Brentuximab vedotin

Phase I study of the anti-endothelin B receptor antibody-drug conjugate DEDN6526A in patients with metastatic or unresectable cutaneous, mucosal, or uveal melanoma

Background Endothelin B receptor (ET_BR) is involved in melanoma pathogenesis and is overexpressed in metastatic melanoma. The antibody-drug conjugate DEDN6526A targets ET_BR and is comprised of the humanized anti-ET_BR monoclonal antibody conjugated to the anti-mitotic agent monomethyl auristatin E (MMAE). Methods This Phase I study evaluated the safety, pharmacokinetics, pharmacodynamics, and anti-tumor activity of DEDN6526A (0.3-2.8 mg/kg) given every 3 weeks (q3w) in patients with metastatic or unresectable cutaneous, mucosal, or uveal melanoma. Results Fifty-three patients received a median of 6 doses of DEDN6526A (range 1-49). The most common drug-related adverse events (>25% across dose levels) were fatigue, peripheral neuropathy, nausea, diarrhea, alopecia, and chills. Three patients in dose-escalation experienced a dose-limiting toxicity (infusion-related reaction, increased ALT/AST, and drug-induced liver injury). Based on cumulative safety data across all dose levels, the recommended Phase II dose (RP2D) for DEDN6526A was 2.4 mg/kg intravenous (IV) q3w. The pharmacokinetics of antibody-conjugated MMAE and total antibody were dose-proportional at doses ranging from 1.8-2.8 mg/kg. A trend toward faster clearance was observed at doses of 0.3-1.2 mg/kg. There were 6 partial responses (11%) in patients with metastatic cutaneous or mucosal melanoma, and 17 patients (32%) had prolonged stable disease ≥6 months. Responses were independent of BRAF mutation status but did correlate with ET_BR expression. Conclusion DEDN6526A administered at the RP2D of 2.4 mg/kg q3w had an acceptable safety profile and showed evidence of anti-tumor activity in patients with cutaneous, mucosal, and uveal melanoma. ClinicalTrials.gov identifier: NCT01522664.

Conjugation of DM1 to anti-CD30 antibody has potential antitumor activity in CD30-positive hematological malignancies with lower systemic toxicity

An anti-CD30 antibody-drug conjugate incorporating the antimitotic agent DM1 and a stable SMCC linker, anti-CD30-MCC-DM1, was generated as a new antitumor drug candidate for CD30-positive hematological malignancies. Here, the in vitro and in vivo pharmacologic activities of anti-CD30-MCC-DM1 (also known as F0002-ADC) were evaluated and compared with ADCETRIS (brentuximab vedotin). Pharmacokinetics (PK) and the safety profiles in cynomolgus monkeys were assessed. Anti-CD30-MCC-DM1 was effective in in vitro cell death assays using CD30-positive lymphoma cell lines. We studied the properties of anti-CD30-MCC-DM1, including binding, internalization, drug release and actions. Unlike ADCETRIS, anti-CD30-MCC-DM1 did not cause a bystander effect in this study. In vivo, anti-CD30-MCC-DM1 was found to be capable of inducing tumor regression in subcutaneous inoculation of Karpas 299 (anaplastic large cell lymphoma), HH (cutaneous T-cell lymphoma) and L428 (Hodgkin's disease) cell models. The half-lives of 4 mg/kg and 12 mg/kg anti-CD30-MCC-DM1 were about 5 days in cynomolgus monkeys, and the tolerated dose was 30 mg/kg in non-human primates, supporting the tolerance of anti-CD30-MCC-DM1 in humans. These results suggest that anti-CD30-MCC-DM1 presents efficacy, safety and PK profiles that support its use as a valuable treatment for CD30-positive hematological malignancies.

Novel and Future Therapeutic Drugs for Advanced Mycosis Fungoides and Sézary Syndrome

Mycosis fungoides (MF) and Sézary syndrome (SS) are the most common subtypes of cutaneous T-cell lymphoma. The majority of MF cases present with only patches and plaques and the lesions are usually limited to the skin. On the other hand, in some cases, patients show skin tumors or erythroderma followed by lymph node involvement and rarely visceral organ involvement. SS is a rare, aggressive cutaneous T-cell lymphoma marked by exfoliative erythroderma, lymphadenopathy, and leukemic blood involvement. Because patients with relapsed or refractory MF/SS display a poor prognosis and the current treatment options are characterized by high rates of relapse, there is unmet need for the efficient treatment. This review provides a discussion of the recent and future promising therapeutic approaches in the management of advanced MF/SS. These include mogamulizumab, brentuximab vedotin, alemtuzumab, immune checkpoint inhibitors, IPH4102 (anti-KIR3DL2 antibody), histone deacetylase inhibitors (vorinostat, romidepsin, panobinostat, belinostat, and resminostat), pralatrexate, forodesine, denileukin diftitox, duvelisib, lenalidomide, and everolimus.

Clinical development of targeted and immune based anti-cancer therapies

Cancer is currently the second leading cause of death globally and is expected to be responsible for approximately 9.6 million deaths in 2018. With an unprecedented understanding of the molecular pathways that drive the development and progression of human cancers, novel targeted therapies have become an exciting new development for anti-cancer medicine. These targeted therapies, also known as biologic therapies, have become a major modality of medical treatment, by acting to block the growth of cancer cells by specifically targeting molecules required for cell growth and tumorigenesis. Due to their specificity, these new therapies are expected to have better efficacy and limited adverse side effects when compared with other treatment options, including hormonal and cytotoxic therapies. In this review, we explore the clinical development, successes and challenges facing targeted anti-cancer therapies, including both small molecule inhibitors and antibody targeted therapies. Herein, we introduce targeted therapies to epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), human epidermal growth factor receptor 2 (HER2), anaplastic lymphoma kinase (ALK), BRAF, and the inhibitors of the T-cell mediated immune response, cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein-1 (PD-1)/ PD-1 ligand (PD-1 L).

Antibody drug conjugates: Progress, pitfalls, and promises

Antibody drug conjugates (ADCs) represent a promising and an efficient strategy for targeted cancer therapy. Comprised of a monoclonal antibody, a cytotoxic drug, and a linker, ADCs offer tumor selectively, reduced toxicity, and improved stability in systemic circulation. Recent approvals of two ADCs have led to a resurgence in ADC research, with more than 60 ADCs under various stages of clinical development. The therapeutic success of future ADCs is dependent on adherence to key requirements of their design and careful selection of the target antigen on cancer cells. Here we review the main components in the design of antibody drug conjugates, improvements made, and lessons learned over two decades of research, as well as the future of third generation ADCs.

Antibody-Based Therapies for Cutaneous T-Cell Lymphoma

Cutaneous T-cell lymphomas (CTCLs) are a group of non-Hodgkin's lymphomas that present in the skin. In early-stage disease, the course is generally chronic and indolent; however, in advanced stages of disease, therapies rarely provide long-lasting responses, and the only potential curative therapy is allogeneic hematopoietic stem-cell transplantation. This has led to the search for novel targeted therapies to better treat more advanced stages of CTCLs that cannot be controlled by typical treatment regimens. One area of advancement has been the development of antibodies specifically targeted to cell types that are known to be involved in CTCL. At present, brentuximab vedotin, an antibody-drug conjugate composed of an anti-cluster of differentiation (CD)-30 antibody covalently linked to monomethyl auristatin E, is approved for the treatment of CD30+ lymphoproliferative disorders [lymphomatoid papulosis (LyP) and primary cutaneous-anaplastic large-cell lymphoma (pc-ALCL)] as well as transformed CD30+ mycosis fungoides (MF). Additionally, mogamulizumab, an anti-chemokine receptor 4 (CCR4) monoclonal antibody, is approved for patients with MF or Sézary syndrome (SS) for whom one prior systemic therapy has failed. Trials are underway looking into the use of immune checkpoint inhibitors in the treatment of CTCLs. As we continue to research CTCL, and as antibody-based therapies continue to advance, more antibody-specific targeted therapy could provide alternative treatment regimens for patients with advanced CTCL.

Peripheral T-Cell Lymphoma, not Otherwise Specified (PTCL-NOS)

Peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) is a World Health Organization (WHO)-defined diagnostic category within the highly heterogeneous group of mature post-thymic T-cell neoplasms. It is the most common subtype of mature post-thymic T-cell neoplasms globally, accounting for up to 35% of PTCL cases in Europe and North America. PTCL-NOS is a diagnosis of exclusion, comprising several disease entities that differ in biology, clinical presentation, and outcome. The diagnosis of PTCL-NOS is made based on the presence of typical histopathological features of lymphoma, an aberrant T-cell immunophenotype, often with a loss of CD5 and CD7, and a clonal T-cell receptor (TCR) gene rearrangement, in the appropriate clinical context. Unlike other types of T-cell lymphoma, recurrent mutations to assist with the diagnosis have not been identified. Patients often present with advanced stage. Prognosis is poor, with a 5-year overall survival (OS) of 20-30%. Anthracycline-based combination chemotherapy remains the most frequently used frontline strategy, with overall response rates (ORR) of 50-60%, and complete response rates (CRR) of 20-30%. Prospective studies with intent-to-treat analyses have shown that consolidation with high-dose chemotherapy and autologous stem cell transplant (ASCT) results in progression-free survivals (PFS) that compare favorably with historical cohorts and may improve OS in selected patient populations. However, randomized data are still lacking. Over the past decade, therapeutic agents approved in the relapsed and refractory setting have produced response rates of up to 33% and median PFS up to 18 months. Overall, outcomes remain poor and there is a dire need for more effective treatments. This review discusses the latest information on the diagnosis and treatment of PTCL-NOS.

CYP Suppression in Human Hepatocytes by Monomethyl Auristatin E, the Payload in Brentuximab Vedotin (Adcetris®), is Associated with Microtubule Disruption

BACKGROUND AND OBJECTIVES

Monomethyl auristatin E (MMAE), the toxin linked to CD30-specific monoclonal antibody of Adcetris^® (brentuximab vedotin), is a potent anti-microtubule agent. Brentuximab vedotin has been approved for the treatment of relapsed or refractory Hodgkin lymphoma and anaplastic large cell lymphoma. Cytochrome P450 (CYP) induction assessment of MMAE was conducted in human hepatocytes to assess DDI potentials and its translation to clinic.

METHODS

MMAE was incubated at 1-1000 nM with cultured primary human hepatocytes for 72 h, and CYP1A2, CYP2B6, and CYP3A4 mRNA expression was assessed by quantitative reverse transcription-polymerase chain reaction and CYP-specific probe substrate by liquid chromatography coupled with mass spectrometry, along with microtubule disruption by immunofluorescence staining using anti-β-tubulin antibody and imaging.

RESULTS

MMAE up to 10 nM had no significant effect on CYP1A2, CYP2B6, and CYP3A4 mRNA expression and activity, whereas at higher concentrations of 100- and 1000-nM MMAE, the CYP mRNA expression and activity were diminished substantially. Further investigation showed that the degree of CYP suppression was paralleled by that of microtubule disruption by MMAE, as measured by increase in the number of β-tubulin-positive aggregates. At the clinical dose, the concentration of MMAE was 7 nM which did not show any significant CYP suppression or microtubule disruption in hepatocytes.

CONCLUSIONS

MMAE was not a CYP inducer in human hepatocytes. However, it caused a concentration-dependent CYP mRNA suppression and activity. The CYP suppression was associated with microtubule disruption, supporting the reports that intact microtubule architecture is required for CYP regulations. The absence of CYP suppression and microtubule disruption in vitro at the clinical plasma concentrations of MMAE (< 10 nM) explains the lack of pharmacokinetic drug interaction between brentuximab vedotin and midazolam, a sensitive CYP3A substrate, reported in patients.

Current Strategies and Applications for Precision Drug Design

Since Human Genome Project (HGP) revealed the heterogeneity of individuals, precision medicine that proposes the customized healthcare has become an intractable and hot research. Meanwhile, as the Precision Medicine Initiative launched, precision drug design which aims at maximizing therapeutic effects while minimizing undesired side effects for an individual patient has entered a new stage. One of the key strategies of precision drug design is target based drug design. Once a key pathogenic target is identified, rational drug design which constitutes the major part of precision drug design can be performed. Examples of rational drug design on novel druggable targets and protein-protein interaction surfaces are summarized in this review. Besides, various kinds of computational modeling and simulation approaches increasingly benefit for the drug discovery progress. Molecular dynamic simulation, drug target prediction and in silico clinical trials are discussed. Moreover, due to the powerful ability in handling high-dimensional data and complex system, deep learning has efficiently promoted the applications of artificial intelligence in drug discovery and design. In this review, deep learning methods that tailor to precision drug design are carefully discussed. When a drug molecule is discovered, the development of specific targeted drug delivery system becomes another key aspect of precision drug design. Therefore, state-of-the-art techniques of drug delivery system including antibody-drug conjugates (ADCs), and ligand-targeted conjugates are also included in this review.

A novel chemotherapeutic protocol for peritoneal metastasis and inhibition of relapse in drug resistant ovarian cancer

The majority of ovarian cancer patients are diagnosed in late stages of the disease, in which the tumor cells have leaked into the peritoneum and are present as tumorspheres. These tumorspheres are rich in cancer stem‐like cells (CSCs), which are resistant to therapy and are a major source of relapse. The purpose of this research was to identify a safe therapeutic approach that could eradicate the peritoneal CSC‐rich tumorspheres and inhibit relapse. Highly metastatic ascitic cells (OVASC‐1) that are resistant to standard‐of‐care chemotherapy due to upregulation of MDR1 gene were obtained from a patient with ovarian carcinoma and recurrent disease. CSC‐rich tumorspheres were generated, characterized, and treated with different chemotherapeutics. The most effective drug combination that could eradicate tumorspheres at nanomolar levels despite upregulation of MDR1 gene was identified. Luciferase‐expressing OVASC‐1 cells were implanted in the peritoneum of nude mice and treated with the identified drug combination. The progression of disease, response to therapy and recurrence were studied by quantitative imaging. Toxicity to abdominal tissues was studied by histopathology. Mice implanted with intraperitoneal (IP) OVASC‐1 xenografts showed limited response to combination therapy with cisplatin/paclitaxel at the maximum tolerated dose. Despite overexpression of MDR1 on OVASC‐1 cells, mice treated with our combination IP low‐dose MMAE and SN‐38 chemotherapy showed complete response without relapse. No signs of toxicity to abdominal tissues were observed. While MMAE and SN‐38 are not administered as free drugs due to their high potency and potential for systemic toxicity, our low‐dose localized therapy approach effectively restricted the cytotoxic effects to the tumor cells in the peritoneum. Consequently, maximum efficacy with minimal adverse effects was achieved. These remarkable results with IP low‐dose combination chemotherapy encourage investigation into its potential clinical application as either first‐line therapy or in cases of acquired resistance to cisplatin and paclitaxel.

Dermal xanthomatous infiltrates after brentuximab vedotin therapy in mycosis fungoides with large-cell transformation: A novel histologic finding

Mycosis fungoides (MF) is the most common variant of cutaneous T-cell lymphomas. Large-cell transformation of MF has been associated with disease progression and overall poor outcome. The expression of CD30, which defines anaplastic large cell lymphoma (ALCL) and lymphomatoid papulosis, might also occur in a subset of patients with MF, with or without large-cell transformation. Brentuximab vedotin is an anti-CD30 monoclonal antibody which has been proven to be a safe and effective therapeutic agent in the treatment of CD30-positive lymphomas, such as Hodgkin lymphoma and ALCL. Recently, brentuximab vedotin has been shown to have a significant clinical activity in treatment-refractory or advanced MF or Sezary syndrome with a wide-range of CD30 expression levels. We report a patient with MF tumor stage with large-cell transformation and low CD30 expression with good response to brentuximab vedotin and unusual extensive xanthomatous changes in the follow-up biopsy.

Neurological complications of new chemotherapy agents

This last decade has yielded more robust development of cancer treatments and first-in-class agents than ever before. Since 2006, nearly one hundred new drugs have received regulatory approval for the treatment of hematological and solid organ neoplasms. Moreover, older conventional therapies have received approval for new clinical indications and are being used in combination with these newer small-molecule targeted treatments. The nervous system is vulnerable to many of the traditional cancer therapies, manifesting both already well-described acute and chronic toxicities. However, newer agents may produce toxicities that may seem indistinguishable from the underlying cancer. Early recognition of neurotoxicities from new therapeutics is vital to avoid irreversible neurological injury. This review focuses on cancer therapies in use in the last 10 years and approved by the FDA from January 2006 through January 1, 2017.

A retrospective examination of the US Food and Drug Administration's clinical pharmacology reviews of oncology biologics for potential use of therapeutic drug monitoring

Background

Biologics have gained traction for use in oncology, but have demonstrate clinical variability for efficacy and safety. Therapeutic drug monitoring (TDM) can benefit patients’ outcomes from a biologic therapy when the latter has a defined therapeutic window. A clinically relevant therapeutic window may exist for biologics with established exposure-response (E–R) relationships for efficacy and/or safety and a documented maximum tolerated dose (MTD). Additionally, the inter-individual variability (IIV) on the clearance (CL) parameter could determine risks for patients falling outside the proposed therapeutic window.

Materials and methods

The US Food and Drug Administration (FDA)-approved oncology biologics between 2005–2016 were reviewed via FDA “Purple Book” (FDA-repository for licensed biologics). Data were extracted from biologics’ pharmacokinetic models available on the clinical pharmacology reviews published on the FDA-Approved Drug Products website. Evaluated features for biologics with established E–R relationships for efficacy and/or safety and MTD include an IIV for the CL and various other covariates including demographic factors, disease factors, blood chemistry, or immunogenicity.

Results

Five therapies were identified with documented E–R relationships for both efficacy and safety including, Yervoy^®(ipilimumab), Zaltrap^® (ziv-aflibercept), Portrazza^® (necitumumab), Adcetris^® (brentuximab-vedotin), and Blincyto^® (blinatumomab). The corresponding IIV on CL were: 34%, 33%, 29%, 47%, and 97%, respectively. Among the five therapies, only three had defined MTD including, brentuximab-vedotin, necitumumab, and blinatumomab.

Conclusion

Of the medications examined, blinatumomab was identified as the anticancer drug with the most available information for the establishment of TDM, and hence, may benefit through the use of TDM to optimize effectiveness and minimize patients’ toxicity. The approach used here may provide a generalizable framework to retrospectively identify anticancer biologics with high IIV that may benefit from TDM to improve patients’ clinical outcome.

Phase I study of safety and pharmacokinetics of the anti-MUC16 antibody-drug conjugate DMUC5754A in patients with platinum-resistant ovarian cancer or unresectable pancreatic cancer

BACKGROUND

MUC16 is a tumor-specific antigen overexpressed in ovarian (OC) and pancreatic (PC) cancers. The antibody-drug conjugate (ADC), DMUC5754A, contains the humanized anti-MUC16 monoclonal antibody conjugated to the microtubule-disrupting agent, monomethyl auristatin E (MMAE).

PATIENTS AND METHODS

This phase I study evaluated safety, pharmacokinetics (PK), and pharmacodynamics of DMUC5754A given every 3 weeks (Q3W, 0.3-3.2 mg/kg) or weekly (Q1W, 0.8-1.6 mg/kg) to patients with advanced recurrent platinum-resistant OC or unresectable PC. Biomarker studies were also undertaken.

RESULTS

Patients (66 OC, 11 PC) were treated with DMUC5754A (54 Q3W, 23 Q1W). Common related adverse events (AEs) in >20% of patients (all grades) over all dose levels were fatigue, peripheral neuropathy, nausea, decreased appetite, vomiting, diarrhea, alopecia, and pyrexia in Q3W patents, and nausea, vomiting, anemia, fatigue, neutropenia, alopecia, decreased appetite, diarrhea, and hypomagnesemia in Q1W patients. Grade ≥3-related AE in ≥5% of patients included neutropenia (9%) and fatigue (7%) in Q3W patients, and neutropenia (17%), diarrhea (9%), and hyponatremia (9%) in Q1W patients. Plasma antibody-conjugated MMAE (acMMAE) and serum total antibody exhibited non-linear PK across tested doses. Minimal accumulation of acMMAE, total antibody, or unconjugated MMAE was observed. Confirmed responses (1 CR, 6 PRs) occurred in OC patients whose tumors were MUC16-positive by IHC (2+ or 3+). Two OC patients had unconfirmed PRs; six OC patients had stable disease lasting >6 months. For CA125, a cut-off of ≥70% reduction was more suitable for monitoring treatment response due to the binding and clearance of serum CA125 by MUC16 ADC. We identified circulating HE4 as a potential novel surrogate biomarker for monitoring treatment response of MUC16 ADC and other anti-MUC16 therapies in OC.

CONCLUSIONS

DMUC5754A has an acceptable safety profile and evidence of anti-tumor activity in patients with MUC16-expressing tumors. Objective responses were only observed in MUC16-high patients, although prospective validation is required.

CLINICAL TRIAL NUMBER

NCT01335958.

Primary cutaneous anaplastic large cell lymphoma

Primary cutaneous anaplastic large cell lymphoma (PC-ALCL) is a CD30+ lymphoproliferative disorder (LPD) of the skin with a relatively good prognosis in the absence of high-stage disease. CD30+ LPDs comprise approximately 25%-30% of primary cutaneous lymphomas and as a group represent the second most common clonal T-cell neoplasm of the skin behind mycosis fungoides. Diagnosis of PC-ALCL relies strongly on clinicopathologic correlation given the potential morphologic, clinical and molecular overlap with the other cutaneous CD30+ LPD, lymphomatoid papulosis, and more aggressive hematolymphoid neoplasms.

CD30-positive cutaneous lymphoma: report of four cases with an emphasis on clinicopathological correlations

The classification of cutaneous lymphomas is multidisciplinary and requires the correlation between clinical, histopathological, immunohistochemical, and molecular diagnostic elements. In this article, we present four different cases of CD30-positive T-cell lymphoma with cutaneous manifestations. We compare cases with definitive diagnosis of papulosis lymphomatoid type C, primary cutaneous anaplastic large T-cell lymphoma, systemic anaplastic large T-cell lymphoma with secondary skin involvement, and mycosis fungoides with large cell transformation, highlighting the importance of clinicopathological correlation to classify these cases.

Preparation and Antitumor Activity of CS5931, A Novel Polypeptide from Sea Squirt Ciona Savignyi

CS5931 is a novel anticancer agent isolated from the sea squirt Ciona savignyi. However, its content in the species is very low, and developing a novel approach for production of the polypeptide is promising. In the present study, we expressed and purified the polypeptide from E. coli, and the fermentation conditions were studied using response surface methodology. The yield of CS5931 was increased from 2.0 to 7.5 mg/L. The denaturing and renaturation conditions were also studied. Using the optimized renaturation condition, the anticancer activity of refolding CS5931 was increased significantly; the value of IC₅₀ was decreased from 23.2 to 11.6 μM. In vivo study using xenograft nude mice bearing HCT116 cancer cells revealed that CS5931 was able to inhibit the growth of tumor significantly. The study provides a useful approach for obtaining enough amount of CS5931 for further study. This study is also important for developing the polypeptide as a novel anticancer agent.

Marked enhancement of lysosomal targeting and efficacy of ErbB2-targeted drug delivery by HSP90 inhibition

Targeted delivery of anticancer drugs to tumor cells using monoclonal antibodies against oncogenic cell surface receptors is an emerging therapeutic strategy. These strategies include drugs directly conjugated to monoclonal antibodies through chemical linkers (Antibody-Drug Conjugates, ADCs) or those encapsulated within nanoparticles that in turn are conjugated to targeting antibodies (Antibody-Nanoparticle Conjugates, ANPs). The recent FDA approval of the ADC Trastuzumab-TDM1 (Kadcyla; Genentech; San Francisco) for the treatment of ErbB2-overexpressing metastatic breast cancer patients has validated the strong potential of these strategies. Even though the activity of ANPs and ADCs is dependent on lysosomal traffic, the roles of the endocytic route traversed by the targeted receptor and of cancer cell-specific alterations in receptor dynamics on the efficiency of drug delivery have not been considered in these new targeted therapies. For example, constitutive association with the molecular chaperone HSP90 is thought to either retard ErbB2 endocytosis or to promote its recycling, traits undesirable for targeted therapy with ANPs and ADCs. HSP90 inhibitors are known to promote ErbB2 ubiquitination, targeting to lysosome and degradation. We therefore hypothesized that ErbB2-targeted drug delivery using Trastuzumab-conjugated nanoparticles could be significantly improved by HSP90 inhibitor-promoted lysosomal traffic of ErbB2. Studies reported here validate this hypothesis and demonstrate, both in vitro and in vivo, that HSP90 inhibition facilitates the intracellular delivery of Trastuzumab-conjugated ANPs carrying a model chemotherapeutic agent, Doxorubicin, specifically into ErbB2-overexpressing breast cancer cells, resulting in improved antitumor activity. These novel findings highlight the need to consider oncogene-specific alterations in receptor traffic in the design of targeted drug delivery strategies. We suggest that combination of agents that enhance receptor endocytosis and lysosomal routing can provide a novel strategy to significantly improve therapy with ANPs and ADCs.

Immuno-PET Imaging of CD30-Positive Lymphoma Using 89Zr-Desferrioxamine-Labeled CD30-Specific AC-10 Antibody

The CD30-specific antibody-drug conjugate, brentuximab vedotin, is approved for the treatment of relapsed, refractory Hodgkin lymphomas and systemic anaplastic large T-cell lymphomas. Multiple ongoing clinical trials are investigating brentuximab vedotin efficacy in other CD30-positive hematologic malignancies. Because CD30 expression varies among different types of lymphoma and can also change during the course of treatment, companion diagnostic imaging of CD30 could be a valuable tool in optimizing patient-specific brentuximab vedotin treatment regimens.

METHODS

The mouse antihuman CD30 antibody AC-10 was radiolabeled with the positron-emitting radionuclide (89)Zr. The stability and specificity of (89)Zr-desferrioxamine (DFO)-labeled CD30-specific AC-10 antibody ((89)Zr-DFO-AC-10) was evaluated in vitro. The pharmacokinetics of (89)Zr-DFO-AC-10 was studied in BALB/c nude mice bearing subcutaneous human Karpas 299 tumors (CD30-positive model) or A-431 tumors (CD30-negative model) using PET/CT imaging, biodistribution studies, and autoradiography.

RESULTS

AC-10 was conjugated with a DFO B chelator and radiolabeled with (89)Zr to give formulated (89)Zr-DFO-AC-10 with a radiochemical yield of 80%, radiochemical purity greater than 99%, and specific activity of 111-148 MBq/mg. (89)Zr-DFO-AC-10 was stable in mouse and human sera and preserved the immunoreactivity toward CD30. Biodistribution data showed the highest tissue accumulation of (89)Zr-DFO-AC-10 in CD30-positive tumors, with 37.9% ± 8.2% injected activity per gram of tissue at 72 h after injection, whereas uptake in CD30-negative tumors was 11.0% ± 0.4%. The specificity of (89)Zr-DFO-AC-10 binding to CD30 in vivo was confirmed by blocking studies. Time-activity curves showed that between 24 and 144 h after injection, tumor-to-muscle ratios increased from 18.9 to 51.8 in the CD30-positive model and from 4.8 to 8.7 in the CD30-negative model. Tumor-to-blood ratios also increased, from 3.2 to 13.6 and from 1 to 2 in the CD30-positive and -negative models, respectively.

CONCLUSION

Our results demonstrate that for measuring CD30 expression, (89)Zr-DFO-AC-10 is a sensitive PET agent with high tumor-to-normal-tissue contrast. (89)Zr-DFO-AC-10 is a promising CD30-imaging radiotracer for clinical translation in patients with various lymphomas and other diseases.

Antibody-drug conjugates as novel anti-cancer chemotherapeutics

Over the past couple of decades, antibody-drug conjugates (ADCs) have revolutionized the field of cancer chemotherapy. Unlike conventional treatments that damage healthy tissues upon dose escalation, ADCs utilize monoclonal antibodies (mAbs) to specifically bind tumour-associated target antigens and deliver a highly potent cytotoxic agent. The synergistic combination of mAbs conjugated to small-molecule chemotherapeutics, via a stable linker, has given rise to an extremely efficacious class of anti-cancer drugs with an already large and rapidly growing clinical pipeline. The primary objective of this paper is to review current knowledge and latest developments in the field of ADCs. Upon intravenous administration, ADCs bind to their target antigens and are internalized through receptor-mediated endocytosis. This facilitates the subsequent release of the cytotoxin, which eventually leads to apoptotic cell death of the cancer cell. The three components of ADCs (mAb, linker and cytotoxin) affect the efficacy and toxicity of the conjugate. Optimizing each one, while enhancing the functionality of the ADC as a whole, has been one of the major considerations of ADC design and development. In addition to these, the choice of clinically relevant targets and the position and number of linkages have also been the key determinants of ADC efficacy. The only marketed ADCs, brentuximab vedotin and trastuzumab emtansine (T-DM1), have demonstrated their use against both haematological and solid malignancies respectively. The success of future ADCs relies on improving target selection, increasing cytotoxin potency, developing innovative linkers and overcoming drug resistance. As more research is conducted to tackle these issues, ADCs are likely to become part of the future of targeted cancer therapeutics.

Management of relapsed or refractory hodgkin lymphoma with second-generation antibody-drug conjugates: focus on brentuximab vedotin

Brentuximab vedotin (Adcetris, Seattle Genetics) is an antibody-drug conjugate (ADC) that joins an anti-CD 30 monoclonal antibody with the anti-tubulin agent monomethyl auristatin E via a dipeptide linker. It has demonstrated significant activity in CD 30-positive lymphomas and is currently approved by the US FDA for treatment of Hodgkin lymphoma that has relapsed following autologous stem-cell transplantation, or after two lines of chemotherapy in non-transplant candidates. Brentuximab vedotin has also been approved for the treatment of relapsed anaplastic large-cell lymphoma after front-line chemotherapy. We briefly review the biology of Hodgkin lymphoma, with a focus on the pathogenic role of CD 30 as well as the development of CD 30-targeted therapy. We also discuss both the current role of brentuximab vedotin in the management of relapsed and refractory Hodgkin lymphoma and the likely future developments for this agent.

Current methods for the synthesis of homogeneous antibody-drug conjugates

Development of efficient and safe cancer therapy is one of the major challenges of the modern medicine. Over the last few years antibody-drug conjugates (ADCs) have become a powerful tool in cancer treatment with two of them, Adcetris® (brentuximab vedotin) and Kadcyla® (ado-trastuzumab emtansine), having recently been approved by the Food and Drug Administration (FDA). Essentially, an ADC is a bioconjugate that comprises a monoclonal antibody that specifically binds tumor surface antigen and a highly potent drug, which is attached to the antibody via either cleavable or stable linker. This approach ensures specificity and efficacy in fighting cancer cells, while healthy tissues remain largely unaffected. Conventional ADCs, that employ cysteine or lysine residues as conjugation sites, are highly heterogeneous. This means that the species contain various populations of the ADCs with different drug-to-antibody ratios (DARs) and different drug load distributions. DAR and drug-load distribution are essential parameters of ADCs as they determine their stability and efficacy. Therefore, various drug-loaded forms of ADCs (usually from zero to eight conjugated molecules per antibody) may have distinct pharmacokinetics (PK) in vivo and may differ in clinical performance. Recently, a significant progress has been made in the field of site-specific conjugation which resulted in a number of strategies for synthesis of the homogeneous ADCs. This review describes newly-developed methods that ensure homogeneity of the ADCs including use of engineered reactive cysteine residues (THIOMAB), unnatural amino acids, aldehyde tags, enzymatic transglutaminase- and glycotransferase-based approaches and novel chemical methods. Furthermore, we briefly discuss the limitation of these methods emphasizing the need for further improvement in the ADC design and development.

Enteropathy-associated T-cell lymphoma: improving treatment strategies

Enteropathy-associated T-cell lymphoma (EATL) is a rare and usually rapidly fatal intestinal T-cell non-Hodgkin lymphoma. It arises from intraepithelial lymphocytes and has a high association with coeliac disease. The high mortality of EATL is associated not only with the very aggressive and often chemotherapy-refractory nature of the lymphoma. The poor condition of patients due to prolonged and severe malnutrition compromises the ability to deliver chemotherapy. There are no standardized treatment protocols, and the optimal therapy for EATL remains unclear. The primary step of treatment consists of local debulking, preferably as early as possible after EATL diagnosis. Morbidity and mortality seem to rise with advanced stages of disease due to tumour size progression, worse nutritional status and a higher risk of emergency surgery due to perforation. Standard induction therapy for EATL is anthracycline-based chemotherapy, preferably resumed between 2 and 5 weeks after surgery (depending on clinical condition). Intensification of therapy using high-dose chemotherapy followed by consolidation with BEAM and autologous stem cell transplantation is associated with better outcome. Notably, this treatment strategy has only been applied in patients eligible for this aggressive regimen which might reflect selection bias. Unfortunately, prognosis of EATL remains poor; 5-year survival varies from 8 to 60% depending on the eligibility to receive additional steps of therapy. New treatment strategies are urgently needed for a better prognosis of this lethal complication of coeliac disease. Brentuximab vedotin (anti-CD30) might be promising when added to conventional chemotherapy and is suggested as upfront treatment in EATL.

Methods for site-specific drug conjugation to antibodies

Antibody drug conjugates (ADCs) are an emerging class of targeted therapeutics with the potential to improve therapeutic index over traditional chemotherapy. Drugs and linkers have been the current focus of ADC development, in addition to antibody and target selection. Recently, however, the importance of conjugate homogeneity has been realized. The current methods for drug attachment lead to a heterogeneous mixture, and some populations of that mixture have poor in vivo performance. New methods for site-specific drug attachment lead to more homogeneous conjugates and allow control of the site of drug attachment. These subtle improvements can have profound effects on in vivo efficacy and therapeutic index. This review examines current methods for site-specific drug conjugation to antibodies, and compares in vivo results with their non-specifically conjugated counterparts. The apparent improvement in pharmacokinetics and the reduced off target toxicity warrant further development of this site-specific modification approach for future ADC development.

Hepatitis C virus reactivation in cancer patients in the era of targeted therapies

The purpose of this review is to summarize the evidence of hepatitis C reactivation in cancer patients in the era of targeted therapies. Targeted therapies are novel therapeutics frequently used in cancer patients. During treatment with targeted therapies, viral replication is one of the major problems that can occur. The PubMed database, ASCO, and ASCO Gastrointestinal Cancer Symposium abstracts were searched up until September 15, 2013 using the following search keywords: “targeted therapies, rituximab, alemtuzumab, brentuximab, hepatitis, hepatitis C reactivation, tyrosine kinase inhibitors, imatinib, mammalian target of rapamycin (mTOR) inhibitors, everolimus, anti-HER therapies, trastuzumab, pertuzumab, lapatinib, anti-epidermal growth factor receptor therapies, cetuximab, panitumumab, and ipilimumab”. Papers considered relevant for the aim of this review were selected by the authors. The data about rituximab-induced hepatic flare in hepatitis C virus (HCV) positive patients is controversial. However, there is the possibility of life-threatening hepatic flare that can develop after HCV ribonucleic acid (HCV-RNA) viral load increases. Routine follow-up of liver function tests should be advised. Especially in high-risk patients, such as those with baseline chronic active hepatitis and cirrhosis, and where there are plans to administer rituximab concomitantly with corticosteroids, it is advised to have close follow-up of HCV viral load. The data is insufficient to make accurate statements about the association of alemtuzumab therapy and HCV reactivation. However, alemtuzumab may cause deep immunosuppression. Due to this, it is better to follow up with liver function tests and HCV RNA levels during alemtuzumab therapy. Brentuximab has effects on antibody dependent cellular toxicity and may decrease humoral immunity. Thus, we believe that during brentuximab treatment of HCV infected patients, clinicians may encounter hepatitis C reactivation. There have been no reported cases of hepatitis C reactivation with imatinib therapy. However, there are many reports of hepatitis B reactivation with imatinib treatment. Based on the evidence of hepatitis B reactivation with imatinib and the effects of imatinib on immune system functions, we suggest that imatinib therapy might be a risk factor for HCV reactivation. Anti-human epidermal growth factor receptor 2 therapies are not associated with hepatic flare in HCV infected patients. Post-transplant studies reported that mTOR was safely administered to patients with active hepatitis C without causing hepatic flare. Cetuximab and panitumumab have not been associated with HCV reactivation. Two cases of HCV infected melanoma were safely treated with ipilimumab without any HCV reactivation or hepatic flare. Targeted therapies are a new and emerging area of oncology treatment modalities. While treating HCV infected cancer patients, clinicians should be mindful of the immunosuppressive properties of targeted therapies. Further randomized trials are needed to establish algorithms for this issue.

Monoclonal Antibodies in Cancer Therapy: Mechanisms, Successes and Limitations

Rituximab was the first chemotherapeutic monoclonal antibody (CmAb) approved for clinical use in cancer therapeutics in 1997 and has significantly improved the clinical outcomes in non-Hodgkin's lymphoma. Since then, numerous CmAbs have been developed and approved for the treatment of various haematologic and solid human cancers. In this review, the classification, efficacy and significantly reduced toxicity of CmAbs available for use in the United States of America are presented. Finally, the limitations of CmAbs and future considerations are explored.

Natural product and natural product derived drugs in clinical trials

The 25 Natural Product (NP)-derived drugs launched since 2008 and the 100 NP-derived compounds and 33 Antibody Drug Conjugates (ADCs) in clinical trials or in registration at the end of 2013 are reviewed.

CD30 expression by bone marrow mast cells from different diagnostic variants of systemic mastocytosis

AIMS

CD30 expression by bone marrow (BM) mast cells (MC) has been reported recently in systemic mastocytosis (SM) patients. The aim of this study was to investigate the potential diagnostic and prognostic value of CD30 expression in SM as assessed by multiparameter flow cytometry.

METHODS AND RESULTS

A total of 163 consecutive BM samples corresponding to 142 SM patients and 21 non-mastocytosis cases were studied. CD30 was positive in most SM patients (80%), but in only one non-mastocytosis case (4.8%). When combined with CD25, CD30 contributed to an improved accuracy over that of CD25 alone (98% versus 93%) mainly because most (eight of nine) of the well-differentiated SM (WDSM), who lacked CD25, were CD30(+). Similar levels of expression of CD30 were observed among all different subgroups of SM except mast cell leukaemia; among indolent SM (ISM) patients, no significant association was observed between the levels of CD30 expression and other clinical and biological features of the disease.

CONCLUSIONS

The increased expression of CD30 associated with absence of CD25 contributes to the diagnosis of WDSM and its distinction from other subtypes of SM. By contrast, CD30 expression did not contribute either to prognostic stratification of ISM or to the differential diagnosis between ISM and aggressive SM cases.

Targeting cellular apoptotic pathway with peptides from marine organisms

Apoptosis is a critical defense mechanism against the formation and progression of cancer and exhibits distinct morphological and biochemical traits. Targeting apoptotic pathways becomes an intriguing strategy for the development of chemotherapeutic agents. Peptides from marine organisms have become important sources in the discovery of antitumor drugs, especially when modern technology makes it more and more feasible to collect organisms from seas. This primer summarizes several marine peptides, based on their effects on apoptotic signaling pathways, although most of these peptides have not yet been studied in depth for their mechanisms of action. Novel peptides that induce an apoptosis signal pathway are presented in association with their pharmacological properties.