.

More than 20% of patients with non–clear cell RCC had a germline mutation, and half of this group could benefit from direct systemic therapy.

A Call for Better Screening for Hereditary Renal Cell Carcinoma

Lisocabtagene maraleucel, a CD19-directed 4-1BB CAR T-cell product, produced durable responses in patients with heavily pretreated relapsed-refractory diffuse large B cell lymphoma (R/R DLBCL) and appears to have manageable acute toxicities, investigators of the TRANSCEND NHL 001 trial (ClinicalTrials.gov identifier: NCT02631044) have found. Results of the study (

) were reported at the 2018 American Society of Clinical Oncology (ASCO) Annual Meeting, held June 1–5 in Chicago.

“Our update report includes 102 evaluable patients in the entire study, and 73 patients with relapsed/refractory DLBCL who represent patients being accrued in the pivotal cohort,” said study presenter Jeremy S. Abramson, MD, Clinical Director of the Lymphoma Program at Massachusetts General Hospital Cancer Center, Boston, Massachusetts. “Our response rate among all subjects was 75%, with complete responses in 55%. We also see evidence of a dose-response relationship between treatment arms.”

Dr. Abramason presented the updated safety and long-term clinical outcomes (6-month and 12-month) data resulting from an evaluation of lisocabtagene maraleucel in R/R aggressive NHL. The study included patients with R/R DLBCL, primary mediastinal B-cell lymphoma (PMBCL), follicular lymphoma grade 3B (FL3B), and mantle cell lymphoma (MCL); all patients had adequate organ function. Treatments included lymphodepletion with fludarabine and cyclophosphamide, followed by lisocabtagene maraleucel. The team investigated multiple dose levels and administration schedules for the therapies studied.

The researchers opted for a dose of 108 CAR T cells (dose level 2) for the current investigation. The primary objective of this study was to assess safety, pharmacokinetics, and antitumor response. “Among relapsed/refractory DLBCL and transformed follicular lymphoma patients treated in dose level 2, the best overall and complete response rates were 78% and 62%, respectively, and 49% of patients were in ongoing response at 6 months,” Dr. Abramason told Cancer Network.

He said durable responses were seen in all high-risk subgroups, including primary refractory disease and double hit lymphomas. “Dose level 2 has been taken forward in relapsed/refractory DLBCL and transformed follicular lymphoma in the pivotal phase of the trial. The high rates of response and durability are encouraging in this very high risk patient population,” said Dr. Abramason.

Among 102 evaluable patients, the researchers observed any-grade cytokine release syndrome (CRS) in 39% of patients. However, Dr. Abramson noted that this was a low-grade adverse event in nearly all patients, with only a single patient experiencing severe CRS. Neurotoxicity was observed in 23% of the patients, and it was severe in 13%. He said all of the toxicities were virtually always reversible, and there were no deaths from CRS or neurotoxicity. “These data demonstrate remarkable efficacy and safety of this CAR T-cell product, which is uniquely characterized by a defined cell composition which results in a precise dose of CD8 and CD4 CAR+ T cell administered to each patient,” said Dr. Abramson.

In TRANSCEND NHL 001, the CD19-directed 4-1BB CAR T-cell product lisocabtagene maraleucel yielded durable responses in heavily pretreated R/R DLBCL.

Durable Responses in R/R DLBCL With CAR-T Product Lisocabtagene Maraleucel 

The field of cellular therapy for myeloma is evolving rapidly, and a paradigm shift in treatment is on the horizon, according to Adam D. Cohen, MD, Director of Myeloma Immunotherapy at the Abramson Cancer Center, Philadelphia, Pennsylvania. At the 2018 American Society of Clinical Oncology (ASCO) Annual Meeting, held from June 1–5 in Chicago, he delivered an Education Session presentation, “CAR-T and Cellular Therapy in Myeloma,” and contributed a chapter to the 

, “CAR T Cells and Other Cellular Therapies for Multiple Myeloma: 2018.” Dr. Cohen noted that gene-modified T cells, particularly B-cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T cells, are yielding promising response rates in early studies of patients with highly refractory myeloma.

He said that while there have been significant advances in therapy for myeloma over the past 5 years, the disease is still incurable in most patients. Dr. Cohen said outcomes remain particularly poor for patients who have adverse cytogenetics or disease that is resistant to multiple lines of therapy.

“Despite multiple new drug approvals for myeloma, the majority of patients develop resistance and ultimately succumb to their disease. CAR T cells represent a novel immune-based approach with the potential to overcome drug resistance and other poor prognostic features,” Dr. Cohen told Cancer Network.

Dr. Cohen emphasized that cellular therapies have the potential to overcome drug resistance and induce long-term remissions. He said the two primary approaches that are being studied are non––gene-modiï¬ed strategies and gene-modiï¬ed strategies. Non–gene-modified strategies rely on the endogenous antimyeloma T-cell repertoire. Gene-modified strategies employ a new T-cell receptor (TCR) or a CAR to confer novel antigen speciï¬city. So far, CAR T cells have been the first out of the gate to show the greatest activity.

Dr. Cohen said multiple antigen targets are being explored for myeloma. These include BCMA, CD19, CD38, CD138, and SLAMF7. Currently, however, BCMA is showing the most promise. Dr. Cohen said preliminary data from four phase I studies of BCMA CAR T cells have been reported. The four trials have included 90 evaluable patients with relapsed/refractory disease, and each trial employed a diï¬erent CAR construct.

The data revealed response rates ranging from 60% to 100%, including minimal residual disease at effective doses. However, response durability has been more variable. Dr. Cohen said this variability may be related to differences in CAR T-cell products or in responses to lymphodepleting regimens. He said other problems of variability may be related to patient selection criteria and/or underlying biology/prognostic factors.  

“The biggest pro is the potential to induce durable remissions with a single treatment, which is very different than the current treatment paradigm in myeloma, where continuous drug therapy is the norm. The biggest cons are the logistical challenges in collecting, manufacturing, and administering the CAR T cells, which currently can be done only at specialized centers,” said Dr. Cohen.

Toxicities associated with these treatments include cytokine release syndrome and neurotoxicity. These adverse events can be severe and remain challenging. However, Dr. Cohen said they are reversible in almost all patients and perhaps may be mitigated by earlier use of the immunosuppressive agent tocilizumab.

Multiple BCMA CAR T-cell studies are ongoing, said Dr. Cohen, adding that investigators are now exploring a variety of combinations with immunomodulatory drugs, checkpoint inhibitors, and various gene-edited cellular products. 

Therapy with CAR T cells may benefit patients with highly refractory multiple myeloma, said U Penn’s Adam Cohen at ASCO 2018.

Cellular Therapies for Multiple Myeloma: A Paradigm Shift 

Gene editing techniques now are paving the way for an “off-the-shelf” CAR T-cell strategy for treatment of relapsed and refractory T-cell acute lymphoblastic leukemia (T-ALL) and non-Hodgkin T-cell lymphoma (T-NHL) without a requirement for autologous T cells. Researchers are 

 that they have used the gene-editing technology CRISPR to engineer human T cells that can attack human T-cell cancers.

The researchers engineered the T cells so any donor’s T cells could be used. A matched donor with similar immunity is not required and neither are the patient’s own T cells. “We were able to efficiently (> 90%) delete both copies of CD7 and the T-cell receptor alpha subunit (TRAC) and insert a unique CAR to CD7 in human T cells, which maintains normal killing function of these genetically manipulated human T cells in vitro and in vivo. We were able to show that these genetically modified CAR T cells kill both CD7+ human T-ALL cells and T-NHL in vitro and in vivo in immunodeficient mice,” said senior author John F. DiPersio, MD, PhD, who is a professor of medicine in oncology at Washington University School of Medicine in St. Louis, Missouri.

Dr. DiPersio’s team first generated a novel CAR T-cell strategy targeting CD7, allowing for the targeting and killing of all cells with CD7 on the surface. To prevent T-cell fratricide, the researchers used CRISPR/Cas9 gene editing to remove CD7 from healthy T cells. In addition, they used CRISPR gene editing to simultaneously eliminate the therapeutic T cells’ ability to see healthy tissues as foreign. “Our multiplex gene editing of CD7 and TRAC renders these T cells immune to fratricide and from causing graft versus host disease (GvHD).  Thus, this represents the first “off-the-shelf” third party CAR T allowing for targeting of both T-ALL, T-NHL, and natural killer (NK) malignancies (also CD7+) without risk of fratricide or GvHD.” Dr. DiPersio told 

The researchers demonstrated that this approach is effective in mice with T-ALL taken from patients. Mice treated with the gene-edited T cells targeted to CD7 survived 65 days, compared with 31 days in a comparison group that received engineered T cells targeting a different protein. The researchers found no evidence of GvHD in the mice. In addition, the study revealed that the therapeutic T cells remained in the blood for at least 6 weeks after the initial injection, suggesting it could ramp up again to kill cancerous T cells if they return.

“The development of CAR T to T-cell and NK-cell malignancies has now been accomplished through the use of CRISPR/Cas9 gene editing and lentiviral gene transduction technologies. This provides the first pathway for overcoming major obstacles of targeting T-cell and NK-cell malignancies using cellular therapy,” said Dr. DiPersio, who is also the deputy director of Siteman Cancer Center. The researchers now hope to translate these findings into the clinic specifically for the treatment of children and adults with relapsed and refractory T-cell hematologic malignancies.  The first clinical trial is set to begin in the next 12 to 18 months.

Using CRISPR/Cas9 gene editing to remove CD7 from healthy T cells, researchers have found a way to use third party T cells for CAR-T therapy in T-cell hematologic malignancies.

“Off-The-Shelf” Third Party T Cells for CAR-T Therapy Under Investigation

Combining DNA-demethylating agents (DNA methyltransferase inhibitors) with histone deacetylase inhibitors (HDACis) may pack a double punch against non-small cell lung cancer (NSCLC), according to a recently published 

.  Researchers have found that this novel drug combination therapy appears to prime NSCLC to respond better to  immunotherapy.

The combination therapy triggered a chemical cascade increasing the attraction of immune cells to fight tumors and diminished the work of the cancer gene 

. Based on these findings, investigators have launched a clinical trial of the combination therapy in patients with advanced NSCLC.

“We were pleased with our findings,” said senior study author Stephen Baylin, MD, who is a professor of oncology and medicine at the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins in Baltimore, Maryland. “It was better news than we had anticipated.”

He said immune checkpoint therapy has been a tremendous step forward. However, he noted that less than half of patients with lung cancer benefit from checkpoint inhibitor therapy. In this current study, he said the two-drug epigenetic therapy combination worked exceedingly well even before adding the immune checkpoint inhibitors.

In a series of experiments, the researchers studied the combination of 5-azacytidine with the three HDACis (entinostat, mocetinostat, and givinostat) in human cancer cell lines and in NSCLC mouse models. The treatments were found to alter the tumor microenvironment. In cancer cell lines, 5-azacytidine worked against the cancer gene 

, causing down regulation of the entire MYC signaling program; adding the HDACis further depleted MYC. Together, the drugs prevented cancer cell proliferation, simultaneously attracted more immune system T cells to the area of the tumor, and activated these cells for tumor recognition.

In mouse models, the strongest response was observed when using 5-azacytidine plus givinostat. In one mouse model with a mutant form of NSCLC, this drug combination given for 3 months yielded prevention of benign precursor tumors from becoming cancerous and resulted in a 60% reduction of overall area of benign tumor appearance in the lungs. By contrast, a similar group of mice given a placebo universally developed large cancerous lesions in the lungs. Treatment with an alternating schedule of 5-azacytidine with givinostat and 5-azacytidine with mocetinostat not only reduced the growth of rapidly growing primary tumors but also dramatically reduced metastatic occurrence in a second mouse model.

Dr. Baylin and colleagues at Memorial Sloan Kettering Cancer Center in New York and Fox Chase Cancer Center in Philadelphia have started to enroll patients in a phase I/Ib clinical trial to evaluate if giving mocetinostat with guadecitabine can boost immune checkpoint therapy responses in patients with advanced NSCLC. “Thirty to 40 patients are being enrolled. I think it will take a year to start to see if we are getting something special and then we would expand,” Dr. Baylin said in an interview with 

The combination therapy increased the attraction of immune cells to fight non-small cell lung cancer and also boosted the response to immune checkpoint inhibitors.

DNA-Demethylating Agents Combined with Histone Deacetylase Inhibitors May Help Combat NSCLC

Japanese researchers are proposing a whole new avenue for combating multiple myeloma (MM). Researchers at Osaka University 

 that they have found a new target for a monoclonal antibody–based treatment for patients with MM.

They conducted a study to see if a cancer-specific antigen formed by the modification of proteins during or after synthesis, such as glycosylation or conformational changes, could open up a new treatment avenue. The team theorized new antigen epitopes could be discovered by thoroughly searching for cancer-specific monoclonal antibodies and characterizing the recognized antigens.

Study investigator Naoki Hosen and his colleagues applied this strategy to identify novel therapeutic targets for MM. The team screened more than 10,000 anti-MM monoclonal antibody clones and identified MMG49 as an MM-specific monoclonal antibody uniquely recognizing a subset of integrin Î²7, a cell-surface receptor that facilitates cell-extracellular matrix adhesion.

MMG49 reacted to MM cells, but not other bone marrow cell types in MM patient samples. For this investigation, the team used candidate monoclonal antibodies to stain bone marrow cells from patients with MM. They identified MMG49 as a candidate that exhibited distinct binding to MM cells but negligible binding to normal leukocytes or non-MM cells in 45 of 51 MM samples. This prompted the researchers to design a chimeric antigen receptor (CAR) that incorporates a fragment derived from MMG49. The resulting MMG49 CAR T-cell therapy was found to have anti-MM effects without damaging normal blood cells.

“We found that the activated integrin Î²7 serves as a specific target for CAR T-cell therapy against MM,” said Hosen. “It will be tested in a clinical trial in 2 years.”

The researchers demonstrated that elevated expression and constitutive activation of integrin Î²7 resulted in high MMG49 reactivity on MM cells. They also found that MMG49 binding was hardly detectable in other cell types and this included normal integrin Î²7 + lymphocytes. The researchers concluded that MMG49 CAR T-cell therapy appears promising and warrants further investigation.

“A structure of a wild-type protein in an activated state can serve as a target for cancer immunotherapy. Our findings suggest that cancer immunotherapeutic targets may yet be identified in many cell surface proteins that undergo conformational changes, even if the expression of the proteins themselves is not cancer-specific,” Hosen told 

MMG49 has been identified as a monoclonal antibody that can be targeted using CAR T-cell therapy for patients with multiple myeloma.

MMG49 Identified as a New Target in Multiple Myeloma

Researchers in California are now proposing a new combination therapy approach to improve treatments of multiple myeloma and mantle cell lymphoma. Currently, treatment resistance is common but investigators at Stanford University have found a potential new target to prevent resistance. Writing in 

 that resistance could be linked to a protein called Nrf1, which appears to respond to proteasome insufficiency or pharmacological inhibition by upregulating proteasome subunit gene expression.

“We found that one of the resistance mechanisms against proteasome inhibitor cancer drugs, a transcriptional proteasome ‘bounce back’ response, is dependent on the deglycosylating enzyme NGLY1 [N-glycanase 1]. This was a surprise because not much was known about how Nrf1 is biosynthesized and processed,” said study investigator Carolyn Bertozzi, a professor of chemistry at Howard Hughes Medical Institute at Stanford University in Stanford, California.

She and her colleagues started working on this from the view of the rare hereditary disease NGLY1 deficiency, and they were surprised to discover that one of the major deficits in these patients is loss of Nrf1 function. Proteasome inhibitors, including bortezomib and carfilzomib, have been effective in treating certain types of blood cancers. However, the drugs have been limited by treatment resistance. Previous studies have suggested that resistance could be linked to Nrf1.

When proteasome inhibitors go into action, Nrf1 is spurred into overdrive to restore the cells' normal activities and keep them alive. By studying NGLY1 deficiency, a seemingly unrelated condition, Bertozzi and colleagues appear to have found a new way of attacking treatment resistance.

The researchers found that NGLY1 is responsible for activating Nrf1 and they demonstrated that dampening NGLY1 allowed a proteasome inhibitor to continue doing its work.

“When Nrf1 was identified as a possible mediator of proteasome inhibitor resistance, it was with some dismay because transcription factors are notoriously ‘undruggable’, and therefore it was not clear what action could be taken to disable this resistance pathway. But NGLY1 is an enzyme that is quite amenable to drug development,” Bertozzi told 

The team established proof of concept for this notion in this current paper. Bertozzi said it may be possible to disable Nrf1 by inhibiting NGLY1, which is far more tractable than efforts to inhibit Nrf1 directly. It is hoped that this line of investigation could lead to the development of new combination therapeutics for blood cancers.

“We hypothesize based on these findings that co-therapy with an NGLY1 blocker could enhance the potency and/or durability of proteasome inhibitors such as Velcade [bortezomib] and Kyprolis [carfilzomib]. Such co-therapy may also extend the use of proteasome inhibitors to other cancer subtypes that are presently considered refractory to proteasome inhibitor therapy. We are following-up with studies that address this notion directly,” said Bertozzi.

A proof-of-concept study has demonstrated that resistance to treatment in multiple myeloma and mantle cell lymphoma could be linked to a protein called Nrf1, which appears to respond to proteasome insufficiency or pharmacological inhibition.