Phase 1 trial of navitoclax and sorafenib in patients with relapsed or refractory solid tumors with hepatocellular carcinoma expansion cohort

Navitoclax (ABT-263) is an oral BCL2 homology-3 mimetic that binds with high affinity to pro-survival BCL2 proteins, resulting in apoptosis. Sorafenib, an oral multi kinase inhibitor also promotes apoptosis and inhibits tumor angiogenesis. The efficacy of either agent alone is limited; however, preclinical studies demonstrate synergy with the combination of navitoclax and sorafenib. In this phase 1 study, we evaluated the combination of navitoclax and sorafenib in a dose escalation cohort of patients with refractory solid tumors, with an expansion cohort in hepatocellular carcinoma (HCC). Maximum tolerated dose (MTD) was determined using the continual reassessment method. Navitoclax and sorafenib were administered continuously on days 1 through 21 of 21-day cycles. Ten patients were enrolled in the dose escalation cohort and 15 HCC patients were enrolled in the expansion cohort. Two dose levels were tested, and the MTD was navitoclax 150 mg daily plus sorafenib 400 mg twice daily. Among all patients, the most common grade 3 toxicity was thrombocytopenia (5 patients, 20%): there were no grade 4 or 5 toxicities. Patients received a median of 2 cycles (range 1-36 cycles) and all patients were off study treatment at data cut off. Six patients in the expansion cohort had stable disease, and there were no partial or complete responses. Drug-drug interaction between navitoclax and sorafenib was not observed. The combination of navitoclax and sorafenib did not increase induction of apoptosis compared with navitoclax alone. Navitoclax plus sorafenib is tolerable but showed limited efficacy in the HCC expansion cohort. These findings do not support further development of this combination for the treatment of advanced HCC. This phase I trial was conducted under ClinicalTrials.gov registry number NCT01364051.

Peripheral blood blast rate of clearance is an independent predictor of clinical response and outcomes in acute myeloid leukaemia

The day 14 bone marrow aspirate and biopsy (D14BM) is regularly used to predict achievement of complete remission (CR) with induction chemotherapy in acute myeloid leukemia (AML), however its utility has been questioned. Clearance of peripheral blood blasts (PBB) may serve as an early measure of chemosensitivity. PBB rate of clearance (PBB-RC) was calculated for treatment-naive AML patients (n = 164) undergoing induction with an anthracycline and cytarabine (7+3) and with detectable PBB at diagnosis. PBB-RC was defined as the percentage of the absolute PBB count on the day of diagnosis that was cleared with each day of therapy, on average, until D14 or day of PBB clearance. Each 5% increase in PBB-RC approximately doubled the likelihood of D14BM clearance (OR = 1·81; 95% CI: 1·24-2·64, P < 0·005). PBB-RC was also associated with improved CR rates (OR per 5% = 1·97; 95% CI: 1·27-3·01, P < 0·005) and overall survival (OS) [hazard ratio (HR) per 5% = 0·67; 95% CI: 0·52-0·87]. African American patients had poorer OS adjusted for PBB-RC (HR = 2·18; 95% CI: 1·13-4·23), while race was not associated with D14BM or CR rate. PBB-RC during induction chemotherapy is predictive of D14BM clearance, CR, and OS, and can therefore serve as a prognostic marker for clinical outcomes in AML.

Optimizing pegylated asparaginase use: An institutional guideline for dosing, monitoring, and management

The incorporation of L-asparaginase and pegylated asparaginase into pediatric-inspired regimens has conferred a survival advantage in treatment of adults with acute lymphoblastic leukemia. Use of asparaginase products requires careful prevention, monitoring, and management of adverse effects including hypersensitivity, hepatotoxicity, pancreatitis, coagulopathy, and thrombosis. Currently, there is limited published literature to offer guidance on management of these toxicities. At the University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center, a standard of practice guideline was created to prevent and manage asparaginase-related adverse events. By sharing our long-term experience with asparaginase products and clinical management of asparaginase-induced toxicities, this article aims to improve patient safety and optimize treatment outcomes.

Relapsed Philadelphia Chromosome-Positive Pre-B-ALL after CD19-Directed CAR-T Cell Therapy Successfully Treated with Combination of Blinatumomab and Ponatinib

Adults with relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) treated with conventional chemotherapy have dismal outcomes. Novel immunotherapies targeting CD19, including the bispecific T-cell engager blinatumomab and chimeric antigen-receptor T (CAR-T) cells, have revolutionized the treatment of R/R B-ALL. Robust response rates to CAR-T cell therapy after blinatumomab have recently been reported, but it is unknown whether blinatumomab can be effective following failure of anti-CD19 CAR-T cell therapy. Herein, we describe a patient with Philadelphia chromosome-positive B-ALL who relapsed after CD19-directed CAR-T therapy, but subsequently responded to the combination of blinatumomab and the tyrosine kinase inhibitor ponatinib, with the achievement of a complete remission lasting 12 months.

Asparaginase Erwinia chrysanthemi effectively depletes plasma glutamine in adult patients with relapsed/refractory acute myeloid leukemia

Depletion of glutamine (Gln) has emerged as a potential therapeutic approach in the treatment of acute myeloid leukemia (AML), as neoplastic cells require Gln for synthesis of cellular components essential for survival. Asparaginases deplete Gln, and asparaginase derived from Erwinia chrysanthemi (Erwinaze) appears to have the greatest glutaminase activity of the available asparaginases. In this Phase I study, we sought to determine the dose of Erwinaze that safely and effectively depletes plasma Gln levels to ≤ 120 μmol/L in patients with relapsed or refractory (R/R) AML. Five patients were enrolled before the study was halted due to issues with Erwinaze manufacturing supply. All patients received Erwinaze at a dose of 25,000 IU/m² intravenously three times weekly for 2 weeks. Median trough plasma Gln level at 48 h after initial Erwinaze administration was 27.6 μmol/L, and 80% (lower limit of 1-sided 95% CI 34%) of patients achieved at least one undetectable plasma Gln value (< 12.5 μmol/L), with the fold reduction (FR) in Gln level at 3 days, relative to baseline, being 0.16 (p < 0.001 for rejecting FR = 1). No dose-limiting toxicities were identified. Two patients responded, one achieved partial remission and one achieved hematologic improvement after six doses of Erwinaze monotherapy. These data suggest asparaginase-induced Gln depletion may have an important role in the management of patients with AML, and support more pharmacologic and clinical studies on the mechanistically designed asparaginase combinations in AML.

Unique amplification of BCR-ABL1 gene fusion in a case of T-cell acute lymphoblastic leukemia

Background

ABL1 gene translocations can be seen in precursor T-acute lymphoblastic leukemia (T-ALL). The typical translocation partner is the NUP214 gene. BCR-ABL translocations are relatively rare in this entity. Furthermore, while there have been unique patterns of amplification noted among the NUP214-ABL fusion genes, there have been few such reports among cases with BCR-ABL fusion genes.

Case presentation

Here we report a unique case of a 44-year old patient with T-ALL in which the blasts demonstrated a derivative chromosome 9 involving a 9;22 translocation and a dicentric Philadelphia chromosome 22 with a homogeneously staining region at the interface of the 9;22 translocation, leading to BCR-ABL1 gene amplification. Fluorescence in-situ hybridization (FISH) showed abnormal BCR/ABL1 fusions with the BCR-ABL1 gene amplification in 48% of the interphase cells analyzed. The translocation was confirmed by SNP array.

Conclusions

We present a novel derivative chromosome 9 that shows BCR-ABL gene fusion along with a dicentric Philadelphia chromosome 22 with BCR-ABL1 gene amplification. This is a unique pattern of BCR-ABL fusion which has never been described in T-ALL. It is significant that the patient responded to standard treatment with the CALGB 10403 protocol and supplementation with a tyrosine kinase inhibitor. Identification of additional patients with this pattern of BCR-ABL fusion will allow for enhanced risk assessment and prognostication.

Synthesis, characterization and antineoplastic activity of bis-aziridinyl dimeric naphthoquinone - A novel class of compounds with potent activity against acute myeloid leukemia cells

The synthesis, characterization and antileukemic activity of rationally designed amino dimeric naphthoquinone (BiQ) possessing aziridine as alkylating moiety is described. Bis-aziridinyl BiQ decreased proliferation of acute myeloid leukemia (AML) cell lines and primary cells from patients, and exhibited potent (nanomolar) inhibition of colony formation and overall cell survival in AML cells. Effective production of reactive oxygen species (ROS) and double stranded DNA breaks (DSB) induced by bis-aziridinyl BiQ is reported. Bis-dimethylamine BiQ, as the isostere of bis-aziridinyl BiQ but without the alkylating moiety did not show as potent anti-AML activity. Systemic administration of bis-aziridinyl BiQ was well tolerated in NSG mice.

Preclinical and first-in-human phase I studies of KW-2450, an oral tyrosine kinase inhibitor with insulin-like growth factor receptor-1/insulin receptor selectivity

Numerous solid tumors overexpress or have excessively activated insulin-like growth factor receptor-1 (IGF-1R). We summarize preclinical studies and the first-in-human study of KW-2450, an oral tyrosine kinase inhibitor with IGF-1R and insulin receptor (IR) inhibitory activity. Preclinical activity of KW-2450 was evaluated in various in vitro and in vivo models. It was then evaluated in a phase I clinical trial in 13 patients with advanced solid tumors (NCT00921336). In vitro, KW-2450 inhibited human IGF-1R and IR kinases (IC50 7.39 and 5.64 nmol/L, respectively) and the growth of various human malignant cell lines. KW-2450 40 mg/kg showed modest growth inhibitory activity and inhibited IGF-1-induced signal transduction in the murine HT-29/GFP colon carcinoma xenograft model. The maximum tolerated dose of KW-2450 was 37.5 mg once daily continuously; dose-limiting toxicity occurred in two of six patients at 50 mg/day (both grade 3 hyperglycemia) and in one of seven patients at 37.5 mg/day (grade 3 rash). Four of 10 evaluable patients showed stable disease. Single-agent KW-2450 was associated with modest antitumor activity in heavily pretreated patients with solid tumors and is being further investigated in combination therapy with lapatinib/letrozole in patients with human epidermal growth factor receptor 2-postive metastatic breast cancer.

Phase I Safety, Pharmacokinetic, and Pharmacodynamic Study of the Poly(ADP-ribose) Polymerase (PARP) Inhibitor Veliparib (ABT-888) in Combination with Irinotecan in Patients with Advanced Solid Tumors

PURPOSE

PARP is essential for recognition and repair of DNA damage. In preclinical models, PARP inhibitors modulate topoisomerase I inhibitor-mediated DNA damage. This phase I study determined the MTD, dose-limiting toxicities (DLT), pharmacokinetics (PK), and pharmacodynamics (PD) of veliparib, an orally bioavailable PARP1/2 inhibitor, in combination with irinotecan.

EXPERIMENTAL DESIGN

Patients with advanced solid tumors were treated with 100 mg/m(2) irinotecan on days 1 and 8 of a 21-day cycle. Twice-daily oral dosing of veliparib (10-50 mg) occurred on days 3 to 14 (cycle 1) and days -1 to 14 (subsequent cycles) followed by a 6-day rest. PK studies were conducted with both agents alone and in combination. Paired tumor biopsies were obtained after irinotecan alone and veliparib/irinotecan to evaluate PARP1/2 inhibition and explore DNA damage signals (nuclear γ-H2AX and pNBS1).

RESULTS

Thirty-five patients were treated. DLTs included fatigue, diarrhea, febrile neutropenia, and neutropenia. The MTD was 100 mg/m(2) irinotecan (days 1 and 8) combined with veliparib 40 mg twice daily (days -1-14) on a 21-day cycle. Of 31 response-evaluable patients, there were six (19%) partial responses. Veliparib exhibited linear PK, and there were no apparent PK interactions between veliparib and irinotecan. At all dose levels, veliparib reduced tumor poly(ADP-ribose) (PAR) content in the presence of irinotecan. Several samples showed increases in γ-H2AX and pNBS1 after veliparib/irinotecan compared with irinotecan alone.

CONCLUSIONS

Veliparib can be safely combined with irinotecan at doses that inhibit PARP catalytic activity. Preliminary antitumor activity justifies further evaluation of the combination. Clin Cancer Res; 22(13); 3227-37. ©2016 AACR.

A direct interaction between NQO1 and a chemotherapeutic dimeric naphthoquinone

BACKGROUND

Multimeric naphthoquinones are redox-active compounds that exhibit antineoplastic, antiprotozoal, and antiviral activities. Due to their multimodal effect on perturbation of cellular oxidative state, these compounds hold great potential as therapeutic agents against highly proliferative neoplastic cells. In our previous work, we developed a series of novel dimeric naphthoquinones and showed that they were selectively cytotoxic to human acute myeloid leukemia (AML), breast and prostate cancer cell lines. We subsequently identified the oxidoreductase NAD(P)H dehydrogenase, quinone 1 (NQO1) as the major target of dimeric naphthoquinones and proposed a mechanism of action that entailed induction of a futile redox cycling.

RESULTS

Here, for the first time, we describe a direct physical interaction between the bromohydroxy dimeric naphthoquinone E6a and NQO1. Moreover, our studies reveal an extensive binding interface between E6a and the isoalloxazine ring of the flavin adenine dinucleotide (FAD) cofactor of NQO1 in addition to interactions with protein side chains in the active site. We also present biochemical evidence that dimeric naphthoquinones affect the redox state of the FAD cofactor of NQO1. Comparison of the mode of binding of E6a with those of other chemotherapeutics reveals unique characteristics of the interaction that can be leveraged in future drug optimization efforts.

CONCLUSION

The first structure of a dimeric naphthoquinone-NQO1 complex was reported, which can be used for design and synthesis of more potent next generation dimeric naphthoquinones to target NQO1 with higher affinity and specificity.

Disparities in black and white patients with multiple myeloma referred for autologous hematopoietic transplantation: a single center study

BACKGROUND

Racial disparity in the incidence of multiple myeloma is well established; however, to the authors' knowledge, little is known regarding the impact of racial differences on disease characteristics, response to therapy, and clinical outcome.

METHODS

The authors studied 453 patients (174 of whom were black and 279 of whom were white) who underwent transplant between 2000 and 2013. The median follow-up was 4.4 years.

RESULTS

Black patients were significantly younger than white patients (median age, 54 years vs 59 years; P<.0001), more frequently presented with anemia (P = .04), had more of the immunoglobulin G isotype (P<.001), and had a borderline favorable cytogenetic risk (P = .06). Overall response to induction was similar, but deeper responses were observed in more white patients compared with black patients receiving immunomodulatory drug-based induction (P = .02). Referral for transplant was significantly delayed in black individuals (median, 1.3 years vs 0.9 years; P = .003). Overall survival from the time of transplant was similar for black and white patients, with medians of 6.2 years and 5.7 years, respectively, but survival from the time of diagnosis was significantly longer among black individuals (median, 7.7 years vs 6.1 years; P = .03). Maintenance therapy was found to positively impact progression-free survival but not overall survival, irrespective of race.

CONCLUSIONS

The results of the current study confirm ethnic differences in age, referral patterns, response to therapy, and overall survival. Future validation of these disparities is urgently needed.

Schistocytes, echinocytes, iron deficiency anemia, and thrombocytopenia - hematologic manifestations of splenic angiosarcoma

Splenic angiosarcoma is a rare and aggressive malignancy with an incidence of less than one per million and a fatality rate over 90%.  Early diagnosis is of great importance for optimal management.  Here, we report the case of a patient with splenic angiosarcoma who presented with prominent schistocytes, echinocytes, thrombocytopenia, and iron deficiency anemia, which in combination with radiographic evidence of a splenic mass, raised the suspicion for angiosarcoma and resulted in a prompt surgical intervention with curative intent. Resolution of the hematologic findings following splenectomy suggests that patients with this malignancy should be monitored for recurrent hematologic abnormalities as they may herald recurrence of the disease. We present a literature review on the hematologic manifestations that is associated with this malignant disease.

Asparaginase in the treatment of non-ALL hematologic malignancies

Asparaginases are among the most effective agents against acute lymphoblastic leukemia (ALL) and are Food and Drug Administration-approved for the treatment of pediatric and adult ALL. However, the efficacy of these drugs for the treatment of other hematologic malignancies particularly acute myeloid leukemia is not well established. The mechanism of action of asparaginases has thought to be related to a swift and sustained reduction in serum L-asparagine, which is required for rapid proliferation of metabolically demanding leukemic cells. However, asparagine depletion alone appears not to be sufficient for effective cytotoxic activity of asparaginase against leukemia cells, because glutamine can rescue asparagine-deprived cells by regeneration of asparagine via a transamidation chemical reaction. For this reason, glutamine reduction is also necessary for full anti-leukemic activity of asparaginase. Indeed, both Escherichia coli and Erwinia chrysanthemi asparaginases possess glutaminase enzymatic activity, and their administrations have shown to reduce serum glutamine level by deamidating glutamine to glutamate and ammonia. Emerging data have provided evidence that several types of neoplastic cells require glutamine for the synthesis of proteins, nucleic acids, and lipids. This fundamental role of glutamine and its metabolic pathways for growth and proliferation of individual malignant cells may identify a special group of patients whose solid or hematologic neoplasms may benefit significantly from interruption of glutamine metabolism. To this end, asparaginase products deserve a second look particularly in non-ALL malignant blood disorders. Here, we review mechanisms of anti-tumor activity of asparaginase focusing on importance of glutamine reduction, pharmacology of asparaginase products, in vitro activities as well as clinical experience of incorporating asparaginase in therapeutic regimens for non-ALL hematologic malignancies.

Ten-day decitabine as initial therapy for newly diagnosed patients with acute myeloid leukemia unfit for intensive chemotherapy

We retrospectively reviewed outcomes in 45 previously untreated patients with acute myeloid leukemia (AML) considered unfit for chemotherapy who were treated with 10-day courses of decitabine 20 mg/m(2) daily outside of a clinical trial, with no cut-offs for organ function or performance status (PS). Nineteen had Eastern Cooperative Group performance status (ECOG PS) ≥ 2, and 39 had ≥ 2 comorbidities. Fourteen patients (31%) achieved complete remission (CR) and five (11%) CR with incomplete count recovery, for an overall response rate of 42%, after a median of 2 (range, 1-4) courses. The only pretreatment characteristic that differed significantly between responders and non-responders was percent marrow blasts (median 42% vs. 65%; p = 0.01). Median overall survival was 9.0 months; it was 19.4 and 2.3 months for responders and non-responders, respectively (p < 0.001). Thus 10-day decitabine therapy has efficacy in patients with AML considered unfit for chemotherapy, and may serve as a backbone for the addition of other novel agents.

Target Selection Issues in Drug Discovery and Development

Targets for cancer treatments have been proposed which address oncogenes mutated in tumors (pathogenic targets). Yet additional opportunities may come from molecules expressed in the tissue of origin (ontogenic); allow drug handling (pharmacological) or address the tumor microenvironment. The key is to define an assay that defines a therapeutic index which can be achieved in modulated target function.

PRECEDENT: a randomized phase II trial comparing vintafolide (EC145) and pegylated liposomal doxorubicin (PLD) in combination versus PLD alone in patients with platinum-resistant ovarian cancer

PURPOSE

Vintafolide (EC145) is a folic acid-desacetylvinblastine conjugate that binds to the folate receptor (FR), which is expressed on the majority of epithelial ovarian cancers. This randomized phase II trial evaluated vintafolide combined with pegylated liposomal doxorubicin (PLD) compared with PLD alone. The utility of an FR-targeted imaging agent, (99m)Tc-etarfolatide (EC20), in selecting patients likely to benefit from vintafolide was also examined.

PATIENTS AND METHODS

Women with recurrent platinum-resistant ovarian cancer who had undergone ≤ two prior cytotoxic regimens were randomly assigned at a 2:1 ratio to PLD (50 mg/m(2) intravenously [IV] once every 28 days) with or without vintafolide (2.5 mg IV three times per week during weeks 1 and 3). Etarfolatide scanning was optional. The primary objective was to compare progression-free survival (PFS) between the groups.

RESULTS

The intent-to-treat population comprised 149 patients. Median PFS was 5.0 and 2.7 months for the vintafolide plus PLD and PLD-alone arms, respectively (hazard ratio [HR], 0.63; 95% CI, 0.41 to 0.96; P = .031). The greatest benefit was observed in patients with 100% of lesions positive for FR, with median PFS of 5.5 compared with 1.5 months for PLD alone (HR, 0.38; 95% CI, 0.17 to 0.85; P = .013). The group of patients with FR-positive disease (10% to 90%) experienced some PFS improvement (HR, 0.873), whereas patients with disease that did not express FR experienced no PFS benefit (HR, 1.806).

CONCLUSION

Vintafolide plus PLD is the first combination to demonstrate an improvement over standard therapy in a randomized trial of patients with platinum-resistant ovarian cancer. Etarfolatide can identify patients likely to benefit from vintafolide.

PRECEDENT: A Randomized Phase II Trial Comparing Vintafolide (EC145) and Pegylated Liposomal Doxorubicin (PLD) in Combination Versus PLD Alone in Patients With Platinum-Resistant Ovarian Cancer

Purpose

Vintafolide (EC145) is a folic acid–desacetylvinblastine conjugate that binds to the folate receptor (FR), which is expressed on the majority of epithelial ovarian cancers. This randomized phase II trial evaluated vintafolide combined with pegylated liposomal doxorubicin (PLD) compared with PLD alone. The utility of an FR-targeted imaging agent, 99mTc-etarfolatide (EC20), in selecting patients likely to benefit from vintafolide was also examined.

Patients and Methods

Women with recurrent platinum-resistant ovarian cancer who had undergone ≤ two prior cytotoxic regimens were randomly assigned at a 2:1 ratio to PLD (50 mg/m2 intravenously [IV] once every 28 days) with or without vintafolide (2.5 mg IV three times per week during weeks 1 and 3). Etarfolatide scanning was optional. The primary objective was to compare progression-free survival (PFS) between the groups.

Results

The intent-to-treat population comprised 149 patients. Median PFS was 5.0 and 2.7 months for the vintafolide plus PLD and PLD-alone arms, respectively (hazard ratio [HR], 0.63; 95% CI, 0.41 to 0.96; P = .031). The greatest benefit was observed in patients with 100% of lesions positive for FR, with median PFS of 5.5 compared with 1.5 months for PLD alone (HR, 0.38; 95% CI, 0.17 to 0.85; P = .013). The group of patients with FR-positive disease (10% to 90%) experienced some PFS improvement (HR, 0.873), whereas patients with disease that did not express FR experienced no PFS benefit (HR, 1.806).

Conclusion

Vintafolide plus PLD is the first combination to demonstrate an improvement over standard therapy in a randomized trial of patients with platinum-resistant ovarian cancer. Etarfolatide can identify patients likely to benefit from vintafolide.

Validation of tumour models for use in anticancer nanomedicine evaluation: the EPR effect and cathepsin B-mediated drug release rate

Purpose

Intravenously (i.v.) administered nanomedicines have the potential for tumour targeting due to the enhanced permeability and retention (EPR) effect, but in vivo tumour models are rarely calibrated with respect to functional vascular permeability and/or mechanisms controlling intratumoural drug release. Here the effect of tumour type and tumour size on EPR-mediated tumour localisation and cathepsin B-mediated drug release was studied.

Methods

Evans Blue (10 mg/kg) and an N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer–doxorubicin (Dox) conjugate (FCE28068) (5 mg/kg Dox-equiv) were used as probes and tumour levels (and Dox release) measured at 1 h after i.v. administration in a panel of murine and human xenograft tumours.

Results

Evans Blue and FCE28068 displayed similar tumour levels in the range of 2–18 % dose/g at 1 h for B16F10 and L1210. Approximately half of the tumour models evaluated exhibited tumour size-dependent accumulation of FCE28068; smaller tumours had the highest accumulation. Administration of free Dox (5 mg/kg) produced tumour levels of <2.5 % dose/g independent of tumour size. Whereas the degree of EPR-mediated targeting showed ~12-fold difference across the tumour models evaluated, Dox release from FCE28068 at 1 h displayed ~200-fold variation.

Conclusions

Marked heterogeneity was seen in terms of EPR effect and Dox release rate, underlining the need to carefully calibrate tumour models used to benchmark nanomedicines against known relevant standard agents and for optimal development of strategies for late pre-clinical and clinical development.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-013-2209-7) contains supplementary material, which is available to authorized users.

A phase I/II study of carfilzomib 2-10-min infusion in patients with advanced solid tumors

PURPOSE

Tolerability, pharmacokinetics (PK), pharmacodynamics, and antitumor activity of carfilzomib, a selective proteasome inhibitor, administered twice weekly by 2-10-min intravenous (IV) infusion on days 1, 2, 8, 9, 15, and 16 in 28-day cycles, were assessed in patients with advanced solid tumors in this phase I/II study.

METHODS

Adult patients with solid tumors progressing after ≥1 prior therapies were enrolled. The dose was 20 mg/m(2) in week 1 of cycle 1 and 20, 27, or 36 mg/m(2) thereafter. The maximum tolerated dose or protocol-defined maximum planned dose (MPD) identified during dose escalation was administered to an expansion cohort and to patients with small cell lung, non-small cell lung, ovarian, and renal cancer in phase II tumor-specific cohorts.

RESULTS

Fourteen patients received carfilzomib during dose escalation. The single dose-limiting toxicity at 20/36 mg/m(2) was grade 3 fatigue, establishing the MPD as the expansion and phase II dose. Sixty-five additional patients received carfilzomib at the MPD. Adverse events included fatigue, nausea, anorexia, and dyspnea. Carfilzomib PK was dose proportional with a half-life <1 h. All doses resulted in at least 80 % proteasome inhibition in blood. Partial responses occurred in two patients in phase I, with 21.5 % stable disease after four cycles in evaluable patients in the expansion and phase II cohorts.

CONCLUSION

Carfilzomib 20/36 mg/m(2) was well tolerated when administered twice weekly by 2-10-min IV infusion. At this dose and infusion rate, carfilzomib inhibited the proteasome in blood but demonstrated limited antitumor activity in patients with advanced solid tumors.

Clinical and laboratory studies of the novel cyclin-dependent kinase inhibitor dinaciclib (SCH 727965) in acute leukemias

Purpose

Dinaciclib inhibits cyclin-dependent kinases 1, 2, 5, and 9 with a better therapeutic index than flavopiridol in preclinical studies. This study assessed the activity of dinaciclib in acute leukemia both in the clinic and in vitro.

Methods

Adults with relapsed/refractory acute myeloid leukemia (n = 14) and acute lymphoid leukemia (n = 6) were treated with dinaciclib 50 mg/m² given as a 2-h infusion every 21 days.

Results

Most patients had dramatic but transient reduction in circulating blasts; however, no remissions were achieved on this schedule. The most common toxicities were gastrointestinal, fatigue, transaminitis, and clinical and laboratory manifestations of tumor lysis syndrome, including one patient who died of acute renal failure. Dinaciclib pharmacokinetics showed rapid (2 h) achievement of maximum concentration and a short elimination/distribution phase. Pharmacodynamic studies demonstrated in vivo inhibition of Mcl-1 expression and induction of PARP cleavage in patients’ peripheral blood mononuclear cells 4 h after dinaciclib infusion, but the effects were lost by 24 h and did not correlate with clinical outcome. Correlative in vitro studies showed that prolonged exposures to dinaciclib, at clinically attainable concentrations, result in improved leukemia cell kill.

Conclusions

While dinaciclib given as a 2-h bolus did not exhibit durable clinical activity, pharmacokinetic and pharmacodynamic data support the exploration of prolonged infusion schedules in future trials in patients with acute leukemias.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-013-2249-z) contains supplementary material, which is available to authorized users.

Unbalanced 11;18 translocation in an acute erythroid leukemia after radioactive iodine therapy

Therapy-related acute myeloid leukemia (t-AML) is well described after chemotherapy or radiotherapy for diverse malignancies. Radioisotope therapy is also recognized as a less-common cause of t-AML. We describe a patient with acute erythroid leukemia after radioactive iodine administration for papillary thyroid cancer, with an unbalanced 11;18 translocation resulting in three copies of 11q, including the MLL gene. Although an increased incidence of chronic myeloid leukemia has been documented after radioactive iodine exposure, acute leukemia in this setting has been less frequently seen. Moreover, to our knowledge, the chromosome abnormality present in our patient has not been previously reported. The literature on cytogenetic abnormalities in t-AML after radioactive iodine administration is reviewed.

Phase 1 dose-escalation, pharmacokinetic, and cerebrospinal fluid distribution study of TAK-285, an investigational inhibitor of EGFR and HER2

INTRODUCTION

This phase 1 study assessed safety, maximum tolerated dose (MTD), pharmacokinetics, cerebrospinal fluid (CSF) distribution, and preliminary clinical activity of the receptor tyrosine kinase inhibitor TAK-285.

METHODS

Patients with advanced, histologically confirmed solid tumors and Eastern Cooperative Oncology Group performance status ≤2 received daily oral TAK-285; daily dose was escalated within defined cohorts until MTD and recommended phase 2 dose (RP2D) were determined. Eleven patients were enrolled into an RP2D cohort. Blood samples were collected from all cohorts; CSF was collected at pharmacokinetic steady-state from RP2D patients. Tumor responses were assessed every 8 weeks per Response Evaluation Criteria in Solid Tumors.

RESULTS

Fifty-four patients were enrolled (median age 60; range, 35-76 years). The most common diagnoses were cancers of the colon (28 %), breast (17 %), and pancreas (9 %). Escalation cohorts evaluated doses from 50 mg daily to 500 mg twice daily; the MTD/RP2D was 400 mg twice daily. Dose-limiting toxicities included diarrhea, hypokalemia, and fatigue. Drug absorption was fast (median time of maximum concentration was 2-3 h), and mean half-life was 9 h. Steady-state average unbound CSF concentration (geometric mean 1.54 [range, 0.51-4.27] ng/mL; n = 5) at the RP2D was below the 50 % inhibitory concentration (9.3 ng/mL) for inhibition of tyrosine kinase activity in cells expressing recombinant HER2. Best response was stable disease (12 weeks of nonprogression) in 13 patients.

CONCLUSIONS

TAK-285 was generally well tolerated at the RP2D. Distribution in human CSF was confirmed, but the free concentration of the drug was below that associated with biologically relevant target inhibition.

Abstract 3268: Targeting leukemia metabolism: augmentation of anti-leukemic activity of arsenic trioxide (As2O3) against non-APL AML cell lines in presence of dichloroacetate (DCA)

Background: DCA increases pyruvate dehydrogenase activity via inhibition of pyruvate dehydrogenase kinase, which shunts pyruvate away from lactate production into the mitochondrial respiration, resulting in enhanced mitochondrial activity. As2O3 is approved for treatment of relapsed/refractory acute promyelocytic leukemia (APL). As2O3 as a single agent or in combination with cytarabine is ineffective for treatment of non-APL acute myeloid leukemia (AML) by most studies. As2O3 affects several different molecular targets and cellular functions such as decreasing mitochondrial membrane potential by opening permeability transition pore complex in membranes, reactive oxygen species production, and caspase pathways activation. We hypothesized that combination of DCA, as a mitochondrial respiration enhancer, and As2O3, which impairs mitochondrial activity, would have anti-leukemic synergistic effects and potentially overcome drug resistance particularly in relapsed/refractory AML.

Methods: IC50s for As2O3 and DCA were generated for two AML cell lines, MOLM-14 and MV4-11, the latter carries FLT3-ITD mutation. Cells were treated with DCA at IC30 and As2O3 either concurrently for 72 h or sequentially with 48 h exposure to DCA followed by the addition of As2O3 (100 nM - 5μM) for 48 h. Each experiment was terminated with WST-1 (Roche). Viability of cells was assessed by trypan blue exclusion. Experiments were performed in triplicate.

Results: IC50s for As2O3 and DCA were 0.88 ± 0.02 μM and 15.87 ± 1.22 mM for MOLM-14, 0.54 ± 0.03 μM and 19.08 ± 2.25 mM for MV4-11, respectively. When treated concurrently, the potentiation factors were 1.8 and 1.3 for MOLM-14 and MV4-11, respectively. When the cells were pretreated or "primed" with DCA for 48 h and then exposed to As2O3 for 48 h, the potentiation factors were 2 and 1.8 for MOLM-14 and MV4-11, respectively. Viability tests showed a 33-50% increase in cell kill when DCA and As2O3 were used in combination compared to As2O3 or DCA alone. The number of viable cells remaining after combination treatment was significantly lower than the number of viable cells after either treatment alone when treated sequentially or concurrently (p&lt;0.05). Further mechanistic studies and preclinical models are ongoing to best predict the future clinical dose and schedule.

Conclusion: Combination of DCA (IC30, 11 mM) and As2O3 whether used sequentially or concurrently in AML cells caused significantly more cellular damage as compared to either drug alone. To the best of our knowledge, this is the first report of the combination of DCA+As2O3 against AML cells. These data suggest that targeting cellular metabolism in leukemia may provide a therapeutic option for AML patients with unfavorable risk, such as relapsed/refractory, FLT3-ITD or who are not candidates for cytotoxic agents and warrant further clinical investigation.

Citation Format: Ashkan Emadi, Mariola Sadowska, Brandon A. Carter-Cooper, Rena G. Lapidus, Edward A. Sausville. Targeting leukemia metabolism: augmentation of anti-leukemic activity of arsenic trioxide (As2O3) against non-APL AML cell lines in presence of dichloroacetate (DCA). [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3268. doi:10.1158/1538-7445.AM2013-3268

A phase II study of temozolomide in patients with advanced aerodigestive tract and colorectal cancers and methylation of the O6-methylguanine-DNA methyltransferase promoter

Responses of patients with gliomas to temozolomide are determined by O(6)-methylguanine-DNA methyltransferase (MGMT) and mismatch repair (MMR) pathways. This phase II study (NCT00423150) investigated whether MGMT promoter methylation predicts response in patients with advanced aerodigestive tract and colorectal cancers (CRC). Tumor and serum samples were screened for MGMT promoter methylation. In methylation-positive patients, 150 mg/m(2) temozolomide was administered daily on a seven-day-on, seven-day-off schedule for each 28-day cycle. The primary efficacy endpoint was response rate (RR). MMR status was determined by a microsatellite instability assay. Among 740 patients screened, 86 were positive for MGMT promoter methylation and enrolled. Nineteen percent of the screened population (137/740) had confirmed tissue and/or serum MGMT promoter methylation, including 25% (57 of 229) for CRC, 36% (55 of 154) for esophageal cancer, 11% (12 of 113) for head and neck cancer, and 5% (13 of 242) for non-small cell lung carcinoma. Among patients with valid methylation results in both tissue and serum samples, concordance was 81% (339 of 419). The majority of enrolled patients (69 of 86; 80%) had microsatellite stable cancer. Overall RR was 6% (5 of 86 partial responses); all responders had microsatellite stable cancer. Temozolomide resulted in low RRs in patients enriched for MGMT methylation. MGMT methylation status varied considerably in the patient population. Although serum methylation assay is an option for promoter methylation detection, tissue assay remains the standard for methylation detection. The low RR of this cohort of patients indicates that MGMT methylation as a biomarker is not applicable to heterogeneous tumor types, and tumor-specific factors may override validated biomarkers.

Phase I study of folate conjugate EC145 (Vintafolide) in patients with refractory solid tumors

PURPOSE

EC145 (vintafolide), a conjugate of folic acid and the vinca alkaloid desacetylvinblastine hydrazide (DAVLBH), is a ligand for the folate receptor (FR), with activity against FR-positive tumor xenografts in vivo. This phase I study determined the maximum-tolerated dose (MTD) of EC145 administered as a bolus intravenous injection or 1-hour infusion in patients with refractory solid tumors.

PATIENTS AND METHODS

EC145 was administered as a bolus injection or 1-hour infusion on days 1, 3, and 5 and days 15, 17, and 19 of each 28-day cycle with dose escalation in cohorts of three to six patients until the MTD was identified. Plasma pharmacokinetics were determined on days 1 and 3 of the first cycle.

RESULTS

The MTD of EC145 was 2.5 mg when administered as either a bolus injection or 1-hour infusion. Constipation was the dose-limiting toxicity with both routes. Constipation, nausea, fatigue, and vomiting were the most commonly reported adverse events. One partial response to therapy was observed in a patient with metastatic ovarian cancer.

CONCLUSION

EC145 administered by bolus injection or as a 1-hour infusion at a dose of 2.5 mg on days 1, 3, and 5 and days 15, 17, and 19 of a 28-day cycle has an acceptable safety profile in patients with advanced cancer. On the basis of these findings, phase II studies of EC145 have been initiated in patients with advanced epithelial ovarian cancer and non-small-cell lung cancer.

Disease response and survival outcomes in acute myeloid leukemia (AML) patients unfit for chemotherapy treated with 10-day decitabine as initial therapy

6611

Background: AML is primarily a disease of older adults, with a median age of 67 years at diagnosis. Many patients are considered unfit for chemotherapy due to poor performance status and/or comorbidities, prompting investigation of less intensive approaches. A clinical trial in which 10-day courses of decitabine 20mg/m2 were given every 28 days as initial therapy demonstrated a promising complete remission (CR) rate and disease-free survival (DFS). We used this regimen to treat AML patients unfit for chemotherapy outside of a clinical trial. Methods: Charts of 32 newly diagnosed AML patients treated with 10-day courses of decitabine 20mg/m2 as initial therapy at the University of Maryland Greenebaum Cancer Center between September 2010 and November 2011 were retrospectively reviewed. If patients attained bone marrow blasts <5%, 5-day courses were administered subsequently and were continued until disease progression. Results: Median age at diagnosis was 74 years (range, 52-86). 18 patients were male and 14 female. 23 were Caucasian, 7 African-American and 1 Hispanic. 10 patients (31%) had performance status ≥ 2. All had significant cardiac, pulmonary and/or renal disease. Karyotype risk group was unfavorable in 17 patients, intermediate in 14 and unknown in one. There were 9 CRs and 1 partial remission, for an overall response rate of 31%, following a median of 2 (range, 1 to 4) courses. 21 patients did not respond to treatment following 1 to 6 courses, and one died within 29 days of treatment initiation. 21 patients (65%) were hospitalized at least once for fever or infection during treatment. Of the 9 patients who achieved CR, 5 had normal, 3 complex and 1 unknown karyotypes. Median DFS was 390 days (range, 87+-468+) and median OS 180 days (range, 15-623+). Six-month OS was 37.5% and 1-year OS 16.5%. Conclusions: AML patients unfit for chemotherapy treated with 10-day decitabine 20mg/m2 outside of a clinical trial had a higher response rate than reported for 5-day decitabine, but a lower response rate than in the reported clinical trial of the 10-day regimen. Additional novel treatment approaches are needed for these patients.

P1-12-20: The Safety and Tolerability of Vorinostat in Combination with Lapatinib in Advanced Solid Tumors

Background: Lapatinib has been previously shown to markedly decrease cancer stem cells (CSC) in HER2−positive breast cancer. In preclinical models, we have demonstrated that histone deacetylase inhibitors (HDACi) such as vorinostat can induce differentiation and decrease CSC. The combination of vorinostat and lapatinib is synergistic with a combination index of 0.32 (synergism if CI &lt;1). We therefore undertook a pilot study to evaluate the combination of these two drugs in advanced solid tumors.

Method: Patients were eligible if they were: age ≥ 18 years with incurable solid tumors, ECOG PS 0–2, adequate organ function, and no prior exposure to HDACi. The first 3 patients received lapatinib at the dose of 1,250 mg continuous daily and vorinostat 300 mg 4 days on 3 days off. The second dose level with lapatinib 1,250 mg continuous daily and vorinostat 400 mg 4 days on 3 days off were administered in 6 patients. Cycles were repeated every 21 days until disease progression. Echocardiogram and radiologic evaluation were performed every 12 weeks. During the first cycle, pharmacokinetic (PK) evaluation was performed on days 18 and 21.

Results: Nine consented patients (7 with metastatic breast cancer, 1 with non-small cell lung cancer, and 1 with thyroid cancer) have been enrolled with the median age of 52 (range 25–66). Patients received an average of 6 prior treatments (range 2–10). No dose limiting toxicity or drug related death have been observed. Grade 1–2 toxicities including diarrhea, fatigue, muscle cramps and stomatitis were observed. No grade 3 or 4 hepatic, renal or cardiac toxicity were observed (including no QTc prolongation and no significant reduction in the left ventricular ejection fraction). Patients have received the maximum of 7 cycles (median 3 cycles, range 2–7). Response: as of June 2011, 2 patients are still on treatment. Two patients achieved stable disease (triple negative metastatic breast cancer and HER2−positive breast cancer), 6 patients with progressive disease, and 1 patient is too early to evaluate for response. PK analysis will be presented at the time of the meeting.

Conclusions: The combination of vorinostat and lapatinib is tolerable and has some antitumor activity in heavily pretreated advanced solid tumors. A phase II study in HER2−positive metastatic breast cancer is underway with lapatinib 1,250 mg continuous daily and vorinostat 400 mg 4 days on 3 days off.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-12-20.

Safety, efficacy, pharmacokinetics, and pharmacodynamics of the combination of sorafenib and tanespimycin

PURPOSE

Heat shock protein (Hsp) 90 inhibition affects the Raf kinase signaling pathway and could enhance antitumor effects of sorafenib, a Raf kinase inhibitor. The combination of sorafenib and tanespimycin [17-allyl-amino-geldanamycin (17-AAG); NSC 330507/KOS-953] was evaluated in a phase I trial with the primary objective of defining a phase II dose.

PATIENTS AND METHODS

The dose cohorts consisted of fixed continuous oral dosing of 400 mg sorafenib twice daily, starting at 14 days before tanespimycin, which was administered intravenously at escalating doses (starting at 300 mg/m,(2) with 50 mg/m(2) increments), on days 1, 8, and 15 in a 28-day cycle. Toxicity was assessed weekly, and response was evaluated every two cycles.

RESULTS

Twenty-seven toxicity-evaluable patients were enrolled and treated at four dose levels. Predominant primary malignancies were renal cancer (12), melanoma (6), and colorectal cancer (4). Dose-limiting toxicities of grade 4 transaminitis and grade 3 hand-foot syndrome in one patient each were observed at 450 mg/m(2) of tanespimycin. One hundred fourteen cycles were administered with a median of four cycles (range 1-17 cycles). Plasma concentrations of sorafenib and metabolites reached steady state after 7 days. Tanespimycin did not alter sorafenib concentrations. Pharmacodynamics showed a decrease in Hsp90 levels and induction of Hsp70. Clinical efficacy was observed in 9 of 12 renal cancer patients and 4 of 6 melanoma patients

CONCLUSIONS

Recommended phase II doses of this combination are 400 mg sorafenib twice daily and 400 mg/m(2) tanespimycin on days 1, 8, and 15, every 28 days. Clinical and pharmacodynamic activity was observed in kidney cancer and melanoma.

Abstract 5413: Maximal Power Design and Analysis of Drug Combination Studies: Applications to Vorinostat with Cytosine Arabinoside and Etoposide and Other Combination Studies

Drug combinations are the hallmark of cancer therapy. Preclinical experiments on multi-drug combinations are important steps to bring the therapy to clinic. A statistical approach for evaluating the joint effect of the combination is necessary because even in vitro experiments often demonstrate significant variation in dose-effect. Such variation needs to be accounted for in the experimental design and analysis. Our research has developed a maximal power (MP) design and interaction index surface (IIS) analysis methods for in vitro and in vivo (e.g., xenograft) combination studies so that the joint effect of a combination can be estimated efficiently and the most synergistic combination can be identified. We demonstrate that these statistical methods and software have resulted in the identification of highly synergistic dose combinations that could have been missed with classic methods.

The first study is the combination of vorinostat (suberoylanilide hydroxamic acid) combined with ara-C and with etoposide in leukemia cell lines. The doses in the experiment were generated by the MP design and the data analyzed using the IIS approach so that synergistic, additive and antagonistic interaction dose regions are identified. Cytotoxic antagonism resulted when vorinostat was combined concomitantly with ara-C; however, when vorinostat was given first followed by a drug-free interval before ara-C treatment, this sequential combination was mostly synergistic. Etoposide combined with vorinostat was additive to synergistic, and the synergism became more pronounced when etoposide was given post a drug-free interval after vorinostat. These findings are used in designing the CTEP trial (NCI 6829: Phase I trial of vorinostat in combination with cytarabine and etoposide in patients with advanced acute leukemia and high-risk myelodysplastic syndromes, PI: Gojo/Ross). The interim results on toxicity and response have been consistent with the model.

Another study utilized a novel thiazolidine compound plus Sorafnib where initial experiments using classic methods failed to identify synergistic combinations. Subsequent experiments using the MP methodologies demonstrated significant synergistic drug combinations. The SynStat R program for the design and analysis of drug synergy is available at http://www.umgcc.org/research/biostat_software.htm).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5413.

Biodistribution of HPMA copolymer-aminohexylgeldanamycin-RGDfK conjugates for prostate cancer drug delivery

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymer-RGD (Arg-Gly-Asp) conjugates targeting the alpha(v)beta(3) integrin present on angiogenic blood vessels and some tumor types have shown increased accumulation in solid tumors and possess properties that suggest their use for site-specific drug delivery. Geldanamycin (GDM) is a benzoquinoid ansamycin that binds to heat-shock protein 90 (HSP90), effective for the treatment of multiple cancer types including prostate, but has dose-limiting cytotoxicity. We recently reported the synthesis of HPMA copolymer-aminohexyl-geldanamycin (AH-GDM) conjugates containing RGDfK that demonstrated favorable properties of drug release, in vitro binding to the alpha(v)beta(3) integrin, cytotoxicity in human prostate cancer cells, and tolerability in nude mice greater than 2-fold equivalent free drug doses. In this study the biodistribution of 125I-radiolabeled HPMA copolymer-AH-GDM conjugates with and without RGDfK in both non-tumor-bearing and DU145 prostate tumor xenograft-bearing nude mice was evaluated. At 60 mg/kg drug equivalent polymer doses in non-tumor-bearing mice both conjugates showed fast elimination from blood and decreasing accumulation in all other organs. Kidney accumulation predominated and was higher for the conjugate containing RGDfK. In tumor-bearing mice, trace quantities of the conjugate containing RGDfK showed increased tumor accumulation as compared to the conjugate without RGDfK. Also evaluated were free drug concentrations in prostate tumor xenografts following treatments of 30 and 60 mg/kg drug-equivalent copolymer conjugates (with and without RGDfK) compared with 30 mg/kg free AH-GDM. Overall, 60 mg/kg treatment of RGDfK-containing conjugate showed significantly higher (p < 0.001) tumor drug concentrations compared with all other treatments. The targetable conjugates can effectively deliver higher amounts of geldanamycin to the tumor compared to nontargetable systems.

A phase I trial of UCN-01 and prednisone in patients with refractory solid tumors and lymphomas

PURPOSE

UCN-01 potently inhibits protein kinase C, phosphatidylinositide-dependent kinase-1, and checkpoint kinase 1, which are involved in regulating cell cycle progression. We designed a phase I study to determine the maximum tolerated dose (MTD) of UCN-01 with prednisone in patients with advanced malignancies.

METHODS

UCN-01 was administered as a continuous intravenous infusion over 72 h in cycle 1 and 36 h in subsequent cycles. Prednisone was given orally at 60 mg/m(2) per day for five consecutive days within each 28-day cycle. Standard dose escalation was employed, and MTD was defined as the dose at which no more than one of six patients experienced a dose-limiting toxicity (DLT). Plasma pharmacokinetics of UCN-01 were assessed.

RESULTS

Fifteen patients received a total of 55 courses of treatment. The MTD and the recommended phase II dose of UCN-01 in this combination is 72 mg/m(2) total dose over 72 h for cycle 1 followed by 36 mg/m(2) per cycle over 36 h. All patients experienced hyperglycemia but responded to insulin treatment. Hypophosphatemia was a DLT in two patients. There were no cumulative toxicities. No objective responses were observed, but five patients had stable disease, including two patients with lymphoid malignancies who had prolonged disease stabilizations. UCN-01 has a long terminal half-life and low clearance; there was wide inter-patient variability in peak concentrations.

CONCLUSION

UCN-01 can be safely administered in combination with prednisone without unacceptable toxicity. The prolonged stable disease in two patients with lymphoid malignancies is a proof of principle for the evaluation of cyclin-dependent kinase inhibitors in oncology.

Clinical pharmacokinetics and exposure-toxicity relationship of a folate-Vinca alkaloid conjugate EC145 in cancer patients

The clinical pharmacokinetics and exposure-toxicity relationship were determined for EC145, a conjugate of folic acid and the Vinca alkaloid desacetylvinblastine hydrazide (DAVLBH), in cancer patients. EC145 plasma concentration and toxicity data were obtained from a first-in-man phase I study and analyzed by nonlinear mixed effect modeling with NONMEM. EC145 concentration-time profile after intravenous administration was well described by a 2-compartment model with a first-order elimination process from the central compartment. BSA was identified as a significant covariate on EC145 clearance, accounting for 14.6% of interindividual variation on EC145 clearance. Population estimates for the clearance, steady-state volume of distribution, distribution, and elimination half-lives were 56.1 L/h, 26.1 L, 6 minutes, and 26 minutes, respectively. Constipation and peripheral neuropathy were the most common and clinically relevant toxicities. The clearance and area under the concentration-time curve (AUC) were significant predictors for the incidence of EC145-induced constipation but not peripheral neuropathy. In conclusion, EC145 is rapidly distributed and eliminated in cancer patients. BSA is a statistically significant covariate on EC145 clearance, but its clinical relevance remains to be defined. EC145-induced constipation occurs at a higher frequency in the patients with lower EC145 clearance, where the drug exposure tends to be higher.

Targetable HPMA copolymer-aminohexylgeldanamycin conjugates for prostate cancer therapy

PURPOSE

This study focuses on the synthesis and characterization of N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-cyclo-RGD (Arg-Gly-Asp) conjugates for delivery of geldanamycin to prostate tumors.

MATERIALS AND METHODS

HPMA copolymers containing aminohexylgeldanamycin (AH-GDM) with and without the targeting peptide RGDfK were synthesized and characterized. Drug release from copolymers was evaluated using cathepsin B. Competitive binding of copolymer conjugates to alpha(v)beta(3) integrin was evaluated in prostate cancer (PC-3) and endothelial (HUVEC) cell lines and in vitro growth inhibition was assessed. The maximum tolerated dose for single i.v. injections of free drug and the conjugates was established in nude mice.

RESULTS

HPMA copolymers containing AH-GDM and RGDfK showed active binding to the alpha(v)beta(3) integrin similar to that of free peptide. Similarly, growth inhibition of cells by conjugates was comparable to that of the free drug. Single intravenous doses of HPMA copolymer-AH-GDM-RGDfK conjugates in mice were tolerated at 80 mg/kg drug equivalent, while free drug caused morbidity at 40 mg/kg. No signs of toxicity were present in mice receiving HPMA copolymer-AH-GDM-RGDfK over the 14-day evaluation period.

CONCLUSION

Results of in vitro activity and in vivo tolerability experiments hold promise for the utility of HPMA copolymer-AH-GDM-RGDfK conjugates for treatment of prostate cancer with greater efficacy and reduced toxicity.

Preclinical studies of vorinostat (suberoylanilide hydroxamic acid) combined with cytosine arabinoside and etoposide for treatment of acute leukemias

PURPOSE

Vorinostat [suberoylanilide hydroxamic acid (SAHA)] is a potent histone deacetylase inhibitor with promising clinical efficacy as an anticancer agent. In this preclinical study, we evaluated combining cytosine arabinoside [1-beta-D-arabinofuranosylcytosine (ara-C)] and/or etoposide with vorinostat for use in the treatment of acute leukemias.

EXPERIMENTAL DESIGN

Cell survival was examined in vitro in HL-60 human myeloid leukemia cells and K562 myeloid blast crisis chronic myelogenous leukemia cells, using the 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide inner salt and/or fluorescein diacetate/propidium iodide assays. Drug interactions were analyzed by the combination index method (CalcuSyn) and by a novel statistical method that we developed (SynStat). Cell cycle phase distribution was measured by flow cytometry.

RESULTS

Cytotoxic antagonism resulted when vorinostat was combined concomitantly with ara-C; however, when vorinostat was given first followed by a drug-free interval before ara-C treatment, this sequential combination was mostly synergistic. Etoposide combined with vorinostat was additive to synergistic, and the synergism became more pronounced when etoposide was given after vorinostat. Cell cycle analyses revealed that the sequence-dependent interaction of vorinostat and ara-C or etoposide reflected the arrest of cells in G1 or G2 phase during vorinostat treatment and recovery into S phase after removal of vorinostat.

CONCLUSIONS

These findings using two independent methods to assess drug combination effects provide a preclinical rationale for phase I trials of the sequential combination of vorinostat followed by ara-C and etoposide in patients with advanced or refractory leukemias. CalcuSyn findings were concordant with those of SynStat, validating the use of the latter in analyzing drug interactions.

A mechanistic perspective of monoclonal antibodies in cancer therapy beyond target-related effects

Several monoclonal antibodies are now in clinical use for cancer therapy, and many others are currently undergoing clinical evaluation. These agents offer unique specificity against key molecular targets on tumor cells or in the tumor microenvironment. The clinical efficacy of monoclonal antibodies is generally attributed to target-specific mechanisms resulting from neutralizing or inhibiting a growth factor or receptor that drives cell proliferation and tumor growth. Several targets, including CD20, human epidermal growth factor receptor 2, vascular endothelial growth factor, and epidermal growth factor receptor, have been validated in specific malignancies on the basis of monoclonal antibody efficacy. However, monoclonal antibodies also have the potential to activate immune-mediated effector functions, including antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity. These functions result from interactions involving the Fc domain of the antibody, and, consequently, may vary by antibody, isotype, and Fc modification, such as changes in glycosylation. Accordingly, all monoclonal antibodies directed against a given target should not be considered equivalent in their ability to stimulate immune-mediated effector functions.

Phase 1 and pharmacologic study of MS-275, a histone deacetylase inhibitor, in adults with refractory and relapsed acute leukemias

MS-275 is a benzamide derivative with potent histone deacetylase (HDAC) inhibitory and antitumor activity in preclinical models. We conducted a phase 1 trial of orally administered MS-275 in 38 adults with advanced acute leukemias. Cohorts of patients were treated with MS-275 initially once weekly x 2, repeated every 4 weeks from 4 to 8 mg/m2, and after 13 patients were treated, once weekly x 4, repeated every 6 weeks from 8 to 10 mg/m2. The maximum-tolerated dose was 8 mg/m2 weekly for 4 weeks every 6 weeks. Dose-limiting toxicities (DLTs) included infections and neurologic toxicity manifesting as unsteady gait and somnolence. Other frequent non-DLTs were fatigue, anorexia, nausea, vomiting, hypoalbuminemia, and hypocalcemia. Treatment with MS-275 induced increase in protein and histone H3/H4 acetylation, p21 expression, and caspase-3 activation in bone marrow mononuclear cells. No responses by classical criteria were seen. Our results show that MS-275 effectively inhibits HDAC in vivo in patients with advanced myeloid leukemias and should be further tested, preferably in patients with less-advanced disease.

Inhibition of Mitochondrial Respiration as a Source of Adaphostin-induced Reactive Oxygen Species and Cytotoxicity

Adaphostin is a dihydroquinone derivative that is undergoing extensive preclinical testing as a potential anticancer drug. Previous studies have suggested that the generation of reactive oxygen species (ROS) plays a critical role in the cytotoxicity of this agent. In this study, we investigated the source of these ROS. Consistent with the known chemical properties of dihydroquinones, adaphostin simultaneously underwent oxidation to the corresponding quinone and generated ROS under aqueous conditions. Interestingly, however, this quinone was not detected in intact cells. Instead, high performance liquid chromatography demonstrated that adaphostin was concentrated by up to 300-fold in cells relative to the extracellular medium and that the highest concentration of adaphostin (3000-fold over extracellular concentrations) was detected in mitochondria. Consistent with a mitochondrial site for adaphostin action, adaphostin-induced ROS production was diminished by >75% in MOLT-4 rho(0) cells, which lack mitochondrial electron transport, relative to parental MOLT-4 cells. In addition, inhibition of oxygen consumption was observed when intact cells were treated with adaphostin. Loading of isolated mitochondria to equivalent adaphostin concentrations caused inhibition of uncoupled oxygen consumption in mitochondria incubated with the complex I substrates pyruvate and malate or the complex II substrate succinate. Further analysis demonstrated that adaphostin had no effect on pyruvate or succinate dehydrogenase activity. Instead, adaphostin inhibited reduced decylubiquinone-induced cytochrome c reduction, identifying complex III as the site of inhibition by this agent. Moreover, adaphostin enhanced the production of ROS by succinate-charged mitochondria. Collectively, these observations demonstrate that mitochondrial respiration rather than direct redox cycling of the hydroquinone moiety is a source of adaphostin-induced ROS and identify complex III as a potential target for antineoplastic agents.