The Clinical Significance of Molecular Response in Indolent Follicular Lymphomas

Past, present and future of prognostic scores in follicular lymphoma

Although most follicular lymphoma (FL) patients have prolonged survival, the identification of those at risk of early progression, multiple relapses or histological transformation is essential for the improvement of long-term outcomes. In this sense, a plethora of prognostic indexes have been developed in the last decades. However, determining which one is more accurate and clinically meaningful remains a challenge. Key factors for the external validity of available indexes include characteristics of the study population, treatment intervention, and design of the study. While initial risk scores were composed of clinical, biochemical, and hematological variables, genomic and imaging data have been incorporated in recent years. Despite an obvious step forward in the knowledge of the natural history and biology of FL, predictions remain inaccurate. Further research will likely incorporate information from circulating tumor DNA and artificial intelligence models to refine the prognostic classification of the heterogeneous FL population.

The Role of Quantitative Polymerase Chain Reaction in the Management of Follicular Lymphoma Patients

Aims and background

In order to increase the prognostic significance of polymerase chain reaction (PCR) data it has been suggested that quantitative PCR can be used to measure tumor burden. However, this option has not yet been definitely supported or refuted in patients with follicular lymphoma (FL). We decided to evaluate whether knowledge of the quantitative level of minimal residual disease and its variations can be of use in the management of FL patients.

Methods

We used qualitative and competitive PCR to study 11 patients with refractory or relapsed FL harboring the t(14;18) translocation who underwent autologous (nine patients) or allogeneic (two patients) stem cell transplantation (SCT). Competitive PCR was performed with a multiple competitor carrying specific sequences including Bcl2/lgH MBR and mcr, and the β-globin gene.

Results

After a median post-SCT follow-up of 44 months (range, 12-62), overall survival was 91% and disease-free survival 82%. The quantitative PCR data showed that: 1) effective chemotherapy before SCT substantially (1-2 log) reduced the tumor burden in the bone marrow (BM); 2) the increase in rearranged DNA detected in BM was associated with disease progression and relapse; 3) a PCR-negative autograft seemed to lead to lasting molecular remission even when it was performed in patients with a low level of BM infiltration before transplant; and 4) allo-SCT made and maintained the BM PCR negative even in the presence of a greater tumor burden before SCT. Six of the nine patients having CR after SCT (four auto and two allo) are in continuous molecular remission.

Conclusions

In FL patients qualitative and quantitative PCR may provide data that can be helpful for the prognostic evaluation of tumor progression and the early detection of impending relapse by highlighting biological features such as the quality of the infused material, the tumor burden at transplant, and the behavior of tumor cells after transplant.

The biological Markers of Non-Hodgkin'S Lymphomas: Their Role in Diagnosis, Prognostic Assessment and Therapeutic Strategy

The biological markers of non-Hodgkin's lymphomas (NHL) are distinguished in three categories: serological, immunophenotypic, and molecular markers. The clinical importance of biological markers in NHL is based on their support of morphologic diagnosis, their role in staging and prognostic assessment, and their contribution to monitoring minimal residual disease (MRD). The most important serological markers reflect the tumor load (beta-2 microglobulin, β2-M), proliferative activity (lactic dehydrogenase, LDH), and invasive potential of lymphomas (CA 125). LDH and β2-Mare included as important prognostic parameters in widely used staging systems. Immunophenotypic analysis identifies specific markers of lineage (B or T-cells), maturation level, cell proliferation, and clonality. Results of immunophenotyping are particularly useful in low to intermediate-grade NHLs to support the morphologic diagnosis and facilitate the detection of MRD after treatment. The molecular markers are genetic lesions involved in the pathogenesis of some categories of NHL. Their use as markers for diagnosis is justified by the selective association with specific lymphoma categories: follicular, mantle cell, diffuse large cell, and anaplastic large cell lymphomas. Molecular lesions are the most specific and sensitive markers for evaluating MRD. Today the biological markers of NHL are widely employed for diagnosis, staging, and prognostic assessment. Their systematic use may complement clinical parameters in the stratification of NHL patients, who may thus become candidates for treatments of different intensity. The detection of MRD after first-line treatment identifies patients at high risk of relapse who require additional therapy to cure their disease.

Current prognostic and predictive factors in follicular lymphoma

Follicular lymphoma (FL) is generally considered an indolent disorder. With modern day treatments, long remissions are often achieved both in the front-line and relapsed setting. However, a subset of patients has a more aggressive course and a worse outcome. Their identification is the main purpose of modern day prognostic tools. In this review, we attempt to summarize the evidence concerning prognostic and predictive factors in FL, including (1) pre-treatment factors, from baseline clinical characteristics and imaging tests to histological grade, the microenvironment and genomic abnormalities; (2) post-treatment factors, i.e., depth of response, measured both by imaging tests and minimal residual disease; (3) factors at relapse and duration of response; and (4) prognostic factors in histological transformation. We conclude that, despite the existence of numerous tools, the availability of some of them is still limited; they generally suffer from notable downsides, and most have unproven predictive value, thus having scarce bearing on the choice of regimen at present. However, with the technological and scientific developments of the last few years, the potential for these prognostic factors is promising, particularly in combination, which will probably, in time, help guide therapeutic decisions.

High-throughput sequencing for noninvasive disease detection in hematologic malignancies

Noninvasive monitoring of minimal residual disease (MRD) has led to significant advances in personalized management of patients with hematologic malignancies. Improved therapeutic options and prolonged survival have further increased the need for sensitive tumor assessment that can inform treatment decisions and patient outcomes. At diagnosis or relapse of most hematologic neoplasms, malignant cells are often easily accessible in the blood as circulating tumor cells (CTCs), making them ideal targets to noninvasively profile the molecular features of each patient. In other cancer types, CTCs are generally rare and noninvasive molecular detection relies on circulating tumor DNA (ctDNA) shed from tumor deposits into circulation. The ability to precisely detect and quantify CTCs and ctDNA could minimize invasive procedures and improve prediction of clinical outcomes. Technical advances in MRD detection methods in recent years have led to reduced costs and increased sensitivity, specificity, and applicability. Among currently available tests, high-throughput sequencing (HTS)-based approaches are increasingly attractive for noninvasive molecular testing. HTS-based methods can simultaneously identify multiple genetic markers with high sensitivity and specificity without individual optimization. In this review, we present an overview of techniques used for noninvasive molecular disease detection in selected myeloid and lymphoid neoplasms, with a focus on the current and future role of HTS-based assays.

Persistence of minimal residual disease in bone marrow predicts outcome in follicular lymphomas treated with a rituximab-intensive program

PCR negativity is a strong outcome predictor after rituximab-intensive immunochemotherapy at multiple posttreatment times. PCR is predictive even when maintenance is delivered, and accumulation of PCR-negative results further reduces the likelihood of relapse.

Clinical implications and prognostic role of minimal residual disease detection in follicular lymphoma

The identification of patients at high risk of relapse is a critical goal of modern translational research in oncohematology. Minimal residual disease (MRD) detection by polymerase chain reaction-based methods is routinely employed in the management of patients with acute lymphoblastic leukemia. Current knowledge indicates that it is also a useful prognostic tool in several mature lymphoproliferative disorders and particularly in follicular lymphoma (FL). Based on this evidence clinical trials employing MRD-based risk stratification are currently ongoing in FL. In this review the 'state of the art' of MRD evaluation in FL is discussed. A short description of technical issues and recent methodological advances is provided. Then, the bulk of the review focuses on critical take-home messages for clinicians working in the field. Finally, we discuss future perspectives of MRD detection and more generally outcome prediction in FL.

Flow cytometric MRD detection in selected mature B-cell malignancies

The quantification of submicroscopic minimal residual disease (MRD) after therapy proved to have independent prognostic significance in many mature B-cell malignancies. With the advent of routine bench-top cytometers capable of simultaneously analyzing ≥ 4 colors and with improved standardization, flow cytometry has become the method of choice for MRD assessments in some lymphoma entities. Herein we describe general aspects of flow cytometric standardization. Using chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL) as examples we explain in detail the application of flow cytometry for MRD detection.

Minimal residual disease detection in lymphoma and multiple myeloma: impact on therapeutic paradigms

Early identification of patients at high risk of relapse is a major goal of current translational research in oncohematology. Minimal residual disease (MRD) detection by polymerase chain reaction-based methods is currently part of the routine clinical management of patients with acute lymphoblastic leukemia. However, the current knowledge indicates that it is also a useful prognostic tool in several mature lymphoproliferative disorders. Its utility is currently well established in follicular lymphoma, mantle cell lymphoma, and multiple myeloma. In some of these entities, clinical trials employing MRD as a decision-making tool are currently ongoing. In the present review, we will discuss the 'state of the art' of MRD evaluation in these three neoplasms with the ultimate aim of providing critical take-home messages for clinicians working in the field. Moreover, we will outline the role of MRD detection in the design of future clinical trials.

Biology and treatment of follicular lymphoma

Follicular lymphoma (FL) is the second most common lymphoid tumor. It is composed of elements resembling those of normal germinal centers. In particular, it is constituted by small centrocytes and large centroblasts, typically CD10+, CD19+, CD20+, CD79a+ and BCL6+, with follicular growth pattern. The molecular hallmark of FL is the t(14;18)(q32;q21) translocation, which leads to inappropriate BCL2 expression. This feature, other than representing a pathogenetic primary event, constitutes a suitable diagnostic marker, as well as a target for minimal residual disease monitoring and, hopefully, future therapies. Clinically, FL presents with indolent behavior, characterized by prompt response to initial therapy but almost invariably subsequent relapses. Novel approaches, including stem cell transplantation, monoclonal antibodies and innovative agents, should be then considered for improving long-term results.

Prognostic tools in follicular lymphomas

Despite significant improvements in treatment modalities over the 10 years, the clinical course of patients with follicular lymphoma (FL) remains heterogeneous. Thus, prognostic indexes are still required to direct treatment choices and for the design of clinical trials. Investigators have conducted a variety of studies aimed at integrated assessment of biological and clinical features in order to identify novel prognostic factors and scoring systems. Genetic studies focused on tumor cells and the tumor microenvironment represent a step forward in understanding the biology of FL and are likely to provide new prognostic tools for future clinical use. Several prognostic factors have been identified and are currently used in combination to establish prognostic scores and to support therapeutic decisions. The FL International Prognostic Index (FLIPI) is currently used for defining individual risk of death. More recently, FLIPI2 was developed by the same group that built FLIPI as a new model for prognostic definition of patients with FL. The model was defined using prospectively collected data from patients who also received the monoclonal therapeutic antibody rituximab and stratifies patients into three risk categories for disease progression. Since many biological factors are not yet clinically validated or easily assessable, clinical data still represent the major source of prognostic information. The progressive development of new and more effective therapies for the treatment of FL makes the study of prognosis a dynamic and evolving area of clinical research.

Prognostic Factors in Follicular Lymphoma

Follicular lymphoma (FL) is one of the most common types of non-Hodgkin's lymphoma. It is usually diagnosed at an advanced stage, for which many treatment options exist, however, no curative standard therapy has been identified. The outcome is highly variable with a median survival of approximately 10 years. The life expectancy of patients with FL has been extended with the use of rituximab, a monoclonal antibody targeting the CD20 antigen on FL cells, but there remains a group of patients who fail to respond to chemoimmunotherapy and die early of their disease. Transformation of FL to an aggressive histology is an important event with high morbidity and mortality. The Follicular Lymphoma International Prognostic Index has become the clinically useful prognostic tool, but gives only a rough estimate of expected outcome. There is a need for useful biomarkers for prediction of the disease course of single patients to individualize therapy, especially in the new era of chemoimmunotherapy.

BCL-2/IgH polymerase chain reaction status at the end of induction treatment is not predictive for progression-free survival in relapsed/resistant follicular lymphoma: results of a prospective randomized EORTC 20981 phase III intergroup study

PURPOSE

The prognostic value of residual BCL2/immunoglobulin heavy chain (BCL2/IgH) -positive cells in peripheral blood (PB) or bone marrow (BM) after induction treatment in follicular lymphoma (FL) is still controversial. In a prospective randomized phase III intergroup trial of 465 patients with relapsed/resistant follicular lymphoma (FL), we showed that addition of rituximab to cyclophosphamide, doxorubicin, vincristine, and prednisone induction results in increased overall and complete response rates, and that rituximab maintenance strongly improves median progression-free survival (PFS) as well as overall survival. Here, we studied whether BCL2/IgH major break point levels in PB/BM correlated with response rates/quality for the induction phase and PFS for the maintenance phase.

PATIENTS AND METHODS

Samples were obtained before and after induction therapy and at the end of the 2 years maintenance/observation period. BCL2/IgH major break point-positive cells were quantified by genomic quantitative polymerase chain reaction in 792 samples from 238 patients.

RESULTS

Pretreatment BCL2/IgH levels had no significant prognostic value for overall response or complete remission rates after induction treatment, but pretreatment positive BM results had an adverse prognostic value for PFS from first randomization (P = .023). Importantly, BCL2/IgH levels at the end of induction treatment had no prognostic value for PFS from second randomization. The highly significant improved PFS by rituximab maintenance was observed in both BCL2/IgH PB/BM-positive and -negative groups.

CONCLUSION

Postinduction BCL2/IgH major break point status in BM/PB is not useful for decisions on subsequent therapy for patients with relapsed/resistant FL.

Lymphoma in adolescents and young adults

Non-Hodgkin (NHL) and Hodgkin (HL) lymphomas are represented prominently in the adolescent and young adult (AYA) population. These diseases represent 11% of total cancer diagnoses in children, 4% in those 40 years of age and older, and 13% in AYA (aged 15-39 years). Although age-adjusted incidence rates of NHL increase with age, the more aggressive lymphomas are seen more commonly in the younger population with a transition to low-grade, indolent subtypes as the population ages. Burkitt lymphoma, diffuse large B-cell lymphoma, lymphoblastic lymphoma, and anaplastic large cell lymphoma make up the most common subtypes in the AYA population, although within the subgroup age 30-39 years, follicular lymphoma becomes more prominent. As a result, much of the armamentarium in the treatment of aggressive NHL and HL in adults is based on data from pediatric clinical trials. There are obvious limitations to this approach. It is vital that we gain a more thorough understanding of the biology and therapeutic responsiveness of NHL and HL in the AYA population. Thus, we must leverage the large prospective and retrospective trials that have been completed to date and redirect our approaches to cancer care in this unique population. We review the epidemiological data on NHL and HL from the Surveillance, Epidemiology and End Results registries as a cornerstone for a comparative analysis of therapeutic outcomes available in this population.

Quantitative PCR Analysis for Bcl-2/IgH in a Phase III Study of Yttrium-90 Ibritumomab Tiuxetan As Consolidation of First Remission in Patients With Follicular Lymphoma

Purpose

The randomized First-Line Indolent Trial (FIT) was conducted in patients with advanced follicular lymphoma (FL), to evaluate the safety and efficacy of yttrium-90 (90Y) ibritumomab tiuxetan given as consolidation of complete or partial remission. This study of minimal residual disease was undertaken in parallel, to determine the rate of conversion from bcl-2 polymerase chain reaction (PCR) –detectable to –undetectable status and the corresponding effect on progression-free survival (PFS).

Patients and Methods

Blood samples from 414 patients (90Y-ibritumomab, n = 208; control, n = 206) were evaluated using real-time quantitative polymerase chain reaction (RQ-PCR); 186 were found to have the bcl-2 rearrangement and were thus eligible for inclusion in the RQ-PCR analysis.

Results

Overall, 90% of treated patients converted from bcl-2 PCR–detectable to –undetectable disease status, compared with 36% in the control group. Treatment significantly prolonged median PFS in patients converting to bcl-2 PCR-undetectable status (40.8 v 24.0 months in the control group; P < .01, hazard ratio [HR], 0.399). In patients who had bcl-2 PCR-detectable disease at random assignment, treatment significantly prolonged median PFS (38.4 v 8.2 months in the control group; P < .01, HR, 0.293).

Conclusion

Eradication of PCR-detectable disease occurred more frequently after treatment with 90Y-ibritumomab tiuxetan and was associated with prolongation of PFS.

The persistence of t(14;18)-bearing cells in lymph nodes of patients with follicular lymphoma in complete remission: the evidence for 'a lymphoma stem cell'

Monitoring of t(14;18) in blood or bone marrow in follicular lymphoma (FL) remains controversial. We attempted to monitor t(14;18) in lymph nodes by ultrasound-guided fine needle aspirations (UG-FNA). First, we confirmed t(14;18) in 27/31 UG-FNAs of lymph nodes with fluorescent in situ hybridisation (FISH) and/or polymerase chain reaction (PCR) in patients with advanced disease. In complete (CR) and molecular remission, there were repeated 18 UG-FNAs in 17 patients. Five of 18 UG-FNA were technically unsuccessful and 6/18 samples contained fibrosis. Despite that, these patients had a better prognosis. In 7/7 aspirations in six patients, t(14;18) was detected. Three patients are still in CR, even one of them remains in long lasting remission despite two consecutive evidences of t(14;18) in UG-FNA. Another three of these patients relapsed a few months after UG-FNA. This study is proof of the principle of the detection of residual t(14;18) bearing cells in previously involved lymph nodes despite patients being in remission.

Follicular lymphoma international prognostic index 2: a new prognostic index for follicular lymphoma developed by the international follicular lymphoma prognostic factor project

PURPOSE

The aim of the F2 study was to verify whether a prospective collection of data would enable the development of a more accurate prognostic index for follicular lymphoma (FL) by using parameters which could not be retrospectively studied before, and by choosing progression-free survival (PFS) as principal end point.

PATIENTS AND METHODS

Between January 2003 and May 2005, 1,093 patients with a newly diagnosed FL were registered and 942 individuals receiving antilymphoma therapy were selected as the study population. The variables we used for score definition were selected by means of bootstrap resampling procedures on 832 patients with complete data. Procedures to select the model that would minimize errors were also performed.

RESULTS

After a median follow-up of 38 months, 261 events for PFS evaluation were recorded. beta2-microglobulin higher than the upper limit of normal, longest diameter of the largest involved node longer than 6 cm, bone marrow involvement, hemoglobin level lower than 12 g/dL, and age older than 60 years were factors independently predictive for PFS. Using these variables, a prognostic model was devised to identify three groups at different levels of risk. The 3-year PFS rate was 91%, 69%, and 51% for patients at low, intermediate, and high risk, respectively (log-rank = 64.6; P < .00001). The 3-year survival rate was 99%, 96%, and 84% for patients at low, intermediate, and high risk, respectively (P < .0001).

CONCLUSION

Follicular Lymphoma International Prognostic Index 2 is a simple prognostic index based on easily available clinical data and may represent a promising new tool for the identification of patients with FL at different risk in the era of immunochemotherapy.

Role of the molecular staging and response in the management of follicular lymphoma patients

Bcl-2/IgH rearrangement is the molecular hallmark of follicular lymphoma which is present in 70 - 90% of cases at diagnosis. The significance of the bcl-2 rearrangement at onset of disease and of its clearing after treatment (molecular response) is still controversial. The aims of the present analysis are: to evaluate the incidence of bcl-2 rearrangement in blood and marrow in a cohort of patients systematically investigated at diagnosis, to describe the correlation between bcl-2 and presenting features, to clarify the correlation of molecular response with outcome. Of 98 patients studied at initial staging for the presence of bcl-2 rearrangement, 64 (65%) showed bcl-2/IgH rearrangement in peripheral blood (PB) and/or bone marrow (BM) (58 at Major Breakpoint Region, MBR, and 6 at minor cluster region, mcr) while no bcl-2/IgH rearrangement was detected in the remaining 34 (35%) (germline status). No statistically significant differences were found between bcl-2 positive and bcl-2 negative cases as concerns presenting clinical features and response to first-line therapy. The median event-free survival, EFS, was not reached for the bcl-2 negative patients in PB and was 11 months for bcl-2 positive patients (statistically significant, P = 0.01) and, similarly, the median EFS was not reached for the bcl-2 negative patients in BM and was 11 months for bcl-2 positive patients (statistically significant, P = 0.04). Of the 64 bcl-2 positive cases, patients were analysed for molecular response (48 in BM and 40 in PB): 16 were molecular responders in BM and 20 were molecular responders in PB. The median EFS was 19 months for molecular responders in PB and 9 months for non-responders; 1-year-EFS was 68% (95% CI; 49 - 88), for responders in PB and 42% (95% CI; 22 - 61) for non-responders (P = 0.05). The median EFS was 11 months both for molecular responders and non-responders in BM; 1-year-EFS was 52% for responders in BM (CI; 30 - 73), and 43% (CI 33 - 71) for non-responders (P = 0.7). No clinical feature showed significant correlation with PB and BM molecular responses. This analysis shows that bcl-2 rearrangement in blood and bone marrow is frequently detected at staging, even in stage I disease. Absence of the bcl-2 rearrangement is related to a better EFS and the achievement of a molecular response in peripheral blood after therapy is associated with a better EFS.

Prognostic factors for non-Hodgkin's lymphoma patients treated with chemotherapy may not predict outcome in patients treated with rituximab

Several factors predict outcome for patients with non-Hodgkin's lymphoma (NHL) after chemotherapy. However, predictors of response to rituximab have not been identified. Baseline characteristics for 166 NHL patients (130 follicular) in a phase III trial of rituximab were analysed by univariate and multivariate methods to determine whether any of 27 factors predict response and/or response duration. In a univariate analysis, response to rituximab was associated with follicular histology, no prior fludarabine therapy, prior autologous bone marrow transplantation (ABMT), lack of bone marrow involvement or extranodal disease, positive bcl-2 in blood, and fewer relapses. By univariate analysis, longer median time to progression (TTP) and/or duration of response (DR) after rituximab therapy was associated with International Prognostic Index lower-risk group, multiagent chemotherapy, and low/normal serum lactate dehydrogenase (LDH) or beta2 microglobulin. In the multivariate analysis, response to rituximab correlated with follicular histology, prior ABMT, multiagent chemotherapy, and no bone marrow involvement; longer TTP and/or DR correlated with low/normal serum LDH or beta2 microglobulin, high CD3+ cells, and response to last chemotherapy. The follicular lymphoma international prognostic index (FLIPI) did not correlate consistently with response to rituximab or response duration. Several factors associated with prognosis following chemotherapy did not correlate with response to rituximab or response duration. NHL patients can respond to rituximab despite having factors associated with a poor outcome to chemotherapy.

Overview of lymphoma diagnosis and management

The malignant lymphomas, including both Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL), represent a diverse group of diseases that arise from a clonal proliferation of lymphocytes. Each of the more than 30 unique types of lymphoma is a disease with a distinct natural history. This biologic heterogeneity gives rise to marked differences among the lymphomas with respect to epidemiology, pathologic characteristics, clinical presentation, and optimal management. This article emphasizes the principles of diagnosis, including appropriate pathologic evaluation and staging considerations, and focuses on the clinical presentation, staging, and optimal management strategies for the most common types of lymphoma.

Commercial LightCycler-based quantitative real-time PCR compared to nested PCR for monitoring of Bcl-2/IgH rearrangement in patients with follicular lymphoma

Translocation of chromosomes 14 and 18 [t(14;18)] for detection of minimal residual disease in follicular lymphoma patients can be analyzed by nested polymerase chain reaction (PCR) or by quantitative PCR like LightCycler-based assays. We have compared both methods in blood and bone marrow samples of 28 patients enrolled in a clinical study on immunochemotherapy. In 42% of samples, the bcl2-IgH rearrangement was detectable by nested PCR, but not by LightCycler PCR. Nested PCR was able to reveal a significant drop in positive bone marrow or peripheral blood samples after therapy. In contrast, with LightCycler PCR, the detected drop in t(14;18)-positive cells did not reach statistical significance. The majority of patients showed positive results with nested PCR of peripheral blood or bone marrow without any associations to presence or absence of histological bone marrow (BM) infiltration by lymphoma cells. With LightCycler PCR, the numbers of positive cells were higher in samples from patients with BM infiltration of lymphoma cells (1.9 x 10(-2)) compared to samples from patients without involvement (4.08 x 10(-5)). A similar trend was seen in samples derived from the peripheral blood. Positivity for t(14;18) after therapy in two patients correlated with clinical relapse 6 months later. The data shown here demonstrate a lower sensitivity of LightCycler vs. nested PCR for detection of t(14;18). The usefulness of nested PCR for t(14;18) for risk stratification after primary therapy has to be validated in larger trials.

Rapid and sustained clearance of circulating lymphoma cells after chemotherapy plus rituximab: clinical significance of quantitative t(14;18) PCR monitoring in advanced stage follicular lymphoma patients

This study of first-line treatment in advanced-stage follicular lymphoma patients analysed the effects of MCP (mitoxantrone, chlorambucil and prednisolone) chemotherapy alone or in combination with rituximab (R-MCP) on circulating lymphoma cells (CLC) and assessed the prognostic value of a quantitative monitoring of CLC. CLC numbers were determined by quantitative polymerase chain reaction (PCR) for the t(14;18)-translocation or by allele-specific PCR for rearranged immunoglobulin heavy chain genes. We analysed blood samples from 43 patients treated in a randomized trial comparing eight cycles of MCP versus R-MCP. Clearance of CLC at the end of therapy was achieved in 21/25 patients (84%) treated with R-MCP compared with 0/18 after MCP alone (P < 0.0001). A > or = 2 log CLC reduction was associated with a favourable clinical response (P = 0.0004) and prolonged event-free survival (P = 0.02). In R-MCP patients, stable CLC numbers or consistently PCR-negative blood samples were associated with a continuing clinical remission whereas in two patients a relapse was preceded by a > or = 2 log CLC increase. This study demonstrated that R-MCP led to a rapid and sustained eradication of CLC and a > or = 2 log CLC reduction was associated with a superior quality and duration of the clinical response.

Follicular lymphomas

Follicular lymphomas constitute approximately 30% of all non-Hodgkin lymphomas. These lymphomas are characterized by at least partially follicular growth pattern, but diffuse areas may be present. The proportions of follicular or diffuse areas vary also from case to case, which seems to be associated with prognosis. Follicular lymphomas should not be divided into distinct subtypes, but rather shows a continuous gradation in the number of large cells. On the bases of this grading, three groups have been defined: grades 1-3. There is a consensus that grade 3 follicular lymphomas, namely grade 3b, should be discriminated from lower-grade cases. The cells of follicular lymphomas express surface immunoglobulin, more frequently IgM+/-IgD>IgG>IgA, B-cell-associated antigens, CD10+/-; they are CD5-, CD23-/+, CD43-, and CD11c-. Follicular lymphomas express bcl-2 proteins, which is useful in distinguishing reactive from neoplastic follicles. t(14;18) is present in 70-95% of follicular lymphomas, involving rearrangement of bcl-2 gene. Clinical behavior of follicular lymphomas is heterogeneous and differs according to the histologic grade and extension of disease. Moreover, the evaluation of these malignancies is conditioned by therapeutic decision, which is also determined by main prognostic factors. The International Prognostic Index for aggressive lymphomas is not optimal for follicular lymphomas. Conversely, the Italian Lymphoma Intergroup Index and, more recently, the Follicular Lymphoma International Prognostic Index (FLIPI), designed in pre-rituximab era, seem to correlate well with outcome. Several active therapeutic approaches from the "wait and watch" strategy to the allogeneic transplantation are available for management of patients with follicular lymphoma. Therapeutic decision is mostly conditioned by patient's characteristics, stage, histologic grade, tumor burden, and risk-predicting factors.

Molecular genetic analysis of haematological malignancies II: mature lymphoid neoplasms

Molecular genetic techniques have become an integral part of the diagnostic assessment for many lymphomas and other chronic lymphoid neoplasms. The demonstration of a clonal immunoglobulin or T cell receptor gene rearrangement offers a useful diagnostic tool in cases where the diagnosis is equivocal. Molecular genetic detection of other genomic rearrangements may not only assist with the diagnosis but can also provide important prognostic information. Many of these rearrangements can act as molecular markers for the detection of low levels of residual disease. In this review, we discuss the applications of molecular genetic analysis to the chronic lymphoid malignancies. The review concentrates on those disorders for which molecular genetic analysis can offer diagnostic and/or prognostic information.

Clinical and molecular prognostic factors in follicular lymphoma

The observed variability in the clinical course of follicular lymphoma (FL), along with the diverse range of therapeutic options available, necessitates accurate prognostic stratification of the individual patient. A number of clinical, laboratory, and pathologic parameters have been associated with both good and poor risk disease; in some instances these have been incorporated into readily calculable prognostic indices. With new insights into disease biology and the resulting identification of biomarkers that have arisen from the analysis of both the genome and the transcriptome, more accurate individualization of prognosis will be realized. At present the clinical application of such biomarkers, however, remains largely in its infancy. This review examines the clinical and molecular prognostic features that have been identified as of value in FL.

Prognosis of follicular lymphomas

Follicular lymphoma (FL) is as an indolent neoplasia with median survival measured in decades. Nevertheless, some patients have poor progression-free survival and overall survival. Several treatment approaches are proposed for patients with FL, however criteria to rationalize treatment decisions are lacking. Studies have been performed to build up prognostic indices that are useful for defining risk-adapted treatment recommendations. Available indices are based on parameters that have an independent role in predicting patient survival and that are variably correlated with the features of the disease, with the characteristics of the patient and with the effects of treatment. Two new prognostic indices have recently been proposed for FL: the Italian Lymphoma Intergroup (ILI) index and the Follicular Lymphoma International prognostic Index (FLIPI). Both indices are based on large series of patients and exhibit differences in their ability to discriminate between patients with different probabilities of survival. In recent years, with the advent of gene expression profile studies, our knowledge of the biology of FL is changing as novel data become available about the lymphoma cell and about the role of the microenvironment; these studies have already provided novel prognostic tools for identifying patients with more aggressive disease. Further data and large international cooperative studies are needed to translate into clinical practice the novel acquisitions of biology and therapeutics.

Limitations and practical procedure in BclII-Ig heavy chain gene rearrangement real-time quantitative polymerase chain reaction

Follicular lymphoma is characterized by the t(14;18)(q32;q21) translocation, which juxtaposes Ig heavy chain gene (IgH) sequences with the BclII gene. Several publications have highlighted the importance of molecular follow-up in follicular lymphoma, demonstrating that the detection of cells bearing the BclII-IgH rearrangement by real-time quantitative polymerase chain reaction (RQ-PCR) can anticipate a clinical relapse. In this context, we developed a BclII-IgH RQ-PCR. We began with SYBR Green I detection technology but observed that this system does not allow an accurate measurement of the tumor load when working with genomic DNA. While we were designing the assay using Taqman technology, Moppett et al (Moppett J, van der Velden VHJ, Wijkhuijs AJM, Hancock J, van Dongen JJM, Goulden N: Inhibition affecting RQ-PCR-based assessment of minimal residual disease in acute lymphoblastic leukemia: reversal by addition of bovine serum albumin. Leukemia 2003, 17:268-270) reported PCR inhibition problems in around 15% of blood and bone marrow samples, affecting the DNA quantification and thus the assessment of minimal residual disease. They demonstrated that this PCR inhibition could be partially resolved by adding nonacetylated bovine serum albumin. In our studies, we observed the same phenomenon in a single follicular lymphoma case and extended our study to other available cases. As a result, we suggest a new RQ-PCR procedure that is based on Taqman probe technology and that takes into account the PCR inhibition problems, making this assay more reliable in a routine molecular laboratory.

Improvement of Overall and Failure-Free Survival in Stage IV Follicular Lymphoma: 25 Years of Treatment Experience at The University of Texas M.D. Anderson Cancer Center

Purpose

Advanced-stage follicular lymphoma is considered incurable. The pace of improvements in treatment has been slow. This article analyzes five sequential cohorts of patients with stage IV follicular lymphoma treated between 1972 and 2002.

Methods

Five consecutive studies (two were randomized trials) involving 580 patients were analyzed for overall survival (OS), failure-free survival (FFS), and survival after first relapse. A proportional hazards analysis, and subset analyses using the follicular lymphoma international prognostic index (FLIPI) score were performed. Treatment regimens included: cyclophosphamide, doxorubicin, vincristine, prednisone, bleomycin (CHOP-Bleo); CHOP-Bleo followed by interferon alfa (IFN-α); a rotation of three regimens (alternating triple therapy), followed by IFN-α; fludarabine, mitoxantrone, dexamethasone (FND) followed by IFN-α; and FND plus delayed versus concurrent rituximab followed by IFN-α.

Results

Improvements in 5-year OS (from 64% to 95%) and FFS (from 29% to 60%) indicate steady progress, perhaps partly due to more effective salvage therapies, but the FFS data also indicate improved front-line therapies; these observations held true after controlling for differences in prognostic factors among the cohorts. The FLIPI model adds rigor to and facilitates comparisons among the different cohorts. An unexpected finding in this study was a trend toward an apparent FFS plateau.

Conclusion

Evolving therapy, including the incorporation of biologic agents, has led to stepwise significant outcome improvements for patients with advanced-stage follicular lymphoma. The apparent plateau in the FFS curve, starting approximately 8 to 10 years from the beginning of treatment, raises the issue of the potential curability of these patients.

Purine Analogue Combinations for Indolent Lymphomas

Indolent lymphomas are a group of lymphoid malignancies with differing patterns of behavior and responses to treatment. The progress in treating patients with hairy cell leukemia (HCL) using nucleoside analogues can be used as a model for other indolent B-lymphoproliferative disorders, such as follicular lymphoma. Recent advancements in therapeutic options available for these patients include combination therapy with agents that have differing mechanisms of action and non-overlapping toxicity. It has been shown that patients who are candidates for aggressive therapy might receive benefit, including disease-free survival and overall survival, from combination purine analogue therapy. Using these more aggressive therapeutic approaches earlier in the disease course and as maintenance therapy may further enhance outcomes. With the advent of these new therapies along with the molecular evaluation of these regimens, we may be nearing the time where the goal for more advanced indolent lymphoma will be to achieve a cure.

Follicular lymphoma in early stages: high risk of relapse and usefulness of the Follicular Lymphoma International Prognostic Index to predict the outcome of patients

BACKGROUND AND OBJECTIVES

Patients with follicular lymphoma (FL) in advanced stages are currently deemed incurable with standard treatments. However, FL is considered to be eradicable in the small group of patients presenting with localized disease. The objective of this study was to analyze the clinical features and the outcome of a series of patients with FL in early stages with a long follow-up.

PATIENTS AND METHODS

A total of 48 patients (25m/23f; median age: 50 yr) diagnosed consecutively with FL in Ann Arbor stage I (25 cases) or II (23) at a single institution with a median follow-up of 9.5 yr were included in the study. Main biological and clinical characteristics at diagnosis, including Follicular Lymphoma International Prognostic Index (FLIPI) were analyzed; treatment and response were assessed and analyzed for prognosis.

RESULTS

The histologic subtypes were: FL type I, 20 cases (42%); type II, 24 (50%); type III, three (6%); and unclassifiable, one (2%). Distribution according to FLIPI was: low risk (36 cases) and intermediate risk (five cases). Treatment mainly consisted of combination chemotherapy (CHOP in 34 cases) plus involved-field radiotherapy in 26 cases. Forty patients (89%) achieved a complete response (CR), three (7%) a partial response, and two (4%) were non-responders; the remaining three patients did not receive therapy. No initial variable predicted CR achievement. About 57% of the patients in CR eventually relapsed with a relapse risk of 46% at 10 yr. Intermediate-risk FLIPI predicted failure-free survival. Histologic transformation was observed in six patients with a 10-yr risk of transformation of 13%. Twelve patients died during follow-up, in two cases as a result of unrelated causes. Overall survival (OS) at 10 yr was 79%. The FLIPI was the sole variable predicting OS.

CONCLUSIONS

Although the majority of patients with localized FL achieve CR, the risk of relapse is high. The FLIPI is of prognostic value in these patients.

Detection and monitoring of minimal residual disease by quantitative real-time PCR

BACKGROUND

The detection of malignant cells by quantitative real-time PCR has become state of the art for diagnosis, monitoring response to treatment and detection of minimal residual disease (MRD) in patients with leukemia or lymphoma. In order to be used in high-throughput analyses technical details have to be standardized to improve reproducibility and comparability of quantitative results obtained in different laboratories.

METHODS

Molecular monitoring of disease activity during and after treatment based on the detection of malignant cells in circulation or bone marrow by quantitative real-time PCR will be helpful to develop individualized treatment strategies for every patient.

CONCLUSIONS

The effectiveness of any kind of innovative treatment with specific antibodies, cellular immunotherapy or molecules designed for specific targets of tumor cells can be controlled at a very high level of sensitivity and accuracy. Based on quantitative results indicative for success or treatment failure, therapeutic changes upon the detection of progressive disease at the molecular level can be made even before symptoms or signs of clinical relapse occur. Hopefully, this will lead to higher cure rates and improved long-term survival.

A prospective randomized study to compare the molecular response rates between central lymphatic irradiation and intensive alternating triple chemotherapy in the treatment of stage I–III follicular lymphoma

PURPOSE

This study was undertaken to compare the molecular response (MR) rates of 2 regimens, central lymphatic irradiation (CLI) and alternating triple therapy (ATT), in the treatment of Stage I-III follicular lymphoma. MR was defined as disappearance of t(14;18) (q32;q21) amplified by polymerase chain reaction (PCR).

PATIENTS AND METHODS

Sixty-five patients with Stage I to III follicular lymphoma were randomized. CLI consisted of the mantle, abdomen, and pelvic radiation fields. ATT alternated among CHOD-Bleo, ESHAP, and NOPP for 12 courses. Bone marrow (BM) and peripheral blood (PB) samples were obtained before treatment for PCR analysis. PCR-positive patients were followed by PCR analysis. The random-effects logistic model was fitted to the data from the posttreatment PCRs. The factors included in the model were treatment arm, type of PCR (BM vs. PB), and time to PCR sample procurement from the date of registration.

RESULTS

At a median follow-up of 71 months, the 5-year relapse-free survival (RFS) rates were 45% and 54% for CLI and ATT, respectively (p = 0.42). The probability of attaining an MR increased with time after registration (p = 0.007), was lower for BM compared with PB (p = 0.012), and was higher for ATT than for CLI (p = 0.020).

CONCLUSION

ATT regimen achieved a higher MR than CLI, although both arms had similar 5-year RFS.

The Role of Mitoxantrone in the Treatment of Indolent Lymphomas

With the introduction of newer therapeutic approaches, survival in indolent non-Hodgkin's lymphoma (NHL) appears to be improving. Mitoxantrone (Novantrone; Serono, Inc.; Rockland, MA, http://www.seronousa.com), an anthracenedione with low cardiotoxic potential, has demonstrated activity in indolent NHL in combination with fludarabine (Fludara; Berlex Laboratories; Wayne, NJ, http://www.berlex.com) and other agents. In a Southwest Oncology Group trial (SWOG 9501), treatment with fludarabine and mitoxantrone (FM) induced a complete remission (CR) rate of 44% and a partial remission (PR) rate of 50% in untreated patients. The estimated 4-year progression-free survival (PFS) rate was 38%. In a multicenter Italian trial comparing the efficacy of FM with that of cyclophosphamide, doxorubicin (Adriamycin; Bedford Laboratories; Bedford, OH, http://www.bedfordlabs.com), vincristine (Oncovin; Eli Lilly and Company; Indianapolis, IN, http://www.lilly.com), and prednisone (Deltasone; Pfizer Pharmaceuticals; New York, NY, http://www.pfizer.com), CHOP, followed by rituximab (Rituxan; Genentech, Inc.; South San Francisco, CA, http://www.gene.com) for patients with incomplete clinical or molecular responses, the CR and molecular response rates were significantly higher in the FM arm, but the PFS and overall survival (OS) rates did not differ between the two arms. However, FM was also significantly less toxic than CHOP. The administration of rituximab following chemotherapy resulted in higher clinical and molecular response rates in both arms. In a separate trial, FM plus dexamethasone (Decadron; Merck and Co., Inc.; Whitehouse Station, NJ, http://www.merck.com), FND, plus concurrent rituximab produced a CR rate of 92%. In a randomized German study, patients with indolent lymphomas received FM plus cyclophosphamide (FCM) or FCM with rituximab. PFS and OS times were significantly better for patients who received combined chemoimmunotherapy. Mitoxantrone-based regimens are highly active and well tolerated in patients with both relapsed and previously untreated indolent lymphomas. The addition of rituximab appears to increase the activity of the FM, FND, and FCM regimens. Although the results of the Italian multicenter study support the superiority of FM over CHOP in terms of clinical and molecular responses and tolerability, additional studies using rituximab in combination with both of these regimens should be attempted to determine the possible further benefit of both in the management of indolent lymphoma. Because cure remains elusive in patients with indolent lymphoma, maximum prolongation of PFS with minimal toxicity and maximum preservation of quality of life should remain central goals of treatment.

Rituximab in Combination With Fludarabine Chemotherapy in Low-Grade or Follicular Lymphoma

Purpose

To evaluate the safety and efficacy of fludarabine plus rituximab in treatment-naïve or relapsed patients with low-grade and/or follicular non-Hodgkin's lymphoma.

Patients and Methods

This was an open-label, single-arm, single-center phase II study enrolling 40 patients. During the first week of the study, patients received two infusions of rituximab 375 mg/m2 administered 4 days apart. Seventy-two hours after the second infusion of rituximab, patients received the first of six cycles of fludarabine chemotherapy (25 mg/m2/d for 5 days on a 28-day cycle). Single infusions of rituximab were administered 72 hours before the second, fourth, and sixth cycles of fludarabine, and two infusions of rituximab were given 4 weeks after the last cycle of fludarabine. Treatment duration was 26 weeks.

Results

An overall response rate of 90% (80% complete response rate) was achieved in the intent-to-treat population. Similar response rates were seen in treatment-naïve and previously treated patients. The median duration of response has not been reached at 40+ months. The median follow-up time in this study is 44 months (range, 15 to 66 months). In patients positive for the 14;18 translocation in blood and/or marrow at enrollment, molecular remission was achieved in 88% of cases, with patients remaining negative for up to 4 years to date. Hematologic toxicity was manageable, and except for a 15% incidence of herpes simplex/zoster infections, infectious complications were rare. Nonhematologic toxicities were minimal.

Conclusion

Rituximab plus fludarabine was well tolerated and associated with an excellent complete response rate, including molecular remissions, in patients with low-grade or follicular lymphoma.

Fludarabine Plus Mitoxantrone With and Without Rituximab Versus CHOP With and Without Rituximab As Front-Line Treatment for Patients With Follicular Lymphoma

Purpose

Promising new therapeutic options for follicular lymphoma (FL) include fludarabine plus mitoxantrone (FM) and the mouse/human anti-CD20 antibody, rituximab. We performed a randomized comparative trial of FM with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) front-line chemotherapy with and without sequential rituximab.

Patients and Methods

All previously untreated CD20+ FL patients presenting in 15 Italian cooperative institutions from October 1999 were randomly allocated to FM or CHOP. Following clinical or molecular restaging, patients in complete remission (CR) with bcl-2/IgH negativity (CR−) received no further treatment; those in CR with bcl-2/IgH positivity (CR+) received rituximab, as did those in partial remission (PR) with bcl-2/IgH negativity (PR−) or positivity (PR+); nonresponders (NR subgroup) were off study.

Results

After chemotherapy, the FM arm achieved higher rates of CR (68% [49 of 72 patients] v 42% [29 of 68 patients]; P = .003) and CR− (39% [28 of 72 patients] v 13 of 68 patients [19%]; P = .001). Rituximab elicited CR− in 55 of 95 treated patients (58%). The final CR− rate was higher in the FM arm (71% [51 of 72 patients] v 51% [35 of 68 patients]; P = .01). However, with a median follow-up of 19 months (range, 9 to 37 months), no statistically significant difference was found among the various study arms in terms of both progression-free (PFS) and overall survival (OS).

Conclusion

These results indicate that FM is superior to CHOP for front-line treatment of FL and that rituximab is an effective sequential treatment option. However, they also confirm that this superiority is unlikely to translate into either better PFS or OS.

Molecular response of follicular lymphoma to cyclophosphamide, doxorubicin, vincristine, prednisone C(H)OP or COP-based therapy as measured by polymerase chain reaction evidence of translocation (14;18)(q32;q21)

PURPOSE

Existing data suggest that conventional C(H)OP (cyclophosphamide, doxorubicin, vincristine, prednisone) regimen may not be intensive enough to achieve molecular response, as measured by polymerase chain reaction (PCR) evidence of translocation (14;18)(q32:q21) for follicular lymphoma. This study was undertaken to study the molecular response rate of follicular lymphoma to C(H)OP-based therapy and to analyze prognostic factors for molecular response.

PATIENTS AND METHODS

Twenty patients with pretreatment PCR evidence of t(14;18)(q32; q21) and at least one posttreatment PCR analysis after the initiation of the treatment with C(H)OP with or without radiation therapy constituted the basis for this analysis. The random effects logistic model was used to analyze the data. The following factors were investigated for their relationship to molecular response: gender, age, beta2-microglobulin, use of radiation therapy, Ann Arbor stage, and international Prognostic Index for malignant lymphoma.

RESULTS

Median follow-up was 56 months (range, 23-153 months). A total of 135 PCR results were available, 33 from bone marrow and 102 from peripheral blood. Overall, there was a clear and steady decreasing trend toward loss of PCR positivity with increasing time aftertreatment. By univariate analysis, stage > or = 3, stage = 4, International Prognostic Index > or = 2, and no radiation therapy were adverse factors for molecular response. On multivariate analysis, Ann Arbor stage IV and no radiation therapy were independent risk factors for PCR positivity, both for the peripheral blood data analyzed alone and for all data combined.

DISCUSSION

It is possible to achieve molecular response with C(H)OP with or without radiation therapy in patients with follicular lymphoma. Response rate depends on the Ann Arbor stage and radiation therapy.

Quantitative Assessment of Disease Involvement by Follicular Lymphoma Using Real-Time Polymerase Chain Reaction Measurement of t(14;18)-Carrying Cells

Chromosomal translocation t(14:18)(q32;q21) is one of the most common karyotypic abnormalities in non-Hodgkin's lymphomas. It occurs in more than 85% of follicular lymphoma (FL) cases. Real-time polymerase chain reaction (Q-Rt-PCR) analysis using double-labeled fluorogenic probes is a new tool in the detection and quantification of t(14;18)-carrying cells. We analyzed 239 specimens with Q-Rt-PCR to detect and quantify t(14;18)-carrying cells. To investigate the clinical usefulness of the quantitative assessment, we analyzed the clinical correlation with 92 FL patients of varying clinical status. Of 59 previously untreated patients, patients with stage IV disease had significantly higher quantities of t(14;18)-carrying cells measurable in the bone marrow or the peripheral blood than patients in clinical stages I to III (P = .003 and .043, respectively). Moreover, of the 33 posttherapy patients. the patients in complete remission appeared to have lower detectable levels of t(14;18)-carrying cells than patients in partial remission or with recurrent disease. Q-Rt-PCR permits a sensitive and quantitative assessment of the extent of disease involvement in patients with t(14;18)-carrying FL. The technique has the potential to be a useful tool in the diagnosis of FL, disease assessment, and prognosticating patients' clinical outcomes.

Ex vivo B cell depletion using the Eligix B Cell SC system and autologous peripheral blood stem cell transplantation in patients with follicular non-Hodgkin's lymphoma

One limitation of ASCT is the potential reinfusion of tumor cells contaminating PBSC. The Eligix B cell SC system consists of high-density microparticles coated with anti-B cell antibodies. To determine if this system eliminates B cells and lymphoma cells from PBSC, immunocytochemistry and PCR of the bcl-2/IgH rearrangement were performed, and correlated with patient outcome after ASCT. Eligible patients (n=29) had relapsed or transformed follicular NHL with bone marrow involvement <20%, and all lymph nodes <5 cm. PBSCs were mobilized with cyclophosphamide/G-CSF (n=21), and patients were conditioned with cyclophosphamide, carmustine and etoposide. Using immunocytochemistry on PBSC, the median number of CD20+ cells pre-purge was 310/10(6) (range 0-16692) and post-purge was 0.75/10(6); the median log B cell depletion was 2.7 (range 1.4-3.9). B cell depletion correlated with PFS after ASCT (P=0.06). Of 17 available samples for PCR, only four had a detectable t(14;18) breakpoint. After purging, all four remained PCR+; two had a 1-3 log depletion of lymphoma cells. At median follow-up of 18 months, 10 patients, including five infused with PCR-negative PBSC, have had disease progression. The paucity of PCR-informative patients, possibly related to in vivo rituximab therapy, limited the utility of minimal residual disease as a surrogate marker of clinical outcome.

Minimal residual disease (MRD) in follicular lymphoma in the era of immunotherapy with rituximab

The t(14;18)-translocation can be detected by PCR analysis in more than 90% of cytogenetically t(14;18)-positive follicular lymphomas (FLs), thus providing an easily accessible marker for molecular disease monitoring. Various technical aspects of the detection of residual lymphoma cells as well as the prognostic and clinical significance of the detection of minimal residual disease (MRD) after radiotherapy, chemotherapy and therapy with the monoclonal antibody rituximab are discussed. Up to now the comparability of the different studies investigating minimal residual disease in follicular lymphoma patients is hampered by the use of a variety of PCR techniques. A more standardized quantitative approach based on the real-time PCR technique will provide a powerful tool for the evaluation and optimization of therapy for each individual patient.