A new, sensitive ELISA method has been developed which measures catabolites in cells and media upon processing of antibody-drug conjugates (ADCs) by target cancer cells. This ELISA method, exemplified for maytansinoid ADCs, uses competitive inhibition by a maytansinoid analyte of the binding of biotinylated antimaytansine antibody to an immobilized BSA-maytansinoid conjugate. Synthetic standards of several maytansinoid catabolites derived from ADCs with different linkers were tested and showed similar inhibition curves, with an EC50 of about 0.1 nM (0.03 pmol in an assay volume of 0.25 mL). This high sensitivity allowed quantification of catabolites from a methanolic cell extract and from the medium, generated from an ADC in 1 day using only about 1 million cells. The processing of anti-EpCAM and anti-CanAg ADCs with noncleavable linker (SMCC-DM1), disulfide linker (SPDB-DM4), and charged sulfonate-bearing disulfide linker (sulfo-SPDB-DM4), each containing an average of about four maytansinoid molecules per antibody, were compared in colon cancer cell lines (COLO 205 and HT-29). An 8-10-fold higher total level of catabolite was observed for anti-CanAg ADCs than for anti-EpCAM ADCs upon processing by COLO 205 cells, consistent with a higher cell-surface expression of CanAg. In a multidrug resistant HCT-15 colon cancer cell line, the anti-EpCAM-SPDB-DM4 linker conjugate was not cytotoxic and showed a significantly lower level of catabolite within cells compared to that in medium, presumably due to Pgp-mediated efflux of the nonpolar DM4 catabolite. In contrast, sulfo-SPDB-DM4 and SMCC-DM1 linker conjugates were cytotoxic, which correlated with higher amounts of catabolites found within the HCT-15 cells relative to amounts in medium. In a nonmultidrug resistant HT-29 cell line, the anti-EpCAM-SPDB-DM4 linker conjugate was cytotoxic, with most of the catabolite found in cells and little in the medium. In conclusion, this highly sensitive ELISA method for measurement of ADC catabolite is convenient for screening multiple ADC parameters such as linkers and antibodies in a number of cell lines, does not require concentration of sample or extraction of media, and is complementary to other reported methods such as radiolabeling of ADCs or mass spectrometry.

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The maytansinoid antibody-drug conjugates (ADCs) in clinical development for cancer therapy each contain a derivative of the microtubule-targeting agent, maytansine, covalently attached to the antibody via an engineered linker. A sample of any of these conjugates contains molecules with different numbers of maytansinoid molecules, or "drug" loads, the relative abundance of which can be determined by mass spectrometry. We examined the accuracy of the Poisson distribution and the binomial distribution in predicting the relative abundance of species with different drug loads for three antibody-maytansinoid conjugates with different antibodies and linker-maytansinoid pairings. We used variance, calculated from the experimental mass distribution data, as the parameter to determine the optimal value n of the binomial distribution number of trials. The accuracy of the Poisson distribution in predicting distribution of the species abundance in these conjugates varied among the conjugates. In contrast, the accuracy of the binomial distribution was similar for all three conjugates and comparable to the best accuracy of the Poisson distribution, as supported by a paired t-test.

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The aim of the study was to determine the effect of renal impairment and prior platinum-based chemotherapy on the toxicity and pharmacokinetics of oral topotecan and to identify recommended doses for patients with renal impairment or prior platinum-based (PB) chemotherapy.
A multicentre phase I toxicity and pharmacokinetic study of oral topotecan was conducted in patients with advanced solid tumours. Patients were grouped by normal renal function with limited or prior PB chemotherapy or impaired renal function (mild [creatinine clearance (CLcr)  = 50-79 ml min(-1) ], moderate [CLcr  = 30-49 ml min(-1) ], severe [CLcr <30 ml min(-1) ]).
Fifty-nine patients were evaluable. Topotecan lactone and total topotecan area under the concentration-time curve (AUC) was significantly increased in patients with moderate and severe renal impairment (109% and 174%, respectively, topotecan lactone and 148% and 298%, respectively, total topotecan). Asian patients (23 in total) had higher AUCs than non-Asian patients with the same degree of renal impairment. Thirteen dose-limiting toxicities (DLTs) were observed, which were mostly haematological. The maximum tolerated dose (MTD) was 2.3 mg m(-2) day(-1) , given on days 1 to 5 in a 21 day cycle, for patients with prior PB chemotherapy or mild renal impairment, and 1.2 mg m(-2) day(-1) for patients with moderate renal impairment (suggested dose 1.9 mg m(-2) day(-1) for non-Asians). Due to incomplete enrolment of patients with severe renal impairment, the MTD was determined as ≥ 0.6 mg m(-2) day(-1) in this cohort.
Oral topotecan dose adjustments are not required in patients with prior PB chemotherapy or mildly impaired renal function, but reduced doses are required for patients with moderate or severe renal impairment.
© 2015 The British Pharmacological Society.

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The MAGE-A3 recombinant protein combined with AS15 immunostimulant (MAGE-A3 Cancer Immunotherapeutic) is under development by GlaxoSmithKline for the treatment of lung cancer and melanoma. We performed non-clinical safety studies evaluating potential local and systemic toxic effects induced by MAGE-A3 Cancer Immunotherapeutic in rabbits (study 1) and cynomolgus monkeys (study 2). Animals were allocated to two groups to receive a single (rabbits) or 25 repeated (every 2 weeks) injections (monkeys) of MAGE-A3 Cancer Immunotherapeutic (treatment groups) or saline (control groups). All rabbits were sacrificed 3 days post-injection and monkeys 3 days following last injection (3/5 per gender per group) or after a 3-month treatment-free period (2/5 per gender per group). Local and systemic reactions and MAGE-A3-specific immune responses (monkeys) were assessed. Macroscopic and microscopic (for rabbits, injection site only) post-mortem examinations were performed on all animals. No systemic toxicity or unscheduled mortalities were recorded. Single (rabbits) and repeated (monkeys; up to four times at the same site) injections were well tolerated. Following five to seven repeated injections, limb circumferences increased up to 26% (5 h post-injection), but returned to normal after 1-8 days. Three days after the last injection, enlargements of iliac, popliteal, axillary and inguinal lymph nodes, and increased incidence or severity of mononuclear inflammatory cell infiltrates was observed in injected muscles of treated monkeys. No treatment-related macroscopic findings were recorded after the treatment-free period. MAGE-A3-specific antibody and T-cell responses were raised in all treated monkeys, confirming test item exposure. Single or repeated intramuscular injections of MAGE-A3 Cancer Immunotherapeutic were well tolerated in rabbits and monkeys.
Copyright © 2014 GlaxoSmithKline Vaccines. Journal of Applied Toxicology published by John Wiley & Sons, Ltd.

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Twenty-two patients with pathologically confirmed glioblastoma who had received concurrent CCRT with TMZ underwent conventional MRI including T1-weighted imaging(T1WI), T2-weighted imaging(T2WI), fluid attenuated inversion recovery(FLAIR)and contrast-enhanced T1WI(T1Ce). Five GLCM texture maps of contrast, energy, entropy, correlation and homogeneity were generated for each MRI series. Of the aforementioned 5 texture features, the most significant features were contrast and correlation on T2WI with areas under ROC curve of 0.883 and 0.892, respectively, and they had the same sensitivity of 75%, specificity of 100%, accuracy of 86.4%, PPV of 100% and NPV of 76.9% in differentiation true progression from pseudoprogression.
Copyright © 2015. Published by Elsevier Inc.

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