XTX101, a tumor-activated, Fc-enhanced anti-CTLA-4 monoclonal antibody, demonstrates tumor-growth inhibition and tumor-selective pharmacodynamics in mouse models of cancer.

Introduction: The clinical benefit of the anti-CTLA-4 monoclonal antibody (mAb) ipilimumab has been well established but limited by immune-related adverse events, especially when ipilimumab is used in combination with anti-PD-(L)1 mAb therapy. To overcome these limitations, we have developed XTX101, a tumor-activated, Fc-enhanced anti-CTLA-4 mAb.

Methods: XTX101 consists of an anti-human CTLA-4 mAb covalently linked to masking peptides that block the complementarity-determining regions, thereby minimizing the mAb binding to CTLA-4.

Discovery of mobocertinib, a potent, oral inhibitor of EGFR exon 20 insertion mutations in non-small cell lung cancer.

In the treatment of non-small cell lung cancer (NSCLC), patients harboring exon 20 insertion mutations in the epidermal growth factor receptor (EGFR) gene (EGFR) have few effective therapies because this subset of mutants is generally resistant to most currently approved EGFR inhibitors. This report describes the structure-guided design of a novel series of potent, irreversible inhibitors of EGFR exon 20 insertion mutations, including the V769_D770insASV and D770_N771insSVD mutants. Extensive structure-activity relationship (SAR) studies led to the discovery of mobocertinib (compound 21c), which inhibited growth of Ba/F3 cells expressing the ASV insertion with a half-maximal inhibitory concentration of 11 nM and with selectivity over wild-type EGFR.

Mobocertinib (TAK-788): A Targeted Inhibitor of Exon 20 Insertion Mutants in Non-Small Cell Lung Cancer.

Most exon 20 insertion (ex20ins) driver mutations in non-small cell lung cancer (NSCLC) are insensitive to approved EGFR tyrosine kinase inhibitors (TKI). To address the limitations of existing therapies targeting -mutated NSCLC, mobocertinib (TAK-788), a novel irreversible EGFR TKI, was specifically designed to potently inhibit oncogenic variants containing activating ex20ins mutations with selectivity over wild-type EGFR. The and activity of mobocertinib was evaluated in engineered and patient-derived models harboring diverse ex20ins mutations.

Exploratory Analysis of Brigatinib Activity in Patients With Anaplastic Lymphoma Kinase-Positive Non-Small-Cell Lung Cancer and Brain Metastases in Two Clinical Trials.

Purpose In patients with crizotinib-treated, anaplastic lymphoma kinase gene ( ALK)-rearranged non-small-cell lung cancer (ALK-positive NSCLC), initial disease progression often occurs in the CNS. We evaluated brigatinib, a next-generation ALK inhibitor, in patients with ALK-positive NSCLC with brain metastases. Patients and Methods Patients with ALK-positive NSCLC received brigatinib (90 to 240 mg total daily) in a phase I/II trial (phI/II; ClinicalTrials.

Activity and safety of brigatinib in ALK-rearranged non-small-cell lung cancer and other malignancies: a single-arm, open-label, phase 1/2 trial.

Background: Anaplastic lymphoma kinase (ALK) gene rearrangements are oncogenic drivers of non-small-cell lung cancer (NSCLC). Brigatinib (AP26113) is an investigational ALK inhibitor with potent preclinical activity against ALK mutants resistant to crizotinib and other ALK inhibitors. We aimed to assess brigatinib in patients with advanced malignancies, particularly ALK-rearranged NSCLC.

The Potent ALK Inhibitor Brigatinib (AP26113) Overcomes Mechanisms of Resistance to First- and Second-Generation ALK Inhibitors in Preclinical Models.

Purpose: Non-small cell lung cancers (NSCLCs) harboring ALK gene rearrangements (ALK) typically become resistant to the first-generation anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor (TKI) crizotinib through development of secondary resistance mutations in ALK or disease progression in the brain. Mutations that confer resistance to second-generation ALK TKIs ceritinib and alectinib have also been identified. Here, we report the structure and first comprehensive preclinical evaluation of the next-generation ALK TKI brigatinib.

Discovery of Brigatinib (AP26113), a Phosphine Oxide-Containing, Potent, Orally Active Inhibitor of Anaplastic Lymphoma Kinase.

In the treatment of echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase positive (ALK+) non-small-cell lung cancer (NSCLC), secondary mutations within the ALK kinase domain have emerged as a major resistance mechanism to both first- and second-generation ALK inhibitors. This report describes the design and synthesis of a series of 2,4-diarylaminopyrimidine-based potent and selective ALK inhibitors culminating in identification of the investigational clinical candidate brigatinib. A unique structural feature of brigatinib is a phosphine oxide, an overlooked but novel hydrogen-bond acceptor that drives potency and selectivity in addition to favorable ADME properties.

Ponatinib versus imatinib for newly diagnosed chronic myeloid leukaemia: an international, randomised, open-label, phase 3 trial.

Background: Ponatinib has shown potent activity against chronic myeloid leukaemia that is resistant to available treatment, although it is associated with arterial occlusion. We investigated whether this activity and safety profile would result in superior outcomes compared with imatinib in previously untreated patients with chronic myeloid leukaemia.

Methods: The Evaluation of Ponatinib versus Imatinib in Chronic Myeloid Leukemia (EPIC) study was a randomised, open-label, phase 3 trial designed to assess the efficacy and safety of ponatinib, compared with imatinib, in newly diagnosed patients with chronic-phase chronic myeloid leukaemia.

Compound mutations in BCR-ABL1 are not major drivers of primary or secondary resistance to ponatinib in CP-CML patients.

BCR-ABL1 kinase domain mutations can confer resistance to first- and second-generation tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia (CML). In preclinical studies, clinically achievable concentrations of the third-generation BCR-ABL1 TKI ponatinib inhibit T315I and all other single BCR-ABL1 mutants except T315M, which generates a single amino acid exchange, but requires 2 sequential nucleotide exchanges. In addition, certain compound mutants (containing ≥2 mutations in cis) confer resistance.

Ponatinib inhibits polyclonal drug-resistant KIT oncoproteins and shows therapeutic potential in heavily pretreated gastrointestinal stromal tumor (GIST) patients.

Purpose: KIT is the major oncogenic driver of gastrointestinal stromal tumors (GIST). Imatinib, sunitinib, and regorafenib are approved therapies; however, efficacy is often limited by the acquisition of polyclonal secondary resistance mutations in KIT, with those located in the activation (A) loop (exons 17/18) being particularly problematic. Here, we explore the KIT-inhibitory activity of ponatinib in preclinical models and describe initial characterization of its activity in patients with GIST.

A phase 2 trial of ponatinib in Philadelphia chromosome-positive leukemias.

Background: Ponatinib is a potent oral tyrosine kinase inhibitor of unmutated and mutated BCR-ABL, including BCR-ABL with the tyrosine kinase inhibitor-refractory threonine-to-isoleucine mutation at position 315 (T315I). We conducted a phase 2 trial of ponatinib in patients with chronic myeloid leukemia (CML) or Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-positive ALL).

Methods: We enrolled 449 heavily pretreated patients who had CML or Ph-positive ALL with resistance to or unacceptable side effects from dasatinib or nilotinib or who had the BCR-ABL T315I mutation.

Combined targeting of FGFR2 and mTOR by ponatinib and ridaforolimus results in synergistic antitumor activity in FGFR2 mutant endometrial cancer models.

Purpose: Activating mutations in FGFR2 have been identified as potential therapeutic targets in endometrial cancer, typically occurring alongside genetic alterations that disrupt the mTOR pathway, such as PTEN loss. These observations suggest that the mTOR pathway may act in concert with oncogenic FGFR2 to drive endometrial cancer growth in a subset of patients. The aim of this study was to examine the therapeutic potential of a rational drug combination based on the simultaneous targeting of mutant-FGFR2 and mTOR-driven signaling pathways in endometrial cancer cells.

Fragment growing and linking lead to novel nanomolar lactate dehydrogenase inhibitors.

Lactate dehydrogenase A (LDH-A) catalyzes the interconversion of lactate and pyruvate in the glycolysis pathway. Cancer cells rely heavily on glycolysis instead of oxidative phosphorylation to generate ATP, a phenomenon known as the Warburg effect. The inhibition of LDH-A by small molecules is therefore of interest for potential cancer treatments.

Ponatinib in refractory Philadelphia chromosome-positive leukemias.

Background: Resistance to tyrosine kinase inhibitors in patients with chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph-positive ALL) is frequently caused by mutations in the BCR-ABL kinase domain. Ponatinib (AP24534) is a potent oral tyrosine kinase inhibitor that blocks native and mutated BCR-ABL, including the gatekeeper mutant T315I, which is uniformly resistant to tyrosine kinase inhibitors.

Methods: In this phase 1 dose-escalation study, we enrolled 81 patients with resistant hematologic cancers, including 60 with CML and 5 with Ph-positive ALL.

Dimerizer-mediated regulation of gene expression in vivo.

Several systems have been developed that allow transcription of a target gene to be chemically controlled, usually by an allosteric modulator of transcription factor activity. An alternative is to use chemical inducers of dimerization, or "dimerizers," to reconstitute active transcription factors from inactive fusion proteins. The most widely used system employs the natural product rapamycin, or a biologically inert analog, as the dimerizing drug.

Dimerizer-mediated regulation of gene expression in vitro.

Several systems have been developed that allow transcription of a target gene to be chemically controlled, usually by an allosteric modulator of transcription factor activity. An alternative is to use chemical inducers of dimerization, or "dimerizers," to reconstitute active transcription factors from inactive fusion proteins. The most widely used system employs the natural product rapamycin, or a biologically inert analog, as the dimerizing drug.

Dimerizer-mediated regulation of gene expression.

Several systems have been developed that allow transcription of a target gene to be chemically controlled, usually by an allosteric modulator of transcription factor activity. An alternative is to use chemical inducers of dimerization, or "dimerizers," to reconstitute active transcription factors from inactive fusion proteins. The most widely used system employs the natural product rapamycin, or a biologically inert analog, as the dimerizing drug.

Synergistic activity of the mTOR inhibitor ridaforolimus and the antiandrogen bicalutamide in prostate cancer models.

Although androgen ablation therapy is the foundation of current prostate cancer treatment, most patients ultimately develop castration-resistant disease. One proposed mechanism to account for androgen receptor (AR) activity in the castrate environment is via crosstalk with other signaling pathways. Specifically, reciprocal interactions between the AKT/mTOR and AR pathways have been implicated in prostate cancer progression.

Ponatinib (AP24534), a multitargeted pan-FGFR inhibitor with activity in multiple FGFR-amplified or mutated cancer models.

Members of the fibroblast growth factor receptor family of kinases (FGFR1-4) are dysregulated in multiple cancers. Ponatinib (AP24534) is an oral multitargeted tyrosine kinase inhibitor being explored in a pivotal phase II trial in patients with chronic myelogenous leukemia due to its potent activity against BCR-ABL. Ponatinib has also been shown to inhibit the in vitro kinase activity of all four FGFRs, prompting us to examine its potential as an FGFR inhibitor.

Analysis of the pharmacodynamic activity of the mTOR inhibitor ridaforolimus (AP23573, MK-8669) in a phase 1 clinical trial.

Purpose: As part of a phase 1 dose-escalation trial, the pharmacodynamic activity of the mammalian target of rapamycin (mTOR) inhibitor ridaforolimus was assessed in multiple tissues by measuring levels of phosphorylated 4E binding protein-1 (p-4E-BP1) or S6, two downstream markers of mTOR activity.

Methods: 32 patients (pts) were dosed intravenously with ridaforolimus once daily for 5 consecutive days (QD × 5) every 2 weeks. The pharmacodynamic activity of ridaforolimus was assessed in peripheral blood mononuclear cells (PBMCs; 32 pts), skin (28 pts), and tumor specimens (3 pts) collected before and after dosing by measuring levels of p-4E-BP1 by immunoblot analysis or pS6 by immunohistochemistry.

Phase II study of the mammalian target of rapamycin inhibitor ridaforolimus in patients with advanced bone and soft tissue sarcomas.

Purpose: Ridaforolimus is an inhibitor of mammalian target of rapamycin, an integral component of the phosphatidyl 3-kinase/AKT signaling pathway, with early evidence of activity in sarcomas. This multicenter, open-label, single-arm, phase II trial was conducted to assess the antitumor activity of ridaforolimus in patients with distinct subtypes of advanced sarcomas.

Patients And Methods: Patients with metastatic or unresectable soft tissue or bone sarcomas received ridaforolimus 12.

Ridaforolimus for patients with progressive or recurrent malignant glioma: a perisurgical, sequential, ascending-dose trial.

Purpose: This perisurgical phase 1 study evaluated the pharmacokinetics, pharmacodynamics, and safety of the mammalian target of rapamycin (mTOR) inhibitor ridaforolimus in patients (N = 10) with progressive or recurrent primary grade IV malignant glioma, who failed standard therapy. The primary objective of the study was to determine the maximum tolerated dose (MTD) of ridaforolimus.

Methods: Treatment was administered intravenously at doses of 12.

Crizotinib-resistant mutants of EML4-ALK identified through an accelerated mutagenesis screen.

Activating gene rearrangements of anaplastic lymphoma kinase (ALK) have been identified as driver mutations in non-small-cell lung cancer, inflammatory myofibroblastic tumors, and other cancers. Crizotinib, a dual MET/ALK inhibitor, has demonstrated promising clinical activity in patients with non-small-cell lung cancer and inflammatory myofibroblastic tumors harboring ALK translocations. Inhibitors of driver kinases often elicit kinase domain mutations that confer resistance, and such mutations have been successfully predicted using in vitro mutagenesis screens.

Antitumor activity of ridaforolimus and potential cell-cycle determinants of sensitivity in sarcoma and endometrial cancer models.

Ridaforolimus is a nonprodrug rapamycin analogue that potently inhibits mTOR and has shown significant activity in patients with metastatic sarcoma and endometrial cancer, two diseases where high unmet need remains. Here, we evaluated the activity of ridaforolimus in preclinical models of these tumor types and used these models to explore molecular correlates of sensitivity. The in vitro sensitivity of a panel of sarcoma and endometrial cancer cell lines was established by measuring the effect of ridaforolimus on cell proliferation rate, revealing broad inhibition at low nanomolar concentrations.