Safety of obinutuzumab alone or combined with chemotherapy for previously untreated or relapsed/refractory chronic lymphocytic leukemia in the phase IIIb GREEN study.

The safety of obinutuzumab, alone or with chemotherapy, was studied in a non-randomized, open-label, non-comparative, phase IIIb study (GREEN) in previously untreated or relapsed/refractory chronic lymphocytic leukemia. Patients received obinutuzumab 1000 mg alone or with chemotherapy (investigator's choice of fludarabine-cyclophosphamide for fit patients, chlorambucil for unfit patients, or bendamustine for any patient) on days 1, 8 and 15 of cycle 1, and day 1 of cycles 2-6 (28-day cycles), with the cycle 1/day 1 dose administered over two days. The primary end point was safety/tolerability. Between October 2013 and March 2016, 972 patients were enrolled and 971 treated (126 with obinutuzumab monotherapy, 193 with obinutuzumab-fludarabine-cyclophosphamide, 114 with obinutuzumab-chlorambucil, and 538 with obinutuzumab-bendamustine). Grade ≥3 adverse events occurred in 80.3% of patients, and included neutropenia (49.9%), thrombocytopenia (16.4%), anemia (9.6%), and pneumonia (9.0%); rates were similar in first-line and relapsed/refractory patients, and in first-line fit and unfit patients. Using expanded definitions, infusion-related reactions were observed in 65.4% of patients (grade ≥3, 19.9%; mainly seen during the first obinutuzumab infusion), tumor lysis syndrome in 6.4% [clinical and laboratory; highest incidence with obinutuzumab-bendamustine (9.3%)], and infections in 53.7% (grade ≥3, 20.1%). Serious and fatal adverse events were seen in 53.1% and 7.3% of patients, respectively. In first-line patients, overall response rates at three months post treatment exceeded 80% for all obinutuzumab-chemotherapy combinations. In the largest trial of obinutuzumab to date, toxicities were generally manageable in this broad patient population. Safety data were consistent with previous reports, and response rates were high. (clinicaltrials.gov identifier: 01905943).

Pregnancy occurring during or following adjuvant trastuzumab in patients enrolled in the HERA trial (BIG 01-01).

Only few case reports describe the pregnancy course and outcome of breast cancer patients, who were under treatment with trastuzumab at the time of conception or who have completed trastuzumab therapy before becoming pregnant. The HERA trial is a large phase III randomized clinical trial in which patients with early HER2-positive breast cancer were randomized to receive 1 or 2 years of trastuzumab or observation following completion of primary chemotherapy. To examine the effect of trastuzumab on pregnancy outcome, we report all pregnancy events that occurred until March 2010 in patients enrolled in the study. For the sake of this analysis, patients were assigned to three groups: (1) pregnancy occurring during and up to 3 months after trastuzumab exposure (group 1); (2) pregnancy occurring >3 months of last trastuzumab dose (group 2); and (3) pregnancy occurring in patients without prior exposure to trastuzumab (group 3). Sixteen, 45 and 9 pregnancies took place in groups 1, 2, and 3, respectively. 25 and 16% of patients in groups 1 and 2 experienced spontaneous abortion, the former being higher than figures reported in the general population. However, short-term fetal outcome appeared normal across the three groups. Only 2 congenital anomalies were reported, one in group 2 and one in group 3. No congenital anomalies were reported in those exposed to trastuzumab in utero. This is the first report from a large randomized trial assessing the effect of trastuzumab on pregnancy course and outcome. Based on our results, trastuzumab does not appear to affect fetal outcome in patients who manage to complete their pregnancy. We are currently initiating a collaboration to collect similar data from the other large adjuvant trastuzumab trials to confirm these findings.

Obinutuzumab plus fludarabine and cyclophosphamide in previously untreated, fit patients with chronic lymphocytic leukemia: a subgroup analysis of the GREEN study.

GREEN (NCT01905943) is a nonrandomized, open-label, single-arm, phase 3b study investigating the safety and efficacy of obinutuzumab alone or in combination with chemotherapy in chronic lymphocytic leukemia (CLL). We report the preplanned subgroup analysis of 140 previously untreated, fit CLL patients who received obinutuzumab plus fludarabine and cyclophosphamide (G-FC). The primary endpoint was safety and tolerability. Efficacy was the secondary endpoint. Obinutuzumab 1000 mg was administered intravenously on Day (D)1 (dose split D1‒2), D8 and D15 of Cycle (C)1, and D1 of C2-6 (28-day cycles). Standard intravenous/oral doses of fludarabine and cyclophosphamide were administered on D1-3 of C1-6. Overall, 87.1% of patients experienced grade ≥ 3 adverse events (AEs), including neutropenia (67.1%) and thrombocytopenia (17.1%). Serious AEs were experienced by 42.1% of patients. Rates of grade ≥ 3 infusion-related reactions and infections were 19.3% and 15.7%, respectively. Overall response rate was observed in 90.0%, with 46.4% of patients achieving complete response (CR; including CR with incomplete marrow recovery). Minimal residual disease negativity rates were 64.3% in peripheral blood and 35.7% in bone marrow (intent-to-treat analysis). After a median observation time of 25.6 months, 2 year progression-free survival was 91%. Frontline G-FC represents a promising treatment option for fit patients with CLL.

Obinutuzumab plus bendamustine in previously untreated patients with CLL: a subgroup analysis of the GREEN study.

GREEN (NCT01905943) is a non-randomized, open-label phase IIIb study investigating obinutuzumab alone or plus chemotherapy in chronic lymphocytic leukemia (CLL). We report a preplanned subgroup analysis of 158 previously untreated CLL patients receiving obinutuzumab-bendamustine (G-B). Patients received six 28-day cycles (C) of G-B: obinutuzumab day (D)1/D2 of C1 (25 mg D1/975 mg D2), 1000 mg D8 and D15 of C1, and D1 of C2-6; and bendamustine 70/90 mg/m2 D1 and D2 of C1-6. The primary endpoint was safety/tolerability. Grade ≥3 adverse events (AEs) occurred in 82.3% of patients, including neutropenia (49.4%), thrombocytopenia (12.0%) and febrile neutropenia (10.8%). Serious AEs included neutropenia (12.7%), febrile neutropenia (9.5%) and pneumonia (7.6%). Rates of grade ≥3 infections and infusion-related reactions were 20.3% and 17.1%, respectively. Due to tumor lysis syndrome (TLS; 8.2%), including two associated fatalities (one in another study cohort), additional risk-minimization measures were implemented. Overall response rate was 81.0%. After 32.8 months' median observation time, 2-year progression-free survival was 81.8%. Minimal residual disease was undetectable in 59.5% (94/158) and 27.8% (44/158) of patients for blood and bone marrow, respectively. Frontline G-B appears to have manageable toxicity with clinical activity in CLL. Careful TLS risk assessment, pretreatment and monitoring is required.

Sp100 is important for the stimulatory effect of homeodomain-interacting protein kinase-2 on p53-dependent gene expression.

HIPK2 shows overlapping localization with p53 in promyelocytic leukemia (PML) nuclear bodies (PML-NBs) and functionally interacts with p53 to increase gene expression. Here we demonstrate that HIPK2 and the PML-NB resident protein Sp100 synergize for the activation of p53-dependent gene expression. Sp100 and HIPK2 interact and partially colocalize in PML-NBs. The cooperation of HIPK2 and Sp100 for the induction of p21(Waf1) is completely dependent on the presence of p53 and the kinase function of HIPK2. Downregulation of Sp100 levels by expression of siRNA does not interfere with p53-mediated transcription, but obviates the enhancing effect of HIPK2. In summary, these experiments reveal a novel function for Sp100 as a coactivator for HIPK2-mediated p53 activation.

NDR kinase is activated by RASSF1A/MST1 in response to Fas receptor stimulation and promotes apoptosis.

Human NDR1 and 2 (NDR1/2) are serine-threonine protein kinases in a subgroup of the AGC kinase family. The mechanisms of physiological NDR1/2 activation and their function remain largely unknown. Here we report that Fas and TNF-alpha receptor stimulation activates human NDR1/2 by promoting phosphorylation at the hydrophobic motif (Thr444/442). Moreover, NDR1/2 are essential for Fas receptor-induced apoptosis as shown by the fact that NDR knockdown significantly reduced cell death whereas overexpression of the NDR1 kinase further potentiated apoptosis. Activation of NDR1/2 by death receptor stimulation is mediated by the tumor suppressor RASSF1A. Furthermore, RASSF1A-induced apoptosis largely depends on the presence of NDR1/2. Fas receptor stimulation promoted direct phosphorylation and activation of NDR1/2 by the mammalian STE20-like kinase 1 (MST1), a downstream effector of RASSF1A. Concurrently, the NDR1/2 coactivator MOB1 induced MST1-NDR-MOB1 complex formation, which is crucial for MST1-induced NDR1/2 phosphorylation upon induction of apoptosis. Our findings identify NDR1/2 as novel proapoptotic kinases and key members of the RASSF1A/MST1 signaling cascade.

Autoregulatory control of the p53 response by caspase-mediated processing of HIPK2.

The serine/threonine kinase HIPK2 phosphorylates the p53 protein at Ser 46, thus promoting p53-dependent gene expression and subsequent apoptosis. Here, we show that DNA damaging chemotherapeutic drugs cause degradation of endogenous HIPK2 dependent on the presence of a functional p53 protein. Early induced p53 allows caspase-mediated cleavage of HIPK2 following aspartic acids 916 and 977. The resulting C-terminally truncated HIPK2 forms show an enhanced induction of the p53 response and cell death, thus allowing the rapid amplification of the p53-dependent apoptotic program during the initiation phase of apoptosis by a regulatory feed-forward loop. The active HIPK2 fragments are further degraded during the execution and termination phase of apoptosis, thus ensuring the occurrence of HIPK2 signaling only during the early phases of apoptosis induction.

Phosphorylation-dependent control of Pc2 SUMO E3 ligase activity by its substrate protein HIPK2.

Sumoylation serves to control key cellular functions, but the regulation of SUMO E3 ligase activity is largely unknown. Here we show that the polycomb group protein Pc2 binds to and colocalizes with homeodomain interacting protein kinase 2 (HIPK2) and serves as a SUMO E3 ligase for this kinase. DNA damage-induced HIPK2 directly phosphorylates Pc2 at multiple sites, which in turn controls Pc2 sumoylation and intranuclear localization. Inducible phosphorylation of Pc2 at threonine 495 is required for its ability to increase HIPK2 sumoylation in response to DNA damage, thereby establishing an autoregulatory feedback loop between a SUMO substrate and its cognate E3 ligase. Sumoylation enhances the ability of HIPK2 to mediate transcriptional repression, thus providing a mechanistic link for DNA damage-induced transcriptional silencing.

Covalent modification of human homeodomain interacting protein kinase 2 by SUMO-1 at lysine 25 affects its stability.

The HIPK2 protein is a critical regulator of apoptosis and functionally interacts with p53 to increase gene expression. Here we show that human HIPK2 is modified by sumoylation at lysine 25, as revealed by in vivo and in vitro experiments. While SUMO-1 modification of HIPK2 has no influence on its ability to phosphorylate p53 at serine 46, to induce gene expression, and to mediate apoptosis, a non-sumoylatable HIPK2 mutant displays a strongly increased protein stability. The N-terminal SUMO-1 modification site is conserved between all vertebrate HIPK2 proteins and is found in all members of the HIPK family of protein kinases. Accordingly, also human HIPK3 is modified by sumoylation.

Expression profiles of androgen independent bone metastatic prostate cancer cells indicate up-regulation of the putative serine-threonine kinase GS3955.

PURPOSE: We established gene expression profiles by gene array analysis in the LNCaP model of human prostate cancer progression and evaluated genes differentially expressed in the androgen independent and bone metastatic C4-2 cell line compared to the androgen dependent and nonmetastatic parental LNCaP cell line. MATERIALS AND METHODS: Gene expression profiles were generated using Atlas cDNA arrays (Clontech, Palo Alto, California), comprising 1,176 genes. Intrinsic expression of the novel serine/threonine kinase GS3955 in LNCaP, C4-2 and PC-3 prostate cancer cells, and expression when stimulated with growth factors, was monitored by real-time reverse transcriptase-polymerase chain reaction. Furthermore, expression in human tumor specimens was evaluated. Cellular localization of GS3955 protein was analyzed by expressing it as a fusion with green fluorescent protein. RESULTS: Comparable numbers of genes were up-regulated and down-regulated in C4-2 compared to LNCaP. The novel serine/threonine kinase GS3955 was markedly up-regulated (greater than 40-fold) in C4-2, differentially regulated in LNCaP and C4-2 by insulin-like growth factor-1, and variably expressed in human prostate tumor specimens. Moreover, GS3955 was shown to localize in the cell cytoplasm and nucleus. CONCLUSIONS: Differential expression and mitogenic regulation of the serine/threonine kinase GS3955 in LNCaP and C4-2 suggest its functional involvement in the development of androgen independence and/or metastatic potential. GS3955 is also expressed in human prostate cancer specimens and further analysis may provide insights into the biology of prostate cancer progression.