Consensus recommendations on the management of toxicity associated with CD3×CD20 bispecific antibody therapy.

ABSTRACT: Bispecific antibodies (BsAb) that target CD3 and CD20 represent a new milestone in the treatment of patients with B-cell non-Hodgkin lymphoma. These drugs have demonstrated remarkable single-agent activity in patients with heavily pretreated disease, and 3 drugs have so far received regulatory approvals in various countries. However, BsAbs can potentially lead to severe toxicity associated with T-cell activation, particularly cytokine release syndrome (CRS). The anticipated widespread use of these off-the-shelf products poses challenges for implementation and highlights the need for guidance in anticipating, mitigating, and managing adverse events. In clinical trials, guidance for the evaluation and treatment of CRS and neurotoxicity associated with BsAb therapy has been modeled after algorithms originally created for chimeric antigen receptor (CAR) T-cell therapies and other immune effector therapies, yet notable differences in timing, quality, and severity exist between the toxicities of BsAbs and CAR T-cell therapies. We therefore convened an international panel of academic and community practice physicians, advanced practitioners, registered nurses, and pharmacists with experience using CD3×CD20 BsAbs in clinical trial and off-trial settings to provide comprehensive, consensus-based recommendations specific to the assessment and management of CD3×CD20 BsAb-related toxicities.

Bispecific antibodies for the treatment of B-cell lymphoma: promises, unknowns, and opportunities.

Treatment paradigms for B-cell non-Hodgkin lymphomas (B-NHL) have shifted dramatically in the last 2 decades following the introduction of highly active immunotherapies such as rituximab. Since then, the field has continued to witness tremendous progress with the introduction of newer, more potent immunotherapeutics, including chimeric antigen receptor T-cell therapy, which have received regulatory approval for and currently play a significant role in the treatment of these diseases. Bispecific antibodies (BsAb) are a novel class of off-the-shelf T-cell redirecting drugs and are among the most promising immunotherapeutics for lymphoma today. BsAb may target various cell-surface antigens and exist in different formats. Anti-CD20xCD3 BsAb have demonstrated remarkable single-agent activity in patients with heavily pretreated B-NHL with a manageable toxicity profile dominated by T-cell overactivation syndromes. Much work remains to be done to define the optimal setting in which to deploy these drugs for B-NHL treatment, their ideal combination partners, strategies to minimize toxicity, and, perhaps most importantly, pharmacodynamic biomarkers of response and resistance. In this review, we provide an update on BsAb development in B-NHL, from discovery to clinical applications, highlighting the achievements, limitations, and future directions of the field.

Diffuse large B-cell lymphoma involving osseous sites: utility of response assessment by PET/CT and good longterm outcomes.

Osseous involvement by diffuse large B-cell lymphoma (DLBCL-bone) is a heterogeneous disease. There is limited data regarding response assessment by positron emission tomography with fluorodeoxyglucose, which may demonstrate residual avidity despite a complete response. We analyzed clinical data of patients with newly diagnosed DLBCL and identified all cases with DLBCL-bone. End of treatment scans were reviewed by two independent experts classifying osseous lesions into Deauville (DV) ≤3; DV ≥4, or reactive uptake in the bone marrow (M), site of fracture (F) or surgery (S). We compared outcomes of DLBCL-bone to other extranodal sites (EN) matched on International Prognotic Index features and regimen. Of 1,860 patients with DLBCL (bone 16%; EN 45%; nodal 39%), 41% had localized disease and 59% advanced. Only 9% (n=27) of patients with initial bone involvement had residual fluorodeoxyglucose avidity at the osseous site. In half of these cases, the uptake was attributed to F/S/M, and of the remaining 13, only two were truly refractory (both with persistent disease at other sites). Overall survival and progression-free survival (PFS) were found to be similar for early- stage nodal DLBCL and DLBCL-bone, but inferior in EN-DLBCL. Advanced-stage disease involving the bone had a similar 5-year PFS to nodal disease and EN-DLBCL. After matching for International Prognotic Index and treatment regiments, PFS between bone and other EN sites was similar. Osseous involvement in DLBCL does not portend a worse prognosis. End of treatment DV ≥4 can be expected in 5-10% of cases, but in the absence of other signs of refractory disease, may be followed expectantly.

Emapalumab as salvage therapy for adults with malignancy-associated hemophagocytic lymphohistiocytosis.

Not available.

Combined oral 5-azacytidine and romidepsin are highly effective in patients with PTCL: a multicenter phase 2 study.

Peripheral T-cell lymphomas (PTCLs) are uniquely vulnerable to epigenetic modifiers. We demonstrated in vitro synergism between histone deacetylase inhibitors and DNA methyltransferase inhibitors in preclinical models of T-cell lymphoma. In a phase 1 trial, we found oral 5-azacytidine and romidepsin to be safe and effective, with lineage-selective activity among patients with relapsed/refractory (R/R) PTCL. Patients who were treatment naïve or who had R/R PTCL received azacytidine 300 mg once per day on days 1 to 14, and romidepsin 14 mg/m2 on days 8, 15, and 22 every 35 days. The primary objective was overall response rate (ORR). Targeted next-generation sequencing was performed on tumor samples to correlate mutational profiles and response. Among 25 enrolled patients, the ORR and complete response rates were 61% and 48%, respectively. However, patients with T-follicular helper cell (tTFH) phenotype exhibited higher ORR (80%) and complete remission rate (67%). The most frequent grade 3 to 4 adverse events were thrombocytopenia (48%), neutropenia (40%), lymphopenia (32%), and anemia (16%). At a median follow-up of 13.5 months, the median progression-free survival, duration of response, and overall survival were 8.0 months, 20.3 months, and not reached, respectively. The median progression-free survival and overall survival were 8.0 months and 20.6 months, respectively, in patients with R/R disease. Patients with tTFH enjoyed a particularly long median survival (median not reached). Responders harbored a higher average number of mutations in genes involved in DNA methylation and histone deacetylation. Combined azacytidine and romidepsin are highly active in PTCL patients and could serve as a platform for novel regimens in this disease. This trial was registered at www.clinicaltrials.gov as #NCT01998035.

Oral 5-azacytidine and romidepsin exhibit marked activity in patients with PTCL: a multicenter phase 1 study.

The peripheral T-cell lymphomas (PTCLs) are uniquely sensitive to epigenetic modifiers. Based on the synergism between histone deacetylase inhibitors and hypomethylating agents that we established in preclinical PTCL models, we conducted a phase 1 study of oral 5-azacytidine (AZA) and romidepsin (ROMI) in patients with advanced lymphoid malignancies, with emphasis on PTCL. According to a 3 + 3 design, patients were assigned to 1 of 7 cohorts with AZA doses ranging from 100 mg daily on days 1 to 14 to 300 mg daily on days 1 to 21, ROMI doses ranging from 10 mg/m2 on days 8 and 15 to 14 mg/m2 on days 8, 15, and 22, with cycles of 21 to 35 days. Coprimary end points included maximum tolerated dose (MTD) and dose-limiting toxicity (DLT). We treated a total of 31 patients. The MTD was AZA 300 mg on days 1 to 14 and ROMI 14 mg/m2 on days 8, 15, and 22 on a 35-day cycle. DLTs included grade 4 thrombocytopenia, prolonged grade 3 thrombocytopenia, grade 4 neutropenia, and pleural effusion. There were no treatment-related deaths. The combination was substantially more active in patients with PTCL than in those with non-T-cell lymphoma. The overall response rate in all, non-T-cell, and T-cell lymphoma patients was 32%, 10%, and 73%, respectively, and the complete response rates were 23%, 5%, and 55%, respectively. We did not find an association between response and level of demethylation or tumor mutational profile. This study establishes that combined epigenetic modifiers are potently active in PTCL patients. This trial was registered at www.clinicaltrials.gov as NCT01998035.

A phase 1 study of romidepsin and pralatrexate reveals marked activity in relapsed and refractory T-cell lymphoma.

Peripheral T-cell lymphomas (PTCL) are a group of rare malignancies characterized by chemotherapy resistance and poor prognosis. Romidepsin and pralatrexate were approved by the US Food and Drug Administration for patients with relapsed/refractory PTCL, exhibiting response rates of 25% and 29% respectively. Based on synergy in preclinical models of PTCL, we initiated a phase 1 study of pralatrexate plus romidepsin in patients with relapsed/refractory lymphoma. This was a single institution dose-escalation study of pralatrexate plus romidepsin designed to determine the dose-limiting toxicities (DLTs), maximum tolerated dose, pharmacokinetic profile, and response rates. Patients were treated with pralatrexate (10 to 25 mg/m2) and romidepsin (12 to 14 mg/m2) on 1 of 3 schedules: every week × 3 every 28 days, every week × 2 every 21 days, and every other week every 28 days. Treatment continued until progression, withdrawal of consent, or medical necessity. Twenty-nine patients were enrolled and evaluable for toxicity. Coadministration of pralatrexate and romidepsin was safe, well tolerated, with 3 DLTs across all schedules (grade 3 oral mucositis × 2; grade 4 sepsis × 1). The recommended phase 2 dose was defined as pralatrexate 25 mg/m2 and romidepsin 12 mg/m2 every other week. Twenty-three patients were evaluable for response. The overall response rate was 57% (13/23) across all patients and 71% (10/14) in PTCL. The phase 1 study of pralatrexate plus romidepsin resulted in a high response rate in patients with previously treated PTCL. A phase 2 study in PTCL will determine the efficacy of the combination. This trial was registered at www.clinicaltrials.gov as #NCT01947140.

Survival benefit in patients with peripheral T-cell lymphomas after treatments with novel therapies and clinical trials.

The peripheral T-cell lymphomas (PTCL) are rare and heterogeneous diseases characterized by an unfavorable prognosis. Chemotherapy is standard upfront treatment in most patients, but responses are short-lived with few FDA-approved "novel" agents available. We sought to define the impact of these novel agents as single agents or in clinical trials on the outcomes of patients with PTCL. From January 1994 to May 2019, adult patients with PTCL who were managed at our institution were included in this analysis. In addition to patients with incomplete data, those diagnosed with large granular lymphocytic leukemia and cutaneous T-cell lymphoma (CTCL) except for transformed mycosis fungoides were excluded. Statistical analyses were performed using SAS version 9.4. There were 219 patients included in the analysis. The median age at diagnosis was 56 years (range, 18-90 years). First line therapies mostly consisted of combination chemotherapy (75%). There was a statistical difference among patients who received chemotherapy, novel agents alone and in chemotherapy-free combinations, other, and no treatment (P < .0001). In patients who were treated with second line chemotherapy, novel agents alone and in combination without chemotherapy, or other, there was a still a survival benefit favoring novel agents (P = .0417). In the third line, there was no statistical difference among the three groups (P = .569). All patients who received novel therapies and underwent autologous stem cell transplant (autoSCT) achieved a complete response (CR) and had a better survival compared with patients who underwent chemotherapy who had a 70% CR rate prior to autoSCT (P = .046). Exposure to FDA-approved novel agents, immunoepigenetic trials, and clinical trials in general was associated with an overall survival (OS) benefit (P = .003, P = .04, and P = .006, respectively). These data suggest that patients who receive novel agents have superior outcomes compared with patients without exposure to novel therapies who receive chemotherapy-predicated treatments.

Brentuximab vedotin plus bendamustine in relapsed or refractory Hodgkin's lymphoma: an international, multicentre, single-arm, phase 1-2 trial.

BACKGROUND: Brentuximab vedotin is currently approved for patients with relapsed or refractory Hodgkin's lymphoma who previously received an autologous stem cell transplant or two previous multiagent chemotherapy regimens, and for patients with relapsed or refractory systemic anaplastic large-T-cell lymphoma who previously received at least one chemotherapy regimen. A high proportion of patients with CD30-expressing relapsed or refractory lymphomas have durable responses to single-agent brentuximab vedotin and show longer progression-free survival than do patients treated with chemotherapy. In patients with Hodgkin's lymphoma and peripheral T-cell lymphoma, treatment with bendamustine alone only achieves modest improvements in progression-free survival compared with that for chemotherapy. The objective of this study was to explore the safety and clinical activity of the combination of brentuximab vedotin plus bendamustine in heavily pretreated patients with relapsed or refractory Hodgkin's lymphoma and anaplastic large-T-cell lymphoma. METHODS: In this international, multicentre, single-arm, phase 1-2 trial, eligible patients were aged 18 years or older, had histologically confirmed relapsed or refractory Hodgkin's lymphoma or anaplastic large-T-cell lymphoma, had biopsy-proven CD30-positive tumours, had an Eastern Cooperative Oncology Group performance status of 2 or less, and received at least one previous multiagent chemotherapy regimen. In phase 1, patients were assigned following a 3+3 dose-escalation design to one of four cohorts to receive one dose of either 1·2 mg/kg or 1·8 mg/kg of brentuximab vedotin intravenously on day 1 of a 21 day cycle, plus one dose of bendamustine (70 mg/m2, 80 mg/m2, or 90 mg/m2) on days 1 and 2 of the treatment cycle. In phase 2, all patients were assigned to receive brentuximab vedotin plus bendamustine at the recommended phase 2 dose from phase 1. The primary endpoints were maximum tolerated dose and dose-limiting toxicity for phase 1, and the proportion of patients achieving an overall response in phase 2. For both phases 1 and 2, all patients receiving at least one dose of study drug were evaluable for toxicity and all patients completing at least one cycle of therapy were evaluable for response. The study is ongoing but no longer recruiting patients. This trial is registered with ClinicalTrials.gov, number NCT01657331. FINDINGS: Between July 26, 2012, and May 31, 2017, we enrolled and assigned 65 patients to treatment (64 [98%] with Hodgkin's lymphoma and one [2%] with anaplastic large-T-cell lymphoma; 28 [43%] during phase 1 and 37 [57%] during phase 2). In the phase 1 part, the maximum tolerated dose of the combination was not reached. Dose-limiting toxicities were observed in three (11%) of 28 patients, including grade 4 neutropenia at 1·8 mg/kg brentuximab vedotin plus 80 mg/m2 of bendamustine in two (7%) patients and diffuse rash at 1·2 mg/kg brentuximab vedotin plus 70 mg/m2 of bendamustine in one (4%) patient. The recommended phase 2 dose was deemed to be 1·8 mg/kg of brentuximab vedotin and 90 mg/m2 of bendamustine, which are the standard doses of the drugs when given as single agents. In the phase 2 part, an overall response was achieved in 29 (78% [95% CI 62-91]) of 37 patients. Serious adverse events included grade 3 lung infection in five (14%) of 37 patients in the phase 2, and grade 3-4 neutropenia in 16 (25%) of 65 patients across phases 1 and 2. There were no treatment-related deaths. INTERPRETATION: This study shows that brentuximab vedotin plus bendamustine, with a favourable safety profile, is an active salvage regimen for heavily pretreated patients with relapsed or refractory Hodgkin's lymphoma. This salvage regimen can potentially serve as an efficacious and safe alternative to platinum-based chemotherapy before autologous stem cell transplant. FUNDING: Seattle Genetics, Lymphoma Research Fund of Columbia University and National Center for Advancing Translational Sciences, and National Institutes of Health.

Approach to patients with essential thrombocythaemia and very high platelet counts: what is the evidence for treatment?

Treatment of essential thrombocythaemia (ET) is directed at decreasing the risk of complications of the disease, including arterial and venous thrombosis and bleeding episodes. Established risk factors for vascular events in patients with ET include advanced age (>60 years) and prior history of thrombosis or haemorrhage. The role, if any, of other potential risk factors, including cardiovascular risk factors, leucocytosis, high haematocrit, and JAK2 V617F has been analysed in multiple studies. The impact of thrombocytosis on the risk of vascular events has also been investigated. Many clinicians consider an elevated platelet count to be a risk factor for thrombosis or, when extreme, bleeding and utilize this as a criterion to start cytoreductive therapy. However, the relationship between thrombocytosis and vascular events is controversial and solid evidence to support the use of cytoreductive therapy in ET patients who have no other risk factors is lacking. In this review, we discuss current treatment recommendations for patients with ET, the biology underlying vascular events and risk factors thereof. We then review the evidence on the management of patients with ET and extreme thrombocytosis.

The underappreciated risk of thrombosis and bleeding in patients with myelofibrosis: a review.

Bleeding and thrombosis are long recognized complications of myelofibrosis (MF) and contribute significantly to its morbidity and mortality. However, so far, few studies have evaluated the frequency of these events, their characteristics, and their prognostic impact. Based on these studies, thrombotic events in MF are about as common as in essential thrombocytemia (ET) but less common than in polycythemia vera (PV), while bleeding events are relatively more common in MF than in ET or PV. The emergence of the concept of prefibrotic primary MF (PMF), which is associated with a higher frequency of thrombohemorrhagic complications than ET, and the growing evidence that prefibrotic PMF may also have a different thrombotic and bleeding risk profiles than fibrotic (overt) PMF have emphasized the need for a reappraisal of the risk of thrombosis and hemorrhage in patients with MF. In this review, we discuss the frequency of thrombosis and bleeding in patients with MF, including prefibrotic PMF and their established and potential risk factors.

The evolution of arsenic in the treatment of acute promyelocytic leukemia and other myeloid neoplasms: Moving toward an effective oral, outpatient therapy.

The therapeutic potential of arsenic derivatives has long been recognized and was recently rediscovered in modern literature. Early studies demonstrated impressive activity of this compound in patients with relapsed acute promyelocytic leukemia (APL). Over the last 2 decades, intravenous arsenic trioxide has been used successfully, both alone and in combination with other agents, for the treatment of APL and, with some success, of other myeloid neoplasms. Arsenic trioxide is currently part the standard of care for patients with APL. More recently, oral formulations of this compound have been developed and are entering clinical practice. In this review, the authors discuss the evolution of arsenic in the treatment of APL and other myeloid neoplasms.

Correlation between FDG/PET, histology, characteristics, and survival in 332 patients with chronic lymphoid leukemia.

Richter syndrome (RS) is associated with poor outcome. The prognosis of patients with histologically aggressive chronic lymphocytic leukemia (CLL), or HAC, has not been studied. We aimed to correlate 2-deoxy-2-[(18)F]fluoroglucose/positron emission tomography (FDG/PET) data, histological diagnosis, clinical characteristics, and survival in patients with CLL. A total of 332 patients with CLL were histologically classified as: 95 RS, 117 HAC, and 120 histologically indolent CLL (HIC). HAC and RS patients had higher maximum standardized uptake value (SUVmax), more frequent constitutional symptoms, poorer performance status (PS), lower hemoglobin and platelets, and higher lactate dehydrogenase and ß-2-microglobulin. An SUVmax ≥10 strongly correlated with mortality (overall survival [OS], 56.7 vs 6.9 months in patients with SUVmax <10 vs ≥10). Survival of patients with RS and HAC was similar among patients with SUVmax <10 or ≥10. SUVmax ≥10, PS ≥2, bulky disease, and age ≥65 were independently associated with shorter OS. In patients undergoing both fine-needle aspiration and biopsy, the former proved diagnostically inadequate in 23%, 29%, and 53% of HIC, HAC, and RS, respectively. FDG/PET is a useful diagnostic tool in patients with CLL and suspected transformation. Patients with HAC show different characteristics and worse prognosis compared with those with HIC. Patients with different CLL phases, but similar SUVmax have similar outcome. Tissue biopsy should be preferred for diagnosing RS.

Single nucleotide polymorphisms and inherited risk of chronic lymphocytic leukemia among African Americans.

The incidence of chronic lymphocytic leukemia (CLL) is significantly lower in African Americans than whites, but overall survival is inferior. The biologic basis for these observations remains unexplored. We hypothesized that germline genetic predispositions differ between African Americans and whites with CLL and yield inferior clinical outcomes among African Americans. We examined a discovery cohort of 42 African American CLL patients ascertained at Duke University and found that the risk allele frequency of most single nucleotide polymorphisms known to confer risk of development for CLL is significantly lower among African Americans than whites. We then confirmed our results in a distinct cohort of 68 African American patients ascertained by the CLL Research Consortium. These results provide the first evidence supporting differential genetic risk for CLL between African Americans compared with whites. A fuller understanding of differential genetic risk may improve prognostication and therapeutic decision making for all CLL patients.

Trial watch: bispecific antibodies for the treatment of relapsed or refractory large B-cell lymphoma.

Immunotherapy has shaped the treatment approach to diffuse large B-cell lymphoma (DLBCL), with rituximab leading to remarkable improvements in outcomes for both relapsed and treatment-naïve patients. Recently, groundbreaking immunotherapies like chimeric antigen receptor T-cells have entered the treatment arena for relapsed/refractory (R/R) DLBCL and gained regulatory approval in several countries. The concept of harnessing a patient's own T-cells to combat cancer has been further explored through the development of bispecific antibodies (BsAbs), a class of engineered antibody products designed to simultaneously target two different antigens. These novel drugs have demonstrated impressive single-agent activity and manageable toxicity in patients with heavily pretreated B-cell non-Hodgkin lymphoma. In this review, we provide an up-to-date overview of recently completed or ongoing BsAbs trials in patients with R/R DLBCL, including single-agent results, emerging combination data, and novel constructs.

CNS Bridging Radiotherapy Achieves Rapid Cytoreduction Prior to CAR T Cell Therapy for Aggressive B-Cell Lymphoma.

CAR T-cell therapy (CAR T) for central nervous system lymphoma (CNSL) is a promising strategy, yet responses are frequently not durable. Bridging radiotherapy (BRT) is used for extra-cranial lymphoma where it can improve CAR T outcomes through cytoreduction of high-risk lesions. We hypothesized that BRT would achieve similar, significant cytoreduction prior to CAR T for CNSL (CNS-BRT). We identified CNSL patients with non-Hodgkin B-cell lymphoma who received CNS-BRT prior to commercial CAR T. Cytoreduction from CNS-BRT was calculated as change in lesion size prior to CAR T. Twelve patients received CNS-BRT, and the median follow up among survivors is 11.8 months (IQR: 8.5 - 21.9). Ten patients had CNSL (9 secondary, 1 primary) and 2 patients had epidural disease (evaluable for toxicity). All ten patients with CNSL had progressive disease at the time of CNS-BRT. 1/12 patients experienced grade ≥ 3 cytokine release syndrome (CRS), and 3/12 patients experienced grade ≥ 3 immune effector cell-associated neurotoxicity syndrome (ICANS). CNS-BRT achieved a 74.0% (95% confidence interval: 62.0 - 86.0) mean reduction in lesion size from baseline (p = 0.014) at a median of 12 days from BRT completion and prior to CAR T infusion. Best CNS response included 8 complete responses (CR), 1 partial response (PR), and 1 progressive disease (PD). Three patients experienced CNS relapse outside the BRT field. Preliminary data suggest CNS-BRT achieves rapid cytoreduction and is associated with a favorable CNS response and safety profile. These data support further study of BRT as a bridging modality for CNSL CAR T.

Clinical characteristics, response to therapy, and survival of African American patients diagnosed with chronic lymphocytic leukemia: joint experience of the MD Anderson Cancer Center and Duke University Medical Center.

BACKGROUND: Little is known regarding racial disparities in characteristics and outcomes among patients with chronic lymphocytic leukemia (CLL). METHODS: The characteristics and outcomes of untreated African American (AA) patients with CLL (n = 84) were analyzed and compared with a reference nonblack (NB) patient population (n = 1571). RESULTS: At the time of presentation, AA patients had lower median hemoglobin levels (12.9 g/dL vs 13.7 g/dL), higher ß2 microglobulin levels (2.7 mg/dL vs 2.4 mg/dL), greater frequency of constitutional symptoms (27% vs 10%), unmutated immunoglobulin heavy-chain variable region (IGHV) mutation status (65% vs 47%), ζ-chain-associated protein kinase 70 (ZAP70) expression (58% vs 32%), and deletion of chromosome 17p or chromosome 11q (28% vs 17%; P ≤ 02 for each comparison). Fifty-one percent of AA patients and 39% of NB patients required first-line therapy and 91% and 88%, respectively, received chemoimmunotherapy. Overall response rates to treatment were 85% for AA patients and 94% for NB patients (P = .06); and the complete response rates were 56% and 58%, respectively (P = .87). The median survival of AA patients was shorter compared with that of NB patients (event-free survival: 36 months vs 61 months; P = .007; overall survival: 152 months vs not reached; P = .0001). AA race was an independent predictor of shorter event-free and overall survival in multivariable regression models. CONCLUSIONS: The current results indicated that AA patients with CLL have more unfavorable prognostic characteristics and shorter survival compared with their NB counterparts.

Significance of deeper molecular responses in patients with chronic myeloid leukemia in early chronic phase treated with tyrosine kinase inhibitors.

Most patients with chronic myeloid leukemia (CML) in chronic phase (CP) treated with tyrosine kinase inhibitors (TKI) achieve complete cytogenetic response (CCyR). An increasing number of patients also achieve deep molecular responses (MR). We determined the frequency and significance of deep MR after TKI therapy for CML in CP. MR included: major molecular response (MMR), MR4, MR4.5, and undetectable transcripts (UND), i.e., BCR-ABL/ABL of ≤0.1, ≤0.01, ≤0.0032%, and undetectable transcripts, respectively. Four hundred eighty-three patients received imatinib 400 mg/day (IM400, 71, July 2000 to April 2001), imatinib 800 mg/day (IM800, 204, June 2001 to July 2005), nilotinib (106, July 2005 to date), or dasatinib (102, November 2005 to date). UND rates at 36 months were 18.1, 30.6, 29.2, and 28.6%, respectively. Patients achieving UND have superior transformation-free survival (TFS) and overall survival (OS) versus those obtaining ≤MMR, but not other MR levels. At the 18- and 24-month landmark analysis, patients achieving UND have no advantage in TFS and OS compared to those achieving a lesser degree of MR. Among patients achieving MR4.5, those who maintain it for ≥2 years (susMR4·5) have no additional benefit in TFS or OS. Most patients with early CP CML receiving TKI achieve MMR. BCR-ABL transcripts become undetectable in a significant fraction of them. Deeper MR at 18 or 24 months are not associated with a benefit in TFS or OS. Furthermore, achieving susMR4·5 does not appear to further reduce the risk of transformation or death.