INA03, a potent transferrin-competitive antibody-drug conjugate against CD71, for a safer acute leukemia treatment.

Innovative strategies to enhance efficacy and overcome drug resistance in hematologic cancers such as antibody-drug conjugates (ADCs) have shifted the paradigm of conventional care by delivering promising outcomes in cancer therapies with a significant reduction in the risk of relapse. The transferrin receptor 1, CD71, known to be overexpressed in malignant cells, is considered a potent anti-tumoral target. Therefore, we have developed an anti-CD71 ADC, INA03, a humanized antibody conjugated to the monomethyl auristatin E (MMAE) through a 3-arylpropiolonitrile-valine-citruline linker. In this study, we investigated both potency and safety of INA03, in competition with transferrin (Tf), the CD71's natural ligand, as a novel strategy to specifically target highly proliferative cells. The high expression of CD71 was confirmed on different leukemic cell lines, allowing INA03 to bind efficiently. Subsequently, INA03 rapidly internalizes into lysosomal compartments, where its cytotoxic drug is released following cathepsin-B cleavage. Downregulating CD71 expression using shRNA highlighted that INA03-induced cell death was dependent on CD71 density at the cell surface. INA03 intravenous treatment in acute leukemia mouse models significantly reduced tumor burden, increased mice survival and showed no residual disease compared to conventional chemotherapies. Since INA03 competes with the human Tf, a double knock-in (hCD71/hTf) competent mouse model was generated to mimic human pharmacokinetics and pharmacodynamics. INA03 administration in hCD71/hTf mice did not reveal, even at high doses, any improper toxicities. Hence, these data demonstrate promising pre-clinical efficacy and safety of INA03 and support its development as a novel acute leukemia treatment.

Peripheral blood 8 colour flow cytometry monitoring of hairy cell leukaemia allows detection of high-risk patients.

Although purine analogues have significantly improved the outcome of hairy cell leukaemia (HCL) patients, 30-40% relapse, illustrating the need for minimal residual disease (MRD) markers that can aid personalized therapeutic management. Diagnostic samples from 34 HCL patients were used to design an 8-colour flow cytometry (8-FC) tube for blood MRD (B/RD) analysis (188 samples) which was compared to quantitative IGH polymerase chain reaction (Q-PCR) on 83 samples and to qualitative consensus IGH PCR clonality analysis on 165 samples. Despite heterogeneous HCL phenotypes at diagnosis, discrimination from normal B lymphocytes was possible in all cases using a single 8-FC tube, with a robust sensitivity of detection of 10(-4) , comparable to Q-PCR at this level, but preferable in terms of informativeness, simplicity and cost. B/RD assessment of 15 patients achieving haematological complete remission after purine analogues was predictive of a clinically significant relapse risk: with a median follow-up of 95 months; only one of the nine patients with reproducible 8-FC B/RD levels below 10(-4) (B/RD(neg) ) relapsed, compared to 5/6 in the B/RD(pos) group (P = 0.003). These data demonstrate the clinical interest of a robust 8-FC HCL B/RD strategy that could become a surrogate biomarker for therapeutic stratification and new drug assessment, which should be evaluated prospectively.

Therapeutic drug monitoring of imatinib in chronic myeloid leukemia: experience from 1216 patients at a centralized laboratory.

This study set out to examine in a large real-life cohort of patients with chronic myeloid leukemia (CML) the impact of imatinib threshold of 1000 ng/mL on molecular response, as suggested in a small subset of patients. Patient plasma samples were submitted from around France to a central facility, free of charge under the auspices of the European Treatment and Outcome Study (EUTOS) for CML. Submitting physicians were required to complete an 'imatinib monitoring request form', including details of why therapeutic drug monitoring (TDM) was requested, dose and duration of imatinib treatment, cytogenetic and molecular response, adverse events, and concurrent medications. Imatinib trough plasma concentration (C(min)) was measured at the central facility. Among 1985 eligible plasma samples analyzed, from 1216 CML patients, imatinib C(min) correlated positively with reported imatinib dose, but interpatient variability in C(min) was high (60%). A logistic regression analysis revealed that treatment duration and imatinib C(min) > 1000 ng/mL were significantly associated with major and complete molecular responses with odds ratios of 1.69 and 2.08, respectively. These data support in real-life setting that imatinib C(min) threshold of 1000 ng/mL is associated with major and complete molecular response and that TDM could play an important role in dose optimization.

Evidence that resistance to nilotinib may be due to BCR-ABL, Pgp, or Src kinase overexpression.

Targeting the tyrosine kinase activity of Bcr-Abl is an attractive therapeutic strategy in chronic myeloid leukemia (CML) and in Bcr-Abl-positive acute lymphoblastic leukemia. Whereas imatinib, a selective inhibitor of Bcr-Abl tyrosine kinase, is now used in frontline therapy for CML, second-generation inhibitors of Bcr-Abl tyrosine kinase such as nilotinib or dasatinib have been developed for the treatment of imatinib-resistant or imatinib-intolerant disease. In the current study, we generated nilotinib-resistant cell lines and investigated their mechanism of resistance. Overexpression of BCR-ABL and multidrug resistance gene (MDR-1) were found among the investigated mechanisms. We showed that nilotinib is a substrate of the multidrug resistance gene product, P-glycoprotein, using verapamil or PSC833 to block binding. Up-regulated expression of p53/56 Lyn kinase, both at the mRNA and protein level, was found in one of the resistant cell lines and Lyn silencing by small interfering RNA restored sensitivity to nilotinib. Moreover, failure of nilotinib treatment was accompanied by an increase of Lyn mRNA expression in patients with resistant CML. Two Src kinase inhibitors (PP1 and PP2) partially removed resistance but did not significantly inhibit Bcr-Abl tyrosine kinase activity. In contrast, dasatinib, a dual Bcr-Abl and Src kinase inhibitor, inhibited the phosphorylation of both BCR-ABL and Lyn, and induced apoptosis of the Bcr-Abl cell line overexpressing p53/56 Lyn. Such mechanisms of resistance are close to those observed in imatinib-resistant cell lines and emphasize the critical role of Lyn in nilotinib resistance.

Standard chemotherapy with interferon compared with CHOP followed by high-dose therapy with autologous stem cell transplantation in untreated patients with advanced follicular lymphoma: the GELF-94 randomized study from the Groupe d'Etude des Lymphomes de l'Adulte (GELA).

The purpose of this study is to compare our standard chemotherapy regimen (CHVP [cyclophosphamide, doxorubicin, teniposide, and prednisone]) plus interferon with 4 courses of CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) followed by high-dose therapy with autologous stem cell transplantation (ASCT) in treatment-naive patients with advanced follicular lymphoma. Four hundred one patients were included from July 1994 to March 2001: 209 received 12 cycles of CHVP plus interferon alpha for 18 months (CHVP-I arm) and 192 received 4 cycles of CHOP followed by high-dose therapy (HDT) with total body irradiation and ASCT (CHOP-HDT arm). Overall response rates were similar in both groups (79% and 78% after induction chemotherapy, respectively). One hundred thirty-one of the 150 patients eligible for HDT underwent transplantation (87%). Intent-to-treat analysis after a median follow-up of 7.5 years showed that there was no difference between the 2 arms for overall survival (P = .53) or event-free survival (P = .11). Patients with a complete response at the end of the induction therapy had a statistically longer event-free survival and overall survival (P = .02 and < .001, respectively). After long-term follow-up, our study showed that there was no statistically significant benefit in favor of first-line high-dose therapy in patients with follicular lymphoma. High-dose therapy should be reserved for relapsing patients.

High-dose therapy and autologous blood stem-cell transplantation compared with conventional treatment in myeloma patients aged 55 to 65 years: long-term results of a randomized control trial from the Group Myelome-Autogreffe.

PURPOSE: To study the impact of high-dose therapy (HDT) with autologous stem-cell support in patients with symptomatic multiple myeloma (MM) between the ages of 55 and 65 years. PATIENTS AND METHODS: One hundred ninety patients between 55 and 65 years old who had newly diagnosed stage II or III MM were randomly assigned to receive either conventional chemotherapy (CCT; ie, monthly courses of a regimen of vincristine, melphalan, cyclophosphamide, and prednisone) or HDT and autologous blood stem-cell transplantation (using either melphalan alone 200 mg/m(2) intravenous [IV] or melphalan 140 mg/m(2) IV plus busulfan 16 mg/kg orally as pretransplantation cytoreduction). RESULTS: Within a median follow-up of 120 months, median event-free survival (EFS) times were 25 and 19 months in the HDT and CCT groups, respectively. Median overall survival (OS) time was 47.8 months in the HDT group compared with 47.6 months in the CCT group. A trend to better EFS (P = .07) was observed in favor of HDT, whereas OS curves were not statistically different (P = .91). The period of time without symptoms, treatment, and treatment toxicity (TwiSTT) was significantly longer for the HDT patients than for the CCT patients (P = .03). CONCLUSION: With a median follow-up time of approximately 10 years, this randomized trial confirmed a benefit of HDT in terms of EFS and TwiSTT but did not provide evidence for superiority of HDT over CCT in OS of patients aged 55 to 65 years with symptomatic newly diagnosed MM.

High-dose CD34+ cells are not clinically relevant in reducing cytopenia and blood component consumption following myeloablative therapy and peripheral blood progenitor cell transplantation as compared with standard dose.

BACKGROUND: No agreement exists about the number of autologous peripheral blood progenitor cells (PBPCs) to transfuse for optimal hematologic recovery after high-dose chemotherapy. STUDY DESIGN AND METHODS: To determine CD34+ cell dosage following high-dose chemotherapy (in terms of hematologic recovery and blood component consumption), the effects of two schedules of CD34+ cell transfusions in a cohort of patients with myeloma or non-Hodgkin's lymphoma were examined. Forty patients (Group 1) received between 2.5 and 5 x 106 CD34+ cells per kg, with a median of 3.4 x 106 per kg following high-dose chemotherapy, and 40 patients (Group 2), selected to match Group 1 for age, diagnosis, prior therapies, and procedure for PBPC mobilization, received a dose of CD34+ cells >5 x 106 per kg, with a median of 8.4 x 106 per kg (5-33). RESULTS: The median number of days to achieve a neutrophil count of >0.5 x 109 per L and unsupported platelets of >20 x 109 per L was identical for the two groups, but the time required to reach 1.5 x 109 neutrophils per L and 50 x 109 platelets per L was greatly delayed in Group 1. No significant difference was observed for the median number of RBC and platelet transfusions, or for the proportion of patients in each group that did not require either platelet or RBC transfusions. CONCLUSION: Our data confirm a dose-response relationship between CD34+ cell dose transfused and time to hematologic recovery after high-dose chemotherapy. However, the minimal Hb and platelet counts for transfusion independence in the two groups are similar when the CD34+ cell dose is greater than 5 x 106 CD34+ cells per kg. Therefore, our data suggest that it is not necessary to go on with apheresis procedures after 5 x 106 CD34+ cells per kg are harvested to sustain one high-dose chemotherapy.