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CAL101

CAL101, also known as idelalisib (later marketed as Zydelig®), has been extensively studied in numerous clinical trials for various blood cancers, particularly B-cell malignancies. This drug works by inhibiting phosphatidylinositol 3-kinase delta (PI3K-delta), a critical enzyme in the signaling pathways of B-cell cancers. Clinical trials have investigated CAL101 both as a single agent and in combination with other drugs for conditions such as chronic lymphocytic leukemia (CLL), different types of non-Hodgkin lymphoma (NHL), and more recently, for idiopathic pulmonary fibrosis (IPF). This article explores the key findings from these trials, highlighting CAL101’s efficacy, safety profile, and potential benefits for patients with limited treatment options.

Table of Contents

What is CAL101 (Idelalisib)?

CAL101, also known as idelalisib, is a medication used for treating various types of blood cancers. It’s marketed under the brand name Zydelig® and is also referred to as GS-1101 in some clinical trials [1]. This medication belongs to a class of drugs called phosphoinositide-3-kinase (PI3K) inhibitors, which work by blocking certain enzymes that cancer cells need to grow [2].

Idelalisib is primarily used to treat patients with cancers that have returned after previous treatments (relapsed) or have not responded adequately to other therapies (refractory). It represents an important treatment option for patients who have limited alternatives after their cancer has progressed despite earlier treatments [3].

How Does CAL101 Work?

CAL101 works by targeting and inhibiting a specific form of an enzyme called phosphatidylinositol 3-kinase delta (PI3K-delta). This enzyme plays a crucial role in the signaling pathways that support the growth and survival of B-cell cancers [4].

When CAL101 blocks PI3K-delta, it disrupts important cellular processes that cancer cells rely on to survive and multiply. This leads to the death of cancer cells while having less impact on normal cells. The PI3K/Akt/mTOR pathway is particularly important in many B-cell malignancies, and by targeting this pathway, CAL101 can help control cancer growth [5].

Research has shown that CAL101 affects several biological processes in cancer cells, including:

  • Blocking cell signaling pathways necessary for cancer cell survival
  • Interfering with the tumor microenvironment (the area surrounding cancer cells)
  • Potentially affecting immune system function and response to cancer

Medical Conditions Treated with CAL101

CAL101 has been studied and used to treat several types of blood cancers, particularly those affecting B-cells (a type of white blood cell). The main conditions treated with CAL101 include [6] [7]:

Chronic Lymphocytic Leukemia (CLL)

CAL101 is approved for treating CLL in patients who have received at least one prior therapy. CLL is a slow-growing cancer that affects white blood cells called lymphocytes, particularly B lymphocytes. In CLL, these abnormal cells accumulate in the blood, bone marrow, and lymph nodes [8].

Small Lymphocytic Lymphoma (SLL)

SLL is essentially the same disease as CLL but affects primarily the lymph nodes rather than the blood and bone marrow. CAL101 is also used to treat SLL in patients who have had previous treatments [9].

Follicular Lymphoma (FL)

CAL101 is approved for patients with follicular lymphoma who have received at least two prior systemic therapies. Follicular lymphoma is the most common form of indolent (slow-growing) non-Hodgkin lymphoma [10].

Other Indolent Non-Hodgkin Lymphomas

Clinical trials have investigated CAL101 for other types of indolent non-Hodgkin lymphomas, including:

  • Lymphoplasmacytic Lymphoma and Waldenström Macroglobulinemia
  • Marginal Zone Lymphoma

Hodgkin Lymphoma

CAL101 has also been studied in patients with relapsed or refractory Hodgkin Lymphoma, though it’s not currently approved for this indication [11].

Administration and Dosing

CAL101 is administered as an oral medication in tablet form. The standard dosing regimen typically includes [12]:

  • Standard dose: 150 mg taken twice daily
  • Alternative dosing: Some clinical trials have examined different doses ranging from 50 mg to 300 mg twice daily
  • Duration: Treatment generally continues until the disease progresses or unacceptable side effects occur

In some clinical trials, CAL101 is administered using different schedules:

  • Continuous dosing (taken every day)
  • Intermittent dosing (21 days on treatment followed by 7 days off treatment in 28-day cycles)

The medication is typically taken with food or without regard to meals. It’s important to take CAL101 exactly as prescribed by your healthcare provider [13].

Efficacy of CAL101

Clinical trials have demonstrated the effectiveness of CAL101 in treating various blood cancers, particularly in patients who have relapsed or become refractory to other treatments [14].

Chronic Lymphocytic Leukemia (CLL)

In CLL patients who had received prior treatments, studies have shown that CAL101:

  • Improved progression-free survival (the time before cancer progresses)
  • Achieved overall response rates between 39% and 81%, depending on the specific patient population and whether CAL101 was used alone or in combination with other drugs
  • Showed particular benefit in patients with high-risk genetic features such as 17p deletion or TP53 mutations

For example, in one study combining CAL101 with rituximab for previously treated CLL, the combination significantly improved progression-free survival compared to rituximab alone [15].

Follicular Lymphoma and Other Indolent Lymphomas

In patients with follicular lymphoma and other indolent non-Hodgkin lymphomas who had received multiple prior therapies, CAL101 has shown:

  • Overall response rates ranging from 54% to 71%
  • Reduction in the size of lymph nodes in most patients
  • Durable responses in some patients, lasting several months

Hodgkin Lymphoma

In a Phase 2 study of patients with relapsed or refractory Hodgkin Lymphoma, CAL101 demonstrated modest activity with an overall response rate of approximately 20%, with responses typically lasting several months [11].

New Research Areas for CAL101

Researchers continue to investigate CAL101 for additional uses and in new patient populations. Some emerging areas of research include [16]:

Idiopathic Pulmonary Fibrosis (IPF)

A Phase 2 study is examining whether CAL101 can help prevent further decline in lung function in adults with Idiopathic Pulmonary Fibrosis. This represents a significant departure from its traditional use in blood cancers. In this study, CAL101 is administered as an intravenous infusion approximately once a month for 6 months [16].

Acute Lymphoblastic Leukemia (ALL)

Research is investigating CAL101’s potential role in treating relapsed or refractory Acute Lymphoblastic Leukemia, particularly in older patients for whom conventional treatments may not be recommended [17].

Pancreatic Cancer

Studies are exploring CAL101 as a potential treatment for metastatic pancreatic ductal adenocarcinoma, both as a single agent and in combination with chemotherapy [18].

Post-Transplant Maintenance Therapy

CAL101 is being studied as maintenance therapy after autologous stem cell transplantation in patients with indolent or transformed indolent B-cell non-Hodgkin lymphoma [19].

Side Effects and Safety Considerations

As with many cancer treatments, CAL101 can cause side effects that range from mild to severe. Common side effects include [20]:

Common Side Effects:

  • Diarrhea/colitis: This is one of the most common and potentially serious side effects. It can range from mild to severe and may require treatment interruption, dose reduction, or discontinuation
  • Elevated liver enzymes: Regular blood tests are needed to monitor liver function
  • Neutropenia: Low levels of neutrophils (a type of white blood cell), which can increase the risk of infection
  • Infections: Including pneumonia, upper respiratory tract infections, and others
  • Rash: Various types of skin reactions may occur
  • Fatigue: Feeling unusually tired or weak

Serious Side Effects:

  • Severe diarrhea or colitis: Inflammation of the colon that can be severe or life-threatening
  • Pneumonitis: Inflammation of the lungs that can be serious or fatal
  • Serious infections: Including Pneumocystis jirovecii pneumonia (PJP) and cytomegalovirus (CMV) infection
  • Intestinal perforation: A rare but serious condition where a hole forms in the intestine
  • Severe skin reactions: In rare cases, these can be life-threatening

Due to these potential serious side effects, treatment with CAL101 requires careful monitoring by healthcare providers [21].

Patient Monitoring During Treatment

Patients receiving CAL101 typically undergo regular monitoring to detect and manage side effects early. This monitoring often includes [22]:

  • Regular blood tests to check:
    • Complete blood counts (to monitor for neutropenia and other blood cell abnormalities)
    • Liver function tests (to detect liver toxicity)
  • Monitoring for signs of infection, including:
    • Fever
    • Cough
    • Shortness of breath
  • Gastrointestinal symptom monitoring:
    • Tracking bowel movements
    • Checking for signs of colitis
  • Regular clinical assessments to evaluate overall response to treatment and potential side effects

Patients should promptly report any new symptoms or worsening of existing symptoms to their healthcare providers, as early intervention can help manage side effects more effectively [23].

CAL101 in Combination Therapies

CAL101 is often used in combination with other medications to enhance its effectiveness. Clinical trials have studied various combinations including [24]:

CAL101 with Rituximab

This combination has shown improved outcomes in patients with CLL compared to rituximab alone. Rituximab is an antibody that targets CD20, a protein found on the surface of B cells [5].

CAL101 with Bendamustine and Rituximab

This three-drug combination has been studied for both CLL and indolent non-Hodgkin lymphomas [7].

CAL101 with Obinutuzumab

Obinutuzumab is another anti-CD20 antibody that has been studied in combination with CAL101 for CLL treatment [25].

CAL101 with Ofatumumab

Ofatumumab is an anti-CD20 antibody that has been combined with CAL101 in clinical trials for CLL [8].

CAL101 with Novel Agents

Research is exploring combinations with newer targeted therapies, such as:

  • Tirabrutinib (another targeted therapy)
  • Venetoclax (a BCL-2 inhibitor)
  • Pembrolizumab (an immunotherapy agent)

These combination approaches aim to improve efficacy, overcome resistance mechanisms, and potentially reduce side effects by allowing for lower doses of individual drugs [26].

Aspect Details
Drug Name CAL101 (Idelalisib, GS-1101, Zydelig®)
Mechanism of Action Inhibits phosphatidylinositol 3-kinase delta (PI3K-delta), an enzyme important in B-cell development and function
Primary Indications Studied – Chronic Lymphocytic Leukemia (CLL)
– Small Lymphocytic Lymphoma (SLL)
– Follicular Lymphoma
– Waldenstrom Macroglobulinemia
– Marginal Zone Lymphoma
– Idiopathic Pulmonary Fibrosis (IPF)
Typical Dosing – Oral: 150 mg twice daily (most common)
– Alternative doses: 50-300 mg
– For IPF: Intravenous infusions every 4 weeks
Efficacy in Blood Cancers – Overall Response Rates: 40-80% (varies by cancer type and prior treatments)
– Higher response rates when combined with other therapies
– Improvement in progression-free survival compared to standard treatments
Common Combination Therapies – Rituximab
– Ofatumumab
– Bendamustine
– Obinutuzumab
Common Side Effects – Diarrhea/colitis
– Rash
– Fever
– Infections
– Elevated liver enzymes
– Neutropenia
– Fatigue
Serious Adverse Events – Pneumonitis
– Severe infections
– Bowel perforation
– Severe liver toxicity
Patient Populations – Previously treated/relapsed patients (most studies)
– Some trials in previously untreated patients
– Specific trials for patients with 17p deletion in CLL
– Trials for elderly patients (>65 years)
Future Directions – New combinations with targeted therapies
– Testing in additional disease states
– Optimization of dosing schedules to reduce toxicity
– Use in maintenance therapy after stem cell transplantation

FAQ

  • What types of cancer is CAL101 being studied for? CAL101 (idelalisib) has been primarily studied for B-cell cancers including chronic lymphocytic leukemia (CLL), small lymphocytic lymphoma (SLL), follicular lymphoma, Waldenstrom macroglobulinemia, marginal zone lymphoma, and other indolent non-Hodgkin lymphomas. More recently, it's also being investigated for idiopathic pulmonary fibrosis (IPF), which is not a cancer but a serious lung disease.
  • How is CAL101 administered to patients? CAL101 is typically administered as an oral tablet. In most clinical trials, patients receive a dose of 150 mg taken twice daily, though some trials have studied different dosing regimens ranging from 50 mg to 300 mg. For blood cancers, it's generally taken continuously until disease progression or unacceptable toxicity occurs. In some studies, it's administered intravenously, particularly when being tested for new conditions like IPF.
  • What are the main side effects of CAL101? The most common side effects observed in clinical trials include diarrhea, colitis, rash, fever, infections, fatigue, nausea, and elevated liver enzymes. More serious side effects can include pneumonitis (lung inflammation), bowel perforation, and severe infections. Blood count abnormalities like neutropenia, anemia, and thrombocytopenia have also been reported. Close monitoring is required, and dose modifications or treatment interruptions may be necessary to manage these effects.
  • How effective is CAL101 for treating blood cancers? Clinical trials have shown promising efficacy for CAL101, particularly in previously treated patients with CLL and indolent non-Hodgkin lymphomas. Response rates vary by cancer type and prior treatments, but overall response rates (ORR) typically range from 40-80% in relapsed or refractory patients. When combined with other drugs like rituximab, ofatumumab, or bendamustine, even higher response rates have been observed. However, effectiveness varies between individual patients, and not all patients respond to treatment.
  • Is CAL101 used alone or in combination with other treatments? CAL101 has been studied both as a single agent and in combination with other treatments. Many clinical trials have explored combining CAL101 with antibody therapies like rituximab, obinutuzumab, or ofatumumab, and with chemotherapy agents like bendamustine. Combination approaches often show higher response rates than single-agent therapy, though they may also have increased side effects. The appropriate approach depends on the specific cancer type, patient characteristics, and prior treatments.

Ongoing Clinical Trials on CAL101

  • Study on the Effects of CAL101 for Patients with Idiopathic Pulmonary Fibrosis

    Not recruiting

    1 1
    Investigated diseases:
    Investigated drugs:
    Denmark France Italy The Netherlands Norway Romania +1

Glossary

  • Idelalisib: The generic name for CAL101, a drug that inhibits phosphatidylinositol 3-kinase delta (PI3K-delta), an enzyme important in B-cell development and function. Also marketed under the brand name Zydelig®.
  • Chronic Lymphocytic Leukemia (CLL): A type of cancer that affects the blood and bone marrow, characterized by an overproduction of lymphocytes (a type of white blood cell). It typically progresses slowly and affects older adults.
  • Small Lymphocytic Lymphoma (SLL): A type of non-Hodgkin lymphoma affecting the lymph nodes that is very similar to CLL but primarily involves the lymph nodes rather than the blood and bone marrow.
  • Follicular Lymphoma: A slow-growing type of non-Hodgkin lymphoma that arises from B-lymphocytes and typically affects the lymph nodes.
  • Waldenstrom Macroglobulinemia: A rare type of blood cancer characterized by an excess of abnormal white blood cells in the bone marrow that produce large amounts of an abnormal protein called macroglobulin.
  • Marginal Zone Lymphoma: A slow-growing type of non-Hodgkin lymphoma that arises from B-cells in the marginal zone of lymphoid tissue.
  • Indolent Non-Hodgkin Lymphoma (iNHL): A group of slow-growing non-Hodgkin lymphomas that typically respond well to treatment but often return and usually cannot be cured.
  • PI3K-delta: Phosphatidylinositol 3-kinase delta, an enzyme that plays a critical role in the growth and survival of B-cells. CAL101 works by inhibiting this enzyme.
  • Progression-Free Survival (PFS): The length of time during and after treatment that a patient lives with the disease but it does not get worse.
  • Overall Response Rate (ORR): The percentage of patients whose cancer shrinks or disappears after treatment, typically including both complete and partial responses.
  • Complete Response (CR): The disappearance of all signs of cancer in response to treatment.
  • Partial Response (PR): A decrease in the size of a tumor, or in the extent of cancer in the body, in response to treatment.
  • Rituximab: A monoclonal antibody medication that targets the CD20 protein on B-cells and is often used in combination with CAL101 in clinical trials.
  • Ofatumumab: A monoclonal antibody medication that binds to the CD20 protein on B-cells, used in the treatment of CLL and often combined with CAL101 in clinical trials.
  • Bendamustine: A chemotherapy drug used to treat CLL and certain types of non-Hodgkin lymphoma, sometimes used in combination with CAL101.
  • Idiopathic Pulmonary Fibrosis (IPF): A chronic, progressive lung disease characterized by scarring (fibrosis) of the lungs, which makes breathing difficult and prevents oxygen from entering the bloodstream.
  • Forced Vital Capacity (FVC): A measurement of lung function that represents the amount of air that can be forcibly exhaled from the lungs after taking the deepest breath possible.
  • Minimal Residual Disease (MRD): Small numbers of cancer cells that remain in the body during or after treatment and can only be detected by highly sensitive tests.
  • Adverse Event (AE): Any unfavorable and unintended sign, symptom, or disease associated with the use of a medical treatment, whether or not considered related to the treatment.
  • Dose-Limiting Toxicity (DLT): Side effects of a drug that are severe enough to prevent an increase in dose or that require a decrease in dose in clinical trials.
  • Randomized Controlled Trial: A study in which people are allocated at random to receive one of several clinical interventions, including a control or standard treatment.
  • Double-Blind Study: A study in which neither the participants nor the researchers know which participants are receiving the experimental drug and which are receiving a placebo or standard treatment.
  • Relapsed Disease: Cancer that has returned after a period of improvement.
  • Refractory Disease: Cancer that does not respond to treatment.

References

  1. https://clinicaltrials.gov/study/NCT01090414
  2. https://clinicaltrials.gov/study/NCT01659047
  3. https://clinicaltrials.gov/study/NCT01282424
  4. https://clinicaltrials.gov/study/NCT01539291
  5. https://clinicaltrials.gov/study/NCT01203930
  6. https://clinicaltrials.gov/study/NCT01539512
  7. https://clinicaltrials.gov/study/NCT01732926
  8. https://clinicaltrials.gov/study/NCT02135133
  9. https://clinicaltrials.gov/study/NCT01659021
  10. https://clinicaltrials.gov/study/NCT02536300
  11. https://clinicaltrials.gov/study/NCT01393106
  12. https://clinicaltrials.gov/study/NCT01306643
  13. https://clinicaltrials.gov/study/NCT02242045
  14. https://clinicaltrials.gov/study/NCT02136511
  15. https://clinicaltrials.gov/study/NCT02044822
  16. https://clinicaltrials.eu/trial/study-on-the-effects-of-cal101-for-patients-with-idiopathic-pulmonary-fibrosis/
  17. https://clinicaltrials.gov/study/NCT03742323
  18. https://clinicaltrials.gov/study/NCT02468557
  19. https://clinicaltrials.gov/study/NCT03133221
  20. https://clinicaltrials.gov/study/NCT02928510
  21. https://clinicaltrials.gov/study/NCT02662296
  22. https://clinicaltrials.gov/study/NCT02436135
  23. https://clinicaltrials.gov/study/NCT01732913
  24. https://clinicaltrials.gov/study/NCT01569295
  25. https://clinicaltrials.gov/study/NCT01980875
  26. https://clinicaltrials.gov/study/NCT02968563