StemCell Therapy

Using immunotherapy with genetically modified T cells that express chimeric antigen receptors or CARs designed to target tumor-associated molecules, have impressive efficacy in the treatment hematological malignancies.

A CAR is a synthetic construct that, when expressed in T cells, mimics T cell receptor activation and redirects specificity and effector function toward a specified antigen.[1]

In the treatment of cancer, this process is accomplished by linking an extracellular ligand-binding domain specific for a tumor cell surface antigen to an intracellular signaling module that activates T cells upon antigen binding.[1]

The presented studies include results from emerging second-generation cellular immunotherapy products that strive to overcome the limitations of existing products such as resistance and reduce toxicity and simplify treatment.

Cellular immunotherapy uses genetic engineering to enhance the ability of the immune system the bodys defense system against infection and disease to kill malignant cells in the blood, the bone marrow, and other sites, in order to keep cancer from coming back.

CAR T-cell TherapyChimeric antigen receptor T-cell therapies, better known as CAR T-cell therapies, are developed by harvesting a patients own T-cells, the immune systems primary cancer-killing cells, engineering them to target proteins specific to the surface of cancer cells, and reintroducing these modified T-cells back into the patients immune system to kill the cancer cells.

First generationFirst-generation CAR T-cell therapies primarily target CD-19, a protein found on the surface of most normal and malignant B cells in B cell cancers such as lymphoma. These therapies have been shown to produce long-term remissions in about one-third of patients with B-cell lymphomas that have not responded to prior therapies.

We are now seeing efforts to enhance the effectiveness of CAR T-cell therapy by designing products capable of attacking multiple targets, expand the availability of cellular immunotherapy to other blood cancers such as multiple myeloma and replace the complex manufacturing process required for CAR T-cell therapy with a uniform off-the-shelf product, noted Gary Schiller, MD, UCLA Health, an academic medical center which includes a number of hospitals and an extensive primary care network in the Los Angeles, California, region.

One of the phase I studies evaluates an off-the-shelf cellular immunotherapy product that targets two proteins found on the surface of lymphoma cells, including its potential to revive previously administered CAR T-cells that have stopped working.

Another study presents preclinical results for one of the first cellular immunotherapies to be based on off-the-shelf natural killer (NK) cells and the first, according to its manufacturer, to be genetically engineered to contain three active anti-tumor components.

The other two studies, also phase I studies, assess novel CAR T-cell therapies for multiple myeloma that test different dual-target strategies.

One investigational agent is genetically engineered to contain two proteins that attach to BCMA, a protein found almost exclusively on the surface of plasma cells, the immune-system cells that become cancerous in multiple myeloma.

The other is designed to target both BCMA and CD-38, another protein found on the surface of plasma cells. In both studies, many patients achieved minimal residual disease (MRD) negativity, which means that using highly sensitive testing fewer than one myeloma cell per 100,000 cells was identified in the bone marrow. Previous studies have shown that patients who achieve this milestone have a lower risk of relapse after more than three years of follow-up.

Dual-targeted CAR T-cell therapiesThe three phase I studies also hint at the possibility that dual-targeted CAR T-cell therapies might result in fewer patients experiencing moderate to severe cytokine release syndrome (CRS), a known adverse effect caused by an immune response in the body to the activated T cells that are attacking the cancer. CRS causes flu-like symptoms such as fever, body aches, and fatigue, and in severe cases can be life-threatening. Treatment with the drug tocilizumab can reduce CRS symptoms.

Dual-Targeted Antibody Elicits Durable ResponsesPatients with B-cell Non-Hodgkin Lymphoma (NHL) that had returned after or failed to respond to a median of three prior therapies showed complete responses (CR) and durable remissions after being treated with an investigational drug called mosunetuzumab (RG7828; Genentech/Roche). [2]

This investigational agent is a humanized, T-cell bispecific antibody designed to engage T cells and redirect their cytotoxic activity against malignant B cells. The drug works by activating the patients own T-cells, stimulating them to attack and kill cancerous B cells to which they have been introduced by the novel antibody.

Mosunetuzumab simultaneously binds to CD3 epsilon (CD3), a component of the T-cell receptor (TCR) complex, and to CD20, a B-cell surface protein expressed in a majority of B-cell malignancies. This results in crosslinking of the TCR, inducing downstream signaling events that leads to B-cell killing.

Among patients whose lymphoma progressed after treatment with CAR T-cell therapy, 22% had complete remissions when treated with mosunetuzumab. This new drug targets two proteins, one on the surface of tumor cells and the other on the surface of the recipients Tcells.

Unlike CAR T-cell therapy, mosunetuzumab is an off-the-shelf immunotherapy product that can be given to patients without having to genetically modify their T cells, noted lead author Stephen J. Schuster, MD, of Abramson Cancer Center at the University of Pennsylvania in Philadelphia.

Mosunetuzumab generates long-lasting responses with a very tolerable safety profile in patients with B-cell non-Hodgkin lymphomas for whom multiple prior treatments have failed and whose prognosis is poor. Of particular interest, we are seeing durable complete remissions in patients whose lymphomas progressed after CAR T-cell therapy, he added.

The researchers observed many remissions continue after patients stop receiving the drug.

I have stopped therapy in some patients after six months and they have remained in remission. Some patients have remained in remission without additional therapy for more than a year, Schuster said.

New treatment options are needed not only for patients in whom CAR T-cell therapy has failed, but also for those patients whose lymphomas are getting worse so quickly that they cannot wait for CAR T-cell manufacturing, which takes several weeks, Schuster explained.

The data presented during the annual meeting of the American Society of Hematology included 270 patients (median age 62, 172 men) enrolled in the phase I trial in seven countries (the United States, Australia, Canada, Germany, South Korea, Spain, and the United Kingdom). All participating patients had B-cell lymphomas that had come back or not responded to a median of three prior therapies. Two-thirds of patients (67%) had fast-growing lymphomas; 85 (31%) patients had more slow-growing forms of the disease. In 30 patients (11%), the cancer was resistant to or returned after an initial response to CAR T-cell therapy; in 77 patients (29%), the disease had progressed after a stem cell transplant.

All patients were treated with mosunetuzumab by intravenous infusion. They had an imaging test at either six weeks or three months after starting therapy to assess the initial response to treatment, and responses continued to be followed every three months thereafter.

Forty-six of 124 patients with fast-growing lymphomas (37%) had measurable decreases in the extent of their cancer (objective response); 24 of 124 patients (19%) saw all detectable tumors disappear (complete response). A higher response rate was observed in patients with higher exposure to mosunetuzumab. Among patients with slow-growing lymphomas, 42 of 67 (63%) had objective responses and 29 of 67 (43%) had complete responses. Both objective response rate and complete response rate were maintained in subgroups of patients at high risk for relapse.

Complete remissions appear to be long lasting, Schuster said.

With a median follow-up of six months since first complete remission, 24 of 29 patients (83%) who achieved complete remissions of their slow-growing lymphomas and 17 of 24 patients (71%) who achieved complete remissions of their fast-growing lymphomas remain free of disease. In some patients whose cancers progressed after receiving CAR T-cell therapy, highly sensitive molecular testing showed that the previously administered CAR T cells increased in number.

This suggests that, in addition to its ability to kill cancerous B cells, mosunetuzumab may also help augment the effect of the prior CAR-T treatment, Schuster noted.

Cytokine-release syndromeIn this study, 29% of patients treated with mosunetuzumab experienced cytokine-release syndrome that was mostly mild.

Cytokine release syndrome or CRS is caused by a large, rapid release of cytokines into the blood from immune cells affected by the immunotherapy. While most patients have a mild reaction, sometimes patients may have a severe, life threatening, reaction.

In 3% of patients, CRS was treated with tocilizumab (Actemra; Genentech/Roche). Four percent of patients experienced moderately severe neurologic side effects. Patients who received higher doses of mosunetuzumab were no more likely to have CRS or neurologic side effects than patients treated at lower doses.

A study of a higher dose of mosunetuzumab is now enrolling patients and long-term follow-up of these patients will ultimately help to better evaluate the durability of response data.

Larger, randomized trials are needed to further confirm these promising data and determine whether the treatment benefit of mosunetuzumab is enhanced when it is used earlier in the course of lymphoma therapy or in combination with other agents, Schuster concluded.

Novel Off-the-Shelf CARPreclinical studies provide the first evidence that cellular immunotherapy for B cell cancers could ultimately become an off-the-shelf product, capable of being uniformly manufactured in large quantities as prescription drugs are.

We have taken the concept of traditional pharmaceutical drug development and applied it to cellular therapy, explained senior author Bob Valamehr, Ph.D, of Fate Therapeutics, a San Diego biopharmaceutical company.

The product called FT596, is among the first cellular immunotherapies to be based on off-the-shelf NK cells the first line of defense of the immune system and is the first cellular immunotherapy to be genetically engineered to contain three active anti-tumor components, Valamehr explained.

Comparable with standard CAR T-cell therapyFT596 demonstrated comparable ability to kill cancerous white blood cells as standard CAR T-cells and, when combined with the drug rituximab (Rituxan; Genentech/Roche), killed cancerous white blood cells that were no longer responding to standard CAR T-cell therapy due to loss of the CD19 antigen target.

The U.S. Food and Drug Administration (FDA) approved Fate Therapeutics Investigational New Drug Application for FT596 in September 2019 and the company hopes to begin a first-in-human phase I clinical trial for the treatment of B-cell lymphoma and chronic lymphocytic leukemia in the first quarter of 2020.

The primary purpose of this trial will be to assess the safety and activity of FT596 in patients.

ManufacturingThe development and manufacturing of FT596 begins with human induced pluripotent stem cells (iPSCs) that are uniquely capable of unlimited self-renewal and can differentiate into more than 200 types of human cells. These iPSCs are genetically engineered, after which a single genetically engineered cell or clone is selected and multiplied in the laboratory to create a master engineered cell line that can be repeatedly used to generate cancer-fighting immune-system cells such as NK and T cells.

Natural Kiler Cells or NK cells are a type of lymphocyte and a component of innate immune system, the bodys first line of defense against infection and disease. Unlike T-cells, which have to be trained to recognize their target and can kill only cells that display that target on their surface, NK cells do not need special preparation before going on the attack and can kill many different types of transformed or infected cells.

NK cells are multifaceted and can be viewed as a jack-of-all-trades when it comes to protecting the host, whereas T cells can act in only one way, Valamehr explained.

But NK cells are also different in other ways. They are inherently limited in their capacity to multiply and expand when infused into patients, and they have a shorter lifespan.

Valamehr and his colleagues used genetic engineering to address these shortcomings. In addition to engineering FT596 to carry a CAR targeting the CD19 protein, which is produced by nearly all B-cell lymphomas and leukemias, they inserted two other novel proteins: CD16, which boosts and broadens the NK cells ability to kill cancer cells, and IL15, which stimulates FT596 to proliferate and persist.

Valamehr explained that FT596 has been designed to address two more limitations of CAR T-cell therapy .

The investigational agent is an off-the-shelf product. As a result, it significantly improves the current patient-by-patient CAR T-cell treatment paradigm by eliminating the time-consuming and costly process that is currently required to treat a patient with CAR T-cells.

The addition of the CD16 protein gives FT596 broader therapeutic activity and versatility. In combination with rituximab, FT596 has the potential to lead to deeper and more durable responses and overcome resistance that hampers the long-term efficacy of CAR T-cell therapy.

Eliminating the high production cost, weeks of manufacturing time, and complex manufacturing process required for CAR T-cell therapy and replacing it with a mass-produced, off-the-shelf product, promises to expand access to effective cell-based cancer immunotherapy to many more patients who may benefit from it, Valamehr concluded.

Results from CARTITUDE-1 in R/R Multiple MyelomaPatients with multiple myeloma who had received a median of five prior therapies, and for whom standard-of-care treatments were no longer working, had a high response rate when treated with the investigational CAR T-cell therapy JNJ-68284528 (JNJ-4528), which targets BCMA, a protein commonly found on the surface of multiple myeloma cancer cells.

These patients participated in a clinical trials (NCT03548207), supported by Janssen Research & Development, designed to characterize safety of and establish the recommended Phase II dose (RP2D) (Phase Ib) and to evaluate the efficacy of JNJ-68284528 (Phase II).

We are seeing a high response rate, with most patients achieving MRD negativity, noted lead study author Deepu Madduri, MD, of The Tisch Cancer Institute at Mount Sinai in New York.

Considering these patients have all received multiple prior therapies, these results are extremely encouraging, Madduri added.

All evaluable patients receiving this CAR T-cell therapy have achieved MRD-negative disease state and 27 of 29 patients are progression free at a median follow-up of six months, Madduri said.

Multiple myeloma is a cancer of plasma cells, which are found in the bone marrow and are part of the immune system, the bodys defense system against infection. Typical signs and symptoms of multiple myeloma may be bone pain or fractures, high levels of calcium in the blood, kidney damage, and anemia. Multiple myeloma affects an estimated 160,000 people each year, occurs most often in people over 60. The disease is slightly more common in men than in women.

Although new therapies for multiple myeloma have recently become available that can extend patients life expectancy, a cure for the disease remains elusive.

We can get the disease into remission, but most patients unfortunately relapse, and outcomes are very poor for patients who have relapsed multiple times, she said.

Researchers explained that JNJ-4528 is a novel CAR T-cell therapy featuring two molecules that bind to BCMA, a protein found on the surface of multiple myeloma cells.

We are learning that every CAR T-cell therapy is different, Madduri said.

JNJ-4528 has a unique CAR T-cell composition in patients, preferentially enriched in CD8 T cells, which are believed to be one of the most important T cells in killing cancer cells, she noted.

This phase Ib/II trial is continuing to enroll patients.

During the 2019 annual meeting of the American Society of Hematology, Madduri reported results for the first 29 patients enrolled.

Patients T-cells were collected and sent to a laboratory where they were genetically engineered to express JNJ-4528. Prior to re-infusing these CAR T-cells, the patients received three days of chemotherapy to make room in their immune systems for the engineered T-cells.

Following chemotherapy, each patient received a single infusion of the JNJ-4528 CAR T-cells.

After a minimum of 28 days, these patients had blood and bone marrow exams, which was followed by exams at six months, and one year after treatment to assess their response. The primary aims of the trial are to assess the therapys safety and to confirm the dose to be tested in a larger, phase II trial.

The median follow-up time in the current analysis is six months. Overall, 100% of patients had a clinical response to JNJ-4528. Moreover, 66% had a stringent complete response, meaning that sensitive laboratory and microscopic tests found no evidence for myeloma proteins or cells in blood, urine, or bone marrow.

Most patients (93%) experienced some form of CRS. One patient had severe (grade 3) CRS, and one patient died from its complications 99 days after the CAR T-cell infusion. In 76% of patients, CRS was treated with tocilizumab.

To see some patients in this heavily pretreated population surviving for a year or more with a one-time treatment and a manageable safety profile is remarkable, Madduri explained.

These patients feel that they have their quality of life back. They no longer have to come into the clinic for weekly treatments and some are well enough to travel, Madduri concluded.

The phase II portion of this study is ongoing to evaluate the overall response rate of patients treated with JNJ-68284528 (JNJ-4528). Additional clinical studies are evaluating the safety and efficacy of JNJ-4528 in different multiple myeloma treatment settings.

BreakthroughEarlier this week the U.S. Food and Drug Administration (FDA) granted Breakthrough Therapy Designation for JNJ-68284528 (JNJ-4528).

The granting of Breakthrough Therapy Designation for JNJ-68284528 (JNJ-4528) is a significant milestone as we continue to accelerate the global development of this innovative CAR-T therapy in collaboration with Legend Biotech, noted Sen Zhuang, MD, Ph.D., Vice President, Oncology Clinical Development, Janssen Research & Development.

We look forward to continuing to work closely with the U.S. Food and Drug Administration to advance the clinical development program for JNJ-68284528 (JNJ-4528) and ultimately bring this BCMA-targeted immunotherapy to patients living with multiple myeloma who are in need of a new therapeutic option, Zhuang concluded.

Encouraging Results for Dual-Targeted CAR T-Cell TherapyMore than three out of four patients with multiple myeloma that returned or did not respond to at least two therapies remained in remission seven months after treatment with a novel CAR T-cell therapy targeting two proteins that are frequently found on myeloma cells.

Nine patients experiencing sustained remissions in this study, which ws supported by the National Natural Science Foundation of China, the Major Technological Innovation Special Project fund of Hubei Province of China, and Cellyan Therapeutics, were diagnosed with a difficult-to-treat form of multiple myeloma in which the disease has spread beyond the bone marrow.

Roughly one in 10 patients with multiple myeloma develop tumors in the organs or soft tissues such as the blood vessels, muscles, and nerves. These so-called extramedullary tumors respond poorly to treatment, and patients who develop them have a poor outlook and poor health related quality of life (hrQoL)

Our results show that this CAR T-cell product can effectively achieve elimination of extramedullary tumors, said study author Yu Hu, MD, Ph.D, of Union Hospital, Huazhong University of Science and Technology in Wuhan, China.

Although these are preliminary data, they are encouraging for patients with multiple myeloma who have not responded to other therapies, Hu added.

Hu and his colleagues are developing the first CAR T-cell therapy to be genetically engineered to target BCMA and CD38, two proteins found on the surface of plasma cells. Multiple myeloma is a cancer of plasma cells, which are found in the bone marrow and are part of the immune system, the bodys defense system against infection and disease.

Our thinking was that targeting both of these proteins would improve treatment efficacy without increasing toxicity, and induce deeper, more durable remissions, Hu noted.

The first-in-humans phase I trial enrolled 22 patients whose average age was 59, of whom 11 were men. All had multiple myeloma that had returned or not responded to at least three therapies. Nine of the 22 patients had extramedullary tumors. The study aims were to determine the safest and most effective dose of the CAR T-cell therapy as well as to initially evaluate its effectiveness.

Just like in other trials with CAR T-cell therapies, the participating patients received three days of chemotherapy to make room in their immune systems for the engineered T-cells. Then each patient was infused with the dual-targeted CAR T cells. Patients were divided into five groups, with each group receiving a higher dose than the previous one. Depending on the cell dose, patients received either one or two infusions.

At a median of 36 weeks of follow-up, 18 patients (90.9%) had MRD-negative disease. Twelve patients (54.5%) had a stringent complete response, meaning that no plasma cells were detected in the bone marrow. Seven patients (31.8%) had a good or very good partial response, meaning that the level of M-protein (an abnormal protein produced by cancerous plasma cells) in the blood or urine was reduced but still detectable. In eight of the nine patients with extramedullary lesions, these tumors were undetectable on their computed tomography scans. For the 17 patients who remained in remission at seven months after treatment, the median duration of response was 28.8 weeks.

The adverse events observed included 20 patients who experienced CRS, of whom six needed treatment. No serious adverse neurologic effects such as seizures, movement impairment, difficulty speaking or understanding speech, or fatal swelling in the brain were reported.

With this dual-targeted CAR T-cell therapy, we have demonstrated a high response rate, especially a higher rate and longer duration of stringent complete response, compared with other therapies, as well as effective elimination of extramedullary lesions, with no serious neurologic adverse effects and manageable levels of other adverse effects, Hu concluded.

The investigators continue to follow the patients for the next two years. They are also planning to conduct a phase II trial in both China and the United States to test the treatments effectiveness in a larger number of patients.

Clinical trialsA Study of JNJ-68284528, a Chimeric Antigen Receptor T Cell (CAR-T) Therapy Directed Against B-Cell Maturation Antigen (BCMA) in Participants With Relapsed or Refractory Multiple Myeloma (CARTITUDE-1) NCT03548207

References[1] Srivastava S, Riddell SR. Chimeric Antigen Receptor T Cell Therapy: Challenges to Bench-to-Bedside Efficacy. J Immunol. 2018;200(2):459468. doi:10.4049/jimmunol.1701155 [Abstract][2] Schuster SJ, Bartlett NL, Assouline S, Yoon SS, Bosch F, Sehn LH, Cheah CY, Shadman M, et al. Mosunetuzumab Induces Complete Remissions in Poor Prognosis Non-Hodgkin Lymphoma Patients, Including Those Who Are Resistant to or Relapsing After Chimeric Antigen Receptor T-Cell (CAR-T) Therapies, and Is Active in Treatment through Multiple Lines. 61st annual meeting of the American Society of Hematology. Program: General Sessions. Session: Plenary Scientific Session. Hematology Disease Topics & Pathways: antibodies, Follicular Lymphoma, CRS, Diseases, Biological, Therapies, neurotoxicity, Adverse Events, CAR-Ts, Non-Hodgkin Lymphoma, DLBCL, immunotherapy, Lymphoid Malignancies. [Abstract][3] Goodridge JP, Mahmood S, Zhu H, Gaidarova S, Blum R, Bjordahl R, Cichocki F, et al. FT596: Translation of First-of-Kind Multi-Antigen Targeted Off-the-Shelf CAR-NK Cell with Engineered Persistence for the Treatment of B Cell Malignancies. 61st annual meeting of the American Society of Hematology. Program: Oral and Poster Abstracts. Type: Oral. Session: 625. Lymphoma: Pre-ClinicalChemotherapy and Biologic Agents: Targeting Apoptosis Pathways in Lymphoma.[Abstract][4] Madduri D, Usmani SZ, Jagannath S, Singh I, Zudaire E, Yeh TM, Allred AJ, Banerjee A, et al. Results from CARTITUDE-1: A Phase 1b/2 Study of JNJ-4528, a CAR-T Cell Therapy Directed Against B-Cell Maturation Antigen (BCMA), in Patients with Relapsed and/or Refractory Multiple Myeloma (R/R MM). 61st annual meeting of the American Society of Hematology. Program: Oral and Poster Abstracts. Type: Oral Session: 653. Myeloma: Therapy, excluding Transplantation: Novelty in CAR T in Relapsed/Refractory Multiple Myeloma. [Abstract][5] Li C, Mei H, Hu Y, Guo T, Liu L, Jiang H, Tang L, Wu Y, et al. A Bispecific CAR-T Cell Therapy Targeting Bcma and CD38 for Relapsed/Refractory Multiple Myeloma: Updated Results from a Phase 1 Dose-Climbing Trial61st annual meeting of the American Society of Hematology. Program: Oral and Poster Abstracts. Type: Oral. Session: 653. Myeloma: Therapy, excluding Transplantation: Novel Therapy for Relapsed Myeloma. Hematology Disease Topics & Pathways: Biological, Diseases, Adult, Therapies, Lymphoma (any), Adverse Events, CAR-Ts, Elderly, Biological Processes, Technology and Procedures, Cell Lineage, Study Population, Clinically relevant, Lymphoid Malignancies.

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ASH 2019: Second-gen CAR T-Cell Therapy Overcome Resistance, Reduce Toxicity and Simplify Treatment - OncoZine

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