Hormone tablets, abiraterone (Zytiga®) and enzalutamide (Xtandi®) are approved to treat advanced prostate cancer. However, even if these drugs are helpful, their effectiveness usually diminishes over time. Small pilot studies have indicated that using hormone tablets sparingly, for just long enough to control the cancer, followed by a break in treatment and restarting them later, seems to improve how long hormone tablets can control the cancer. This study aims to find out if this pause/restart strategy is better than taking hormone tablets every day continuously. The study will include 168 people with metastatic castrate resistant prostate cancer in the Netherlands and Australia. Patients will be randomly 1:1 assigned between the control group and the experimental group. In the control group, patients will take the treatment with AA/ENZ every day until the prostate cancer doesn't respond anymore to the treatment. In the experimental group, patients will start with daily AA/ENZ until the PSA has declined for \>50%. The treatment will then be paused and monthly PSA measurements will be performed. The treatment will be re-initiated when the PSA has increased to the level of before starting treatment. The treatment will be continued daily until the PSA has again dropped for \>50%. This pause/restart cycle will be repeated until the prostate cancer doesn't respond anymore to the treatment.
Abiraterone and enzalutamide (AA/ENZ) are drugs which are being used to treat metastatic prostate cancer. These drugs are a form of additional hormonal therapy and have been used for many years. For most patients, these drugs work well and the prostate cancer stays under control for several months to years. In all patients, there will be a moment when the prostate cancer doesn't respond anymore to the treatment. This is called resistance. This leads to increasement of PSA, tumor growth on the CT-scan and/or bone scan or decline of condition. The investigators want to establish if it is possible to delay the development of resistance by using the drugs differently. It is now recommended to use AA/ENZ daily until the prostate cancer doesn't respond anymore to the treatment. During treatment, all cancer cells sensitive to treatment will die and all cells resistant for treatment will survive. Based on evolutionary principles, this might not be a wise strategy. The groups of resistant cancer cells will prevail and will grow faster and faster. This will lead to increasement of PSA, tumor growth on the CT-scan and/or bone scan or decline of condition. The investigators want to establish if it is better to not take the treatment drugs daily, but to pause the treatment on regular basis. The theory of the investigators is that, due to just in time pausing the treatment, a part of the treatment sensitive cells will remain alive. These treatment sensitive cancer cells will compete with the treatment resistant cells for limited space and nutrients. In this way, the treatment sensitive cancer cells prevent the accelerating growth of the treatment resistant cancer cells. Due to this phenomenon, the investigator hypothesis is the prostate cancer will respond longer to treatment. It will take longer until a new treatment is necessary or until a patients develops complaints. When the treatment is paused, patients might experience less side effects. It is easy to establish whether the prostate cancer responds to treatment by measuring PSA.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
168
Patients will start taking abiraterone or enzalutamide (AA/ENZ) daily. PSA will be measured every month as well as radiological evaluation by CT-scan and bone scan. Treatment will be continued until PSA has dropped \>50%. The treatment will then be paused. Once the PSA has risen again above the pretreatment baseline, treatment will be re-initiated. AA/ENZ will be stopped again after the PSA declines \>50% from the baseline. This will be continued until criteria for treatment failure are met (death by any cause or at least 2 out of 3 of the following events while on treatment: radiographic progression on CT-scan and/or bone scan, PSA progression or clinical progression).
Use of abiraterone or enzalutamide
Use of abiraterone or enzalutamide
Border Medical Oncology Research Unit / The Border Cancer Hospital
Albury, New South Wales, Australia
RECRUITINGChris O'Brien Lifehouse
Camperdown, New South Wales, Australia
RECRUITINGSt George Hospital
Kogarah, New South Wales, Australia
RECRUITINGCalvary Mater Newcastle
Newcastle, New South Wales, Australia
RECRUITINGGenesis Care North Shore
St Leonards, New South Wales, Australia
RECRUITINGSydney Adventist Hospital
Wahroonga, New South Wales, Australia
RECRUITINGSunshine Coast University Hospital
Birtinya, Queensland, Australia
RECRUITINGMater Hospital Brisbane
South Brisbane, Queensland, Australia
RECRUITINGRoyal Adelaide Hospital
Adelaide, South Australia, Australia
RECRUITINGICON Cancer Centre
Adelaide, South Australia, Australia
RECRUITING...and 9 more locations
Time to treatment failure
Defined as the time from randomization until death by any cause, or the occurrence of ≥2 of the following events: * Radiographic progression according to RECIST 1.1 and/or PWCG3 criteria on the CT-scan and/or WBBS while a subject received treatment with AA/ENZ during the whole period between the imaging tests. NB: Radiologic progression while a subject is off treatment in the experimental arm will trigger the endpoint, but may be an indication to restart treatment and continue with the adaptive dosing strategy * PSA progression, defined as an increase of PSA of \>25% and \>2 ng/mL occurring while a patient is on consecutive treatment with AA/ENZ for at least 8 weeks. * Clinical progression in the judgment of the treating clinician occurring while a patient is on consecutive treatment with AA/ENZ for at least 8 weeks.
Time frame: Time from randomization until death by any cause, or until criteria for treatment failure are met. PSA progression and clinical progression will be measured every 4 weeks, radiographic progression every 12 weeks, both up to 3 years after randomization.
Time to PSA progression while on treatment
defined as the time from randomization until an increase of PSA of \>25% and \>2 ng/mL persisting while a patient is on consecutive treatment for at least 8 weeks (according to PCWG3 criteria) or death. Patients without documented PSA progression or have not died will be censored at the last known time that the patient was progression-free. Patients who are lost to follow up will be censored at their last assessment time. Patients who begin a new anticancer treatment and have not had documented PSA progression will be censored at their last assessment point prior to beginning their new treatment.
Time frame: Time from randomization until an increase of PSA of >25% and >2 ng/mL persisting while a patient is on consecutive treatment for at least 8 weeks or death. PSA will be measured every 4 weeks until 3 years after randomization.
Radiographic progression-free survival while on study treatment
Defined as the time from randomisation to first occurrence of radiographic progression by PCWG3 criteria and/or RECIST 1.1 on the CT-scan and/or WBBS while a subject received treatment with AA/ENZ during the whole period between the imaging tests or death. Patients without documented disease progression or have not died will be censored at the last known time that the patient was progression-free. Patients who are lost to follow up will be censored at their last assessment time. Patients who begin a new anticancer treatment and have not had a documented treatment failure event will be censored at their last assessment point prior to beginning their new treatment.
Time frame: Time from randomization to death or the first occurrence of radiographic progression while a subject received treatment between the imaging tests. Bone scan and CT-scan will be measured every 12 weeks until 3 years after randomization.
Overall survival
defined as the time from randomization to the date of death due to any cause. For patients with no documented death by the end of the study, OS will be censored on the last date the patient was known to be alive. Patients who are lost to follow up will be censored at their last assessment time. Patients who begin a new anticancer treatment and have not had a documented treatment failure event will be censored at their last assessment point prior to beginning their new treatment.
Time frame: Time from randomization to the date of death due to any cause. Measured every 4 weeks up to 3 years after randomizaton and after end of treatment visit every 6 months until 2 years after end of treatment visit.
Time to first skeletal-related event
Time from randomization to first skeletal-related event or death will be assessed. A skeletal-related event is defined as radiation therapy or surgery to bone, pathologic bone fracture, spinal cord compression, or change of anti-neoplastic therapy to treat bone pain. Patients without documented skeletal-related event or have not died will be censored at the last known time that the patient was progression-free. Patients who are lost to follow up will be censored at their last assessment time. Patients who begin a new anticancer treatment and have not had a documented treatment failure event will be censored at their last assessment point prior to beginning their new treatment.
Time frame: Time from randomization to first skeletal-related event or death. Bone scan and CT-scan will be measured every 12 weeks up to 3 years after randomization.
Health Related Quality of Life - FACT-P
FACT-P Quality of Life questionnaire
Time frame: FACT-P questionnaire will be obtained every 12 weeks up to 3 years after randomization
Health Related Quality of Life - EQ-5D-5L
EQ-5D-5L questionnaire.
Time frame: EQ-5D-5L questionnaire will be obtained every 12 weeks up to 3 years after randomization
Health Related Quality of Life - Pain
Pain score per Brief Pain Inventory.
Time frame: Brief Pain Inventory questionnaire will be obtained every 12 weeks up to 3 years after randomization
Adverse events
An adverse event is defined as any symptom, sign, illness, or untoward experience (including a clinically significant laboratory finding classified as Grade 3 or higher by the National Cancer Institute's Common Terminology Criteria for Adverse Events v5.0) that develops or worsens during the course of the study, whether or not the event is considered related to study drug. Such an event should be recorded as an adverse event only after the first dose of study drug is taken. Adverse events will be assessed every 12 weeks.
Time frame: Adverse events will be measured every 12 weeks, up to 3 years after randomization.
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