1 What is this medicine
and what is it used for?
Venetoclax is a first-in-class oral BCL-2 (B-cell lymphoma 2)
inhibitor. BCL-2 is an anti-apoptotic protein that is over-expressed in many
haematological malignancies, allowing cancer cells to evade programmed cell
death (apoptosis). Venetoclax selectively binds BCL-2 and displaces
pro-apoptotic proteins, restoring the cancer cell's ability to undergo
apoptosis.
It is used to treat adults with:
• Chronic lymphocytic leukaemia (CLL) /
small lymphocytic lymphoma (SLL) — as monotherapy after at least two prior
therapies, or in combination with obinutuzumab (first line) or rituximab
(relapsed/refractory).
• Acute myeloid leukaemia (AML) — in
combination with azacitidine, decitabine, or low-dose cytarabine, in adults 75
years or older or unfit for intensive induction chemotherapy.
2 How to take this
medicine
Venetoclax must be taken once daily with a meal and water —
food (particularly a moderate-fat meal) is essential to ensure adequate
absorption. The dose must be increased gradually over 5 weeks using a dose
ramp-up schedule (20 mg → 50 mg → 100 mg → 200 mg → 400 mg weekly) to reduce
the risk of tumour lysis syndrome (TLS). The maintenance dose is 400 mg once
daily (4 tablets).
|
CRITICAL — TUMOUR LYSIS SYNDROME (TLS) RISK: Venetoclax can cause
rapid tumour cell death, releasing intracellular contents into the
bloodstream — this is Tumour Lysis Syndrome (TLS). TLS can cause acute
kidney failure, cardiac arrhythmias, and death if not managed properly. ALL patients must
undergo TLS risk assessment before starting. MANDATORY: 5-week dose
ramp-up schedule — NEVER start at the full 400 mg dose. TLS prophylaxis:
vigorous hydration (1.5–2 L/day minimum) starting 2 days before first dose;
allopurinol or rasburicase as prescribed. Blood tests (uric
acid, potassium, phosphate, calcium, creatinine) before first dose of each
ramp-up step and 6–8 hours after. For high-risk
patients: first doses of the ramp-up steps may require hospitalisation for
monitoring. |
3 Possible side effects
|
Frequency |
Side Effect |
What to Do |
|
Very Common (>10%) |
Neutropenia (low white
blood cells) |
Regular blood counts —
dose holds if severe. Report fever urgently. |
|
Very Common (>10%) |
Nausea / diarrhoea |
Take with food;
anti-emetics and loperamide available if needed. |
|
Very Common (>10%) |
Fatigue |
Rest when needed;
check for anaemia contributing. |
|
Very Common (>10%) |
Anaemia /
thrombocytopenia |
Regular FBC
monitoring; transfusions if indicated. |
|
Common (1–10%) |
Tumour lysis syndrome
(TLS) |
See critical warning
box above — managed with strict monitoring and prophylaxis. |
|
Common (1–10%) |
Upper respiratory
tract infection / pneumonia |
Report any signs of
infection; febrile neutropenia is an emergency. |
|
Common (1–10%) |
Constipation |
Maintain good fluid
and fibre intake. |
|
Seek help urgently |
Fever with
neutropenia, sudden muscle cramps, irregular heartbeat, decreased urine
output (TLS) |
Emergency hospital
admission required. |
4 Who should not take
this medicine
|
Contraindications and Critical Cautions: Strong CYP3A4
inhibitors (ketoconazole, itraconazole, ritonavir, clarithromycin):
CONTRAINDICATED at initiation and ramp-up — dramatically increase venetoclax
levels and TLS risk. If required after maintenance dose established, reduce
venetoclax dose by 75%. P-gp inhibitors: use
with caution. Moderate CYP3A4
inhibitors at ramp-up phase: avoid — increase dose with specialist guidance
only. Grapefruit, Seville
oranges, starfruit: AVOID — inhibit CYP3A4. Pregnancy: venetoclax
is teratogenic — highly effective contraception required during treatment and
for 30 days after (women), 3 months after (men). Live vaccines:
contraindicated during treatment. |
5 Drug interactions
• Strong CYP3A4 inhibitors:
contraindicated during ramp-up (see above).
• Strong CYP3A4 inducers (rifampicin,
carbamazepine, phenytoin, St John's Wort): significantly reduce venetoclax
levels — avoid.
• P-gp substrates with narrow
therapeutic index (digoxin, dabigatran): venetoclax inhibits P-gp — monitor.
• Warfarin: monitor INR; venetoclax may
interact via CYP pathways.
6 Storage
Store at room temperature below 30°C. Keep in original
packaging. Keep out of reach of children. Do not use after expiry date.
7 Prescription
requirement
|
PRESCRIPTION ONLY
MEDICINE (POM) — Specialist haematologist or oncologist prescription only. TLS risk
stratification, mandatory hydration and prophylaxis protocol, and laboratory
monitoring schedule must be in place before prescribing. Many centres require
the first ramp-up doses to be supervised in clinic. |
8 Guidance for patients
& caregivers
The dose ramp-up schedule is not optional — it is the most
critical safety step with venetoclax. Starting at a low dose and increasing
gradually over 5 weeks gives your body time to safely manage the dying cancer
cells. Never take more tablets than prescribed, even if your next week's dose
has arrived.
Drink at least 1.5–2 litres of water every day during the
ramp-up phase and continue throughout treatment. This is one of the most
important things you can do to protect your kidneys from TLS.
Always take venetoclax with a meal. Taking it without food
significantly reduces absorption and may reduce effectiveness. A moderate-fat
meal (e.g. a light cooked breakfast or lunch with some fat content) is
recommended.
9 Pharmacist &
prescriber notes
The 120-tablet pack at 100 mg provides: 3 tablets at Week 3
(300 mg), full 4 tablets at Weeks 4–5 ramp-up (400 mg), and initial supply for
maintenance therapy.
Note that the ramp-up requires 20 mg, 50 mg, 100 mg, and 200
mg dose steps — these lower-strength tablets are separate products; the 100 mg
pack alone is insufficient for initiating ramp-up without the other strengths.
Venetoclax is also available as a 10 mg and 50 mg tablet for
the ramp-up. Full blood count and metabolic panel (Na, K, phosphate, uric acid,
creatinine, Ca) at baseline and 6–8 hours post-first-dose and post-each ramp-up
dose increase for moderate/high TLS risk patients. Obinutuzumab or rituximab
combination: begin obinutuzumab cycle 1 on day 1, venetoclax ramp-up starts day
22 of cycle 1. CYP3A4 management is critical — any new prescription in a
venetoclax patient requires drug interaction review.
10 Frequently asked
questions
Why must I take it with food?
Food — especially moderate fat —
significantly increases venetoclax absorption. Taking it without food can
reduce the amount of medicine reaching your bloodstream, potentially making it
less effective.
Can I eat grapefruit?
No — grapefruit and Seville oranges
inhibit the enzyme (CYP3A4) that breaks down venetoclax, causing drug levels to
rise dangerously. Avoid all grapefruit products during treatment.
Why do I need blood tests so frequently at the start?
Blood tests before and 6–8 hours
after each dose increase during the ramp-up monitor for Tumour Lysis Syndrome
by checking potassium, phosphate, uric acid, and kidney function. Early
detection allows prompt treatment.
How long will I need to take venetoclax?
In CLL with obinutuzumab: typically
12 months (time-limited therapy). In AML combinations: continued until disease
progression or intolerable toxicity. Your haematologist will determine your
specific treatment duration.