Phase 2 Study of G-202 in Patients With Chemotherapy-Naïve Metastatic Castrate-Resistant Prostate Cancer
| Status: | Completed |
|---|---|
| Conditions: | Prostate Cancer, Cancer |
| Therapuetic Areas: | Oncology |
| Healthy: | No |
| Age Range: | 18 - Any |
| Updated: | 3/1/2014 |
| Start Date: | May 2013 |
| End Date: | January 2015 |
An Open-Label, Single-Arm, Phase 2 Study of G-202 in Patients With Chemotherapy-Naïve Metastatic Castrate-Resistant Prostate Cancer
Prostate cancer that has returned after local treatment usually responds to hormone blocking
treatment, but most patients eventually experience disease progression. Further chemotherapy
does not normally lead to a cure or dramatic improvement in the disease and there is a need
to identify new drugs that are beneficial for these patients without unacceptable side
effects. Prodrug chemotherapy is an approach in which an inactive non-toxic agent is
administered to the patient and gets activated within the body at specific locations,
resulting in a higher concentration of the cytotoxic form at a tumour location whilst
avoiding general side effects. G-202 is an example of prodrug chemotherapy. It does not
have many general side effects because it is converted to a cell toxin only at the tumour or
other specific locations in the body. G-202 is activated by Prostate Specific Memory
Antigen (PSMA), a substance expressed by prostate cancer cells and in the blood vessels of
most solid tumours, but not by normal cells or blood vessels in normal tissue. It is
believed that activation of the prodrug G-202 will allow the drug to kill cancer cells,
particularly prostate cancer cells. This study will evaluate the activity and safety of
G-202 in men with castration-resistant prostate cancer (CRPC), which means the cancer has
progressed after hormone blocking treatment, but who have not yet received chemotherapy and
who have no or only a few symptoms from their CRPC. The study will evaluate clinical
activity and safety of G-202 administered on three consecutive days of a 28-day cycle.
treatment, but most patients eventually experience disease progression. Further chemotherapy
does not normally lead to a cure or dramatic improvement in the disease and there is a need
to identify new drugs that are beneficial for these patients without unacceptable side
effects. Prodrug chemotherapy is an approach in which an inactive non-toxic agent is
administered to the patient and gets activated within the body at specific locations,
resulting in a higher concentration of the cytotoxic form at a tumour location whilst
avoiding general side effects. G-202 is an example of prodrug chemotherapy. It does not
have many general side effects because it is converted to a cell toxin only at the tumour or
other specific locations in the body. G-202 is activated by Prostate Specific Memory
Antigen (PSMA), a substance expressed by prostate cancer cells and in the blood vessels of
most solid tumours, but not by normal cells or blood vessels in normal tissue. It is
believed that activation of the prodrug G-202 will allow the drug to kill cancer cells,
particularly prostate cancer cells. This study will evaluate the activity and safety of
G-202 in men with castration-resistant prostate cancer (CRPC), which means the cancer has
progressed after hormone blocking treatment, but who have not yet received chemotherapy and
who have no or only a few symptoms from their CRPC. The study will evaluate clinical
activity and safety of G-202 administered on three consecutive days of a 28-day cycle.
Patients will undergo a screening period of up to 4 weeks. Patients who are deemed eligible
will be entered into the study and undergo treatment with G-202. G-202 will be administered
by intravenous infusion over one hour on Days 1, 2 and 3 of a 28-day treatment cycle. The
G-202 dose will be 40 mg/m2 on Day 1 and 66.8 mg/m2 on Days 2 and 3.
The primary objective of the study is to determine the percentage of patients with
chemotherapy-naïve metastatic castrate-resistant prostate cancer who do not have disease
progression (radiographic or clinical) after 24 weeks of treatment with G-202.
A two-stage study design will be used to evaluate the percentage of patients who do not have
disease progression after 24 weeks of treatment with G-202. If the percent of patients who
are progression-free at 24 weeks is at most 15%, then the clinical efficacy of G-202 in this
patient population will be considered unacceptably low. If, on the other hand, the percent
of patients who are progression-free at 24 weeks is at least 35%, this will be considered
sufficient evidence to consider further clinical investigation. The null hypothesis that the
percent of patients who are progression-free at 24 weeks is at most 15% will be tested
against the alternative hypothesis that the percent is greater than 15% at the one-sided 10%
significance level. In order to avoid a suspension in accrual awaiting interim analysis, a
two-stage study design for evaluating survival probabilities with continual accrual will be
used.
An interim analysis for futility will be conducted after 24 evaluable patients have been
accrued assuming that the time between accrual of the first patient and accrual of the 24th
patient is at least 8 months. If 24 patients are accrued in less than 8 months, accrual will
continue until the time period between the date of accrual of the first patient and the date
of accrual of the last patient is at least 8 months. If the trial is not terminated for
futility after the interim analysis, an additional 10 patients will be accrued for a total
of 34 patients. The two-stage design minimizes the expected duration of accrual under the
null hypothesis.
For the interim analysis, any patient who discontinues participation for reasons other than
safety or disease progression before completing three full cycles and undergoing the 12-week
follow-up assessment will be replaced. Any replaced patient will be included in all study
analyses of the intent-to-treat and safety populations.
Safety will be assessed by the reporting of adverse events, vital signs and assessment of
findings on physical exam and routine laboratory determinations. The severity of adverse
events and laboratory findings will be assessed according to NCI Common Toxicity Criteria
for Adverse Effects (CTCAE) V4.
will be entered into the study and undergo treatment with G-202. G-202 will be administered
by intravenous infusion over one hour on Days 1, 2 and 3 of a 28-day treatment cycle. The
G-202 dose will be 40 mg/m2 on Day 1 and 66.8 mg/m2 on Days 2 and 3.
The primary objective of the study is to determine the percentage of patients with
chemotherapy-naïve metastatic castrate-resistant prostate cancer who do not have disease
progression (radiographic or clinical) after 24 weeks of treatment with G-202.
A two-stage study design will be used to evaluate the percentage of patients who do not have
disease progression after 24 weeks of treatment with G-202. If the percent of patients who
are progression-free at 24 weeks is at most 15%, then the clinical efficacy of G-202 in this
patient population will be considered unacceptably low. If, on the other hand, the percent
of patients who are progression-free at 24 weeks is at least 35%, this will be considered
sufficient evidence to consider further clinical investigation. The null hypothesis that the
percent of patients who are progression-free at 24 weeks is at most 15% will be tested
against the alternative hypothesis that the percent is greater than 15% at the one-sided 10%
significance level. In order to avoid a suspension in accrual awaiting interim analysis, a
two-stage study design for evaluating survival probabilities with continual accrual will be
used.
An interim analysis for futility will be conducted after 24 evaluable patients have been
accrued assuming that the time between accrual of the first patient and accrual of the 24th
patient is at least 8 months. If 24 patients are accrued in less than 8 months, accrual will
continue until the time period between the date of accrual of the first patient and the date
of accrual of the last patient is at least 8 months. If the trial is not terminated for
futility after the interim analysis, an additional 10 patients will be accrued for a total
of 34 patients. The two-stage design minimizes the expected duration of accrual under the
null hypothesis.
For the interim analysis, any patient who discontinues participation for reasons other than
safety or disease progression before completing three full cycles and undergoing the 12-week
follow-up assessment will be replaced. Any replaced patient will be included in all study
analyses of the intent-to-treat and safety populations.
Safety will be assessed by the reporting of adverse events, vital signs and assessment of
findings on physical exam and routine laboratory determinations. The severity of adverse
events and laboratory findings will be assessed according to NCI Common Toxicity Criteria
for Adverse Effects (CTCAE) V4.
Inclusion Criteria:
- Confirmed prostate adenocarcinoma
- Asymptomatic or minimally symptomatic
- Radiographic metastatic or recurrent disease
- Chemically- or surgically-castrated with disease progression
- Castrate testosterone level <50 ng/dL
- Discontinued flutamide, bicalutamide and nilutamide
- Absence of known brain metastases
- Age ≥18 years
- Eastern Cooperative Oncology Group performance status ≤ 2
- Estimated life expectancy ≥ 6 months
- Adequate hematopoietic function as demonstrated by:
- hemoglobin of ≥ 9.0 g/dL without need for sustained blood transfusions
- platelet count ≥100,000 platelet/mm3 (100 x 109/L)
- White Blood Cell (WBC) count ≥ 2.0 x109/L and Absolute Neutrophil Count (ANC)
≥1.5 x109/L
- Adequate hepatobiliary function as demonstrated by:
- Total bilirubin level ≤1.5 times the upper limit of normal (ULN), unless the
patient has Gilbert's syndrome in which case the patient must have a total
bilirubin level ≤ 2.5 x ULN
- alanine aminotransferase (ALT) levels ≤ 2.5 x ULN
- Adequate renal function as demonstrated by creatinine level ≤1.5 x ULN or creatinine
clearance (measured or calculated by Cockcroft-Gault formula) ≥ 50mL/min
- Acceptable coagulation profile (PT or INR, PTT < 1.5 x ULN)
- If of reproductive capacity, willing to use an effective double barrier method of
birth control (i.e., latex condom, diaphragm, cervical cap, etc) during the study and
for 30 days after the last administration of G-202
Exclusion Criteria:
- Prior chemotherapy
- Other concurrent therapy for prostate cancer other than LHRH agonists or antagonists.
- Treatment with therapeutic radionucleotides within 12 weeks of study entry
- Radiation therapy < 4 weeks before study entry
- Documentation of keratosis follicularis
- Pre-existing cardiac condition:
- use of inhibitors or inducers of cytochrome (CYP3A4) iso-enzymes
- Chronic use of opioids for cancer-related pain
- Corrected QT interval > 470 msec
- Active uncontrolled infection, including known history of AIDS, hepatitis B or C
- Proteinuria level > +2 on urine analysis
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