Hematology CAR-T | GileadPro Israel

Both diffuse large B-cell lymphoma (DLBCL) and primary mediastinal large B-cell lymphoma (PMBCL) belong to the group of non-Hodgkin lymphomas. They both arise from degenerated B cells that multiply uncontrollably^3,5.

DLBCL is a cancer of B lymphocytes that develops and matures in the bone marrow and lymph nodes¹³. Arises in deep lymph nodes in the chest or abdomen or superficial lymph nodes in the neck or armpit. However, it can also arise in other places in the body such as the intestines, bones or even the brain or spinal cord. Older people are mostly affected; the risk of disease increases with age^1,2,4.

However, PMBCL (Primary mediastinal large B-cell lymphoma) mostly affects young women in their third or fourth decade of life¹⁰. It usually occurs in the mediastinum, an area in the middle of the chest behind the breastbone. There the lymphoma can grow quickly, press on the windpipe and lead to breathing problems³.

In addition, an indolent (less aggressive) lymphoma can develop into an aggressive lymphoma. For example, transformed follicular lymphoma- Follicular lymphomas which usually grow slowly and arise from cells in the center of the lymph nodes, can transform into aggressive DLBCL⁸.

HGBCL is an introduced category in the updated 2016 revision of the World Health Organization (WHO) classification of lymphoid neoplasms, after originally being classified under DLBCL rather than as a separate entity⁶. It comprises two types of lymphomas: HGBCL with MYC and BCL2 and/or BCL6 rearrangements (also commonly referred to as double/triple-hit)¹⁶.

Diffuse large B-cell lymphoma (DLBCL) is the most common malignant lymphoma in adults^11,12. The risk of the disease increases as the age increases. The average age of onset is over 65 years, but younger people can also develop DLBCL. PMBCL on the other hand, is diagnosed less frequently than DLBCL and accounts for 2%-4% of all non-Hodgkin lymphomas¹⁰.

DLBCL (including activated B-cell (ABC) and germinal centre B-cell-like (GCB) subgroups) is a cancer of B lymphocytes that develops and matures in the bone marrow and lymph nodes¹². In DLBCL, the abnormal B-cell lymphocytes are larger than normal and have stopped responding to signals that usually limit the growth and reproduction of cells. Different variants of the disease can be identified by performing advanced tests on the lymph node specimen¹².

For some lymphomas, genetic alterations are involved, leading to uncontrolled cell proliferation. DLBCL, for instance, develops due to genetic changes over time. Several factors contribute to these irreversible genomic alterations, such as viral or bacterial infections, exposure to chemical pollutants, or a compromised immune system.
Translocations involving the IGH locus and the proto-oncogenes BCL2, BCL6 and MYC are hall-marks of GC-associated B-cell malignancies and are usually referred to as ‘double-hit’ or ‘triple-hit’ lymphomas (high-grade B-cell lymphoma)¹⁶.

Symptoms

The symptoms of malignant lymphoma are frequently non-specific and can overlap with those of other illnesses. As a result, it's not uncommon for malignant lymphoma to be incidentally detected during a medical examination. The uncontrolled growth of lymphoma cells often results in the enlargement of lymph nodes, which can be palpable beneath the skin or exert pressure on adjacent organs, leading to various symptoms.

About one third of patients with DLBCL present with ‘B symptoms’¹² which include fevers, night sweats, and unexplained weight loss¹⁴, and some patients present with symptoms related to organ involvement¹². Additional presenting common signs and symptoms which are similar to other less serious diseases include fatigue, cough, itchy skin, and loss of appetite¹⁵.
When DLBCL spreads to the bone marrow, it can disrupt normal blood cell production, resulting in fatigue and reduced performance due to anemia, an increased tendency to bleed and experience "bruising" due to a decrease in platelet count and a decreased white blood cells count leading to an increased susceptibility to infections.

Primary mediastinal large B-cell lymphoma (PMBCL) originates in the mediastinum, the central area of the chest cavity between the two lungs. When the tumor reaches a certain size, it can exert pressure on nearby organs like the trachea, lungs, or major blood vessels. This can result in symptoms like coughing, breathlessness, or swallowing difficulties. Unlike some other lymphomas, bone marrow involvement is infrequently seen in PMBCL¹⁰.

Staging and risk factors

Staging and identifying risk factors play a critical role in determining the prognosis for patients with diffuse large B-cell lymphoma (DLBCL) or primary mediastinal large B-cell lymphoma (PMBCL).
When there is suspicion of a malignant lymphoma like DLBCL or PMBCL, a comprehensive medical evaluation is typically conducted. This includes a thorough physical examination to assess for signs such as swollen lymph nodes or an enlarged spleen. Since malignant lymphoma can affect areas beyond superficially detectable lymph nodes, doctors often order imaging tests, such as abdominal and neck ultrasounds, chest X-rays, or abdominal, chest, and pelvic computed tomography (CT) scans. In cases of suspicion, doctors frequently perform tissue sampling procedures such as blood tests and on occasion, bone marrow tests are also carried out as part of the diagnostic process.
Stage classification and identification of risk factors do not presently influence treatment decisions but are essential for estimating a patient's prognosis.
Through the diagnostic examinations described, doctors continue to determine which parts of the body are affected by DLBCL. This enables staging according to the Ann Arbor classification.

The stages of the Ann Arbor classification can be summarized as follow:¹⁷

Stage I: Involvement of a single lymph node region

Stage II: Involvement of several lymph node regions on one side of the diaphragm

Stage III: Involvement of lymph node regions on both sides of the diaphragm

Stage IV: Widespread organ involvement, such as in the bone marrow and/or liver

Beyond the Ann Arbor stage, there exist additional factors that can impact a patient's response to treatment and, to some degree, allow for an evaluation of the expected disease course.
The International Prognostic Index (IPI) is employed to determine a patient's likelihood of recovery and their anticipated response to standard therapy. The following are considered as risk factors:¹⁷

Based on the number of risk factors a patient exhibits, their prognostic risk can be categorized as low, low-intermediate, high-intermediate, or high.

Treatment

In recent years, there has been continuous improvement in treatment options for the relatively common DLBCL, leading to the achievement of cure rates. Given DLBCL's aggressive and fast-growing nature, it is crucial to initiate treatment as soon as the disease's extent is determined, allowing for the selection of an appropriate treatment approach based on that assessment.
The main guidelines for the treatment of the disease are the European guideline, the ESMO and the American NCCN guideline.

Given the aggressive nature of diffuse large B-cell lymphoma (DLBCL), it is imperative to initiate treatment promptly upon confirming the diagnosis and assessing the extent of cancer spread. The established standard therapeutic approach for DLBCL involves immunochemotherapy¹⁴.
The treatment of primary mediastinal large B-cell lymphoma (PMBCL) is based on that of DLBCL¹⁴.

Nearly 60% of patients who undergo a disease relapse will do so within the initial 12 months following their first remission²⁰.
Until recently, the only option for cure for patients with who are R/R DLBCL was a high-dose chemotherapy and Autologous bone marrow transplantation¹⁹. Only about 50% of patients who are resistant or whose disease has changed after the first line can be suitable for transplantation due to age or other diseases²¹. Due to the resistance for chemotherapy, only 50% of the patients who were destined for transplantation, will continue to the stage of high-dose chemotherapy and transplantation²¹.

From 2023 Yescarta, a CAR-T cell therapy, has been reimbursed into the Medical Services Basket of Israel for adult patients diagnosed with DLBCL experiencing relapse within 12 months after completing or showing resistance to initial chemoimmunotherapy. Patients with primary refractory disease or relapse after an initial response are characterized by poor outcome and CAR T-cell therapy holds the potential to provide a path to recovery for certain individuals^19,23.
CAR T-cell therapy is a treatment based on genetically engineered T cells obtained from the patient. The engineered cells express a Chimeric Antigen Receptor (CAR) that is linked to the CD19 antigen found on the surface of B cells. When these engineered cells bind to cancer cells, the co-stimulatory domain and the CD3-zeta activating domain activate downstream signaling cascades, leading to T cell activation, proliferation, and the release of various cytokines. This sequence of processes ultimately leads to apoptosis and necrosis of the cells expressing the CD19 sequence.

After two or more lines of systemic therapy in patients with R/R DLBCL, CAR T-cell therapy remains a viable treatment option. Additionally, alternative options include Allo-SCT (Allogeneic Stem Cell Transplantation) and the use immunochemotherapies for individuals who are ineligible for transplantation.

Non-Hodgkin lymphomas are divided into subtypes based on the type of lymphocytes (B or T cells) or the growth rate and spread of the malignant lymphocytes (fast-growing and aggressive or slow-growing and indolent).
Indolent non-Hodgkin lymphoma is a subtype that begins from B cells and grows at a slow or indolent pace. Follicular lymphoma, a type of indolent non-Hodgkin lymphoma, is the most common subtype (about 20% of cases) and affects lymph nodes, bone marrow, and the spleen. This disease is more common in individuals over the age of 50^1,2.

Symptoms and diagnosis

Indolent non-Hodgkin lymphoma can progress slowly, but it can also transform into a more aggressive form and change into diffuse large B-cell lymphoma (DLBCL)^3,4. Patients with indolent lymphoma may experience symptoms such as weight loss, loss of appetite, fever, infections, night sweats, fatigue, rashes, and chest, abdominal, or bone pain. Patients with follicular lymphoma typically experience lumps, fatigue, or discomfort^3,4.

The diagnosis is based on histology from a biopsy of a lymph node or other affected tissue. Immunohistochemical staining is positive in virtually all cases for cell surface CD19, CD20, CD10 and monoclonal immunoglobulin, as well as cytoplasmic expression of bcl-2 protein. The overwhelming majority of cases have the characteristic t(14;18) translocation involving the IgH/bcl-2 genes⁶.

Staging and risk factors

After the initial diagnosis, patients with indolent non-Hodgkin lymphoma with low disease stage generally respond to a variety of initial treatment options. However, the disease often recurs. Patients with advanced disease typically require multiple subsequent treatment regimens, leading to shorter and diminishing periods of remission. Some patients experience therapy-resistant disease, transformation to DLBCL, or die due to aggressive therapy-resistant relapse ⁵.

The Follicular Lymphoma International Prognostic Index (FLIPI) uses five independent predictors of inferior survival: ⁷

Other factors such as time to relapse of less than 2 years from chemoimmunotherapy and specific gene mutations may also be useful for prognosis⁸.

FLIPI-2 includes additional prognostic factors such as beta-2 microglobulin levels and bone marrow involvement, which can provide a more precise assessment of prognosis compared to FLIPI. Another prognostic prognostic measure is Groupe d'Etude des Lymphomes Folliculaires (GELF) Criteria(*). GELF criteria define tumor burden as high if any of the following criteria are present:

FLIPI-2 and GELF criteria are frequently used in clinical practice for assessing prognosis in follicular lymphoma¹⁴.

Treatment

Most of treated patients ultimately experience disease relapse, regardless of their initial disease stage. Therefore, treatment is administered to symptomatic patients only¹³.
In the first-line treatment, patients may be treated with radiation therapy, immunotherapy or systemic chemotherapy based on their tumor burden and stage disease^9,11.

There is no consensus regarding the best treatment for patients relapsed/refractory follicular lymphoma.
The choice of second-line treatment is based on the stage of the disease, the type of tumor and the location, previous treatments, and the characteristics of the patient, such as age and general condition^3-5.
There are several guidelines that discuss several treatment options for patients with R/R FL, including the NCCN, ESMO and NICE. The treatments include immunotherapy and/or systemic chemotherapy.

Since 2023, The inclusion of Yescarta as a CAR-T cell therapy has been reimbursed into the Medical Services Basket of Israel for patients with relapsed/refractory follicular lymphoma after two or more lines of systemic therapy:  CAR-T cell therapy.
CAR T-cell therapy is a treatment based on genetically engineered T cells obtained from the patient. The engineered cells express a Chimeric Antigen Receptor (CAR) that is linked to the CD19 antigen found on the surface of B cells. When these engineered cells bind to cancer cells, the co-stimulatory domain and the CD3-zeta activating domain activate downstream signaling cascades, leading to T cell activation, proliferation, and the release of various cytokines. This sequence of processes ultimately leads to apoptosis and necrosis of the cells expressing the CD19 sequence.

Although the prognosis of FL is positive, the disease can still be fatal in a subgroup of patients with histologic transformation remaining a major problem.

Mantle cell lymphoma (MCL) is categorized as a non-Hodgkin lymphoma, originating from B cells that undergo malignant transformation in the peripheral zone of a lymph node, called the Mantle zone.
First, the degenerated B cells accumulate at their place of origin, for example in the spleen or the lymph nodes, and can later spread throughout the body.
Mantle cell lymphoma is considered a rare cancer, accounting for approximately 5–7% of all lymphomas. Interestingly, for reasons that are not yet fully understood, men are affected by this condition four times more frequently than women^4,5.
Onset of the disease typically occurs in older individuals, with the average age for new cases being around 65 years^1,2,4.

In mantle cell lymphoma, a genetic abnormality occurs where a fragment from both chromosome number 11 and chromosome 14 breaks off and attaches to the other chromosome. This type of genetic alteration is referred to as a translocation. As a result of this translocation, the affected B cells start overproducing a protein called cyclin D1, leading to uncontrolled cell multiplication ^6,12.
Additional factors contributing to the pathogenesis of the malignant growth include: the tumor's microenvironment and its ability to suppress the body's immune response against it (by secreting substances like CSF1 and IL10). These factors enable it to "hide" from the body's immune system cells, whose role is to identify and destroy tumor cells, and additionally, to suppress their activity¹³.

Symptoms^11,12

During diagnosis, bone marrow involvement with tumor cells will be found in 70-80% of patients, and in 40% of patients, malignant cells will be detected in the peripheral blood. Tumor cells will be found in the digestive system in 20% of cases, and in less than 5% of cases, there may be involvement of the central nervous system^{1, 6, 12}.

It's important to note that there are no distinctive or typical symptoms that specifically point to MCL, which can make early diagnosis challenging. The disease is often detected when symptoms related to lymph node or spleen enlargement become noticeable.

Staging and risk factors

The initial diagnosis is made by identifying the characteristic malignant cells in a biopsy of a suspicious lymph node, lymphatic organ, or bone marrow. It can also be achieved through isolating the characteristic malignant cells from a peripheral blood test^{9, 14, 15}.
Subsequently, the extent of the disease (staging) needs to be determined, which is done through physical examination, blood counts and chemistry, bone marrow examination, CT or CT-PET scans of the neck, chest, abdomen, and pelvis. Endoscopy of the digestive tract is recommended to rule out digestive tract involvement. Evaluation of cerebrospinal fluid is recommended for patients with neurological symptoms. The disease's staging is divided into four stages (Ann Arbor classification):

Stage I: Involvement of a single lymph node region.

Stage II: Involvement of multiple lymph node regions on one side of the diaphragm.

Stage III: Involvement of lymph node regions on both sides of the diaphragm.

Stage IV: Widespread involvement of organs, such as the bone marrow and/or liver.

To assess the risk category in which the patient falls, it is advisable to evaluate their underlying diseases and the cardiac function using ECG and echocardiography, lung and renal function. Biochemical and genetic markers of the tumor should also be characterized, along with tumor features such as peripheral involvement, central nervous system involvement, tumor burden, and more^{6, 9, 16, 17}. A majority (75% - 95%) of patients receive a diagnosis of an aggressive form of the disease, often found in advanced stages (III/IV)^{1, 2, 7, 8, 10}.

Risk factors and risk groups play a crucial role in assessing the disease's progression. These factors go beyond the disease stage and include:

1. Tumor Growth Rate: The speed at which the tumor grows is determined using the prognostic marker Ki-67. This marker indicates the number of cells currently in a growth phase. A higher Ki-67 value indicates a more rapid multiplication of cancer cells¹⁶.

2. MIPI (Mantle Cell Lymphoma International Prognostic Index): This index is calculated to determine the patient's risk group, which is categorized as low, intermediate (medium), or high risk.
The MIPI considers several risk factors:

These factors, collectively, help determine the prognosis index and the patient's risk group, providing valuable information for treatment planning.

Treatment

In approximately 10-15% of patients, the disease is detected at a very early stage and progresses slowly. In such cases, a "watch and wait" strategy may be employed, meaning treatment is deferred until the disease begins to spread⁹.

The most frequent treatment options are high-dose chemotherapy followed by autologous stem cell transplantation, Bruton Tyrosine Kinase Inhibitor (BTKi), targeted therapies and CART- cell therapy^{9, 14}.

In Israel, CAR-T therapy is indicated for adult patients with MCL who have undergone BTKI treatment, unless they are ineligible for BTKI therapy

Lymphoblastic Leukemia (ALL) is a rare hematological disease characterized by the uncontrolled proliferation and accumulation of blasts in the bone marrow, blood, and various extramedullary sites. In 75% of cases, ALL affects B cells, and it is most diagnosed in children and young adults, although it can also occur in older individuals.
ALL is an aggressive disease, and without treatment, survival is typically measured in weeks to a few months. In current treatments, cure rates in children are over 80%, but in adults, the outlook is different, with cure rates ranging from 20-40%.

The poor prognosis in adults is due to a higher prevalence of factors associated with a more challenging disease and a better resistance to treatments^3-5. The majority of adult patients whose disease relapsed after first-line treatment will not survive for more than a year⁶. The prognosis is particularly grim in refractory patients, patients with early relapse post-treatment, and those who still have signs of the disease despite treatment (Minimal Residual Disease – MRD) ^6,7-9.

Several genetic changes occur in patients with B-cell ALL, including a low number (hypoploidy) or a high number (hyperploidy) of chromosomes. Genetic alterations, such as changes in chromosomal structures and translocations between chromosomes, are also observed^2,10. The relapsed disease is generally characterized by additional mutations beyond the primary chromosomal mutations.¹¹ Mutations of this kind can lead to treatment resistance and relapse¹². One common mutation in adult ALL patients is the Philadelphia chromosome translocation [t(9;22)(q34;q11)], resulting in the fusion of the BCR-ABL1 genes. In 2016, the World Health Organization recognized another group of patients with clinical features resembling Ph-like (Philadelphia-like) chromosomal characteristics¹⁰. Ph-like patients exhibit genetic expression similar to those with the Philadelphia chromosome but lack the cytogenetic feature of BCR-ABL1. Both Ph-like and Philadelphia chromosome mutations are rare in children, but their prevalence increases significantly with age, making them the most common genetic mutations in adult ALL patients.

Symptoms and diagnosis

Clinical features of adult B-ALL are nonspecific and can include symptoms related to various body systems, such as bone marrow failure (anemia, leukopenia, and thrombocytopenia)². Features specific to B-cell ALL may include night sweats, weight loss, fever, bleeding, shortness of breath, petechiae, fatigue, weakness, joint or bone pain, and frequent infections^1,13,14.
Extra-medullary (outside the bone marrow) involvement can include additional symptoms like lymph node swelling, enlarged spleen, and enlarged liver². Central nervous system involvement is seen in about 5-8% of patients and can manifest as symptoms of meningitis (including neck stiffness, photophobia, and headaches).
Gastrointestinal tract involvement can lead to abdominal distension or discomfort^1,13,14. Diagnosis of ALL is confirmed when bone marrow contains more than 20% lymphoblasts (cancerous cells).
In 2016, the World Health Organization (WHO) published guidelines assessing the disease through diagnostic and prognostic steps¹⁵. The diagnostic process involves several steps that aim to reduce the time to initiate treatment. These steps include morphological assessment, immunophenotyping, genetics/cytogenetics, and genomics.
In addition to examining bone marrow, peripheral blood tests and cerebrospinal fluid sampling can be used to determine central nervous system involvement^15,16. Molecular tools for diagnosis, such as Polymerase Chain Reaction (PCR) or various fluorescent stains to check for Minimal Residual Disease (MRD), are utilized. Flow cytometry is also employed¹⁵.

Treatment

Patients who are diagnosed with adult B-ALL and present symptoms, will typically start chemotherapy after diagnosis. The goal of chemotherapy in the first-line treatment consists of three main stages: induction, consolidation, and maintenance^13,16.
In the induction stage, the choice of treatment depends on the disease characteristics and additional risk factors, which may lead to aggressive chemotherapy or the addition of extra drugs. However, not all patients can tolerate high-dose chemotherapy, and approximately 85-90% will respond to first-line chemotherapy, meaning 10-15% of patients are primary refractory².
The consolidation stage aims to eliminate the cancerous cells in the bone marrow¹³. Patients with risk factors may undergo an allogeneic bone marrow transplant at this stage, which offers a chance for a cure but carries significant risks.
The goal of the maintenance phase is to prevent disease relapse. During this stage, patients are regularly assessed for complete remission (CR) and minimal residual disease (MRD) every 3-6 months^13,17. Notably, the disease relapses for a significant portion of patients who initially achieve a complete response, and about half of them transition to second-line treatment¹⁸.

Adult patients diagnosed with relapsed or refractory B-ALL, have the choice of undergoing treatment with CAR T-cell therapy or other immunotherapies, regardless of whether they have Ph+ B-ALL or Ph- B-ALL¹³.
Moreover, alternative treatment options, including targeted therapies, may be considered based on their Ph chromosome translocation status.