Treosulfan (l-threitol-1,4-bis-methanesulfonate; dihydroxybusulfan) is a prodrug of a bifunctional alkylating cytotoxic agent that is approved for the treatment of ovarian carcinomas in a number of European countries. The antitumor activity of treosulfan has been shown in a variety of solid tumors. It is used for the treatment of all types of ovarian cancer, either supplementary to surgery or palliatively. Treosulfan is a prodrug that is converted nonenzymatically first to a mono-epoxide – (2S,3S)- 1,2-epoxy-3,4-butanediol-4-methanesulfonate – and then to a diepoxide – l-diepoxybutane, which is also a metabolite of butadiene – under physiological conditions. Such conversions are assumed to account for the alkylating and therapeutic activities of treosulfan.

X-396 (Ensartinib) is a novel, potent anaplastic lymphoma kinase (ALK) small molecule tyrosine kinase inhibitor (TKI) with additional activity against MET, ABL, Axl, EPHA2, LTK, ROS1 and SLK. Ensartinib has demonstrated activity in ALK treatment naïve and previously treated patients and has a generally well tolerated safety profile. Ensartinib is currently in a global phase 3 trial in ALK positive non-small cell lung cancer (NSCLC) patients. The phase 1/2 clinical findings support the preclinical results that the use of ensartinib may result in favorable therapeutic outcomes in patients with ALK NSCLC, including patients with CNS metastases. In this study, ensartinib was generally well tolerated with the most common adverse event being a rash.

Landiolol (Onoact) is an intravenously administered, ultra short-acting β1-blocker with an elimination half-life of 3-4 min and ≈8-fold greater cardioselectivity than esmolol in vitro. It is approved in Japan for the treatment of intraoperative and postoperative tachyarrhythmias, but in clinical practice is also used to prevent postoperative tachyarrhythmias, such as atrial fibrillation after coronary artery bypass grafting. Randomized controlled trials in patients undergoing open-heart surgery demonstrated that various dosages of landiolol (0.0005-0.04 mg/kg/min) [0.5-40 μg/kg/min] were more effective than diltiazem in converting postoperative atrial fibrillation to normal sinus rhythm during the first 8 h after surgery, and were more effective than placebo (or no landiolol) in preventing the development of atrial fibrillation during the first week after surgery (primary efficacy endpoints). Landiolol was generally well tolerated in clinical trials, with a relatively low risk of hypotension and bradycardia, although routine monitoring of cardiac function during landiolol administration is important. In general, adverse events such as reduced blood pressure resolve quickly after discontinuation of landiolol. Thus, as an ultra short-acting β1-blocker with a rapid onset of action and readily titratable and rapidly reversible effects, landiolol represents an important agent for the management of intraoperative and postoperative tachyarrhythmias.

Ritlecitinib is an orally administered, covalent small-molecule selective dual inhibitor of JAK3 and the TEC kinase family. In vitro studies showed ritlecitinib covalently binds to JAK3 and is more than 10 000 times more potent against JAK3 than against JAK1, JAK2, and tyrosine kinase. Ritlecitinib also inhibits the five members of the TEC kinase family. Ritlecitinib irreversibly inhibits Janus kinase 3 (JAK3) and TEC kinase family by blocking the adenosine triphosphate (ATP) binding site. In cellular settings, ritlecitinib inhibits cytokine induced STAT phosphorylation mediated by JAK3-dependent receptors. Additionally, ritlecitinib inhibits signaling of immune receptors dependent on TEC kinase family members.The FDA has approved ritlecitinib (LITFULO; Pfizer Inc), a once daily oral treatment, for individuals aged 12 years and older with severe alopecia areata. This makes ritlecitinib, in the 50 mg dosage, the first and only treatment approved by the FDA for adolescents with severe alopecia areata. The approval was based on the results of the ALLEGRO phase 2b/3 trial (NCT03732807), which included 718 individuals who had 50% or more scalp hair loss measured by the Severity of Alopecia Tool. Investigators of the study evaluated the safety and efficacy of ritlecitinib at 118 different sites in 18 different countries. Regulatory applications for LITFULO in alopecia areata have been submitted to countries around the world for review, including China, the European Union, Japan, and the United Kingdom. The European Medicines Agency (EMA) has accepted the Marketing Authorization Application (MAA) for ritlecitinib with a decision anticipated in the third quarter of 2023. LITFULO is also being evaluated for vitiligo, Crohn’s disease, and ulcerative colitis.

Nirmatrelvir (PF-07321332) is a new oral antiviral drug developed by Pfizer. Nirmatrelvir is a major bioavailable oral SARS-CoV-2 protease inhibitor with in vitro human coronavirus antiviral activity, and excellent selection of off-target and in vivo immune profiles. The combination of ritonavir and nirmatrelvir under the brand name Paxlovid was approved by the FDA on May 25, 2023, for the treatment of mild-to-moderate COVID-19 in adults who are at high risk for progression to severe COVID-19, including hospitalization or death. Nirmatrelvir is a peptidomimetic inhibitor of the SARS-CoV-2 main protease (Mpro), also referred to as 3C-like protease (3CLpro) or nonstructural protein 5 (nsp5) protease. Inhibition of SARS-CoV-2 Mpro renders it incapable of processing the viral polyproteins pp1a and pp1ab, preventing viral replication. Nirmatrelvir inhibited the activity of recombinant SARS-CoV-2 Mpro in a biochemical assay with a Ki value of 3.1 nM and an IC50 value of 19.2 nM. Nirmatrelvir was found to bind directly to the SARS-CoV-2 Mpro active site by X-ray crystallography.

Zavegepant is a third generation, small-molecule, calcitonin gene-related peptide (CGRP) receptor antagonist being developed by Pfizer, under a license from Bristol-Myers Squibb, for the prevention and treatment of chronic and episodic migraine. In March 2023, zavegepant nasal spray (ZAVZPRET™) received its first approval in the USA for the acute treatment of migraine with or without aura in adults, based on two randomized, double-blind, placebo-controlled studies. Clinical development of an oral formulation of zavegepant is currently underway.

Pirtobrutinib is a small molecule, noncovalent inhibitor of BTK. BTK is a signaling protein of the B-cell antigen receptor (BCR) and cytokine receptor pathways. In B-cells, BTK signaling results in activation of pathways necessary for B-cell proliferation, trafficking, chemotaxis, and adhesion. Pirtobrutinib binds to wild type BTK and BTK harboring C481 mutations, leading to inhibition of BTK kinase activity. In nonclinical studies, pirtobrutinib inhibited BTK-mediated B-cell CD69 expression and inhibited malignant B-cell proliferation. Pirtobrutinib showed dose-dependent anti-tumor activities in BTK wild type and BTK C481S mutant mouse xenograft models. On January 27, 2023, the Food and Drug Administration (FDA) granted accelerated approval to pirtobrutinib (Jaypirca, Eli Lilly and Company) for relapsed or refractory mantle cell lymphoma (MCL) after at least two lines of systemic therapy, including a BTK inhibitor.

Durlobactam is a new member of the diazabicyclooctane class of beta-lactamase inhibitors with broad-spectrum activity against Ambler class A, C, and D serine beta-lactamases. Sulbactam is a first-generation beta-lactamase inhibitor with activity limited to a subset of class A enzymes that also has direct-acting antibacterial activity against Acinetobacter spp. The latter feature is due to sulbactam's ability to inhibit certain penicillin-binding proteins, essential enzymes involved in bacterial cell wall synthesis in this pathogen. Because sulbactam is also susceptible to cleavage by numerous beta-lactamases, its clinical utility for the treatment of contemporary Acinetobacter infections is quite limited. However, when combined with durlobactam, the activity of sulbactam is effectively restored against these notoriously multidrug-resistant strains. In May 2023, the FDA approved Innoviva’s antibiotic, sulbactam-durlobactam (Xacduro), for treatment in patients 18 years of age and older for the treatment of hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia (HABP/VABP) caused by susceptible isolates of ABC.

Fruquintinib is a highly selective small molecule drug candidate that has been shown to inhibit VEGFR 24 hours a day via an oral dose, with lower off-target toxicities compared to other targeted therapies. Mechanistically, Fruquintinib selectively blocks VEGF-mediated receptor autophosphorylation, thus inhibiting endothelial cell proliferation and migration. In preclinical in vitro studies using a 32P-ATP assay, Fruquintinib selectively inhibited the tyrosine kinase activity associated with VEGFR-1, VEGFR-2, and VEGFR-3 at concentrations in the nanomolar range, but showed little inhibition against a panel of 254 kinases related to cell cycle or cell proliferation, including cyclin-dependent kinase (CDK1, 2, 5), the epidermal growth factor receptor (EGFR), the mesenchymal-epithelial transition factor (c-Met), and platelet-derived growth factor receptor β (PDGFRβ) kinase. In cellular assays, Fruquintinib potently inhibited VEGF-stimulated VEGFR phosphorylation and proliferation in human umbilical vein endothelial cells. Fruquintinib demonstrated potent antiangiogenic effect and anti-tumor activity in xenograft models of colon adenocarcinoma (HT-29), non-small cell lung cancer (NSCLC; NCI-H460), renal clear cell carcinoma (Caki-1), and gastric carcinoma (BGC823) in mice treated for 3 weeks. Fruquintinib is currently under joint development in China by Chi-Med and its partner Eli Lilly and Company (“Lilly”). Chi-Med and Lilly jointly announced top-line results from the FRESCO CRC trial on March 3, 2017. In addition, Fruquintinib is being studied in China in Phase III pivotal trial in non-small cell lung cancer (“NSCLC”), known as FALUCA; and a Phase II study using Fruquintinib combined with Iressa® (gefitinib) in the first-line setting for patients with advanced or metastatic NSCLC.

Nirogacestat (PF-3084014) is a tetralin imidazole gamma-secretase inhibitor. Gamma-secretase, a proteolytic enzyme complex, mediates processing of several integral membrane proteins including amyloid precursor protein and Notch. This compound can inhibit both Notch-related pathway in neoplasia and reduces amyloid-β production. Nirogacestat (PF-3084014) is under development by Pfizer for the treatment of cancer.