Health-related quality of life with pembrolizumab monotherapy in patients with previously treated advanced microsatellite instability high/mismatch repair deficient endometrial cancer in the KEYNOTE-158 study.

OBJECTIVE: Pembrolizumab demonstrated a clinically meaningful objective response rate in patients with previously treated, advanced MSI-H/dMMR endometrial cancer in the multicohort phase 2 KEYNOTE-158 study (ClinicalTrials.gov, NCT02628067). We present health-related quality of life (HRQoL) results for these patients. METHODS: This analysis included patients from cohorts D (endometrial cancer with any MSI status) and K (any MSI-H/dMMR solid tumor except colorectal) who had previously treated, advanced MSI-H/dMMR endometrial cancer. Patients received pembrolizumab 200 mg Q3W for 35 cycles. EORTC QLQ-C30 and EQ-5D-3L questionnaires were administered at baseline, at regular intervals during treatment, and 30 days after treatment discontinuation. Pre-specified exploratory analyses included changes from baseline to week 9 in QLQ-C30 global health status (GHS)/QoL and EQ-5D-3L visual analog scale (VAS) score for all patients and by best overall response. RESULTS: 84 of 90 enrolled patients completed ≥1 HRQoL questionnaire and were included in the analysis. QLQ-C30 and EQ-5D-3L compliance rates were 90% and 94%, respectively, at baseline, and 92% and 93% at week 9. Mean (95% CI) QLQ-C30 GHS/QoL scores improved from baseline to week 9 by 6.08 (0.71-11.46) points in the overall population, with greater improvement in patients who achieved complete or partial response (11.67 [5.33-18.00]-point increase). Mean (95% CI) EQ-5D-3L VAS scores improved by 6.00 (2.25-9.75) points in the overall population and 9.11 (5.24-12.98) points in patients with CR/PR. CONCLUSIONS: Pembrolizumab maintained or improved HRQoL in patients with previously treated, advanced MSI-H/dMMR endometrial cancer, further supporting efficacy and safety results from KEYNOTE-158 and pembrolizumab use in this setting.

Pembrolizumab in microsatellite instability high or mismatch repair deficient cancers: updated analysis from the phase II KEYNOTE-158 study.

BACKGROUND: Pembrolizumab demonstrated durable antitumor activity in 233 patients with previously treated advanced microsatellite instability high (MSI-H) or mismatch repair deficient (dMMR) advanced solid tumors in the phase II multicohort KEYNOTE-158 (NCT02628067) study. Herein, we report safety and efficacy outcomes with longer follow-up for more patients with previously treated advanced MSI-H/dMMR noncolorectal cancers who were included in cohort K of the KEYNOTE-158 (NCT02628067) study. PATIENTS AND METHODS: Eligible patients with previously treated advanced noncolorectal MSI-H/dMMR solid tumors, measurable disease as per RECIST v1.1, and Eastern Cooperative Oncology Group performance status of 0 or 1 received pembrolizumab 200 mg Q3W for 35 cycles or until disease progression or unacceptable toxicity. The primary endpoint was objective response rate (ORR) as per RECIST v1.1 by independent central radiologic review. RESULTS: Three hundred and fifty-one patients with various tumor types were enrolled in KEYNOTE-158 cohort K. The most common tumor types were endometrial (22.5%), gastric (14.5%), and small intestine (7.4%). Median time from first dose to database cut-off (5 October 2020) was 37.5 months (range, 0.2-55.6 months). ORR among 321 patients in the efficacy population (patients who received ≥1 dose of pembrolizumab enrolled ≥6 months before the data cut-off date) was 30.8% [95% confidence interval (CI) 25.8% to 36.2%]. Median duration of response was 47.5 months (range, 2.1+ to 51.1+ months; '+' indicates no progressive disease by the time of last disease assessment). Median progression-free survival was 3.5 months (95% CI 2.3-4.2 months) and median overall survival was 20.1 months (95% CI 14.1-27.1 months). Treatment-related adverse events (AEs) occurred in 227 patients (64.7%). Grade 3-4 treatment-related AEs occurred in 39 patients (11.1%); 3 (0.9%) had grade 5 treatment-related AEs (myocarditis, pneumonia, and Guillain-Barre syndrome, n = 1 each). CONCLUSIONS: Pembrolizumab demonstrated clinically meaningful and durable benefit, with a high ORR of 30.8%, long median duration of response of 47.5 months, and manageable safety across a range of heavily pretreated, advanced MSI-H/dMMR noncolorectal cancers, providing support for use of pembrolizumab in this setting.

A review of cancer immunotherapy: from the past, to the present, to the future.

Compared with previous standards of care (including chemotherapy, radiotherapy, and surgery), cancer immunotherapy has brought significant improvements for patients in terms of survival and quality of life. Immunotherapy has now firmly established itself as a novel pillar of cancer care, from the metastatic stage to the adjuvant and neoadjuvant settings in numerous cancer types. In this review article, we highlight how the history of cancer immunotherapy paved the way for discoveries that are now part of the standard of care. We also highlight the current pitfalls and limitations of cancer checkpoint immunotherapy and how novel research in the fields of personalized cancer vaccines, autoimmunity, the microbiome, the tumour microenvironment, and metabolomics is aiming to solve those challenges.

Phase Ib study of atezolizumab combined with cobimetinib in patients with solid tumors.

BACKGROUND: Preclinical evidence suggests that MEK inhibition promotes accumulation and survival of intratumoral tumor-specific T cells and can synergize with immune checkpoint inhibition. We investigated the safety and clinical activity of combining a MEK inhibitor, cobimetinib, and a programmed cell death 1 ligand 1 (PD-L1) inhibitor, atezolizumab, in patients with solid tumors. PATIENTS AND METHODS: This phase I/Ib study treated PD-L1/PD-1-naive patients with solid tumors in a dose-escalation stage and then in multiple, indication-specific dose-expansion cohorts. In most patients, cobimetinib was dosed once daily orally for 21 days on, 7 days off. Atezolizumab was dosed at 800 mg intravenously every 2 weeks. The primary objectives were safety and tolerability. Secondary end points included objective response rate, progression-free survival, and overall survival. RESULTS: Between 27 December 2013 and 9 May 2016, 152 patients were enrolled. As of 4 September 2017, 150 patients received ≥1 dose of atezolizumab, including 14 in the dose-escalation cohorts and 136 in the dose-expansion cohorts. Patients had metastatic colorectal cancer (mCRC; n = 84), melanoma (n = 22), non-small-cell lung cancer (NSCLC; n = 28), and other solid tumors (n = 16). The most common all-grade treatment-related adverse events (AEs) were diarrhea (67%), rash (48%), and fatigue (40%), similar to those with single-agent cobimetinib and atezolizumab. One (<1%) treatment-related grade 5 AE occurred (sepsis). Forty-five (30%) and 23 patients (15%) had AEs that led to discontinuation of cobimetinib and atezolizumab, respectively. Confirmed responses were observed in 7 of 84 patients (8%) with mCRC (6 responders were microsatellite low/stable, 1 was microsatellite instable), 9 of 22 patients (41%) with melanoma, and 5 of 28 patients (18%) with NSCLC. Clinical activity was independent of KRAS/BRAF status across diseases. CONCLUSIONS: Atezolizumab plus cobimetinib had manageable safety and clinical activity irrespective of KRAS/BRAF status. Although potential synergistic activity was seen in mCRC, this was not confirmed in a subsequent phase III study. CLINICALTRIALS.GOV IDENTIFIER: NCT01988896 (the investigators in the NCT01988896 study are listed in the supplementary Appendix, available at Annals of Oncology online).

H3K27 Methylation: A Focal Point of Epigenetic Deregulation in Cancer.

Epigenetics, the modification of chromatin without changing the DNA sequence itself, determines whether a gene is expressed, and how much of a gene is expressed. Methylation of lysine 27 on histone 3 (H3K27me), a modification usually associated with gene repression, has established roles in regulating the expression of genes involved in lineage commitment and differentiation. Not surprisingly, alterations in the homeostasis of this critical mark have emerged as a recurrent theme in the pathogenesis of many cancers. Perturbations in the distribution or levels of H3K27me occur due to deregulation at all levels of the process, either by mutation in the histone itself, or changes in the activity of the writers, erasers, or readers of this mark. Additionally, as no single histone mark alone determines the overall transcriptional readiness of a chromatin region, deregulation of other chromatin marks can also have dramatic consequences. Finally, the significance of mutations altering H3K27me is highlighted by the poor clinical outcome of patients whose tumors harbor such lesions. Current therapeutic approaches targeting aberrant H3K27 methylation remain to be proven useful in the clinic. Understanding the biological consequences and gene expression pathways affected by aberrant H3K27 methylation may lead to identification of new therapeutic targets and strategies.

Challenges in initiating and conducting personalized cancer therapy trials: perspectives from WINTHER, a Worldwide Innovative Network (WIN) Consortium trial.

Advances in 'omics' technology and targeted therapeutic molecules are together driving the incorporation of molecular-based diagnostics into the care of patients with cancer. There is an urgent need to assess the efficacy of therapy determined by molecular matching of patients with particular targeted therapies. WINTHER is a clinical trial that uses cutting edge genomic and transcriptomic assays to guide treatment decisions. Through the lens of this ambitious multinational trial (five countries, six sites) coordinated by the Worldwide Innovative Networking Consortium for personalized cancer therapy, we discovered key challenges in initiation and conduct of a prospective, omically driven study. To date, the time from study concept to activation has varied between 19 months at Gustave Roussy Cancer Campus in France to 30 months at the Segal Cancer Center, McGill University (Canada). It took 3+ years to be able to activate US sites due to national regulatory hurdles. Access to medications proposed by the molecular analysis remains a major challenge, since their availability through active clinical trials is highly variable over time within sites and across the network. Rules regarding the off-label use of drugs, or drugs not yet approved at all in some countries, pose a further challenge, and many biopharmaceutical companies lack a simple internal mechanism to supply the drugs even if they wish to do so. These various obstacles should be addressed to test and then implement precision medicine in cancer.

Phosphorylation of eIF4E promotes EMT and metastasis via translational control of SNAIL and MMP-3.

The progression of cancers from primary tumors to invasive and metastatic stages accounts for the overwhelming majority of cancer deaths. Understanding the molecular events which promote metastasis is thus critical in the clinic. Translational control is emerging as an important factor in tumorigenesis. The messenger RNA (mRNA) cap-binding protein eIF4E is an oncoprotein that has an important role in cancer initiation and progression. eIF4E must be phosphorylated to promote tumor development. However, the role of eIF4E phosphorylation in metastasis is not known. Here, we show that mice in which eukaryotic translation initiation factor 4E (eIF4E) cannot be phosphorylated are resistant to lung metastases in a mammary tumor model, and that cells isolated from these mice exhibit impaired invasion. We also demonstrate that transforming growth factor-beta (TGFß) induces eIF4E phosphorylation to promote the translation of Snail and Mmp-3 mRNAs, and the induction of epithelial-to-mesenchymal transition (EMT). Furthermore, we describe a new model wherein EMT induced by TGFß requires translational activation via the non-canonical TGFß signaling branch acting through eIF4E phosphorylation.

A phase I dose escalation trial of tremelimumab (CP-675,206) in combination with gemcitabine in chemotherapy-naive patients with metastatic pancreatic cancer.

BACKGROUND: Tremelimumab (CP-675,206) is a fully human monoclonal antibody binding to cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) on T cells that stimulates the immune system by blocking the CTLA4-negative regulatory signal. Combination with standard chemotherapy may strengthen antitumor therapy. This is a phase Ib, multisite, open-label, nonrandomized dose escalation trial evaluating the safety, tolerability, and maximum tolerated dose (MTD) of tremelimumab combined with gemcitabine in patients with metastatic pancreatic cancer. PATIENTS AND METHODS: Gemcitabine (1000 mg/m(2) on days 1, 8, and 15 of each 28-day cycles) was administrated with escalating doses of i.v. tremelimumab (6, 10, or 15 mg/kg) on day 1 of each 84-day cycle for a maximum of 4 cycles. The first 18 patients had an initial 4-week gemcitabine-only lead-in period. Dose-limiting toxicities (DLTs) related to tremelimumab were evaluated during the first 6 weeks after the first dose of tremelimumab. RESULTS: From June 2008 to August 2011, 34 patients were enrolled and received at least one dose of tremelimumab. No DLTs related to tremelimumab were observed at any dose, even when the maximum dose established for tremelimumab (15 mg/kg) was used. Most frequent grade 3/4 toxicities were asthenia (11.8%) and nausea (8.8%). Only one patient had a serious drug-related event (diarrhea with dehydration). The median overall survival was 7.4 months (95% confidence interval 5.8-9.4 months). At the end of treatment, two patients achieved partial response. Both patients received tremelimumab 15-mg/kg group (n = 2/19, 10.5%). CONCLUSION: Tremelimumab plus gemcitabine demonstrated a safety and tolerability profile, warranting further study in patients with metastatic pancreatic cancer. CLINICALTRIALSGOV ID: NCT00556023.

Patient perception of the benefit of a BRAF inhibitor in metastatic melanoma: quality-of-life analyses of the BREAK-3 study comparing dabrafenib with dacarbazine.

BACKGROUND: In a randomized phase III study (BREAK-3), dabrafenib showed prolonged progression-free survival (PFS) (median 5.1 versus 2.7 months; hazard ratio = 0.30; 95% confidence interval 0.18-0.53; P < 0.0001) compared with dacarbazine (DTIC) in patients with BRAF V600E metastatic melanoma. Assessing how these results are transformed into a real health benefit for patients is crucial. METHODS: The EORTC QLQ-C30 questionnaire assessed quality of life (QoL) at baseline and follow-up visits. RESULTS: For DTIC, all functional dimensions except role dimension worsened from baseline at follow-up. For dabrafenib, all functionality dimensions remained stable relative to baseline or improved at week 6; mean change in seven symptom dimensions improved from baseline, with appetite loss, insomnia, nausea and vomiting, and pain showing the greatest improvement. In the DTIC arm, symptom dimensions were unchanged or worsened from baseline for all symptoms except pain (week 6), with the greatest exacerbations observed for fatigue and nausea and vomiting. Mixed-model-repeated measures analyses showed significant (P < 0.05) and/or clinically meaningful improvements from baseline in favor of dabrafenib for emotional and social functioning, nausea and vomiting, appetite loss, diarrhea, fatigue, dyspnea, and insomnia at weeks 6 and/or 12. After crossing over to dabrafenib upon progression (n = 35), improvements in all QoL dimensions were evident after receiving dabrafenib for 6 (n = 31) to 12 (n = 25) weeks. CONCLUSIONS: This first reported QoL analysis for a BRAF inhibitor in metastatic melanoma demonstrates that the high tumor response rates and PFS superiority of dabrafenib over DTIC is not only a theoretical advantage, but also transforms in a rapid functional and symptomatic benefit for the patient. ClinicalTrials.gov Identifier: NCT01227889.

166Ho and 90Y labeled 6D2 monoclonal antibody for targeted radiotherapy of melanoma: comparison with 188Re radiolabel.

INTRODUCTION: An approach to radioimmunotherapy (RIT) of metastatic melanoma is the targeting of melanin pigment with monoclonal antibodies (mAbs) to melanin radiolabeled with therapeutic radionuclides. The proof of principle experiments were performed using a melanin-binding antibody 6D2 of IgM isotype radiolabeled with a ß emitter (188)Re and demonstrated the inhibition of tumor growth. In this study we investigated the efficacy of 6D2 antibody radiolabeled with two other longer lived ß emitters (90)Y and (166)Ho in treatment of experimental melanoma, with the objective to find a possible correlation between the efficacy and half-life of the radioisotopes which possess high energy ß (E(max)>1.5 MeV) emission properties. METHODS: 6D2 was radiolabeled with longer lived ß emitters (90)Y and (166)Ho in treatment of experimental melanoma in A2058 melanoma tumor-bearing nude mice. The immunoreactivity of the radiolabeled 6D2 mAb, its in vitro binding to the MNT1 human melanoma cells, the biodistribution and therapy in A2058 human melanoma bearing nude mice as well as dosimetry calculations were performed. RESULTS: When labeled with the longer lived (90)Y radionuclide, the 6D2 mAb did not produce any therapeutic effect in tumor bearing mice while the reduction of the tumor growth by (166)Ho-6D2 was very similar to the previously reported therapy results for (188)Re-6D2. In addition, (166)Ho-labeled mAb produced the therapeutic effect on the tumor without any toxic effects while the administration of the (90)Y-labeled radioconjugate was toxic to mice with no appreciable anti-tumor effect. CONCLUSIONS: (166)Ho-labeled mAb to melanin produced some therapeutic effect on the tumor without any toxic effects while the administration of the (90)Y-labeled radioconjugate was toxic to mice with no appreciable anti-tumor effect. We concluded that the serum half-life of the 6D2 carrier antibody matched well the physical half-life of (166)Ho to deliver the tumoricidal absorbed dose to the tumor. Further investigation of this radionuclide for RIT of melanoma is warranted.

Vorinostat-induced autophagy switches from a death-promoting to a cytoprotective signal to drive acquired resistance.

Histone deacetylase inhibitors (HDACi) have shown promising activity against hematological malignancies in clinical trials and have led to the approval of vorinostat for the treatment of cutaneous T-cell lymphoma. However, de novo or acquired resistance to HDACi therapy is inevitable, and their molecular mechanisms are still unclear. To gain insight into HDACi resistance, we developed vorinostat-resistant clones from the hematological cell lines U937 and SUDHL6. Although cross-resistant to some but not all HDACi, the resistant cell lines exhibit dramatically increased sensitivity toward chloroquine, an inhibitor of autophagy. Consistent with this, resistant cells growing in vorinostat show increased autophagy. Inhibition of autophagy in vorinostat-resistant U937 cells by knockdown of Beclin-1 or Lamp-2 (lysosome-associated membrane protein 2) restores sensitivity to vorinostat. Interestingly, autophagy is also activated in parental U937 cells by de novo treatment with vorinostat. However, in contrast to the resistant cells, inhibition of autophagy decreases sensitivity to vorinostat. These results indicate that autophagy can switch from a proapoptotic signal to a prosurvival function driving acquired resistance. Moreover, inducers of autophagy (such as mammalian target of rapamycin inhibitors) synergize with vorinostat to induce cell death in parental cells, whereas the resistant cells remain insensitive. These data highlight the complexity of the design of combination strategies using modulators of autophagy and HDACi for the treatment of hematological malignancies.

The novel arsenical Darinaparsin circumvents BRG1-dependent, HO-1-mediated cytoprotection in leukemic cells.

Darinaparsin (Dar) is a more potent cytotoxic arsenical than arsenic trioxide (ATO). We hypothesized that the increased cytotoxicity of Dar may be because of a decreased cytoprotective response. We observed that, unlike ATO, Dar does not induce heme oxygenase-1 (HO-1), even though it induces expression of other nuclear factor (erythroid-derived 2)-like 2 (NRF2)-dependent detoxifying enzymes to a greater extent than ATO, in both cancer cell lines and patient-derived leukemic cells. This strengthens the emerging evidence, showing that response to reactive oxygen species (ROS) is stimuli specific. Dar treatment prevents recruitment of the transcriptional coregulator Brahma-related gene 1 (BRG1) to the HMOX1 promoter, which is required for HMOX1 expression. The inability of Dar to induce HO-1 correlates with arrest in G2/M cell cycle phase and BRG1 phosphorylation. Inhibition of HO-1 increases the toxicity of ATO, but has no effect on Dar-induced apoptosis. Accordingly, the lack of HO-1 induction is involved in Dar's enhanced antileukemic properties. Our data highlight cytoprotective responses mediated by HO-1 and BRG1 as a novel target for enhancing the therapeutic range of arsenicals.

Phase I evaluation of the effects of ketoconazole and rifampicin on cediranib pharmacokinetics in patients with solid tumours.

PURPOSE: To investigate any effect of a CYP3A4 inhibitor (ketoconazole) or inducer (rifampicin) on cediranib steady-state pharmacokinetics in patients with advanced solid tumours. METHODS: In two Phase I, open-label trials, patients received once-daily oral doses of cediranib alone [20 mg (ketoconazole study); 45 mg (rifampicin study)] for 7 days followed by cediranib at the same dose with ketoconazole 400 mg/day for 3 days or once-daily rifampicin 600 mg/day for 7 days, respectively. Patients then continued to receive once-daily cediranib. RESULTS: In the ketoconazole study, 46 patients were dosed; 38 were evaluable for C (ss,max), 36 for AUC(ss). gMean AUC(ss) and C (ss,max) for cediranib 20 mg increased by 21 % (94 % CI 9-35 %) and 26 % (94 % CI 10-43 %), respectively, in the presence of ketoconazole. In the rifampicin study, 64 patients were dosed; 44 were evaluable for C (ss,max) and 41 for AUC(ss). gMean AUC(ss) and C (ss,max) for cediranib 45 mg decreased by 39 % (90 % CI 34-43 %) and 23 % (90 % CI 16-30 %), respectively, in the presence of rifampicin. gMean ratios for AUC(ss) and C (ss,max) were >1 for ketoconazole and <1 for rifampicin and CIs were outside the pre-specified equivalence boundaries, indicating a statistically significant effect. Significant inter-patient variability in cediranib AUC(ss) and C (ss,max) was observed. The safety profile of cediranib was similar to that reported previously. CONCLUSIONS: Co-administration of ketoconazole or rifampicin had statistically significant effects on steady-state pharmacokinetics of cediranib in patients with advanced solid tumours. Therefore, caution is advised when administering cediranib with potent enzyme inhibitors or inducers.

Ki 67 is a major, but not the sole determinant of Oncotype Dx recurrence score.

BACKGROUND: Immunohistological assessment of Ki 67 expression is less expensive than Oncotype Dx, which is currently used to identify patients with lymph node-negative breast cancer, who will benefit from adjuvant chemotherapy. METHODS: The relationship of immunohistologically measured Ki 67 to Oncotype DX recurrence score (RS) was examined in 53 cases of T1-2 N0 M0 (oestrogen receptor-positive, HER2/neu negative) breast cancer. RESULTS: There was a strong linear correlation between Ki 67 value and the Oncotype Dx RS. All patients in the low Ki 67 group (Ki 67 of ≤ 10%) had Oncotype Dx RSs of low or intermediate risk. The vast majority of patients (93.8%) in the high-Ki 67 group (Ki 67 ≥ 25%) had oncotype RSs of high or intermediate risk. CONCLUSION: Ki 67 proliferation value is a major, but not the sole determinant of Oncotype Dx score.

Targeting PKC delta-mediated topoisomerase II beta overexpression subverts the differentiation block in a retinoic acid-resistant APL cell line.

Retinoic acid (RA) relieves the maturation block in t(15:17) acute promyelocytic leukemia (APL), leading to granulocytic differentiation. However, RA treatment alone invariably results in RA resistance, both in vivo and in vitro. RA-resistant cell lines have been shown to serve as useful models for elucidation of mechanisms of resistance. Previously, we identified topoisomerase II beta (TOP2B) as a novel mediator of RA-resistance in APL cell lines. In this study, we show that both TOP2B protein stability and activity are regulated by a member of the protein kinase C (PRKC) family, PRKC delta (PRKCD). Co-treatment with a pharmacologic inhibitor of PRKCD and RA resulted in the induction of an RA responsive reporter construct, as well as the endogenous RA target genes, CEBPE, CYP26A1 and RIG-I. Furthermore, the co-treatment overcame the differentiation block in RA-resistant cells, as assessed by morphological analysis, restoration of promyelocytic leukemia nuclear bodies, induction of CD11c cell surface expression and an increase in nitro-blue-tetrazolium reduction. Cumulatively, our data suggest a model whereby inhibition of PRKCD decreases TOP2B protein levels, leading to a loss of TOP2B-mediated repressive effects on RA-induced transcription and granulocytic differentiation.

A novel arsenical has antitumor activity toward As2O3-resistant and MRP1/ABCC1-overexpressing cell lines.

Inorganic arsenic trioxide (As(2)O(3)) is a highly effective treatment for acute promyelocytic leukemia (APL). However, other cancers do not respond well to this form of arsenic at clinically achievable doses. We tested a novel arsenical, S-dimethylarsino-glutathione (darinaparsin) for efficacy in various malignancies in vitro. Darinaparsin is significantly more potent than As(2)O(3) at mediating apoptosis in various malignant cell lines and is highly active against APL cells derived for As(2)O(3) resistance. We provide evidence that darinaparsin triggers apoptosis by inducing signaling pathways that do not completely overlap with As(2)O(3). We show that darinaparsin induces apoptosis and oxidative stress to a greater extent than As(2)O(3), although like As(2)O(3), darinaparsin-induced toxicity is c-Jun NH(2)-terminal kinase-dependent. However, darinaparsin does not induce promyelocytic leukemia/retinoic acid receptor alpha (PML/RAR alpha) degradation or rearrange PML nuclear bodies in APL cells, nor is its toxicity increased by glutathione depletion. Darinaparsin treatment results in higher intracellular arsenic accumulation when compared to As(2)O(3) treatment. This may be explained by our finding that As(2)O(3), but not darinaparsin, is efficiently exported by ABCC1, suggesting increased therapeutic efficacy of darinaparsin in ABCC1-overexpressing tumors. Our studies indicate that darinaparsin efficiently kills tumor cells with increased antioxidant capacity and drug exporters and suggest that darinaparsin may have a broader therapeutic spectrum than As(2)O(3).

Phase I clinical trial of i.v. ascorbic acid in advanced malignancy.

BACKGROUND: Ascorbic acid is a widely used and controversial alternative cancer treatment. In millimolar concentrations, it is selectively cytotoxic to many cancer cell lines and has in vivo anticancer activity when administered alone or together with other agents. We carried out a dose-finding phase I and pharmacokinetic study of i.v. ascorbic acid in patients with advanced malignancies. PATIENTS AND METHODS: Patients with advanced cancer or hematologic malignancy were assigned to sequential cohorts infused with 0.4, 0.6, 0.9 and 1.5 g ascorbic acid/kg body weight three times weekly. RESULTS: Adverse events and toxicity were minimal at all dose levels. No patient had an objective anticancer response. CONCLUSIONS: High-dose i.v. ascorbic acid was well tolerated but failed to demonstrate anticancer activity when administered to patients with previously treated advanced malignancies. The promise of this approach may lie in combination with cytotoxic or other redox-active molecules.

Trolox enhances the anti-lymphoma effects of arsenic trioxide, while protecting against liver toxicity.

Arsenic trioxide (As2O3) is an effective therapy in acute promyelocytic leukemia (APL), but its use in other malignancies is limited by the higher concentrations required to induce apoptosis. We have reported that trolox, an analogue of alpha-tocopherol, increases As2O3-mediated apoptosis in a variety of APL, myeloma and breast cancer cell lines, while non-malignant cells may be protected. In the present study, we extended previous results to show that trolox increases As2O3-mediated apoptosis in the P388 lymphoma cell line in vitro, as evidenced by decrease of mitochondrial membrane potential and release of cytochrome c. We then sought to determine whether this combination can enhance antitumor effects while protecting normal cells in vivo. In BDF1 mice, trolox treatment decreased As2O3-induced hepatomegaly, markers of oxidative stress and hepatocellular damage. In P388 tumor-bearing mice, As2O3 treatment prolonged survival, and the addition of trolox provided a further significant increase in lifespan. In addition, the combination of As2O3 and trolox inhibited metastatic spread, and protected the tumor-bearing mice from As2O3 liver toxicity. Our results suggest, for the first time, that trolox might prevent some of the clinical manifestations of As2O3-related toxicity while increasing its pro-apoptotic capacity and clinical efficacy in hematological malignancies.

Ulcerative dermatitis, thrombocytopenia, and neutropenia in neonatal foals.

This report describes transient ulcerative dermatitis, severe thrombocytopenia, and mild neutropenia in 6 foals from 4 mares from geographically diverse regions of the United States. The foals presented at <4 days of age with oral and lingual ulcers, and crusting and erythema around the eyes, muzzle, and perineal, inguinal, axillary, trunk, and neck regions. There was a severe thrombocytopenia (0-30,000 platelets/microL), leukopenia (1900-3200 white blood cells/microL), and mild neutropenia (500-1800 neutrophils/microL). Four of the 6 foals had petechiae and ecchymotic hemorrhages and 3 had bleeding tendencies. Results of examination of a bone marrow biopsy from 1 foal were normal and results of a platelet surface immunoglobulin test in another were negative. Histopathology of the skin in all foals showed subepidermal clefting with subjacent vascular dilation, dermal hemorrhage, and superficial papillary necrosis. The foals were treated supportively with broad-spectrum antibiotics (5/6), corticosteroids (3/6), gastric ulcer prophylaxis (6/6), whole-blood transfusion (4/6), and platelet-rich plasma (1/6). The skin lesions and thrombocytopenia (>50,000 platelets/microL) improved in 2 weeks (4/6). Two foals had a decline in their platelet counts when the steroids were decreased and needed protracted treatment. All foals survived and were healthy as yearlings. Two mares that had 2 affected foals each, upon subsequent pregnancies to different stallions, had healthy foals when an alternate source of colostrum was given. The findings in the cases in this report suggest a possible relationship between colostral antibodies or some other factor in the colostrum and the thrombocytopenia and skin lesions, although further investigation is warranted to confirm or refute this hypothesis.