Unloxcyt

Pronunciation: un-LOX-sit
Generic name: cosibelimab-ipdl
Dosage form: infusion (1,200 mg)

Medically reviewed by Melisa Puckey, BPharm. Last updated on Feb 12, 2025.

What is Unloxcyt?

Unloxcyt (cosibelimab-ipdl) is used to treat metastatic cutaneous squamous cell carcinoma (cSCC) or locally advanced cSCC in adult patients who are not candidates for curative surgery or curative radiation. Unloxcyt works by reactivating the immune response against the tumor by blocking PD-L1 proteins present on the surface of cells, this increases the ability of the immune system to kill cancer cells. Unloxcyt is given as an infusion every three weeks.

Unloxcyt FDA approval was granted on December 13, 2024, for the treatment of adults with metastatic cutaneous squamous cell carcinoma (mCSCC) or locally advanced CSCC (laCSCC) who are not candidates for curative surgery or curative radiation. Unloxcyt FDA approval was based on Study CK-301-101 (NCT03212404) of Unloxcyt in adults with advanced solid tumor cancers, including cSCC, which showed clinically meaningful objective response rates and duration of response data.

Unloxcyt mechanism of action is a programmed death ligand-1 (PD-L1) blocking antibody. PD-L1 is a protein on the cell surface that is involved in slowing the immune system from attacking cancer cells. By blocking PD-L1, the anti-tumor immune system is reactivated. Unloxcyt has also been shown to have antibody-dependent cell-mediated cytotoxicity (ADCC), potentially making it more effective in specific cancers.

Unloxcyt side effects

Common side effects

Unloxcyt common side effects include: 

• tiredness or weakness (33%)
• muscle or bone pain (25%)
• rash (23%)
• diarrhea (14%)
• low thyroid hormone levels (hypothyroidism)(14%)
• constipation (13%)
• nausea (13%)
• headache (12%)
• itchy skin (12%)
• swelling (11%), 
• infection (10%)
• urinary tract infection (10%). 

These are the side effects that have occurred in 10% or more patients in Study CK-301-101.

Serious Unloxcyt side effects

Unloxcyt can cause your immune system to attack normal organs and tissues in any area of your body and can cause serious side effects. These side effects can sometimes become severe or life-threatening and can lead to death. You can have more than one of these problems at the same time. These problems may happen anytime during treatment or even after your treatment has ended. Call or see your healthcare provider right away if you develop any new or worsening signs or symptoms, including: 

Lung problems

• cough 
• chest pain 
• shortness of breath.

Intestinal problems

• diarrhea (loose stools) or more frequent bowel movements than usual
• stools that are black, tarry, sticky, or have blood or mucus 
• severe stomach-area (abdomen) pain or tenderness. 

Liver problems

• yellowing of your skin or the whites of your eyes 
• dark urine (tea colored)
• severe nausea or vomiting
• bleeding or bruising more easily than normal
• pain on the right side of your stomach area (abdomen).

Hormone gland problems 

• headache that will not go away or unusual headaches
• urinating more often than usual
• eye sensitivity to light
• hair loss
• eye problems
• feeling cold
• rapid heartbeat
• constipation
• increased sweating
• your voice gets deeper
• extreme tiredness
• dizziness or fainting
• weight gain or weight loss
• changes in mood or behavior, such as decreased sex drive, irritability, or forgetfulness
• feeling more hungry or thirsty than usual.

Kidney problems

• decrease in your amount urine
• swelling of your ankles
• blood in your urine
• loss of appetite. 

Skin problems

• rash
• painful sores or ulcers in mouth or nose itching throat, or genital area
• fever or flu-like symptoms
• swollen lymph nodes
• skin blistering or peeling.

Other organs and tissue side effects. These are not all the signs and symptoms of immune system problems that can happen with Unloxcyt. Call or see your healthcare provider right way for any new or worsening signs or symptoms which may include: 

• chest pain, irregular heartbeat, shortness of breath or swelling of ankles 
• confusion, sleepiness, memory problems, changes in mood or behavior, stiff neck, balance problems, tingling or numbness of the arms or legs
• double vision, blurry vision, sensitivity to light, eye pain, changes in eyesight 
• persistent or severe muscle pain or weakness, muscle cramps 
• low red blood cells, bruising.

Infusion reactions. Infusion reactions side effects can sometimes be severe or life-threatening. Signs and symptoms of infusion reactions may include: 

• nausea
• dizziness
• chills or shaking
• feel like passing out
• itching or rash
• fever 
• flushing
• back or neck pain
• shortness of breath or wheezing

Rejection of a transplanted organ. Your healthcare provider should tell you what signs and symptoms you should report and monitor you, depending on the type of organ transplant that you have had.

Complications, including graft-versus-host disease (GVHD), in people who have received a bone marrow (stem cell) transplant that uses donor stem cells (allogeneic). These complications can be serious and can lead to death. These complications may happen if you underwent transplantation either before or after being treated with Unloxcyt your healthcare provider will monitor you for these complications. 

Getting medical treatment right away may help keep these problems from becoming more serious. Your healthcare provider will check you for these problems during your treatment with Unloxcyt. Your healthcare provider may treat you with corticosteroid or hormone replacement medicines. Your healthcare provider may also need to delay or completely stop treatment with Un if you have severe side effects. 

This is not a complete list of side effects, and others may occur. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088

Related/similar drugs

Before taking this medicine

Before taking Unloxcyt, tell your healthcare provider about all your medical conditions, including if you:

• have immune system problems such as Crohn’s disease, ulcerative colitis, or lupus
• have received an organ transplant, including a corneal transplant
• have received or plan to receive a stem cell transplant that uses donor stem cells (allogeneic)
• have received radiation treatment to your chest area
• have a condition that affects your nervous system, such as myasthenia gravis or Guillain-Barré syndrome

Pregnancy

Tell your healthcare provider if you plan to become pregnant, are pregnant or become pregnant during treatment, as Unloxcyt pregnant can harm your unborn baby.

Females who are able to become pregnant:

• You will have a pregnancy test before you start treatment with this medicine
• You should use an effective method of birth control during your treatment and for 4 months after the last dose of this medicine. Talk to your healthcare provider about birth control methods that you can use during this time.
• Tell your healthcare provider right away if you become pregnant or think you may be pregnant during treatment with Unloxyt.

Breastfeeding

Tell your healthcare provider if you are breastfeeding or plan to breastfeed, as it is not known if Unloxcyt passes into your breast milk.

• Do not breastfeed during treatment and for 4 months after the last dose of Unloxcyt

Unloxcyt dosing information

Unloxcyt is given as a 1,200 mg intravenous infusion over 60 minutes every 3 weeks.  

The dose may be delayed or permanently discontinued due to serious side effects.

What other drugs will affect Unloxcyt?

Other drugs may interact with this medicine. Tell your healthcare provider about all the medications you use and take, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Storage

Storage of Unloxcyt Vial

• Store in a refrigerator at 2°C to 8°C (36°F to 46°F) in original carton to protect from light. 
• Do not freeze or shake. 

Storage of Prepared Unloxcyt  Infusion Solution

• Either at room temperature up to 25°C (77°F) for no more than 24 hours from the time of preparation until the end of infusion
• Or under refrigeration at 2°C to 8°C (36°F to 46°F) for no more than 24 hours from time of preparation until end of infusion. If refrigerated, allow the diluted solution to come to room temperature before administration. 
• Discard after 24 hours.
• Do not freeze. 

Ingredients

Active ingredient: cosibelimab-ipdl

Inactive ingredients: acetic acid, mannitol, polysorbate 80, sodium acetate, sodium chloride, and Water for Injection. 

Company 

Unloxcyt Checkpoint Therapeutics, Inc., 95 Sawyer Road, Suite 110 Waltham, MA, 02453

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer