Antibody Drug Conjugates: Nonclinical Safety Considerations

Antibody drug conjugates (ADCs) are biopharmaceutical molecules consisting of a cytotoxic small molecule covalently linked to a targeted protein carrier via a stable cleavable or noncleavable linker. The process of conjugation yields a highly complex molecule with biochemical properties that are distinct from those of the unconjugated components. The impact of these biochemical differences on the safety and pharmacokinetic (PK) profile of the conjugate must be considered when determining the types of nonclinical safety studies required to support clinical development of ADCs. The hybrid nature of ADCs highlights the need for a science-based approach to safety assessment that incorporates relevant aspects of small and large molecule testing paradigms. This thinking is reflected in current regulatory guidelines, where sections pertaining to conjugates allow for a flexible approach to nonclinical safety testing. The aim of this article is to review regulatory expectations regarding early assessment of nonclinical safety considerations and discuss how recent advances in our understanding of ADC-mediated toxicity can be used to guide the types of nonclinical safety studies needed to support ADC clinical development. The review will also explore nonclinical testing strategies that can be used to streamline ADC development by assessing the safety and efficacy of next generation ADC constructs using a rodent screen approach.KEY WORDS: antibody drug conjugates, regulatory guidance, safety assessment, therapeutic index     

Mathematical Models to Explore Potential Effects of Supersaturation and Precipitation on Oral Bioavailability of Poorly Soluble Drugs

Poorly soluble drugs are increasingly formulated into supersaturating drug delivery systems which may precipitate during oral delivery. The link between in vitro drug concentration profiles and oral bioavailability is under intense investigation. The objective of the present work was to develop closed-form analytical solutions that relate in vitro concentration profiles to the amount of drug absorbed using several alternate assumptions and only six parameters. Three parameters define the key features of the in vitro drug concentration-time profile. An additional three parameters focus on physiological parameters. Absorption models were developed based on alternate assumptions; the drug concentration in the intestinal fluid: (1) peaks at the same time and concentration as in vitro, (2) peaks at the same time as in vitro, or (3) reaches the same peak concentration as in vitro. The three assumptions provide very different calculated values of bioavailability. Using Case 2 assumptions, bioavailability enhancement was found to be less than proportional to in silico examples of dissolution enhancement. Case 3 assumptions lead to bioavailability enhancements that are more than proportional to dissolution enhancements. Using Case 1 predicts drug absorption amounts that fall in between Case 2 and 3. The equations developed based on the alternate assumptions can be used to quickly evaluate the potential improvement in bioavailability due to intentional alteration of the in vitro drug concentration vs. time curve by reformulation. These equations may be useful in making decisions as to whether reformulation is expected to provide sufficient bioavailability enhancement to justify the effort.

Electronic supplementary material

The online version of this article (doi:10.1208/s12248-015-9748-2) contains supplementary material, which is available to authorized users.KEY WORDS: amorphous, modeling, oral absorption, solubility, supersaturation     

Estimating sleep from multisensory armband measurements: validity and reliability in teens

Given the recognition that sleep may influence obesity risk, there is increasing interest in measuring sleep parameters within obesity studies. The goal of the current analyses was to determine whether the SenseWear^® Pro3 Armband (armband), typically used to assess physical activity, is reliable at assessing sleep parameters. The armband was compared with the AMI Motionlogger^® (actigraph), a validated activity monitor for sleep assessment, and with polysomnography, the gold standard for assessing sleep. Participants were 20 adolescents (mean age = 15.5 years) with a mean body mass index percentile of 63.7. All participants wore the armband and actigraph on their non‐dominant arm while in‐lab during a nocturnal polysomnographic recording (600 min). Epoch‐by‐epoch sleep/wake data and concordance of sleep parameters were examined. No significant sleep parameter differences were found between the armband and polysomnography; the actigraph tended to overestimate sleep and underestimate wake compared with polysomnography. Both devices showed high sleep sensitivity, but lower wake detection rates. Bland–Altman plots showed large individual differences in armband sleep parameter concordance rates. The armband did well estimating sleep overall, with group results more similar to polysomnography than the actigraph; however, the armband was less accurate at an individual level than the actigraph.     

Correlated Responses to Selection in FAST and SLOW Mice: Effects of Ethanol on Ataxia, Temperature, Sedation, and Withdrawal

A replicated bidirectional selective breeding program has produced lines of mice that differ in locomotor response to ethanol (EtOH). FAST mice were bred for high locomotor activation, whereas SLOW mice were bred for low or depressed locomotor activity in response to 2.0 g/kg of EtOH. We tested FAST and SLOW mice for differences in sensitivity to the incoordinating (1.5 to 2.5 g/kg), hypothermic (3.0 g/kg), and sedative (4.0 g/kg) effects of EtOH, and for differences in sensitivity to withdrawal after acute and chronic EtOH exposure. SLOW mice were more ataxic in a grid test and developed greater tolerance than FAST mice at 2.0 g/kg of EtOH, were more hypothermic than FAST mice, and were more sensitive to the sedative effects of EtOH than FAST mice, as measured by latency to and duration of loss of righting reflex, and by blood ethanol concentrations at regain of the righting reflex. FAST mice had more severe withdrawal seizures after chronic exposure, but did not differ from SLOW mice in withdrawal severity after an acute injection of EtOH. These data suggest that FAST mice are generally more sensitive to central nervous system excitation, and SLOW mice are generally more sensitive to central nervous system sedation by EtOH, and further suggest genetic overlap with respect to genes that mediate locomotor responses to EtOH and genes determining sensitivity to EtOH-induced ataxia, hypothermia, sedation, and withdrawal severity after chronic exposure. Our current observations are in contrast to observations made earlier in selection, in which few line differences in sensitivity to EtOH effects other than locomotor activity were found. Thus, it seems that continued selection for differences in locomotor response to EtOH has produced genetically correlated differences in other EtOH responses.     

Designing a Primary Care–Based Deprescribing Intervention for Patients with Dementia and Multiple Chronic Conditions: a Qualitative Study

BackgroundPatients with dementia and multiple chronic conditions (MCC) frequently experience polypharmacy, increasing their risk of adverse drug events.ObjectivesTo elucidate patient, family, and physician perspectives on medication discontinuation and recommended language for deprescribing discussions in order to inform an intervention to increase awareness of deprescribing among individuals with dementia and MCC, family caregivers and primary care physicians. We also explored participant views on culturally competent approaches to deprescribing.DesignQualitative approach based on semi-structured interviews with patients, caregivers, and physicians.ParticipantsPatients aged ≥ 65 years with claims-based diagnosis of dementia, ≥ 1 additional chronic condition, and ≥ 5 chronic medications were recruited from an integrated delivery system in Colorado and an academic medical center in Maryland. We included caregivers when present or if patients were unable to participate due to severe cognitive impairment. Physicians were recruited within the same systems and through snowball sampling, targeting areas with large African American and Hispanic populations.ApproachWe used constant comparison to identify and compare themes between patients, caregivers, and physicians.Key ResultsWe conducted interviews with 17 patients, 16 caregivers, and 16 physicians. All groups said it was important to earn trust before deprescribing, frame deprescribing as routine and positive, align deprescribing with goals of dementia care, and respect caregivers’ expertise. As in other areas of medicine, racial, ethnic, and language concordance was important to patients and caregivers from minority cultural backgrounds. Participants favored direct-to-patient educational materials, support from pharmacists and other team members, and close follow-up during deprescribing. Patients and caregivers favored language that explained deprescribing in terms of altered physiology with aging. Physicians desired communication tips addressing specific clinical situations.ConclusionsCulturally sensitive communication within a trusted patient-physician relationship supplemented by pharmacists, and language tailored to specific clinical situations may support deprescribing in primary care for patients with dementia and MCC.Electronic supplementary materialThe online version of this article (10.1007/s11606-020-06063-y) contains supplementary material, which is available to authorized users.KEY WORDS: deprescribing, patient-physician communication, dementia     

Safety and tolerability of linaclotide for the treatment of chronic idiopathic constipation and irritable bowel syndrome with constipation: pooled Phase 3 analysis

Background: Linaclotide is approved for treating irritable bowel syndrome with constipation (IBS-C; 290 µg QD) and chronic idiopathic constipation (CIC; 145 µg or 72 µg QD). These analyses aimed to assess linaclotide safety in a large, pooled Phase 3 population.

Methods: In six randomized controlled trials (RCTs), patients received linaclotide (72 µg, 145 µg, 290 µg) or placebo daily for 12–26 weeks; in two long-term safety (LTS) studies, patients received open-label linaclotide for ≤78 additional weeks. Laboratory values, vital signs, and treatment-emergent adverse events (TEAEs) were assessed.

Results: Overall, 3853 patients received ≥1 dose of linaclotide. The most common TEAE was diarrhea (majority [90.5% in RCTs] mild/moderate). Linaclotide patients experienced 1.1 diarrhea TEAE per patient-year in the RCTs (0.2 in placebo), and 0.3 in the LTS studies. In RCTs, 6.9% linaclotide and 3.0% placebo patients discontinued due to any adverse event (AE); 4.0% linaclotide and 0.3% placebo patients discontinued due to diarrhea. In LTS studies, 9.4% patients discontinued due to any AE, and 3.8% due to diarrhea. Serious AEs (SAEs) were rare and similar across treatment groups; there were no SAEs of diarrhea.

Conclusion: These pooled analyses of patients treated for ≤104 weeks confirm linaclotide’s overall safety.     

Novel markers of cell kinetics to evaluate progression from cirrhosis to hepatocellular carcinoma.

BACKGROUND: We investigated cell cycle kinetics of nodular lesions in cirrhosis to differentiate hepatocellular carcinoma (HCC) from its precursor lesions. METHODS: Twelve small HCC, 10 regenerative (RN), six large regenerative (LRN), and five dysplastic nodules (DN), identified in explant cirrhotic livers of five consecutive patients transplanted at Royal Free Hospital in 2002. Immunoperoxidase for MCM2, geminin and Ki67 was performed and the percentage of positive cells counted. RESULTS: The proportion of cells expressing MCM2 was more than those expressing Ki67, which in turn was more than those expressing geminin (overall median=16%, 2% and 0.5%, respectively, P<0.001). There was a statistically significant trend of increasing Ki67 expression (P=0.006), from RN to HCC; this trend was not statistically significant for geminin (P=0.18) or MCM2 (P=0.51). The median percentage of cells expressing Ki67 was 1% in RN, 0.5% in LRN, 2.2% in DN and 5.4% in HCC. The combination of these markers identified four different cell kinetics patterns: 'resting' (G0 cells: MCM2 -ve, Ki67 -ve, geminin -ve); 'licensed' (MCM2 +ve, Ki67 -ve, geminin -ve); 'slowly growing' (G1 phase arrest, MCM2 +ve, Ki67 +ve, low (0.4%) geminin) and expanding (MCM2 +ve, Ki67 +ve, geminin +ve) nodules. CONCLUSIONS: The combination of MCM2, geminin and Ki67 could represent a valuable tool in the understanding of HCC progression in cirrhosis.