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As development of new oncology small molecule therapies is focused mainly on molecularly targeted agents, the dose selection paradigm has shifted from the maximum tolerated dose (MTD)-based approach traditionally utilized with cytotoxic drugs towards determining an optimal dose with long-term tolerability while maintaining efficacy. To assess overall tolerability in recently approved oncology small molecules, we surveyed 54 compounds approved by the FDA since March 2017 with respect to dose intensity, dose modifications, and treatment emergent adverse events (TEAEs). Of the 54 new molecular entities surveyed, only 15 were approved at a label dose equal to the MTD (Label Dose = MTD). Compared to compounds where the label dose was less than the MTD, compounds where the Label Dose = MTD reported overall lower dose intensity and higher dose modifications due to adverse events, though treatment discontinuations due to adverse events were similar. A post-marketing requirement (PMR) for dose optimization was issued for 7 compounds in the dataset, of which 3 were at the Label Dose = MTD. None of these 7 compounds reported a positive exposure-response relationship in efficacy and only 4 reported an exposure-response in safety events. Overall, dose intensity was lower, and incidence of dose modifications, discontinuations, and Grade ≥ 3 TEAEs were higher in compounds issued a PMR vs. the latter. This analysis suggests that while recently approved oncology small molecules have a reasonable relative dose intensity (RDI), the higher incidence of Grade ≥ 3 TEAEs and dose modifications where Label Dose = MTD highlight the continuing need for dose optimization while developing oncology therapeutics. [ABSTRACT FROM AUTHOR]

Combination therapies are often evaluated during the clinical development of oncology investigational agents. A new investigational agent may be combined with one or more approved agent(s) or investigational agent(s). As the initial step to test combination therapies, combination dose escalation of an investigational agent and an approved drug is generally conducted using one of the following designs: sequential design, parallel (staggered) design, healthy participant first‐in‐human prior to first‐in‐patient combination escalation, monotherapy lead‐in (intra‐patient "crossover"), and potentially combination escalation (no monotherapy component). Dose‐finding studies for the combinations of two investigational agents may follow similar principles and considerations, and a more conservative approach may be required. A comparison of the characteristics of these designs indicates an efficient design should consider factors including the predicted difference in dose/exposure‐response relationships between monotherapy and combination therapy, any potential for pharmacokinetic and pharmacodynamic interactions between the combinatory agents, and the benefit/risk to study participants, etc. In this report, we propose application scenarios for each trial design based on the above considerations and a review of the internal database and published external studies. Generation of robust exposure‐response data via an appropriate design will assist the selection of appropriate doses for further assessment to support optimal dose selection as encouraged by the US Food and Drug Administration based on Project Optimus. [ABSTRACT FROM AUTHOR]

The optimal dose for targeted oncology therapeutics is often not the maximum tolerated dose. Pharmacokinetic/pharmacodynamic (PK/PD) modeling can be an effective tool to integrate clinical data to help identify the optimal dose. This case study shows the utility of population PK/PD modeling in selecting the recommended dose for expansion (RDE) for the first‐in‐patient (FIP) study of PF‐06939999, a small‐molecule inhibitor of protein arginine methyltransferase 5. In the dose escalation part of the FIP trial (NCT03854227), 28 patients with solid tumors were administered PF‐06939999 at 0.5 mg, 4 mg, 6 mg, or 8 mg once daily (q.d.) or 0.5 mg, 1 mg, 2 mg, 4 mg, or 6 mg twice daily (b.i.d.). Tolerability, safety, PK, PD biomarkers (plasma symmetrical dimethyl‐arginine [SDMA]), and antitumor response were assessed. Semimechanistic population PK/PD modeling analyses were performed to characterize the time‐courses of plasma PF‐06939999 concentrations, plasma SDMA, and platelet counts collected from 28 patients. Platelet counts were evaluated because thrombocytopenia was the treatment‐related adverse event with clinical safety concern. The models adequately described the PK, SDMA, and platelet count profiles both at individual and population levels. Simulations suggested that among a range of dose levels, 6 mg q.d. would yield the optimal balance between achieving the PD target (i.e., 78% reduction in plasma SDMA) and staying below an acceptable probability of developing grade ≥3 thrombocytopenia. As a result, 6 mg q.d. was selected as the RDE. The model‐informed drug development approach informed the rational dose selection for the early clinical development of PF‐06939999. [ABSTRACT FROM AUTHOR]

Purpose: PF-05280014 is a biosimilar to trastuzumab (Herceptin®). Following demonstration of pharmacokinetic (PK) similarity in healthy volunteers, a comparative clinical study in patients with HER2-positive metastatic breast cancer (mBC) compared the efficacy, safety and immunogenicity of PF-05280014 and trastuzumab sourced from the EU (trastuzumab-EU), both with paclitaxel.Methods: Population PK of PF-05280014 and trastuzumab-EU was evaluated.Results: Overall, 702 patients were treated: PF-05280014 (n = 349) and trastuzumab-EU (n = 353). Peak-and-trough serum drug concentration samples were collected (selected doses) following repeated intravenous administration of PF-05280014 or trastuzumab-EU. Population PK analysis was performed with drug concentration-time data to cycle 17 for each compound, using nonlinear mixed effect modeling. Potential baseline covariates (circulating HER2 concentrations, body weight, Japanese race, Eastern Cooperative Oncology Group status, number of metastatic sites and antidrug antibody status) were evaluated. Concentration-time data of PF-05280014 and trastuzumab-EU were adequately described by a two-compartment model with first-order elimination, with inter-individual variability (IIV) on clearance (CL), volumes of distribution in central compartment (V1) and peripheral compartments, and intercompartment clearance. Similar estimated PK parameters and IIV were obtained for both treatments. For PF-05280014 and trastuzumab-EU, baseline body weight was an influential covariate on CL and V1; the magnitude was comparable between treatments. PK was consistent between the limited number of Japanese and non-Japanese patients for both compounds.Conclusions: PF-05280014 and trastuzumab-EU had similar PK parameters and influential PK covariates in patients with HER2-positive mBC. These results provided further evidence in patients for PK similarity between PF-05280014 and trastuzumab-EU.Clinical Trial Registration: ClinicalTrials.gov, NCT01989676. [ABSTRACT FROM AUTHOR]