Idelalisib
| Evidence Level: L3 | Predicted Indications: 6 |
Table of Contents
Idelalisib: Mantle cell lymphoma
One-Sentence Summary
Idelalisib (Zydelig) is an oral targeted drug originally used for B-cell blood cancers such as chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and follicular lymphoma. The TxGNN model predicts it may be effective for Mantle Cell Lymphoma (MCL). Support so far is limited to 5 early-phase clinical trials and 20 publications, mostly reviews and laboratory studies.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not recorded in the local data |
| Predicted New Indication | Mantle cell lymphoma |
| TxGNN Prediction Score | 0.9984 |
| Evidence Level | L3 (no Phase 3 or randomized efficacy data in MCL; evidence consists of early-phase trials, reviews and preclinical work) |
| Canada Market Status | Marketed (marketed DINs: 2 of 2) |
| Number of DINs | 2 (marketed: 2) |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Detailed mechanism-of-action data are not available in the data compiled for this report. The published literature describes idelalisib as the first-in-class inhibitor of PI3Kδ (phosphatidylinositol 3-kinase delta). This enzyme sits in the B-cell receptor signalling pathway and supports the survival and growth of malignant B cells.
MCL is a B-cell non-Hodgkin lymphoma. Reviews and laboratory studies indicate that it relies on B-cell receptor and PI3K signalling. This is the same biology that underlies idelalisib’s activity in CLL/SLL and follicular lymphoma, and it explains why the model ranks MCL highly.
The picture is not entirely favourable:
- Laboratory work reports that MCL cells can show intrinsic resistance to idelalisib.
- Preclinical studies suggest the resistance may be overcome by combinations. Examples are a P300/CBP inhibitor (A-485), the CDK4/6 inhibitor palbociclib, and propolis, which restores sensitivity in resistant cells by inducing CBX5-mediated ferroptosis.
- Another study found that idelalisib suppresses translation-regulatory pathways in MCL cells.
Overall, the mechanistic rationale is plausible, but no randomized efficacy evidence in MCL has been provided.
Clinical Trial Evidence
| Trial Number | Phase | Status | Enrollment | Key Findings |
|---|---|---|---|---|
| NCT01838434 | Phase 1 / randomized Phase 2 | Completed | 106 | Lenalidomide with or without idelalisib in relapsed/refractory MCL. This is the most MCL-specific trial; no results are provided in the compiled data. |
| NCT01088048 | Phase 1 | Completed | 241 | Safety and activity of idelalisib with chemotherapy, immunomodulatory agents or anti-CD20 antibody in relapsed/refractory indolent lymphoma, MCL or CLL. MCL is only a subset of the population. |
| NCT01796470 | Phase 2 | Terminated | 66 | Entospletinib plus idelalisib in relapsed/refractory blood cancers, including MCL. Early termination limits interpretation. |
| NCT02603445 | Phase 1 | Completed | 20 | Dose escalation of BCL201 plus idelalisib in follicular lymphoma and MCL, focused on safety and tolerability. |
| NCT03151057 | Phase 1 | Terminated | 16 | Idelalisib as maintenance after allogeneic stem cell transplant in B-cell malignancies. Not MCL-specific. |
Literature Evidence
No randomized controlled trials in MCL were found. The most relevant items are listed below, with reviews first.
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 33154951 | 2020 | Review | Frontiers in Oncology | Mechanisms of resistance to BTK and PI3K inhibitors (ibrutinib, idelalisib) in B-cell malignancies, including MCL |
| 24974852 | 2014 | Review | British Journal of Haematology | Current regimens and novel agents for MCL |
| 26360791 | 2015 | Review | Expert Opinion on Pharmacotherapy | Standard and emerging treatment options for MCL |
| 26841011 | 2016 | Review | Cancer Journal | Targeting the PI3K pathway with idelalisib in non-Hodgkin lymphoma |
| 28775119 | 2017 | Review | Haematologica | Incidence and practical management of toxicity with ibrutinib and idelalisib |
| 27342398 | 2017 | Preclinical | Clinical Cancer Research | Idelalisib inhibits cell growth in MCL by suppressing translation-regulatory mechanisms |
| 33850273 | 2022 | Preclinical | Acta Pharmacologica Sinica | P300/CBP inhibitor A-485 overcomes idelalisib resistance in MCL cells in vitro and in vivo |
| 38815797 | 2024 | Preclinical | Cancer Letters | Idelalisib enhances the antitumour effect of palbociclib via PLK1 in B-cell lymphoma (DLBCL and MCL) |
| 40466505 | 2025 | Preclinical | Phytomedicine | CBX5 loss drives PI3Kδ-inhibitor resistance in MCL; propolis restores sensitivity |
| 36297673 | 2022 | Preclinical | Pharmaceutics | A ROR1 inhibitor, alone or combined with idelalisib and other agents, induces apoptosis in MCL cells |
Canada Market Information
| DIN | Product Name | Status |
|---|---|---|
| 02438801 | ZYDELIG | Valid (single-ingredient) |
| 02438798 | ZYDELIG | Valid (single-ingredient) |
Dosage form, manufacturer and approved indication text are not listed in the Canadian licence records compiled for this report.
Cytotoxicity
| Item | Content |
|---|---|
| Cytotoxicity Classification | Targeted therapy (PI3Kδ inhibitor); not a conventional cytotoxic chemotherapy |
| Myelosuppression Risk | Please refer to the package insert warnings and precautions |
| Emetogenicity Classification | Please refer to the package insert warnings and precautions |
| Monitoring Items | Please refer to the package insert warnings and precautions |
| Handling Protection | Please refer to the package insert warnings and precautions |
Safety Considerations
- Trial-reported safety signal: Several Phase 2/3 idelalisib trials in front-line CLL and early-line indolent lymphoma were stopped after a monitoring committee saw increased deaths and serious adverse events with idelalisib combinations. Colitis and diarrhea are also recognized with this drug, and one trial is dedicated to studying the mechanism.
- Drug interactions: The interaction screen returned 100 interacting drugs. Examples are below.
- Major: loperamide, triamcinolone, budesonide, eliglustat.
- Moderate: clarithromycin, dexamethasone, hydrocortisone, betamethasone, bupropion, aprepitant, doxycycline, minocycline, pioglitazone, acarbose, saxagliptin, chenodeoxycholic acid, eluxadoline.
Warnings and contraindications from the Canadian package insert were not available for this report. Please refer to the package insert for full safety information.
Conclusion and Next Steps
Decision: Hold
Rationale: The biological rationale for MCL is reasonable. However, the clinical evidence consists only of Phase 1 and early Phase 2 studies, several of them terminated and with MCL as a minor subset. There is no randomized efficacy data, laboratory work shows intrinsic resistance, and idelalisib carries a serious toxicity history. These points together do not justify moving forward yet.
To proceed, the following is needed:
- MCL-specific efficacy results, such as response rates and progression-free survival, from NCT01838434 and any other MCL-focused studies.
- The Canadian package insert warnings and contraindications, to complete the safety screen.
- Detailed mechanism-of-action data, with attention to the reported resistance in MCL and the combination strategies that might overcome it.
- A comparison against existing MCL therapies, such as BTK inhibitors, to define any unmet need for idelalisib.
- A risk-management plan for hepatic, gastrointestinal, pulmonary, infectious and cutaneous toxicities and for drug interactions.
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.