Simon J. Crabb

Tumor Cavitation: Impact on Objective Response Evaluation in Trials of Angiogenesis Inhibitors in Non-Small-Cell Lung Cancer

PURPOSE We have observed cavitation of lesions in clinical trials of an angiogenesis inhibitor combined with chemotherapy for non-small-cell lung cancer (NSCLC). We hypothesized that cavitation might alter response assessment in such clinical trials. PATIENTS AND METHODS We performed a retrospective radiologic review of patients with NSCLC enrolled onto three National Cancer Institute of Canada Clinical Trials Group (NCIC CTG) trials of platinum-based chemotherapy with or without a small-molecule angiogenesis inhibitor (vascular endothelial growth factor receptor inhibitor [VEGFRI]). Response was assessed both by Response Evaluation Criteria in Solid Tumors (RECIST) guidelines and a novel alternate method in which the longest diameter of any cavity was subtracted from the overall longest diameter of that lesion to measure target lesions. Rates of cavitation were documented. RESULTS Marked cavitation of pulmonary lesions was seen in 24% of 33 patients treated with VEGFRI combined with platinum-based chemotherapy but in none of 18 patients treated with platinum-based chemotherapy alone. Use of the alternate method for response assessment resulted in an alteration of response assessment, time to best response, duration of response, and time of disease progression in a minority of patients compared with RECIST. CONCLUSION Cavitation of target and nontarget lesions is common in NSCLC patients treated with VEGFRIs and platinum-based chemotherapy. Impact on response and time to event outcomes occurred but seems to be less common. Response assessment might be improved by incorporating cavitation into volume assessment for target lesions, potentially altering outcomes of key efficacy parameters in clinical trials. This should be prospectively assessed in clinical trials of angiogenesis inhibitors.

Enantioselective synthesis of tranylcypromine analogues as lysine demethylase (LSD1) inhibitors

Asymmetric cyclopropanation of styrenes by tert-butyl diazoacetate followed by ester hydrolysis and Curtius rearrangement gave a series of tranylcypromine analogues as single enantiomers. The o,- m- and p-bromo analogues were all more active than tranylcypromine in a LSD1 enzyme assay. The m- and p-bromo analogues were micromolar growth inhibitors of the LNCaP prostate cancer cell line as were the corresponding biphenyl analogues prepared from the bromide by Suzuki crosscoupling.

Impact of Molecular Subtypes in Muscle-invasive Bladder Cancer on Predicting Response and Survival after Neoadjuvant Chemotherapy

BACKGROUND An early report on the molecular subtyping of muscle-invasive bladder cancer (MIBC) by gene expression suggested that response to neoadjuvant chemotherapy (NAC) varies by subtype. OBJECTIVE To investigate the ability of molecular subtypes to predict pathological downstaging and survival after NAC. DESIGN, SETTING, AND PARTICIPANTS Whole transcriptome profiling was performed on pre-NAC transurethral resection specimens from 343 patients with MIBC. Samples were classified according to four published molecular subtyping methods. We developed a single-sample genomic subtyping classifier (GSC) to predict consensus subtypes (claudin-low, basal, luminal-infiltrated and luminal) with highest clinical impact in the context of NAC. Overall survival (OS) according to subtype was analyzed and compared with OS in 476 non-NAC cases (published datasets). INTERVENTION Gene expression analysis was used to assign subtypes. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Receiver-operating characteristics were used to determine the accuracy of GSC. The effect of GSC on survival was estimated by Cox proportional hazard regression models. RESULTS AND LIMITATIONS The models generated subtype calls in expected ratios with high concordance across subtyping methods. GSC was able to predict four consensus molecular subtypes with high accuracy (73%), and clinical significance of the predicted consensus subtypes could be validated in independent NAC and non-NAC datasets. Luminal tumors had the best OS with and without NAC. Claudin-low tumors were associated with poor OS irrespective of treatment regimen. Basal tumors showed the most improvement in OS with NAC compared with surgery alone. The main limitations of our study are its retrospective design and comparison across datasets. CONCLUSIONS Molecular subtyping may have an impact on patient benefit to NAC. If validated in additional studies, our results suggest that patients with basal tumors should be prioritized for NAC. We discovered the first single-sample classifier to subtype MIBC, which may be suitable for integration into routine clinical practice. PATIENT SUMMARY Different molecular subtypes can be identified in muscle-invasive bladder cancer. Although cisplatin-based neoadjuvant chemotherapy improves patient outcomes, we identified that the benefit is highest in patients with basal tumors. Our newly discovered classifier can identify these molecular subtypes in a single patient and could be integrated into routine clinical practice after further validation.

Epigenetic therapy: histone acetylation, DNA methylation and anti-cancer drug discovery.

Histone proteins are subject to a diverse range of post-translational modifications which, along with DNA methylation, play a major role in controlling gene expression, cell division, survival and differentiation. Alterations in these chromatin modifications are thought to contribute to important human diseases including cancer. Inhibition of the enzymes that introduce and remove these chromatin modifications is proving an effective approach to cancer therapy and inhibitors of histone deacetylases and DNA methyltransferases have been approved for use in haematological malignancies. Here we provide a background to the biology of chromatin modifications and review some of the evidence validating histone deacetylases and DNA methyltransferases as targets for anti-cancer drug discovery. We then focus on two of the key issues in this field; the identification of novel inhibitors to overcome shortcomings of first generation agents and the potential role of histone deacetylase and DNA methyltransferase inhibitors in combination therapies for oncology. Finally, we highlight some of the challenges that will need to addressed to further progress the development of epigenetic-based therapies for cancer.

Comparative effectiveness of gemcitabine plus cisplatin versus methotrexate, vinblastine, doxorubicin, plus cisplatin as neoadjuvant therapy for muscle‐invasive bladder cancer

Gemcitabine plus cisplatin (GC) has been adopted as a neoadjuvant regimen for muscle‐invasive bladder cancer despite the lack of Level I evidence in this setting.

Will histone deacetylase inhibitors require combination with other agents to fulfil their therapeutic potential

Histone deacetylase inhibitors have progressed rapidly from the laboratory to clinical testing. This review highlights the promising data for their combination with a wide range of established and novel anticancer agents and discusses the mechanisms that underpin these interactions.

Characterisation of the in vitro activity of the depsipeptide histone deacetylase inhibitor spiruchostatin A.

We recently completed the total synthesis of spiruchostatin A, a depsipeptide natural product with close structural similarities to FK228, a histone deacetylase (HDAC) inhibitor (HDI) currently being evaluated in clinical trials for cancer. Here we report a detailed characterisation of the in vitro activity of spiruchostatin A. Spiruchostatin A was a potent (sub-nM) inhibitor of class I HDAC activity in vitro and acted as a prodrug, requiring reduction for activity. Spiruchostatin A was a potent (low nM) inhibitor of the growth of various cancer cell lines. Spiruchostatin A-induced acetylation of specific lysine residues within histones H3 and H4, and increased the expression of p21(cip1/waf1), but did not induce acetylation of alpha-tubulin. Spiruchostatin A also induced cell cycle arrest, differentiation and cell death in MCF7 breast cancer cells. Like FK228, spiruchostatin A was both an inducer and substrate of the ABCB1 drug efflux pump. Whereas spiruchostatin A and FK228-induced protracted histone acetylation, hydroxamate HDI-induced short-lived histone acetylation. Using a subset of HDI-target genes identified by microarray analysis, we demonstrated that these differences in kinetics of histone acetylation between HDI correlated with differences in the kinetics of induction or repression of specific target genes. Our results demonstrate that spiruchostatin A is a potent inhibitor of class I HDACs and anti-cancer agent. Differences in the kinetics of action of HDI may be important for the clinical application of these compounds.

IMA901, a multipeptide cancer vaccine, plus sunitinib versus sunitinib alone, as first-line therapy for advanced or metastatic renal cell carcinoma (IMPRINT): a multicentre, open-label, randomised, controlled, phase 3 trial

BACKGROUND In a phase 2 study in patients with metastatic renal cell carcinoma, overall survival was associated with T-cell responses against IMA901, a vaccine consisting of ten tumour-associated peptides. In this phase 3 trial, we aimed to determine the clinical effect of adding IMA901 to sunitinib, the standard first-line treatment in metastatic renal cell carcinoma with postulated favourable immunomodulatory effects. METHODS The IMPRINT study is an open-label, randomised, controlled, phase 3 trial done at 124 clinical sites in 11 countries. HLA-A*02-positive patients (aged ≥18 years) with treatment-naive, histologically confirmed metastatic or locally advanced (or both) clear-cell renal cell carcinoma were randomly assigned (3:2) to receive sunitinib plus up to ten intradermal vaccinations of IMA901 (4·13 mg) and granulocyte macrophage colony-stimulating factor (75 μg), with one dose of cyclophosphamide (300 mg/m2) 3 days before the first vaccination, or to receive sunitinib alone. Sunitinib (50 mg) was given orally once daily, with each cycle defined as 4 weeks on treatment followed by 2 weeks off treatment, until progression of disease as determined by the investigator, death, or withdrawal of consent. Block randomisation (block size five) was done centrally using an interactive web response system, stratified by prognostic risk, geographical region, and previous nephrectomy. Patients and investigators were not masked to treatment allocation. The primary endpoint was overall survival from randomisation until death of any cause as determined by the investigator, analysed by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01265901. FINDINGS Between Dec 22, 2010, and Dec 15, 2012, we screened 1171 patients, of whom 339 were randomly assigned to receive sunitinib plus IMA901 (n=204) or sunitinib monotherapy (n=135). Patients had a median follow-up of 33·27 months (IQR 29·92-35·64). Median overall survival did not differ significantly between the groups (33·17 months [95% CI 27·81-41·36] in the sunitinib plus IMA901 group vs not reached [33·67-not reached] in the sunitinib monotherapy group; hazard ratio 1·34 [0·96-1·86]; p=0·087). 116 (57%) of 202 patients in the sunitinib plus IMA901 group and 62 (47%) of 132 in the sunitinib group had grade 3 or worse adverse events, the most common of which were hypertension, neutropenia, and anaemia in both groups, and mild-to-moderate transient injection-site reactions (eg, erythema, pruritus) were the most frequent IMA901-related side-effect in the sunitinib plus IMA901 group. Serious adverse events leading to death occurred in four (2%) patients (one respiratory failure and circulatory collapse [possibly related to sunitinib], one oesophageal varices haemorrhage [possibly related to sunitinib], one cardiac arrest [possibly related to sunitinib], and one myocardial infarction) and eight (6%) patients in the sunitinib group (one case each of renal failure, oesophageal varices haemorrhage, circulatory collapse, wound infection, ileus, cerebrovascular accident [possibly treatment related], and sepsis). INTERPRETATION IMA901 did not improve overall survival when added to sunitinib as first-line treatment in patients with metastatic renal cell carcinoma. The magnitude of immune responses needs to be improved before further development of IMA901 in this disease is indicated. FUNDING Immatics Biotechnologies.

Protein recognition by short peptide reversible inhibitors of the chromatin-modifying LSD1/CoREST lysine demethylase.

The combinatorial assembly of protein complexes is at the heart of chromatin biology. Lysine demethylase LSD1(KDM1A)/CoREST beautifully exemplifies this concept. The active site of the enzyme tightly associates to the N-terminal domain of transcription factors of the SNAIL1 family, which therefore can competitively inhibit the binding of the N-terminal tail of the histone substrate. Our enzymatic, crystallographic, spectroscopic, and computational studies reveal that LSD1/CoREST can bind to a hexapeptide derived from the SNAIL sequence through recognition of a positively charged α-helical turn that forms upon binding to the enzyme. Variations in sequence and length of this six amino acid ligand modulate affinities enabling the same binding site to differentially interact with proteins that exert distinct biological functions. The discovered short peptide inhibitors exhibit antiproliferative activities and lay the foundation for the development of peptidomimetic small molecule inhibitors of LSD1.

Total synthesis of largazole and analogues: HDAC inhibition, antiproliferative activity and metabolic stability

The total synthesis of largazole and four analogues is reported. All analogues were nanomolar HDAC inhibitors. The antiproliferative activity is driven by lipophilicity and cell permeability. In murine liver homogenates, largazole is rapidly metabolized (half-life ≤5 min) to the thiol which has a half-life of 51 min.