Bi-specific and tri-specific antibodies- the next big thing in solid tumor therapeutics.

Antibody-based therapy has revitalized the world of cancer therapeutics since rituximab was first approved for the treatment of Non-Hodgkin's Lymphoma. Monoclonal antibodies against cancer antigens have been successful strategies for only a handful of cancer types due to many reasons including lack of antibody specificity and complex nature of tumor milieu which interfere with antibody efficacy. Polyspecific antibodies are promising class of anti-cancer agents which can be directed at multiple tumor antigens to eradicate tumor cells more precisely and effectively. They may overcome some of these limitations and have already changed treatment landscape for some malignancies such as B cell acute lymphoblastic leukemia. Pre-clinical studies and early phase clinical trials have demonstrated that this approach may be an effective strategy even for solid tumors. This review focuses on the development of bispecific and trispecific antibody therapy for the treatment of solid tumor malignancies and highlights the potential they hold for future therapies to come.

Adjuvant ovarian function suppression and cognitive function in women with breast cancer.

BACKGROUND: To examine the effect on cognitive function of adjuvant ovarian function suppression (OFS) for breast cancer. METHODS: The Suppression of Ovarian Function (SOFT) trial randomised premenopausal women with hormone receptor-positive breast cancer to 5 years adjuvant endocrine therapy with tamoxifen+OFS, exemestane+OFS or tamoxifen alone. The Co-SOFT substudy assessed objective cognitive function and patient reported outcomes at randomisation (T0), and 1 year later (T1); the primary endpoint was change in global cognitive function, measured by the composite objective cognitive function score. Data were compared for the pooled tamoxifen+OFS and exemestane+OFS groups vs the tamoxifen alone group using the Wilcoxon rank-sum test. RESULTS: Of 86 participants, 74 underwent both T0 and T1 cognitive testing; 54 randomised to OFS+ either tamoxifen (28) or exemestane (26) and 20 randomised to tamoxifen alone. There was no significant difference in the changes in the composite cognitive function scores between the OFS+ tamoxifen or exemestane groups and the tamoxifen group (mean±s.d., -0.21±0.92 vs -0.04±0.49, respectively, P=0.71, effect size=-0.20), regardless of prior chemotherapy status, and adjusting for baseline characteristics. CONCLUSIONS: The Co-SOFT study, although limited by small samples size, provides no evidence that adding OFS to adjuvant oral endocrine therapy substantially affects global cognitive function.

Immune checkpoint inhibitors in lung cancer: past, present and future.

Inhibitory ligands on tumor cells and their corresponding receptors on T cells are collectively called immune checkpoint molecules and have emerged as druggable targets that harness endogenous immunity to fight cancer. Immune checkpoint inhibitors targeting CTLA-4, PD-1 and PD-L1 have been developed for the treatment of patients with non-small-cell lung cancer and other malignancies, with impressive clinical activity, durable responses and a favorable toxicity profile. This article reviews the development, current status and future directions for some of these agents. The efficacy and safety data for drugs such as ipilimumab, nivolumab, pembrolizumab, atezolizumab and durvalumab are reviewed, along with combination strategies and response evaluation criteria. The toxicity profiles and predictive biomarkers of response are also discussed.

P53 mutations in triple negative breast cancer upregulate endosomal recycling of epidermal growth factor receptor (EGFR) increasing its oncogenic potency.

There is no available targeted therapy for triple-negative or its more aggressive subtype, basal-like breast cancer. Multiple therapeutic strategies based on translational knowledge have not improved the treatment options for triple negative patients. As understanding of molecular pathways that drive tumor development is rapidly increasing, it is imperative to adapt our treatment strategies to perturbations in molecular pathways driving the malignant process. Basal-like breast cancers over-express EGFR (without mutations or EGFR gene amplifications) and have p53 mutations. While EGFR drives the malignant behavior in triple negative breast cancer (TNBC), anti-EGFR therapies have fallen short of the expected results in clinical trials. Here we bring evidence that the less than optimal results of the anti-EGFR therapies may be explained in part by the increased potency of the EGFR signaling due to increased endosomal recycling. The functional connection between EGFR and endosomal trafficking in TNBC is mutant p53 found in the most aggressive forms of TNBC. Mutant p53 acquires oncogenic functions and binds p63 protein, a member of p53 family with tumor suppressor activities. In the absence of functional p63 there is an upregulation of endosomal recycling EGFR and integrin to the membrane with increased proinvasive abilities of cancer cells. Blocking endosomal trafficking combined with anti-EGFR treatments may result in better clinical outcomes in TNBC.

The evolving use of arsenic in pharmacotherapy of malignant disease.

For more than 2,000 years, arsenic and its derivatives have shown medical utility. Owing to the toxicities and potential carcinogenicity of arsenicals, their popularity has fluctuated. The exact mechanism of action of therapeutic arsenic is not well characterized but likely to involve apoptosis, generation of reactive oxygen species, inhibition of intracellular transduction pathways, and cell functions. Arsenic trioxide has received approval for use in patients with relapsed acute promyelocytic leukemia for remission induction. Arsenic has additionally shown activity in a range of solid tumors, myelodysplastic syndrome, multiple myeloma, and in autoimmune diseases. The following is a review of the history of arsenic, its cellular metabolism, pharmacology, genetic basis of disposition, associated toxicities, and clinical efficacy.

Trastuzumab-DM1: a clinical update of the novel antibody-drug conjugate for HER2-overexpressing breast cancer.

Trastuzumab is a monoclonal antibody targeted against the HER2 tyrosine kinase receptor. Although trastuzumab is a very active agent in HER2-overexpressing breast cancer, the majority of patients with metastatic HER2-overexpressing breast cancer who initially respond to trastuzumab develop resistance within 1 year of initiation of treatment and, in the adjuvant setting, progress despite trastuzumab-based therapy. The antibody-drug conjugate trastuzumab-DM1 (T-DM1) was designed to combine the biological activity of trastuzumab with the targeted delivery of a highly potent antimicrotubule agent, DM1 (N-methyl-N-[3-mercapto-1-oxopropyl]-l-alanine ester of maytansinol), a maytansine derivative, to HER2-overexpressing breast cancer cells. T-DM1 is the first antibody-drug conjugate with a nonreducible thioether linker in clinical trials. Phase I and II clinical trials of T-DM1 as a single agent and in combination with paclitaxel, docetaxel and pertuzumab have shown clinical activity and a favorable safety profile in patients with HER2-positive metastatic breast cancer. Two randomized phase III trials of T-DM1 are awaiting final results; the EMILIA trial is evaluating T-DM1 compared with lapatinib plus capecitabine, and early positive results have been reported. The MARIANNE trial is evaluating T-DM1 plus placebo versus T-DM1 plus pertuzumab versus trastuzumab plus a taxane. Here, we summarize evidence from clinical studies and discuss the potential clinical implications of T-DM1.

Investigating the benefit of adding a vena cava filter to anticoagulation with fondaparinux sodium in patients with cancer and venous thromboembolism in a prospective randomized clinical trial.

BACKGROUND: The benefit of adding a vena cava filter to anticoagulation in treating cancer patients with venous thromboembolism remains controversial. We initiated this study as the first prospectively randomized trial to evaluate the addition of a vena cava filter placement to anticoagulation with the factor Xa inhibitor fondaparinux sodium in patients with cancer. METHODS: Sixty-four patients with deep vein thrombosis (86 %) and/or pulmonary embolism (55 %) were randomly assigned to receive anticoagulation with fondaparinux sodium with or without a vena cava filter. Endpoints included rates of complications by treatment arm, recurrent thromboembolism, complete resolution of thromboembolism, and survival rates. RESULTS: No patient had a recurrent deep vein thrombosis; two (3 %) patients had new pulmonary emboli, one in each randomized cohort. Major bleeding occurred in three patients (5 %). Two patients on the vena cava filter arm (7 %) had complications from the filter. Median survivals were 493 days in the anticoagulation only arm and 266 days for anticoagulation + vena cava filter (p < 0.57). Complete resolution of venous thromboembolism occurred in 51 % of patients within 8 weeks of initiating anticoagulation. CONCLUSIONS: No advantage was found for placement of a vena cava filter in addition to anticoagulation with fondaparinux sodium in terms of safety, recurrent thrombosis, recurrent pulmonary embolism, or survival in this prospective randomized trial evaluating anticoagulation plus a vena cava filter in cancer patients. Favorable complete resolution rates of thrombosis were observed on both study arms.

Identification of unique synergistic drug combinations associated with downexpression of survivin in a preclinical breast cancer model system.

An in-vitro 72-h assay using median effect analysis and curve shift analysis was used to evaluate the utility of potentially clinically useful combinations of agents for synergism or antagonism. Six human breast cancer cell lines, both receptor rich and receptor poor, were studied.Panobinostat (LBH-589), a pan histone deacetylase inhibitor with a multitude of biological effects, exhibits time-dependent synergistic effects in breast cancer cell lines with docetaxel, doxorubicin, or gemcitabine in clinically relevant concentrations. Survivin expression was markedly downregulated in the presence of panobinostat with gemcitabine. Bortezomib, a proteasome inhibitor,markedly enhanced the cytotoxic effects of panobinostat combined with gemcitabine. Panobinostat did not demonstrate universal enhancement of cytotoxic drugs,and therefore, synergy was dependent on the second agent selected. No synergy was noted with anti-Her2 agents in Her2 overexpressing cell lines. Metformin combined with panobinostat demonstrated no synergy in this test system. These effects were confirmed by an apoptosis assay and caspase-3 production. A positive drug interaction was identified. The triplet of panobinostat with either doxorubicin/carboplatin or gemcitabine/carboplatin was especially potent in all cell lines. As all these agents are clinically available, further studies of the potent combinations are warranted.

Poly(ADP-ribose) polymerase-1 inhibition: preclinical and clinical development of synthetic lethality.

The hereditary forms of breast cancer identified by BRCA1 and BRCA2 genes have a defect in homologous DNA repair and demonstrate a dependence on alternate DNA repair processes by base excision repair, which requires poly(ADP-ribose) polymerase 1 (PARP-1). siRNA and deletion mutations demonstrate that interference with PARP-1 function results in enhanced cell death when the malignancy has a defect in homologous recombination. These findings resulted in a plethora of agents in clinical trials that interfere with DNA repair, and these agents offer the potential of being more selective in their effects than classic chemotherapeutic drugs. An electronic search of the National Library of Medicine for published articles written in English used the terms "PARP inhibitors" and "breast cancer" to find prospective, retrospective and review articles. Additional searches were done for articles dealing with mechanism of action. A total of 152 articles dealing with breast cancer and PARP inhibition were identified. PARP inhibition not only affects nonhomologous repair, but also has several other nongenomic functions. Mutational resistance to these agents was seen in preclinical studies. To date, PARP-1 inhibitors were shown to enhance cytotoxic effects of some chemotherapy agents. This new class of agents may offer more therapeutic specificity by exploiting a DNA repair defect seen in some human tumors with initial clinical trials demonstrating antitumor activity. Although PARP inhibitors may offer a therapeutic option for selected malignancies, the long-term effects of these agents have not yet been defined.

The histone deacetylase inhibitor panobinostat demonstrates marked synergy with conventional chemotherapeutic agents in human ovarian cancer cell lines.

Although platinum based therapy has improved short term survival of patients with metastatic ovarian cancer, the majority of patients continue to relapse and eventually die of their disease. Currently, a plethora of agents are in development, but how to combine them to enhance efficacy remains largely empiric. We have used short in vitro culture of defined cell lines with application of promising agents and analysis for cell death using a MTT assay to identify potentially useful combinations. Using median effect analysis, curve shift analysis and apoptosis assays, we can identify when agents are synergistic or antagonistic when applied together. Up to three agents can be studied in combination. Using three cell lines: SK-OV3, CaOV-3, and ES-2 (a clear cell tumor), we have identified that panobinostat (LBH-589), a broad histone deacetylase inhibitor in clinical trials, demonstrates global synergy with gemcitabine, with paclitaxel, and additive to synergistic effects with 5'DFUR. The triplet of panobinostat, doxorubicin, and carboplatin is especially synergistic in these cell lines. These effects are cytotoxic and not cytostatic. As all these agents are used clinically, we have identified combinations which warrant further investigation.

Emerging role of small ribonucleic acids in gastrointestinal tumors.

Small regulatory ribonucleic acids (RNAs) are recently recognized as being connected with a growing list of common diseases such as: cancer, heart disease, diabetes and inflammation and to date more than 5,000 publications are recorded on PubMed alone. Specific pathways generate each class of RNAs and their activities converge in the process of silence interference. In gastrointestinal malignancies microRNAs are deregulated, sometimes found in higher or lower levels depending on the type of malignancy and stage of the disease, functioning either as tumor suppressors or as oncogenes they interact forming regulatory loops with known transcription factors and signaling pathways. MiRNAs extracted from archived tissue biopsies can be used effectively as diagnostic, prognostic tools and molecular markers because they are stable over time and resistant to RNAse degradation. The distinct physiology of small RNAs may translate in more targeted cancer therapies in the near future.

Phase I trials of amonafide as monotherapy and in combination with cytarabine in patients with poor-risk acute myeloid leukemia.

Amonafide-l-malate (amonafide) is a unique DNA intercalator that maintains activity in the presence of MDR mechanisms, a frequent cause of treatment-failure in secondary AML. 43 patients with relapsed/refractory or secondary AML or CML blast crisis were enrolled into two phase I dose-escalation studies investigating amonafide as monotherapy or in combination with cytarabine. 3/17 patients in the monotherapy trial and 10/26 patients in the combination trial achieved a complete remission. Between both trials responses occurred in 9/20 patients with secondary AML. Both trials demonstrated an acceptable safety profile and significant antileukemic activity in patients with poor-risk AML, especially those with secondary AML.

Adjuvant chemotherapy for early breast cancer in the elderly.

The use of cytotoxic therapy in the fit elderly breast cancer patient has been tempered with concerns of age, physical function, and co-morbid illness. In the appropriate patient with biologically aggressive disease, such as receptor poor breast cancer, it is reasonable to consider combination chemotherapy as part of an adjuvant program. If this approach is to be employed, the physician must also consider the patient's co-morbid conditions and status of function in society as potential indicators of toxicity or lack of benefit. In this case, a formal geriatric assessment is of value. A Cancer and Leukemia Group B (CALGB) trial of monotherapy vs combination cytotoxic therapy as adjuvant treatment for localized breast cancer patients over 65 years of age has determined that the combination approach is superior to single agent therapy. In an unplanned analysis of receptor rich and receptor poor tumors, the patients with receptor poor tumors seemed to achieve the greatest benefit from combination cytotoxic therapy. Adjuvant chemotherapy can also be considered for patients with high-risk receptor rich breast cancers. However, the use of chemotherapy in the elderly patient with breast cancer is largely based upon data emerging from trials in younger patients. Studies specifically for patients over 65 years of age are urgently needed in this population to provide evidence-based proof of the current approach.

Hypersensitivity to oxaliplatin: an investigation of incidence and risk factors, and literature review.

BACKGROUND: Hypersensitivity is a well-known complication of the platinum agents cisplatin and carboplatin. Although hypersensitivity to oxaliplatin has been noted, the incidence varies significantly in reports. Risk factors for developing reactions specifically to oxaliplatin have not been evaluated. We report the 5-year incidence of hypersensitivity to oxaliplatin in our clinical program, the patient and disease characteristics associated with its occurrence, and review the literature. METHODS: Clinical information on all patients treated with oxaliplatin between September 2002 and August 2007 was retrospectively reviewed. Data from patients who experienced hypersensitivity were compared to patients treated with this agent who did not. Risk factors investigated included age, sex, diagnosis, disease stage, presence of preexisting allergies, chemotherapy received, and use of oxaliplatin in front-line versus salvage therapy. RESULTS: 247 patients received oxaliplatin, with 29 experiencing hypersensitivity, for an incidence of 11.7% (95% CI 7.7-15.8). Grade 3/4 events occurred in 1.6%. Hypersensitivity was associated with younger mean age (54.9 +/- 12.5 vs. 60.4 +/- 12.4 years with reactions vs. those without, p = 0.02), female gender (17.2% of females vs. 6.4% of males, p = 0.01) and with use of oxaliplatin as salvage therapy (23.9% second-line or higher vs. 9.1% front-line, p = 0.01). CONCLUSIONS: Our data demonstrate an incidence of hypersensitivity to oxaliplatin of 11.7%, with grade 3/4 events in 1.6%. As use of this agent becomes more widespread, increased vigilance for this potentially serious complication should be high, especially amongst younger patients, females, and with the use of oxaliplatin as salvage therapy; three newly recognized potential risk factors.

Need for inferior vena cava filters in cancer patients: a surrogate marker for poor outcome.

BACKGROUND: Cancer patients have an increased incidence of venous thromboembolism (VTE). Inferior vena cava (IVC) filters are used extensively in the US, and more than 40 000 are inserted annually. The impact on survival of cancer patients receiving IVC filters has not been studied. METHODS: A retrospective study examined 206 consecutive cancer patients with VTE to compare the effects of IVC filter placement with anticoagulation (AC) therapy on overall survival (OS), as measured from the time of VTE. Patients were classified into 3 treatment groups: AC (n = 62), IVC filter (77), or combination IVC filter + AC (67). RESULTS: Treatment groups did not differ with respect to age, sex, or albumin levels. Median OS was significantly greater in patients treated with AC (13 months) compared with those treated with IVC filters (2 months) or IVC + AC (3.25 months; P < .0002). IVC patients were 1.9 times more at risk of death than AC only (hazard ratio = .528; 95% confidence interval = .374 to .745). Multivariate analysis revealed that performance status and type of thrombus were not confounders and had no effect on OS. CONCLUSION: The need for the insertion of an IVC filter projected markedly reduced survival. Patients requiring an IVC filter rather than AC as initial therapy face a 2-fold increase in risk of death. Whether or not this therapeutic procedure has a positive impact on outcome in cancer patients is uncertain. Complications resulting from thrombosis were also analyzed in this cohort. A prospective randomized trial at our institution is addressing this issue.

In-vitro synergism of m-TOR inhibitors, statins, and classical chemotherapy: potential implications in acute leukemia.

Classical chemotherapy has an active, but limited, role in acute leukemia with relapse common in adult patients. Recent evidence has implicated signal transduction pathways in leukemic progression and also in resistance to cytotoxic therapy. We have used a short-term, in-vitro incubation assay with cytotoxic analysis by MTT, confirmed by histone-associated DNA fragmentation, to evaluate both classical and nonclassical combinations of drugs. Isobologram median effect analysis, confirmed by curve shift analysis, was used to identify synergy and antagonism. Fluvastatin, a prenylation inhibitor, demonstrates global enhancement of the effects of classical agents in both AML-193 and KG-1 cell lines. Similarly, the m-TOR inhibitors, RAD-001 (everolimus) and rapamycin, also cause time-dependent global enhancement of cytotoxic agents. At clinically achievable combinations, RAD-001 perturbs the AKT pathway in vitro. The unique combination of fluvastatin and an m-TOR inhibitor was synergistic in both cell lines. These effects were independent of whether or not human plasma was used in the assay system. These studies suggest several novel combinations of agents that need to be evaluated in the management of leukemia.

Influence of activation state of ErbB-2 (HER-2) on response to adjuvant cyclophosphamide, doxorubicin, and fluorouracil for stage II, node-positive breast cancer: study 8541 from the Cancer and Leukemia Group B.

PURPOSE: ErbB-2 (human epidermal growth factor receptor 2) overexpression may be predictive of relative resistance and/or sensitivity to specific chemotherapeutic agents. Results from a previous study from the Cancer and Leukemia Group B (CALGB 8541) demonstrated an interaction between ErbB-2 and increasing dose of adjuvant cyclophosphamide, doxorubicin, and fluorouracil (CAF) chemotherapy. Other studies have suggested that evaluation of the phosphorylated/activated form of ErbB-2 might be more precise in defining the impact of ErbB-2 in breast cancer. We have evaluated tumor tissue sections from CALGB 8541 patients to determine whether the interaction of ErbB-2 with CAF dose is dependent on ErbB-2 activation state, and whether phosphorylated ErbB-2 is an adverse prognostic factor in patients treated with CAF. PATIENTS AND METHODS: Patients were randomly assigned to one of three dosing regimens of CAF. Paraffin samples from 992 of 1,572 patients who participated in CALGB 8541 were available. Of the 570 tumors with any staining for ErbB-2, 488 had tissue available for assay for phosphorylated ErbB-2, which was performed by immunohistochemistry. RESULTS: Of 910 total assessable cases, 112 of 488 ErbB-2-positive cases (23%) stained positively for phosphorylated ErbB-2. The previously described interaction of dosing regimen of CAF with ErbB-2 was not dependent on phosphorylation status of ErbB-2. CONCLUSION: Monitoring phosphorylation of ErbB-2 with an antiphospho-ErbB-2 antibody did not add further precision to identifying those patients most likely to benefit from increased dose of anthracycline-based adjuvant chemotherapy. Favorable outcomes are observed in ErbB-2-overexpressing patients treated with high-dose CAF regardless of ErbB-2 phosphorylation state.

Novel microtubule-targeting agents - the epothilones.

Epothilones are a new class of antimicrotubule agents currently in clinical trials. Their chemical structures are distinct from taxanes and are more amenable to synthetic modification. Six epothilones have been studied in preclinical and clinical trials: patupilone (epothilone B), ixabepilone (BMS247550), BMS 310705, sagopilone (ZK-EPO), KOS-862 (epothilone D), and KOS-1584. In vitro data have shown increased potency in taxane-sensitive and taxane-resistant cancer cell lines. This enhanced cytotoxic effect has been attributed to epothilone being a poor substrate for p-glycoprotein drug resistance protein and having high affinity to the various beta tubulin isoforms. Phase I clinical data have shown different dose-limiting toxicities for each of the epothilones. These effects are drug specific, dose specific, and schedule of administration specific. While diarrhea and myelosuppression are the dose-limiting toxicities for patupilone and BMS 310705, respectively, neurologic toxicity, as seen with taxanes, is the dose-limiting toxicity of ixabepilone, sagopilone, and KOS-862. In an effort to decrease neurologic toxicity, investigators have modified dosing schedules with limited success. Ixabepilone has the most mature clinical results with published phase II and III data, and regulatory approval for clinical use in the treatment of breast cancer. Ixabepilone has also been combined with other anticancer agents and has regulatory approval in combination with capecitabine for heavily treated breast cancer.

Toxicity of older and younger patients treated with adjuvant chemotherapy for node-positive breast cancer: the Cancer and Leukemia Group B Experience.

PURPOSE: Older node-positive patients treated with newer adjuvant chemotherapy regimens have improvements in relapse-free and overall survival similar to younger patients. We compared toxicity of older and younger patients in three randomized trials of adjuvant chemotherapy. PATIENTS AND METHODS: Toxicity data were available for 93% of 6,642 patients enrolled. The three trials included: Cancer and Leukemia Group B (CALGB) 8541, a comparison of cyclophosphamide, doxorubicin, and fluorouracil in three dose schedules; CALGB 9344: cyclophosphamide and doxorubicin with or without paclitaxel; and CALGB 9741: cyclophosphamide, doxorubicin, and paclitaxel every 2 versus every 3 weeks. National Cancer Institute grade 3 to 5 toxicities were compared among age groups. RESULTS: Seven percent of patients (n = 458) were age 65 or older, 3% were 70 or older, 38% were 51 to 64, and 55% were 50 or younger. Twenty-four deaths (0.4%) were attributed to treatment; seven (1.5%) of 486 in patients 65 or older, 10 (0.40%) of 2,480 in patients who were 51 to 64 years, and seven (0.19%) of 3,676 occurred in patients younger than 50. In multivariate analysis, older patients were significantly more likely to have grade 4 hematologic toxicity, to have discontinued treatment for toxicity, or to have died of acute myeloid leukemia/myelodysplastic syndrome. There were no significant differences in grade 3 to 4 nonhematologic toxicity. CONCLUSION: Healthy older patients who met the strict eligibility criteria for these trials had a higher rate of hematologic toxicity and treatment-related deaths than younger patients, but no increase in nonhematologic toxicity. Elderly patients treated with newer adjuvant chemotherapy regimens derive the same benefits from newer chemotherapy regimens as younger patients but should be cautioned about the increased risk of toxicity and treatment-related death.