ALBERT

Description: Energy & Fuels DOI: 10.1021/ef301952u

Description: Biochemistry DOI: 10.1021/bi400763h

Description: Abstract 292 Introduction: CLL cells derive essential cues from their microenvironment, that may be targets for therapy. To this end the immunomodulatory drug Lenalidomide has shown remarkable clinical activity in monotherapy trials in CLL. However, tumor lysis and tumor flare have been major obstacles in development and marked and unexplained differences in the individual tolerance of the substance remains an unsolved problem. Furthermore, the potential for interaction with standard treatment for CLL is unknown. We employed the combination of Fludarabine and Rituximab for early reduction of tumorload and used it as a backbone to establish a tolerable Lenalidomide dose in combination. Study design: In the induction phase a maximal tolerated dose (MTD) of Lenalidomide in combination with FR was to be determined during 6 cycles of Fludarabine (40mg/m2 po d1-3 q28d) and Rituximab (375mg/m2 iv d4 cycle 1; 500mg/m2 iv d1 cycles 2–6, q28d). In cycle 1 Lenalidomide was added day 7–21 at 2,5 mg. Toxicity permitting, Lenalidomide dose was escalated to 5, 10, 15, 20 and 25mg d1-21 over cycles 2–6. Data from this phase are presented in this planned analysis. Data from a 6 month Lenalidomide/Rituximab maintenance phase will be presented later. Results: The median age of the 45 recruited patients was 66 years (range 43–79). Half of the patients were in stages Rai III/IV and the median β2-MG was 4.4 mg/l. At least one high risk feature from CD38, FISH analysis and mutation status was present in 64% of patients. Five patients stopped treatment during induction (Two due to rashes, two as patient's choice and one due to early Richter's transformation). No systematic toxicity determining an MTD, the primary study endpoint, was found. In striking contrast to a small previous report, 34% of our patients proceeded through dose escalation steps as planned to receive a dose of 25mg of Lenalidomide with their last cycle of FR. The individual MTD was equal or higher than 10mg in 73% of ITT patients and 71% in this group were dose-limited due to individual differences in myelotoxicity. In ITT analysis 27% of patients had an MTD of less than 10mg. Grade 3 and 4 neutropenia was expected in this combination and observed in 88% of patients in any cycle. While it was not used as a dose limiting toxicity per se, 42% of patients were dose-limited due to myelotoxicity at some level. Infectious episodes of grade 3 severity were observed in 5 patients (11%), resulting in a relatively mild rate given the observed myelotoxicity and the phase I/II design. Surprisingly, 1/3 of the patients experienced greater than G2 skin toxicity and this was deemed dose-limiting in nine patients. No tumor lysis or greater than G2 flare reactions were observed. Full response assessment for induction treatment is available for 39 patients. Complete responses were observed in 49% and partial responses in 38% of the ITT population. In 35 patients flow MRD is available and 10 patients have reached MRD negativity. Response quality was not associated with risk factors, age or with lenalidomide dose in those receiving 6 cycles of treatment. Remarkably, one of three patients with deletion 17 achieved an MRD negative CR. Since we could not define a clinical predictor for the patients' tolerance of lenalidomide, we performed extensive immunophenotyping of T cells in pretreatment samples, using markers for functional T cells subsets, their Th polarity and for suppressive or exhausted T cell subsets. Employing a combined endpoint including non-hematological dose-limiting events or MTD 〈 10mg as a comparator, we identified a fraction of non-exhausted memory CD4 cells as highly significant predictor of dose-limiting non-hematologic events (p

Description: Abstract 1773 T cell exhaustion is a state of T cell dysfunction in response to chronic antigen exposure, marked by impaired effector function and the continued expression of inhibitory receptors such as Programmed Death 1 (PD-1) (Wherry EJ. Nat Immunol. 2011 Jun;12(6):492–9.). Because tumour growth in chronic lymphocytic leukaemia (CLL) occurs over a long period of time, we hypothesized that the continued exposure of T cells to a CLL-derived antigen could also lead to a state of T cell exhaustion. We therefore investigated whether T cell exhaustion is induced in CLL by using the Eμ-TCL1 transgenic (tcl1tg) tumour transfer mouse model for this disease (Hofbauer JP, et al. Leukemia. 2011 Sep;25(9):1452-8) and by analyzing primary samples from CLL patients. We found that the number of PD-1+ T cells was increased in both CD4+ and CD8+ populations and in all lymphoid compartments examined of the Eμ-TCL1 transgenic (tcl1tg) tumour recipient mice, but not in recipient mice receiving wildtype (WT) splenocytes showing that leukemic mice have an increased number of T cells displaying an exhausted phenotype that is induced by the presence of CLL cells. We next assessed the expression of the ligands for PD-1 on the surface of murine CLL cells. Peripheral CLL tumour cells showed only a modest increase in PD-L1 expression as compared to WT B cells. However, lymph node and spleen residing tumour cells showed a marked increase in PD-L1 expression, which suggests a microenvironment-induced upregulation of PD-L1 on tumour cells, e.g. by their close contact to accessory cells. To validate our results on primary human CLL samples, we collected peripheral blood from 89 unselected CLL patients and 18 healthy donors and observed an increase in surface expression of PD-1 on the CD4+ and CD8+ T cell populations. While the percentage of PD-1+ CD4+ T cells in chemonaive patients was comparable to healthy donors, chemotherapy drastically increased the number of PD-1-expressing CD4+ T cells (63.81% ±19.75 vs 35.70% ±19.22; p

Description: Introduction Lenalidomide has shown encouraging activity in monotherapy trials in CLL, but tumor lysis and tumor flare presented obstacles in development. We and others previously presented first data on combinations of lenalidomide with standard treatment regimens in CLL. As reported at ASH 2011 we combined Lenalidomide safely and efficaciously with the combination of Fludarabine and Rituximab, achieving early reduction of tumor load without tumor lysis or tumor flare and with high response rates. We also uncovered a patient population unable to tolerate higher Lenalidomide doses and marked by an exhausted T cell subset, measured pre-treatment. We now report final results of this trial, including the maintenance phase. Study design In induction Lenalidomide was combined with Fludarabine (40mg/m2 po d1-3 q28d) and Rituximab (375mg/m2 iv d4 cycle 1; 500mg/m2 iv d1 cycles 2-6, q28d). In cycle 1 Lenalidomide was added day 7-21 at 2.5 mg. Toxicity permitting, Lenalidomide dose was escalated to 5, 10, 15, 20 and 25mg day 1-21 over cycles 2-6. Subsequent maintenance treatment was two-monthly Rituximab at 375mg/m2 and Lenalidomide at the last dose tolerated in combination in a 28 day cycle without interruption for 6 months. The main goal of this treatment phase was to establish safety and efficacy as a secondary endpoint to the study. Results Patient characteristics of 45 recruited patients were previously reported: median age was 66 years and at least one molecular high risk feature was present in 64% of patients. No systematic toxicity determining an MTD in induction, the primary study endpoint, was found. The median daily dose in cycle 6 was 15mg in 40 evaluable patients, with 3 patients receiving the last cycle without lenalidomide. Toxicity and efficacy of the induction regimen were reported previously. Maintenance treatment was started in all 40 patients finishing induction. Three patients that finished without lenalidomide received only Rituximab. The median starting dose for all 40 patients was 15mg daily and 70% started with 10mg upwards. In total, 46% needed dose reductions, with prolonged neutropenia being the main reason, but 47% received doses above 10mg up to cycle 6 of maintenance. Interestingly, 9/13 patients receiving 25mg as maintenance were able to receive the treatment uninterrupted for 6 months, suggesting that a biologically select group may tolerate very high doses. As alluded to the major toxicity was neutropenia with 45% and 27% reaching G3 and G4, respectively. Surprisingly this did not translate into a relevant signal for infections. Grade 3, but no G4 infections, were observed in 5% of patients and all other G3/4 toxicities remained below 5%. Compared to the reported incidence of skin reactions in induction, we did not observe a significant signal in the maintenance phase. Improvement of response from PR after induction to CR at the end of maintenance was observed in 25%. The overall best response in ITT to the regimen during induction and maintenance was CR in 67% and PR in 29%. Median follow up of the study is now 35 months, at which point PFS is 89% and observed median PFS is currently 46 months. Exploratory analyses show no significant influences of age〉65, mutation state or CD38 risk on PFS, but undetectable MRD after induction and high risk cytogenetics showed borderline effects (both p=0.08), the latter (2 cases with del17p and 9 with del11q) being driven by relapses in patients with del11q with a median PFS of 42 months in this group. Conclusions A combination of Lenalidomide with FR followed my maintenance with Lenalidomide and Rituximab proved clinically feasible. While initial dose-finding was complicated by highly individual levels of tolerance to lenalidomide in the combination (with skin toxicity being a major problem), the main toxicity in maintenance was neutropenia. Although the important myelotoxicity did not translate into a rate of infection above that expected after induction treatment, our judgment is, that a more moderate approach to dosing may be warranted in maintenance, since a majority of patients had to be dose-adjusted. Finally, the PFS observed with this induction and maintenance regimen seems encouraging by comparison with other first line regimens. While the exploratory nature of the trial clearly limits this conclusion, we further explore combination approaches with lenalidomide. Disclosures: Egle: Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Research Funding. Off Label Use: Lenalidomide in CLL. Pleyer:Celgene: Honoraria, Research Funding. Fridrik:Roche: Honoraria. Thaler:Roche: Honoraria, Research Funding. Greil:Roche: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Research Funding.