Patent Description:
In the early <NUM>, adult acute lymphoblastic leukemia (ALL) was a rarely curable disease with an overall survival of less than <NUM>%. In the last years, progress has been made in molecular diagnostics of ALL. Stem cell transplantation (SCT) has improved the outcome of ALL and has made treatment more feasible. Though various new targeted drugs are under evaluation, effective targeted therapies for ALL are not yet available. An extensive review found that although children could obtain remission rates of up to <NUM>%, disease-free survival at ten years was <NUM>% for children and <NUM>-<NUM>% for adults (<NPL>). Rapid diagnosis and classification of ALL is increasingly important to identify prognostic and molecular genetic subsets that will be the focus of targeted treatment (<NPL>).

ALL treatment typically today takes place in <NUM> phases: induction (or remission induction), consolidation (intensification) and maintenance and involves the long-term use of chemotherapy. The total treatment usually takes about <NUM> years, with the maintenance phase taking up most of this time. In the past several years, more intensive chemotherapy regimens have been used, which led to better responses to treatment. But these regimens are also more likely to cause side effects, such as low white blood cell counts, which in turn require administration of other drugs that help to prevent or treat these side effects. An important part of treatment for ALL is central nervous system (CNS) prophylaxis - treatment that is meant to ensure the leukemia does not spread to the brain or spinal cord. <NPL>, &<NPL> discloses long-term survival in adult patients with relapsed/ refractory b-precursor acute lymphoblastic leukemia (ALL) who achieved minimal residual disease (MRD) response following anti-CD19 BiTE ® blinatumomab.

Survival rates with modern treatment protocols for ALL patients have reached a plateau where the potential benefit of more aggressive chemotherapeutic regimens is often offset by an excess mortality due to complications, thus making efforts to individualize treatment even more important. This shows that acute lymphoblastic leukemia (ALL) remains for most patients a fulminate and incurable disease. In light of this, there is an urgent need for improved ALL therapies.

Any references in the description to methods of treatment according to the invention refer to a B-cell depleting agent as defined in the claims for use in a method of treatment of the human body by therapy.

The present invention relates to methods and uses for treatment of ALL which involve administration of a B-cell depleting agent. Uses and methods for conserving or increasing the number of long term survivors of ALL are also envisaged. The uses and methods provided herein involve the number of B-cells in the blood of a patient (or group of patients) remaining or falling below one B-cell/ml serum within a predefined period of time.

The present invention relates to a B-cell depleting agent capable of depleting peripheral CD19+ B-cells for use in a method of conserving or increasing the number of long term survivors in a group of patients suffering from relapsed/refractory adult B-precursor acute lymphoblastic leukemia (ALL). The method comprises the step of administering a (therapeutically effective amount of) B cell depleting agent to said patients (b) observing within a first predefined period of time starting with the first day of initial treatment with the B-cell depleting agent the number of B-cells in the blood of said patient and (c) adjusting the treatment regimen or dosage of said B cell depleting agent such that the number of B-cells in the blood of (preferably all of) the patients of said group falls below one B cell/ml serum within a predefined period of time of <NUM> days after the initial treatment with said B cell depleting agent, hereinafter referred to as second predefined period of time, wherein the first predefined period of time is shorter than the second predefined period of time, wherein said B-cell depleting agent is Blinatumomab and said long term survivors are alive for ≥<NUM> months after starting Blinatumomab treatment.

It must be noted that as used herein, the singular forms "a", "an", and "the", include plural references unless the context clearly indicates otherwise. Thus, for example, reference to "a reagent" includes one or more of such different reagents and reference to "the method" includes reference to equivalent steps and methods known to those of ordinary skill in the art that could be modified or substituted for the methods described herein.

Unless otherwise indicated, the term "at least" preceding a series of elements is to be understood to refer to every element in the series.

The term "and/or" wherever used herein includes the meaning of "and", "or" and "all or any other combination of the elements connected by said term".

The term "about" or "approximately" as used herein means within <NUM>%, preferably within <NUM>%, and more preferably within <NUM>% of a given value or range. It includes, however, also the concrete number, e.g., about <NUM> includes <NUM>.

The term "less than" or "greater than" includes the concrete number. For example, less than <NUM> means less than or equal to. Similarly, more than or greater than means more than or equal to, or greater than or equal to, respectively.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integer or step. When used herein the term "comprising" can be substituted with the term "containing" or "including" or sometimes when used herein with the term "having".

When used herein "consisting of" excludes any element, step, or ingredient not specified in the claim element. When used herein, "consisting essentially of" does not exclude materials or steps that do not materially affect the basic and novel characteristics of the claim.

In each instance herein any of the terms "comprising", "consisting essentially of" and "consisting of" may be replaced with either of the other two terms.

It should be understood that this invention is not limited to the particular methodology, protocols, material, reagents, and substances, etc., described herein and as such can vary. The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention, which is defined solely by the claims.

The present inventors have discovered a correlation between (peripheral) B-cell depletion within a defined period of time (<NUM> days) and survival for ≥ about <NUM> months in ALL patients treated with the B-cell depleting agent blinatumomab. In contrast, the present inventors observed that in patients where B-cell depletion took <NUM> days and did not sustain, patients were likely to die in < about <NUM> months. The present inventors therefore concluded that when B-cell depletion can be successfully achieved in a patient (or group of patients) within a specific timeframe, the patient (or group of patients) is likely to be a long-term survivor of ALL and/or to respond favorably to subsequent ALL treatment. Without wishing to be bound by theory, it is speculated that the observed correlation could be attributed to an expansion of the T- and/or TEM-cell population in patients exhibiting a clearance of (peripheral) B cells which may further enhance subsequent ALL treatment via T-cell mediated anti-cancer activity. The means and methods provided herein therefore allow the skilled medical practitioner to quickly evaluate the likelihood of a beneficial outcome of treatment with a given B-cell depleting agent, and hence reduce the administration of agents for treatment of ALL to unresponsive patients. Hence, the present invention provides means and methods for a tailor-made ALL therapy that reduces the risk of side-effects, saves valuable time for treatment with suitable agents, and prevents unnecessary medicinal exposure.

The uses and methods described herein therefore include stratification of ALL patients. "Stratification" refers to sorting patients into those who may or may not benefit from subsequent ALL therapy, in particular ALL therapy involving administration of the B-cell depleting agent applied in the inventive methods and uses.

In accordance with the foregoing, the present invention provides a B-cell depleting agent capable of depleting peripheral CD19+ B-cells for use in a method of conserving or increasing the number of long term survivors in a group of patients suffering from relapsed/refractory adult B-precursor acute lymphoblastic leukemia (ALL). In the aforementioned method, a (therapeutically effective) amount of B cell depleting agent is administered to said group of patients, the number of B-cells in the blood of said patients are observed within a first predefined period of time starting with the first day of initial treatment with the B-cell depleting agent, and the treatment regimen or dosage of a B cell depleting agent is adjusted such that the number of B-cells in the blood of said patients remains or falls below one B cell/ml serum within a second predefined period of time of <NUM> days after the initial treatment with said B cell depleting agent, wherein said B-cell depleting agent is Blinatumomab and said long term survivors are alive for ≥<NUM> months after starting Blinatumomab treatment.

The above-mentioned method is envisaged to be useful in conserving or increasing the number of long-term survivors in a group of ALL patients. , with the help of said method, numbers of long-term survivors in the group of patients treated according to the inventive method ("treated patients") will be preferably at least equal to the number of long-term survivors in the group of patients not treated according to the inventive method ("untreated patients"). Preferably, the number of long-term survivors in the group of treated patients will even exceed the number of long-term survivors in the group of untreated patients. Notably, "untreated patients" may include patients having received another ALL treatment, such as an ALL treatment as described in the section "further ALL treatment".

The means and methods of the present invention are envisioned to be for use in the treatment of relapsed/refractory adult B-precursor acute lymphoblastic leukemia (ALL), all other ALL disclosed herein are for reference only.

"Acute lymphoblastic leukemia" or "ALL", also known as acute lymphocytic leukemia or acute lymphoid leukemia, generally refers to an acute form of leukemia which is typically characterized by the overproduction and/or accumulation of cancerous, immature white blood cells (also referred to as lymphoblasts). As used herein, the term "ALL" includes acute, refractory and relapsed ALL. The term "refractory ALL" as used herein means resistance of the ALL to conventional or standard ALL therapy, such as chemotherapy and/or hematopoietic stem cell transplantation (HSCT), i.e. the conventional or standard ALL therapy is not able to ultimately cure all ALL patients. The term "relapsed ALL" as used herein denotes the return of signs and symptoms of the ALL disease after a patient has enjoyed a remission. For example, after conventional ALL treatment using chemotherapy and/or HSCT, a ALL patient may go into remission with no sign or symptom of the ALL, remains in remission for a couple of years, but then suffers a relapse and has to be treated once again for ALL. The term "ALL" as used herein also includes minimal residual disease (MRD) in a patient with ALL, i.e. the presence of a small numbers of cancerous lymphoblasts remaining in the patient during treatment, or after treatment when the patient is in remission.

The term "ALL" generally encompasses B-cell ALL and T-cell ALL. The term "cancerous" is used herein interchangeably with the term "malignant" to designate cells that are not self-limited in their growth, are capable of invading into adjacent tissues, and may be capable of spreading to distant tissues (metastasizing).

It is envisaged that the methods and uses disclosed herein are particularly useful for treating B-cell ALL, including B-precursor ALL, such as pro-B ALL, pre-B ALL, or common ALL (cALL), and mature B-cell ALL (Burkitt leukemia). The term "ALL" includes both pediatric ALL and adult ALL. The means and methods of the present invention are in particular envisaged to be useful for treatment of relapsed and/or refractory adult B-precursor ALL.

The term "patient" includes all mammals, but is not limited to mouse, rat, dog, horse, camel, primates, etc., primates being preferred and humans, including children and adults, being most preferred. When used herein, the term "subject" is used interchangeably with the term "patient". What is disclosed with reference to a "patient" herein also applies to a group of patients, mutatis mutandis.

The term "pediatric ALL" or "pediatric ALL patient" as referred to herein denotes children aged from one month to <NUM> years. The indicated age is to be understood as the age of the children at diagnosis of the ALL disease. Both time intervals specifically include the upper limit and also the lower limit. This means that for example a time interval "from one month to <NUM> years" includes "one month" and "<NUM> years". <CIT> provides means and methods for treating pediatric or childhood ALL, particularly refractory and/or relapsed pediatric ALL.

The term "adult ALL" or "adult ALL patient" as referred to herein denotes adults aged more than <NUM> years, i.e. patients aged <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> years or more. Even patients with <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> years or older may be treated by the methods and means of the invention. The indicated age is to be understood as the age of the adult at diagnosis of the ALL disease. <CIT> provides means and methods for treating adult ALL.

The term "long term survivor" is used herein to refer to patients living for <NUM> months or longer from initial treatment with the applied B-cell depleting agent, i.e. the time point of receiving the first dose of B-cell depleting agent, e.g. about <NUM> months, about <NUM> months, about <NUM> months, about <NUM> months, or more. It is particularly envisaged that the long term survivors live for about <NUM> months or more after receiving the first dose of b-dell depleting agent.

The invention relates to blinatumomab for the use according to the claims, all other B cell depleting agents disclosed herein are for reference only.

The uses and methods of the present invention involve administration of a (therapeutically effective amount of) B cell depleting agent to a patient (or a group of patients).

In general, any route of administration is conceivable depending, e.g., on the formulation, bioavailability and mechanism of action of the B-cell depleting agent. , the B-cell depleting agent can be administered orally, topically, transdermally, subcutaneously, intravenously, intraperitoneally, intramuscularly or intraocularly. However, any other route may readily be chosen by the person skilled in the art if desired. By "therapeutically effective amount" is meant an amount of the B-cell depleting agent that elicits a desired therapeutic effect, e.g. alleviation or amelioration (complete or partial) of the symptoms or condition of the ALL patient (or group of patients), or any other desired improvement in the patient's (or group of patients') symptoms, disease or condition. The exact amount dose may depend on, e.g., age, body weight, general health, sex, diet, drug interaction and the severity of the condition, as will be ascertainable with routine experimentation by those skilled in the art.

The term "B cell depleting agent" in general refers to an agent capable of reducing and/or controlling the number of B-cells in a patient.

The term thus includes agents that directly or indirectly destroy of some or all B-cells, e.g. by induction of cell death signals, antibody dependent cell-mediated cytotoxicity (ADCC), complement dependent cytotoxicity (CDC), or engagement of cytotoxic T-cells, and agents that block B cell activation or development. The term "B-cell" includes progenitor (or pre-pro) B cells, early pro (or pre-pre)-B cells, late pro (or pre-pre)-B cells, large pre-B cells, small pre-B cells, immature B cells and mature B cells. B cell depletion can be partial or complete, i.e. affect all B-cells or subpopulations of B-cells. Preferred B-cell depleting agents for use in the methods of the invention can reduce (or maintain) the level of B-cells in the blood of a patient (or group of patients) within a second predefined period of time to one B-cell/ml serum or less as ascertainable by the skilled person using routine experimentation as described herein. It is in particular envisaged that B-cell depleting agents used in the methods of the invention are capable of depleting peripheral CD19+ B-cells.

B-cell depleting agents are known in the art and include, without limitation, costimulation blockers (abatacept and <NUM>-related protein-<NUM>), cytokines (tocilizumab and baminercept), B cell receptor-targeted agents (abetimus and edratide), agents targeting CD20, CD22, CD19, CD40-CD40L, B cell activating factor belonging to the TNF family (BAFF) or A proliferation-inducing ligand (APRIL). In accordance with the foregoing, exemplary B-cell depleting agents include anti-CD20 agents (e.g., anti-CD20 antibodies such as rituximab, ofatumumab, ocrelizumab, veltuzumab, tositumomab, ibritumomab), anti-CD25 agents (e.g., anti-CD25 antibodies such as alemtuzumab), BAFF inhibitors (e.g., belimumab, atacicept), anti-CD154 agents (e.g. anti-CD154 antibodies such as ruplizumab, toralizumab), anti-CD19 agents (e.g., MDX-<NUM>), anti-CD22 agents (e.g., epratuzumab) and antithymocyte globulin (ATG).

Without wishing to be bound by theory, it is thought that blinatumomab transiently links CD19+ B cells to CD3+ T-cells, thereby inducing T-cell mediated serial lysis of B-cells and concomitant T-cell proliferation.

Blinatumomab also comprises an amino acid sequence selected from the group consisting of.

The CD19 binding molecule of a CD19 x CD3 antibody is characterized by the VH and VL regions or CDRs as described herein for Blinatumomab.

It is envisaged that the number of B-cells in the blood of the patient (or group of patients) remains or falls below one B cell/ml serum within the second predefined period of time as defined herein.

In general, B-cell numbers can be evaluated through several techniques available in the art, e.g. using the white blood cell (WBC, or leukocytes) count and differential. White blood cells can be counted manually in hemocytometes (Neubauer chamber) or with automated counters. To determine the differential, a drop of blood can be thinly spread over a glass slide, air dried, and stained with a Romanofsky stain, most commonly the Wright or May-Grunewald-Giemsa technique. Cells are then counted and classified using morphologic examination and/or histochemistry as described in <NPL>. Alternatively, leukocytes are isolated from a blood sample and stained with fluorescent-labeled antibodies against lymphocyte cell surface markers and subsequently analyzed by flow cytometry as described in the appended examples. Percentages of each type of lymphocyte are multiplied with absolute lymphocyte numbers to calculate absolute cell numbers for each lymphocyte subpopulation.

It is envisaged that the number of B-cells in the blood of the treated patient (or treated group of patients) remains or falls below one B-cell/ml serum within a second predefined period of time after the initial treatment with said B-cell depleting agent. The initial treatment with the applied B-cell depleting agent preferably means the first treatment with said applied B-cell depleting agent, i.e. the patient (or group of patients) has not received the applied B-cell depleting agent before. Said patient (or group of patients) may, however, have received further ALL treatments as described elsewhere herein before. It is also conceivable that the patient (or group of patients) has received another B-cell depleting agent before the initial treatment with the applied B-cell depleting agent. , when a first B-cell depleting agent has no therapeutic effect, and/or fails to reduce (or maintain) the number of B-cells in the blood of a patient (or group of patients) to one B-cell/ml serum or less, a second B-cell depleting agent may be used. The initial treatment with the second B-cell depleting agent will then start on the first day of treating the patient (or group of patients) with the second B-cell depleting agent. That is, it is conceivable to apply the methods of the invention repeatedly (i.e., in several cycles) with different B-cell depleting agents, the "initial treatment" starting at the day of first treatment with the B-cell depleting agent of the respective cycle. The term "different" B-cell depleting agent also includes the same B-cell depleting agent as used in a preceding cycle, but in a different formulation, concentrations, or the like. It is also conceivable to repeat several cycles of treatment with the same B-cell depleting agent until the desired level of B-cells in the blood of the patient (or group of patients) is achieved.

The "predefined period of time" in which the number of B-cells remains or falls below one B-cell/ml serum is envisaged to be <NUM> days or less, i.e. <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> days or less, referred to as second predefined period of time, wherein the second predefined period of time according to the claimed invention is <NUM> days after the initial treatment with the B-cell depleting agent. The length of the second predefined period of time is ascertainable by the skilled person in the art and may depend on the applied B-cell depleting agent, its concentration, treatment regimen, the type of ALL to be treated, and the like. Without wishing to be bound by theory, it is thought that when the number of B-cells can be adjusted to the desired number of one B-cell/ml serum or less within the second predefined period of time, subsequent treatment is likely to be effective. A possible reason is the expansion of the T- and/or TEM-cell population in patients exhibiting a clearance of (peripheral) B cells, which may enhance the clinical activity of subsequent ALL therapies employing the cytotoxic potential of the T-cell system. "Subsequent treatment" may comprise further treatment with the B-cell depleting agent applied in the inventive method, with another B-cell depleting agent, further ALL treatment as described herein or combinations thereof after the B-cell numbers have been successfully reduced to (or maintained at) one B-cell per ml/serum or less within the second predefined period of time. It is in general also conceivable that no subsequent treatment is necessary. Also, it is envisaged that patients (or groups of patients) in which the number of B-cells in the blood can be reduced to or maintained at one B-cell/ml serum or less within the second predefined period of time are likely to benefit from subsequent ALL therapy, while patients in which the number of B-cells in the blood exceeds one B-cell/ml serum within the second predefined period of time, are not likely to benefit from subsequent ALL therapy.

Means and methods for determining/monitoring the number of B-cells in the blood of a patient (or group of patients) have been defined elsewhere herein. Notably, the first period of time is shorter than the second predefined period of time as defined elsewhere herein. Step (b) of the inventive method is useful in determining whether or not the patient is responsive to the administration of said B-cell depleting agent, i.e. in stratifying patients in to those likely to benefit from subsequent ALL treatment after the first predefined period of time and those who are not. If the number of B-cells remains or falls below one B cell/ml serum within said first predefined period of time, then subsequent treatment is likely to be therapeutically effective.

If, however, the B-cell depleting agent e.g. fails to reduce or maintain the number of B-cells at the desired level of one B-cell/ml serum or less within the first predefined period of time, then the B-cell depleting agent can be adjusted such that the number of B-cells in the blood of the patient (or group of patients) remains or falls below one B cell/ml serum within a second predefined period of time after the initial treatment with said B cell depleting agent.

In general, the first predefined period of time and the second predefined period of time can be of any length, as long as the first predefined period of time is shorter than the predefined period of time. Both periods of time start with the first day of initial treatment with the B-cell depleting agent applied in the inventive methods, i.e. on the same day. The skilled practitioner will readily be able to determine the desired length of the first predefined period of time, depending on, e.g., the B-cell depleting agent, its concentration, formulation, treatment regiment, the ALL type, the physical constitution and findings of the patient (or group of patients), and the second predefined period of time.

Methods of the invention may further involve "adjusting" the B-cell depleting agent. The term "adjusting" refers to an intentional modification of the B-cell depleting agent in order to achieve a number one B-cell/ml serum or less in the treated patient (or group of patients). Thus, the number of B-cells in the blood of an ALL patient is used to adjust the dosage or treatment regimen with the B-cell depleting agent such that the number of B-cells in the blood of said patient remains or falls below one B cell/ml serum within a (first) predefined period of time after the initial treatment with said B cell depleting agent. The adjustment (intentional modification) may involve modification of the dosage, treatment regimen, formulation, or the like. For example, if the number of B-cells in the blood of a patient exceeds one B cell/ml serum within a (first) predefined period, a higher dosage of B-cell depleting agent may be administered, or the B-cell depleting agent may be administered for a prolonged period of time.

The exact dosage of B-cell depleting will depend on the purpose of the treatment (e.g. remission maintenance vs. acute flare of disease), route of administration, age, body weight, general health, sex, diet, time of administration, drug interaction and the severity of the condition, and will be ascertainable by one skilled in the art using known techniques.

Generally, any modification is conceivable as long as it preferably results in the number of B-cells in the blood of the treated patient (group of patients) being reduced to or maintained at a number of one B-cell/ml serum or less within the second predefined period of time. The modification may also include additionally applying further ALL treatments as described herein, and/or administering another B-cell depleting agent.

In accordance with the foregoing, a method of adjusting the dosage or treatment regimen with a B cell depleting agent in a patient suffering from ALL is provided. Said method comprises the step of observing the number of B-cells in the blood of said ALL patient within a predefined first period of time after the initial treatment with said B cell depleting agent and adjusting the dosage or treatment regimen such that the number of B-cells in the blood of said patient remains or falls below one B cell/ml serum within a second predefined period of time after the initial treatment with said B cell depleting agent.

It is also conceivable to use further ALL treatment in combination with the uses and methods of the invention. Further ALL treatment can in general be applied antecedently, simultaneously, and/or subsequently to the uses and methods of the invention.

Hematopoietic stem cell transplantation (HSCT) is a common ALL treatment. The term generally refers to transplantation of hematopoietic stem cells, usually derived from bone marrow or blood, and comprises autologous (i.e., the stem cells are derived from the patient) and allogeneic (i.e., the stem cells are derived from a donor) HSCT. For ALL treatment, allogeneic HSCT is generally preferred. It is also envisaged that the uses and methods of the present invention can be applied before or after HSCT, or both, or in between two HSCT treatments.

Patients (or groups of patients) treated according to the methods of the invention may also receive a chemotherapeutic treatment. In the context of the present invention, a "chemotherapeutic treatment" refers to a treatment with an antineoplastic agent or the combination of more than one of these agents into a standardized treatment regimen. In the context of the present invention, the term "chemotherapeutic treatment" comprises any antineoplastic agent including small sized organic molecules, peptides, oligonucleotides and the like. Agents included in the definition of chemotherapy are, without limitation, alkylating agents, e.g. mechlorethamine, cyclophosphamide, melphalan, chlorambucil, ifosfamide, busulfan, N-Nitroso-N-methylurea (MNU), carmustine (BCNU), lomustine (CCNU), semustine (MeCCNU), fotemustine, streptozotocin, dacarbazine, mitozolomide, temozolomide, thiotepa, mytomycin, diaziquone (AZQ), cisplatin, carboplatin, oxaliplatin, procarbazine and hexamethylmelamine; antimetabolites, e.g. methotrexate, pemetrexed, fluorouracil, capecitabine, cytarabine, gemcitabine, decitabine, Vidaza, fludarabine, nelarabine, cladribine, clofarabine, pentostatin, thioguanine, mercaptopurine; anti-microtubule agents e.g. vincristine, vinblastine, vinorelbine, vindesine, vinflunine, paclitaxel, docetaxel, podophyllotoxin; topoisomerase inhibitors, e.g. irinotecan, topotecan, etoposide, doxorubicin, mitoxantrone, teniposide, novobiocin, merbarone, aclarubicin; cytotoxic antibiotics, e.g. actinomycin, bleomycin, plicamycin, mitomycin, doxorubicin, daunorubicin, epirubicin, idarubicin, pirarubicin, aclarubicin, and mitoxantrone.

Further ALL treatment also includes radiation therapy. CNS treatment or prophylaxis is also envisaged in order to prevent malignant cells from spreading in the CNS, e.g. by intrathecal chemotherapy and/or radiation therapy of the brain and spinal cord.

Since the present inventors speculate that therapeutic success of ALL treatment could be based (in part) of an expansion of the T cell populations resulting in enhanced T-cell anti-cancer activity, inducers and enhancers of T cell activation and/or proliferation, CAR T cells, donor T cells, anti-cytotoxic T-lymphocyte-associated antigen-<NUM> (CTLA-<NUM>) antibodies and others are also envisaged.

The term "treatment" in all its grammatical forms includes therapeutic or prophylactic treatment of ALL. A "therapeutic or prophylactic treatment" comprises prophylactic treatments aimed at the complete prevention of clinical and/or pathological manifestations or therapeutic treatment aimed at amelioration or remission of clinical and/or pathological manifestations. The term "treatment" thus also includes the amelioration or prevention of ALL. The term "treatment" as used herein means in the broadest sense medical procedures or applications that are intended to relieve illness. In the present case, the administration of a B-cell depleting agent (prepared for administration to an ALL patient) as described herein is for the treatment, amelioration or elimination of ALL in patients.

It is envisaged to administer the B-cell depleting agent in the form of a pharmaceutical composition. The term "pharmaceutical composition" particularly refers to a composition suitable for administering to a human or animal, i.e., a composition containing components which are pharmaceutically acceptable. Preferably, a pharmaceutical composition comprises a B-cell depleting agent together with one or more pharmaceutical excipients. The composition may also comprise further ALL agents as described elsewhere herein. The term "excipient" includes fillers, binders, disintegrants, coatings, sorbents, antiadherents, glidants, preservatives, antioxidants, flavoring, coloring, sweeting agents, solvents, co-solvents, buffering agents, chelating agents, viscosity imparting agents, surface active agents, diluents, humectants, carriers, diluents, preservatives, emulsifiers, stabilizers or tonicity modifiers. Pharmaceutical compositions of the invention preferably comprise a therapeutically effective amount of B-cell depleting agent and can be formulated in various forms, e.g. in solid, liquid, gaseous or lyophilized form and may be, inter alia, in the form of an ointment, a cream, transdermal patches, a gel, powder, a tablet, solution, an aerosol, granules, pills, suspensions, emulsions, capsules, syrups, liquids, elixirs, extracts, tincture or fluid extracts or in a form which is particularly suitable for the desired method of administration.

A better understanding of the present invention and of its advantages will be obtained from the following example, offered for illustrative purposes only. The example is not intended to limit the scope of the present invention in any way.

A phase <NUM> study was conducted to evaluate the activity and safety of the bispecific T-cell engager (BiTE®) antibody construct blinatumomab in <NUM> adults with relapsed/refractory B-precursor acute lymphoblastic leukemia (ALL). In the primary analysis, complete remission with full (CR) or partial (CRh) recovery of peripheral counts was observed in <NUM> (<NUM>%) patients and a minimal residual disease (MRD) response (< <NUM>-<NUM>) in <NUM> (<NUM>%) patients (<NUM> responders and <NUM> patients with hypocellular bone marrow). In this long-term follow-up analysis, median relapse-free survival was <NUM> months (median follow-up, <NUM> months), and median overall survival (OS) was <NUM> months (median follow-up, <NUM> months). An MRD response to blinatumomab was associated with significantly longer OS (p = <NUM>). Ten patients (<NUM>%) were long-term survivors, defined as OS ≥ <NUM> months. Six long-term survivors received allogeneic stem cell transplantation (SCT) as consolidation for blinatumomab. Four long-term survivors did not receive allogeneic SCT as consolidation for blinatumomab, including three with no treatment after blinatumomab. One had CD19-negative relapse during the third cycle and achieved another CR with chemotherapy and allogeneic SCT as consolidation for chemotherapy. Neurologic events or cytokine release syndrome led to temporary blinatumomab discontinuation in three long-term survivors, all of whom restarted blinatumomab successfully. Long-term survivors had more rapid clearance of peripheral B-cells and significantly greater T-cell expansion than patients with OS < <NUM> months. These data suggest that long-term survival after blinatumomab treatment might be associated with a high degree of T-cell expansion and MRD response.

The prognosis is poor for adult patients with relapsed/refractory (r/r) B-precursor ALL. Treatment with chemotherapy has been reported to result in median overall survival (OS) from <NUM> to <NUM> months,<NUM>-<NUM> and <NUM>-year OS rates are only <NUM>% to <NUM>%. <NUM>,<NUM> Median OS is <NUM> months among patients who relapse after allogeneic stem cell transplantation (SCT), and <NUM> months among patients who relapse after chemotherapy only (without prior allogeneic SCT).

Blinatumomab, a CD19/CD3 bispecific T-cell engager (BiTE®) antibody construct, leads to redirected lysis of CD19-positive (CD19+) target B cells by inducing a transient cytolytic synapse between the target cells and T cells. <NUM> In an exploratory dose-finding phase <NUM> study in adult patients with r/r B-precursor ALL (including patients in late first relapse ><NUM> months), <NUM>% of patients achieved a complete response (CR) or complete response with partial hematologic recovery (CRh), and <NUM>% of responders achieved a minimal residual disease (MRD) response. <NUM> In addition, MRD response was seen in three patients with hypocellular bone marrow. The study explored both fixed dosing as well as single-step and double-step dosing to prevent severe cytokine release syndrome (CRS). In a confirmatory phase <NUM> study of <NUM> patients with r/r B-precursor ALL, including those with early relapse (less than <NUM> months) after first remission, <NUM>% achieved CR or CRh after two cycles of treatment with blinatumomab. Median relapse-free survival (RFS) was <NUM> months; median OS was <NUM> months.

The first analysis of the aforementioned phase <NUM> dose-finding study had analyzed OS with a median follow-up of <NUM> months. <NUM> The long-term follow-up analysis presented here evaluated OS at a median follow-up of <NUM> months. Long-term survivors were defined as patients who were alive for ≥ <NUM> months after starting blinatumomab treatment. We evaluated clinical characteristics, including disease-related medical history of the long-term survivors before blinatumomab treatment, outcomes of blinatumomab treatment, including hematologic and MRD responses to blinatumomab, adverse events, consolidation with allogeneic SCT, relapses, and T-cell as well as B-cell kinetics during treatment.

This report describes a follow-up analysis of relapse and overall survival; the methods of the primary analysis were described elsewhere. <NUM> This was an open-label, multicenter, exploratory, single-arm, phase <NUM> study in adult patients with r/r B-precursor ALL conducted in collaboration with the German Study Group for Adult Acute Lymphoblastic Leukemia. The target population was Philadelphia chromosome (Ph)-negative and Ph-positive patients with primary refractory disease or relapse. Key exclusion criteria were Ph-positive ALL eligible for dasatinib or imatinib treatment; autologous SCT within <NUM> weeks and allogeneic SCT within <NUM> months before the start of blinatumomab treatment; history or presence of clinically relevant central nervous system (CNS) pathology, active CNS leukemia, active graft-versus-host disease (GVHD) and/or immunosuppressive therapy for GVHD within <NUM> week of blinatumomab treatment start, or active infections. <NUM> The study protocol was approved by the Paul-Ehrlich-Institute and each study site's independent ethics committee, and written informed consent was obtained from all patients. Toxicity and efficacy data were reviewed by an independent data monitoring committee. ClinicalTrials. gov Identifier: NCT01209286.

The first <NUM> cycles of blinatumomab were administered to induce remissions. Bone marrow aspirate or biopsy was obtained before the first blinatumomab cycle and on day <NUM> of each cycle; cytomorphology and MRD were assessed in central reference laboratories. Hematologic complete remission with full recovery of peripheral blood counts (CR) was defined by ≤ <NUM>% blasts in the bone marrow, no evidence of circulating blasts or extra medullary disease, platelets > <NUM>,<NUM>/µL, hemoglobin ≥ <NUM>/dL, and absolute neutrophil count (ANC) > <NUM>,<NUM>/µL. Hematologic complete remission with partial recovery of peripheral blood counts (CRh) was defined by the same criteria but a lower minimum of peripheral blood counts (platelets > <NUM>,<NUM>/µL, hemoglobin ≥ <NUM>/dL, and ANC > <NUM>/µL). An MRD response was defined as MRD < <NUM>-<NUM> by allele-specific real-time quantitative polymerase chain reaction for clonally rearranged immunoglobulin and/or T-cell receptor genes (sensitivity ≥ <NUM>-<NUM>).

Each treatment cycle was <NUM> weeks, including <NUM> weeks of continuous intravenous infusion and a <NUM>-week treatment-free interval. The dose-finding stage used the following dosing schedules: Cohort <NUM> (n = <NUM>) received blinatumomab <NUM>µg/m<NUM>/day; Cohort 2a (n = <NUM>) received <NUM>µg/m<NUM>/day in week <NUM> and then <NUM>µg/m<NUM>/day; Cohort 2b (n = <NUM>) received blinatumomab <NUM>µg/m<NUM>/day in week <NUM>, <NUM>µg/m<NUM>/day in week <NUM>, and then <NUM>µg/m<NUM>/day. In the extension stage, Cohort <NUM> (n = <NUM>) used the dosing schedule from Cohort 2a. In case of CR or CRh, consolidation treatment with up to <NUM> additional cycles of blinatumomab and/or allogeneic SCT was permitted. After one incidence of grade <NUM> CRS, prephase treatment with dexamethasone (≤ <NUM> for <NUM>-<NUM> days) and/or cyclophosphamide (<NUM>/m<NUM> for <NUM>-<NUM> days) was allowed. All patients had mandatory intrathecal CNS prophylaxis with methotrexate <NUM>, cytarabine <NUM>, and dexamethasone <NUM> administered by a spinal tap during screening and on day <NUM> of each cycle. Intravenous dexamethasone <NUM> or equivalent was given within <NUM> hour of treatment start. Adverse events were collected throughout the study and graded by the Common Terminology Criteria for Adverse Events (Version <NUM>).

Using methods that were described previously,<NUM> peripheral blood mononuclear cells were isolated at various time points before and throughout the first and second cycle of blinatumomab treatment and stained with fluorescent-labeled antibodies against the following cell surface markers: CD3+/CD13-/CD14- or CD3+/CD45+ (T cells); CD3+/CD45RA-/CD197- (effector memory T [TEM] cells); and CD19+/CD13-/CD14- or CD19+/CD45+ (B cells). Flow cytometry data was collected on a FACSCanto II (Becton Dickinson, Heidelberg, Germany), or Navios <NUM>/<NUM> instrument (Beckman Coulter, Krefeld, Germany). Statistics were analyzed by the software FCS Express (De Novo Software, Glendale, CA, USA), or Kaluza (Beckman Coulter). Percentages of lymphocyte subpopulations were multiplied by absolute lymphocyte numbers from a differential blood count to calculate absolute cell numbers for each lymphocyte subpopulation. Patients with complete datasets (T and TEM cells, before [=baseline] and on days <NUM>, <NUM>, <NUM>, and <NUM> of each cycle; B cells, additionally on day <NUM> of each cycle) were included in the analysis regardless of blinatumomab dosing regimen.

Relapse-free survival was measured from the time of first CR or CRh to hematologic or extra-medullary relapse or death resulting from any cause. Patients still in remission at data lock were censored at the time of last remission status assessment. Overall survival was measured from the time of first blinatumomab dose to death resulting from any cause. Kaplan-Meier methods were used to estimate the probability of RFS and OS over time, providing median and <NUM>% confidence interval (CI). A Mantel-Byar test was conducted to evaluate the OS benefit associated with achieving an MRD response versus not achieving an MRD response. A log-rank test was conducted to compare OS between patients with prior allogeneic SCT versus those without prior allogeneic SCT. Long-term survivors were defined as patients with OS ≥ <NUM> months. Summary statistics were provided for long-term survivors, including clinical characteristics before blinatumomab treatment, use of allogeneic SCT before/after blinatumomab, treatment responses and relapses, and adverse events. Patients were grouped according to OS < <NUM> months, OS ≥ <NUM> months with further treatment, and OS ≥ <NUM> months without further treatment. The definition of long-term overall survival by duration of at least <NUM> months is based on published data, which show most events occurring with the first <NUM> months.

Thirty-six patients were treated at nine centers in Germany between October <NUM>, <NUM>, and June <NUM>, <NUM>, with follow-up ongoing. As described previously for the primary analysis,<NUM> the rate of CR/CRh was <NUM>% (<NUM> of <NUM> patients). Fifteen patients (<NUM>%) achieved CR, and <NUM> patients (<NUM>%) achieved CRh. The remaining patients had partial remission (n = <NUM>) or hypocellular bone marrow (n = <NUM>); or were refractory to treatment (n = <NUM>) or unevaluable (n = <NUM>). Twenty-two of <NUM> patients with CR/CRh (<NUM>%) had an MRD response (three responders did not achieve an MRD response). An additional three patients with bone marrow that did not fulfill the criteria for partial hematologic recovery had an MRD response. Thus, <NUM> of <NUM> patients (<NUM>%) who were treated with blinatumomab had an MRD response.

At a median follow-up time of <NUM> months, median RFS was <NUM> months (<NUM>% Cl, <NUM>-<NUM> months) (<FIG>). At a median follow-up time of <NUM> months, median OS was <NUM> months (<NUM>% Cl, <NUM>-<NUM> months) (<FIG>). A plateau was reached for RFS after approximately <NUM> months and for OS after approximately <NUM> months. When patients were censored for an MRD response in the analysis of OS, median OS was <NUM> months (<NUM>% Cl, <NUM>-<NUM> months); the Mantel-Byar odds ratio was <NUM> (P =. <NUM>), suggesting a <NUM>% risk reduction associated with an MRD response (<FIG>). There was no difference in OS between patients with prior allogeneic SCT and patients without prior allogeneic SCT (log-rank P =. <NUM>; <FIG>).

Ten of <NUM> patients (<NUM>%) were long-term survivors, defined as OS ≥ <NUM> months after start of blinatumomab treatment. The main clinical characteristics of the long-term survivors are summarized in Table <NUM>. A detailed listing of clinical characteristics for each individual patient is provided in Supplemental Table <NUM>. Of the <NUM> patients, four had undergone allogeneic SCT before blinatumomab treatment and six had not. At screening, bone marrow blasts ranged from <NUM>% to <NUM>% and age ranged from <NUM> to <NUM> years. One of the <NUM> patients had Philadelphia chromosome-positive ALL.

Treatment responses, follow-up treatment, and relapses are summarized in Table <NUM>. Most of the long-term survivors had achieved a CR (<NUM>%) but patients with CRh (<NUM>%) or hypocellular bone marrow (<NUM>%) were also among the long-term survivors. All long-term survivors had achieved an MRD response with blinatumomab treatment. Thus, <NUM> of <NUM> patients (<NUM>%) with an MRD response (including three with hypocellular bone marrow and MRD response) were long-term survivors, while none of the <NUM> patients without an MRD response was a long-term survivor.

Three of the long-term survivors relapsed after blinatumomab treatment, including two with CD19-positive relapse and one with CD19-negative relapse. One of the patients who relapsed received retreatment with blinatumomab, and two received chemotherapy. One patient relapsed within <NUM> months after start of blinatumomab treatment; two patients relapsed later than <NUM> months after start of blinatumomab treatment. Details for the patients who relapsed after blinatumomab treatment are provided in the following sections.

Six of the <NUM> long-term survivors underwent allogeneic SCT as consolidation for blinatumomab (Table <NUM>). Three of six patients previously received allogeneic SCT before blinatumomab treatment. Five of six patients were still alive at the last follow-up for this analysis, including the three patients who received allogeneic SCT before blinatumomab. One of the three patients had achieved hypocellular bone marrow as treatment response to blinatumomab; the other patients achieved a CR or CRh as the best response to blinatumomab treatment.

One long-term survivor died of GVHD <NUM> months after the start of blinatumomab treatment. This patient received allogeneic SCT as consolidation for blinatumomab and had a CD19-positive relapse <NUM> months after allogeneic SCT. The patient achieved another remission with FLAG-IDA chemotherapy and received a second allogeneic SCT as consolidation for the chemotherapy.

Four of the <NUM> long-term survivors did not undergo allogeneic SCT as consolidation for blinatumomab. All four achieved a CR or CRh as the best response to blinatumomab treatment. One of these four patients had received two prior allogeneic SCT. All four patients were still alive at the last follow-up for this analysis. Two of these four patients are in ongoing remission without further treatment. One patient has been alive for <NUM> years since the start of blinatumomab treatment (the patient had a reversible grade <NUM> CRS). The other patient has been alive for <NUM> years since the start of blinatumomab treatment (the patient had a reversible grade <NUM> neurological event). The other two patients relapsed after blinatumomab treatment. One of these patients had two CD19-positive relapses more than <NUM> months after having received <NUM> cycles of blinatumomab but responded to blinatumomab after each relapse with an MRD-negative remission (<NUM> cycles of retreatment each time). The second patient had a CD19-negative relapse during the third cycle of blinatumomab. This patient achieved another remission after FLAG-IDA chemotherapy and received allogeneic SCT as consolidation for the chemotherapy. The patient was still alive at a follow-up of <NUM> months. Relapses in the central nervous system were not reported.

Eight of the <NUM> long-term survivors had neurologic events, primarily headache and tremor (mostly grade <NUM>), and two had CRS (grade <NUM> and <NUM>, respectively). In the exploratory dose-finding study, three patients (<NUM>%) had CRS; and eight patients required treatment interruption because of neurologic events or CRS. <NUM> In three of the long-term survivors grade <NUM> or <NUM> neurologic events or CRS resulted in treatment interruption (Table <NUM>). All three patients achieved a CR or CRh as the best response to blinatumomab treatment and received no other treatment than blinatumomab (two of the three patients are still in remission). The first patient had grade <NUM> focal seizure in the first treatment cycle at a dose of <NUM>µg/m<NUM>/day. This patient resumed treatment, with antiseizure prophylaxis, at a dose of <NUM>µg/m<NUM>/day without further neurologic adverse events. The second patient had grade <NUM> encephalopathy at a dose of <NUM>µg/m<NUM>/day. This patient also resumed treatment at a dose of <NUM>µg/m<NUM>/day without further neurologic adverse events. The third patient had grade <NUM> CRS at a dose of <NUM>µg/m<NUM>/day. The patient had a marrow blast count of <NUM>% before treatment and did not receive prephase treatment with dexamethasone or cyclophosphamide. The patient resumed treatment, with dexamethasone, at a blinatumomab dose of <NUM>µg/m<NUM>/day without further occurrence of CRS. When the dose was escalated to <NUM>µg/m<NUM>/day at the end of week <NUM>, grade <NUM> CRS was recorded which was also mitigated by dexamethasone.

Expansion of CD3+ T cells, which was analyzed by kinetics of mean cell counts during treatment cycles <NUM> and <NUM>, was predominantly observed in patients with OS ≥ <NUM> months, both in cycle <NUM> and in cycle <NUM> (<FIG>). Of note, the most pronounced CD3+ T-cell expansion was observed in the long-term survivor who had a grade <NUM> neurologic adverse event and who had received no other treatment than <NUM> cycles of blinatumomab (<FIG>). In spite of the extensive T-cell expansion, this patient did not show any symptoms or sign of GVHD. No T-cell kinetics were available for the long-term survivor with grade <NUM> CRS who also received only blinatumomab as treatment.

CD3+ T-cell expansion correlated with increasing numbers of CD3+ TEM cells, which are known to be cytolytic and which play an important role in blinatumomab-mediated cytotoxicity against target B cells (<FIG>). Again, the patient with the grade <NUM> neurologic adverse event had the most prominent proliferation of CD3+ TEM cells (<FIG>; OS ≥ <NUM> months without further treatment). Additionally, depletion kinetics of CD19+ B cells differed between patients with OS < <NUM> months and those with OS ≥ <NUM> months with further treatment (<FIG>). Mean B-cell depletion was complete at day <NUM> and sustained throughout treatment cycles <NUM> and <NUM> in patients with OS ≥ <NUM> months. In contrast, in patients with OS < <NUM> months, mean B-cell depletion lasted <NUM> days and was not sustained through day <NUM> (the start of treatment cycle <NUM>).

This long-term follow-up analysis to the primary analysis of the first phase <NUM> study of blinatumomab in adult patients with r/r B-precursor ALL demonstrated a median OS of <NUM> months with <NUM> months of follow-up. Previous studies reported that chemotherapy results in median OS of <NUM> months or less in patients with r/r ALL. <NUM>-<NUM> Recently published results for inotuzumab ozogamicin, an anti-CD22 monoclonal antibody drug conjugate, in r/r ALL reported a median OS of <NUM> months at a weekly dosing schedule. <NUM> One previous study reported that OS with salvage chemotherapy in relapsed ALL is shorter among patients who relapse after allogeneic SCT. <NUM> In the present study, <NUM> of <NUM> patients (<NUM>%) had relapsed after allogeneic SCT before they received blinatumomab, but there was no difference in OS between patients with and without prior allogeneic SCT.

In this follow-up analysis, <NUM> of <NUM> patients (<NUM>%) were long-term survivors, defined as an OS of ≥ <NUM> months. All <NUM> long-term survivors had an MRD response, resulting in a long-term survival rate of <NUM>% in patients with an MRD response. Although collection of larger data sets is warranted, the results indicate that achievement of an MRD response with blinatumomab treatment in r/r B-precursor ALL may translate into clinical benefit in terms of long-term survival.

Four long-term survivors did not receive allogeneic SCT as consolidation for blinatumomab. All four patients are still alive. One of the four patients had a CD19-negative relapse during the third cycle of blinatumomab, achieved another CR with chemotherapy, and received allogeneic SCT as consolidation for the chemotherapy. The other three patients received no other treatment after blinatumomab. All three patients experienced neurologic adverse events or CRS that resulted in interruption of blinatumomab treatment. Similar toxicities were reported in a phase <NUM> study of autologous T cells expressing the <NUM>-28z chimeric antigen receptor (CAR) specific for the CD19 antigen,<NUM> suggesting that toxicities against CD19-expressing target cells may be comparable and possibly independent of the mechanism of T-cell activation. The long-term outcomes of these three patients illustrate that long-term survival following blinatumomab treatment may be achieved with no other subsequent treatment even in relapsed ALL. Adverse events were managed by infusion interruption, and infusion restart was tolerated in all three patients. One patient without allogeneic SCT as consolidation for blinatumomab had a CD19-negative relapse during the third blinatumomab treatment cycle. This patient achieved another remission following chemotherapy. It is possible that the use of blinatumomab to prolong the interval between chemotherapy regimens enhanced sensitivity to the subsequent chemotherapy. Larger data sets are needed to confirm this observation. Patients with CD19-positive relapse after blinatumomab treatment may also be candidates for blinatumomab retreatment. One long-term survivor in this study who relapsed twice responded to retreatment with blinatumomab both times. Thus, blinatumomab treatment might be an alternative to chemotherapy for treatment of relapses after blinatumomab-induced CR followed by blinatumomab maintenance treatment. However, additional research is required to confirm the activity and tolerability of blinatumomab retreatment in this setting.

Long-term survivors had a significantly higher degree of T-cell and TEM-cell expansion during treatment cycles <NUM> and <NUM>. The data suggest that T-cell expansion might be a key factor for the antileukemia activity of blinatumomab in the setting of r/r ALL. The onset of antileukemic effects following blinatumomab infusion has been observed to occur early during treatment, in most cases by the end of the first cycle at the latest. For nonresponders, adding additional cycles of treatment or increasing the blinatumomab dose in the second cycle had little effect on improvement of antileukemic activity. <NUM> In the current study, a dose increase to 30µg/m<NUM>/day on day <NUM> of the first cycle did not result in a higher CR rate (data not shown). Our study results suggest that T-cell expansion and kinetics of peripheral B-cell clearance might be important not only for remission but also for long-term OS. Overall survival of at least <NUM> months was associated with a greater T-cell expansion, compared with OS of less than <NUM> months. The greater T-cell expansion in the long-term survivors was associated with a complete clearance of B cells from peripheral blood within the first <NUM> days of treatment with blinatumomab. One might speculate that the degree of B-cell depletion within the first <NUM> days of treatment might serve as an early indicator for efficacy of blinatumomab, possibly permitting an early adjustment of the blinatumomab regimen via a dose increase.

Claim 1:
A B-cell depleting agent capable of depleting peripheral CD19+ B-cells for use in a method of conserving or increasing the number of long term survivors in a group of patients suffering from relapsed/refractory adult B-precursor acute lymphoblastic leukemia (ALL), said method comprising (a) administering a B-cell depleting agent (b) observing within a first predefined period of time starting with the first day of initial treatment with the B-cell depleting agent the number of B-cells in the blood of said patient and (c) adjusting the treatment regimen or dosage of said B-cell depleting agent such that the number of B-cells in the blood of the patients of said group falls below one B-cell/ml serum within a second predefined period of time of <NUM> days after the initial treatment with said B-cell depleting agent, wherein the first predefined period of time is shorter than the second predefined period of time, wherein said B-cell depleting agent is Blinatumomab and said long term survivors are alive for ≥<NUM> months after starting Blinatumomab treatment.