Voxtalisib

Drug Overview

Voxtalisib (also known by its code names SAR245409 and XL765) is an investigational, orally bioavailable small molecule designed to inhibit two critical pathways involved in cancer cell growth: Phosphoinositide 3-Kinase (PI3K) and the mechanistic Target of Rapamycin (mTOR). It is classified as a dual PI3K/mTOR inhibitor.

In the clinical landscape of March 2026, voxtalisib is recognized for its potent, reversible, and ATP-competitive inhibition of all four Class I PI3K isoforms (α, β, γ, and Δ) as well as both mTOR complexes (mTORC1 and mTORC2). By simultaneously blocking these pathways, voxtalisib aims to overcome the “feedback loops” that often allow cancer cells to survive when only one part of the pathway is targeted.

• Generic Name: Voxtalisib.
• Code Names: SAR245409, XL765.
• Drug Class: Dual PI3K/mTOR Inhibitor; Antineoplastic Agent.
• Mechanism: Inhibition of pan-Class I PI3K and mTORC1/mTORC2.
• Route of Administration: Oral (Capsule or Tablet).
• FDA Approval Status: Investigational. As of March 2026, voxtalisib is not FDA-approved. While it has shown promising activity in specific subtypes of lymphoma, clinical development has been selective, and it is not currently available for commercial use.

What Is It and How Does It Work? (Mechanism of Action)

The PI3K/AKT/mTOR pathway is one of the most frequently mutated pathways in human cancers, acting as a primary driver for cell proliferation, survival, and resistance to therapy.

1. Dual Pathway Blockade

Most first-generation inhibitors target either PI3K or mTOR. However, inhibiting only one can lead to the compensatory activation of the other.

• Pan-PI3K Inhibition: Voxtalisib blocks the activity of all Class I PI3K isoforms, preventing the formation of PIP3, a key signaling lipid that recruits AKT to the cell membrane.
• mTORC1/2 Inhibition: It also inhibits the mTOR complexes, which are responsible for protein synthesis and cell cycle progression.

2. Therapeutic Effects

In preclinical and early clinical models, this dual action results in:

• Apoptosis Induction: Triggering programmed cell death in malignant cells.
• Cell Cycle Arrest: Stopping the rapid division of tumor cells.
• Anti-Angiogenic Effects: Reducing the formation of new blood vessels that tumors need to grow.
• Chemosensitization: Making resistant tumor cells more susceptible to traditional chemotherapy agents like temozolomide.

FDA-Approved Clinical Indications

There are currently no FDA-approved indications for voxtalisib.

Historically, the drug has been evaluated in clinical trials for:

• Relapsed/Refractory Follicular Lymphoma (FL): Where it demonstrated its most significant clinical activity.
• Chronic Lymphocytic Leukemia (CLL) / Small Lymphocytic Lymphoma (SLL): Studied in Phase 2 trials with limited efficacy.
• Glioblastoma (High-Grade Glioma): Evaluated in combination with temozolomide and radiotherapy.
• Advanced Solid Tumors: Including breast, lung, and ovarian cancers.

Dosage and Administration Protocols

As an investigational agent, the “Maximum Tolerated Dose” (MTD) and “Recommended Phase 2 Dose” (RP2D) were determined through rigorous dose-escalation studies.

Clinical Efficacy and Research Results

Clinical trials, most notably the Phase 2 study published in The Lancet Haematology, have highlighted a “mixed” response profile:

• Follicular Lymphoma (FL): Voxtalisib monotherapy showed a notable Overall Response Rate (ORR) of 41.3% in patients with relapsed or refractory FL, including several complete responses. The median progression-free survival (PFS) in this group reached approximately 58 weeks.
• Aggressive Lymphomas: The drug showed limited efficacy in more aggressive subtypes, such as Mantle Cell Lymphoma (MCL) (11.9% ORR) and Diffuse Large B-cell Lymphoma (DLBCL) (4.9% ORR).
• Glioblastoma: Trials combining voxtalisib with temozolomide showed a favorable safety profile and moderate inhibition of the PI3K/mTOR pathway, though it did not significantly upend the standard of care.
• Pharmacokinetics: Voxtalisib has a relatively short steady-state half-life (approximately 2.3 to 4.6 hours), which researchers suggest may contribute to the limited efficacy in aggressive malignancies that require sustained pathway suppression.

Safety Profile and Side Effects

The safety profile of voxtalisib is consistent with other drugs in the PI3K/mTOR inhibitor class.

Common Side Effects (>20%):

• Gastrointestinal: Diarrhea (35%), nausea (27%), and decreased appetite.
• Systemic: Fatigue (32%), pyrexia (fever), and cough.
• Skin: Pruritic rash (itching) was a common dose-limiting toxicity in early studies.

Serious Risks (Grade 3 or Higher):

• Hematologic: Anemia (12%), thrombocytopenia (low platelets), and neutropenia.
• Infections: Pneumonia (8%) and other opportunistic infections.
• Metabolic: Hyperglycemia (high blood sugar) and hypophosphatemia, due to the pathway’s role in glucose metabolism.
• Hepatic: Elevations in liver enzymes (ALT/AST), requiring periodic blood monitoring.

Research Areas

In the fields of Stem Cell and Regenerative Medicine, voxtalisib is a valuable research tool for studying “Pathway Cross-talk.” Because PI3K and mTOR are central to how stem cells decide to either self-renew or differentiate, researchers use voxtalisib to understand how to manipulate these signals in a lab setting. In 2026, there is also renewed interest in “Computational Drug Discovery.” Using deep learning models (like iDCNNPred), scientists are identifying new scaffolds based on voxtalisib’s structure to create next-generation inhibitors that have a longer half-life and fewer metabolic side effects.

Patient Management and Practical Recommendations

Pre-treatment Requirements:

• Blood Glucose Monitoring: Because the drug can cause hyperglycemia, baseline and periodic glucose checks are essential.
• Liver Function Tests (LFTs): Baseline and ongoing monitoring of ALT and AST.

“Do’s and Don’ts” List:

• DO follow the “fasting” window (2 hours before/1 hour after) if prescribed, as food can significantly alter how the drug is absorbed.
• DO report any signs of infection, such as fever or new cough, immediately to the study team.
• DON’T miss your scheduled blood work; metabolic and hematologic toxicities can escalate quickly.
• DON’T start new over-the-counter medications without consulting the oncologist, as many drugs can interact with the enzymes that process voxtalisib.

Legal Disclaimer

The information provided is for educational and informational purposes only and does not constitute medical advice. Voxtalisib (SAR245409, XL765) is an investigational agent and is not approved by the U.S. FDA for any indication. Access is restricted exclusively to registered clinical trials. Always consult with a qualified oncologist regarding your specific diagnosis and eligibility for research participation.