Treatment of BRCA-mutated mCRPC after Androgen Receptor-directed Therapy
TRITON3
The safety of RUBRACA monotherapy was evaluated in patients with BRCA-mutated mCRPC who had progressed following prior treatment with androgen receptor-directed therapy and who had not received treatment with taxane-based chemotherapy in the castration-resistant setting. [see
Clinical Studies(
14.2)]. TRITON3 was a randomized, open-label, multi-center study, in which 298 patients with a deleterious
BRCAmutation received either RUBRACA 600 mg twice daily (n=201) or physicians choice (n=97) of abiraterone acetate or enzalutamide, or docetaxel until disease progression, unacceptable toxicity, or up to 10 cycles for docetaxel. Among the patients who received RUBRACA, 66% were exposed for 6 months or longer and 34% were exposed for greater than one year.
Serious adverse reactions occurred in 27% of patients receiving RUBRACA. Serious adverse reactions in ≥2% of patients included anemia (4%), pneumonia (4%), urinary tract infection (3%), acute kidney injury (3%), myocardial ischemia/infarction (2%), and pulmonary embolism (2%). Fatal adverse reactions occurred in 1.5% of patients treated with RUBRACA, including cardiac failure, myocardial ischemia, and sepsis (1 patient each).
Permanent discontinuation due to adverse reactions occurred in 14% of patients treated with RUBRACA. Adverse reactions which resulted in permanent discontinuation of RUBRACA in ≥2% of patients included anemia (6%), fatigue/asthenia (3%), thrombocytopenia/platelet count decreased (3%), and nausea (2%).
Dosage interruptions of RUBRACA due to adverse reactions occurred in 53% of patients. Adverse reactions which required dosage interruption in ≥5% of patients included anemia (24%), fatigue/asthenia (10%), nausea (8%), and increase in ALT (5%).
Dose reductions of RUBRACA due to an adverse reaction occurred in 36% of patients. Adverse reactions which required dose reduction in ≥5% of patients included anemia (16%) and fatigue/asthenia (8%).
The most common adverse reactions (≥10%) in patients who received RUBRACA were fatigue/asthenia, musculoskeletal pain, nausea, decreased appetite, diarrhea, constipation, vomiting, dyspnea, dysgeusia, edema, abdominal pain, dizziness, weight decreased, rash, headache, peripheral neuropathy, photosensitivity reaction, and urinary tract infection.
The most common select laboratory abnormalities (≥25%) that worsened from baseline in patients who received RUBRACA were increased ALT, decreased neutrophils, decreased phosphate, decreased hemoglobin, increased AST, increased creatinine, increased glucose, decreased lymphocytes, decreased sodium, decreased platelets, increased calcium.
Tables 4 and
5 summarize the adverse reactions and laboratory abnormalities, respectively, in patients with
BRCA-mutated mCRPC in TRITON3.
Table 4. Adverse Reactions in ≥ 10% of Patients with BRCA-mutated mCRPC in TRITON3| a National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE version 5.0)
|
| b Includes multiple related terms
|
| Adverse Reaction | RUBRACA
N=201
| ARPI or Docetaxel
N=97
|
Grades 1-4
a
(%)
| Grades 3-4
(%)
| Grades 1-4
a
(%)
| Grades 3-4
(%)
|
| General disorders and administration site conditions |
| Fatigue/Asthenia | 61 | 7 | 65 | 10 |
| Edema
b
| 18 | 0 | 20 | 0 |
| Musculoskeletal and connective tissue disorders |
| Musculoskeletal pain
b
| 53 | 7 | 57 | 8 |
| Gastrointestinal disorders |
| Nausea | 51 | 2 | 22 | 1 |
| Diarrhea | 31 | 2 | 29 | 1 |
| Constipation | 31 | 2 | 17 | 1 |
| Vomiting | 25 | 1 | 10 | 1 |
| Abdominal pain
b
| 17 | 1 | 10 | 1 |
| Metabolism and nutrition disorders |
| Decreased appetite | 34 | 1 | 20 | 2 |
| Respiratory, thoracic and mediastinal disorders |
| Dyspnea
b
| 19 | 1 | 13 | 1 |
| Nervous system disorders |
| Dysgeusia
b
| 18 | 0 | 12 | 0 |
| Dizziness
b
| 16 | 1 | 9 | 0 |
| Headache
b
| 12 | 0 | 9 | 0 |
| Peripheral neuropathy
b
| 12 | 1 | 26 | 1 |
| Investigations |
| Weight decreased | 16 | 1 | 13 | 0 |
| Skin and subcutaneous tissue disorders |
| Rash
b
| 13 | 1 | 6 | 0 |
| Photosensitivity reaction
b
| 12 | 1 | 0 | 0 |
| Infections and infestations |
| Urinary tract infection
b
| 10 | 3 | 4 | 1 |
Clinically relevant adverse reactions occurring in <10% of patients treated with RUBRACA include cough, hemorrhage, fall, hypertension, dyspepsia, pruritus, pyrexia, stomatitis, venous thromboembolism, arrhythmia, hypersensitivity, and febrile neutropenia.
Table 5. Laboratory Abnormalities in ≥ 25% of Patients with BRCA-mutated mCRPC in TRITON3| aDenominator for each laboratory parameter is based on the number of patients with a baseline and post-treatment laboratory value available for 192 to 201 patients in the RUBRACA Arm and 94 to 97 patients in the ARPI or Docetaxel Arm.
|
| bNCI CTCAE version 5.0; decrease in phosphate is graded using NCI CTACE Version 4.03
|
| Laboratory Parameter | Rubraca
N=201
a
| ARPI or Docetaxel
N=97
a
|
Grades 1-4
b
(%)
| Grades 3-4
(%)
| Grades 1-4
b
(%)
| Grades 3-4
(%)
|
| Chemistry |
| Increase in ALT | 68 | 4 | 8 | 0 |
| Decrease in phosphate | 64 | 8 | 45 | 5 |
| Increase in AST | 59 | 2 | 7 | 0 |
| Increase in creatinine | 56 | 1 | 16 | 0 |
| Increase in glucose | 45 | 6 | 38 | 3 |
| Decrease in sodium | 35 | 5 | 21 | 4 |
| Increase in calcium | 29 | 3 | 19 | 2 |
| Hematology |
| Decrease in neutrophils | 67 | 9 | 24 | 10 |
| Decrease in hemoglobin | 60 | 23 | 31 | 2 |
| Decrease in lymphocytes | 43 | 14 | 45 | 17 |
| Decrease in platelets | 34 | 6 | 4 | 0 |
TRITON2
The safety of RUBRACA 600 mg twice daily was evaluated in a single arm trial (TRITON2) [see Clinical Studies (14.2)]. TRITON2 enrolled 209 patients with HRR-mutated mCRPC, including 115 with BRCA-mutated mCRPC. Among the patients with
BRCA-mutated mCRPC, the median duration of RUBRACA treatment was 6.5 months (range 0.5 to 26.7).
Fatal adverse reactions occurred in 1.7% of patients who received RUBRACA, including acute respiratory distress syndrome and pneumonia (1 patient each).
Permanent discontinuation of RUBRACA due to an adverse reaction occurred in 8% of patients.
Dosage interruption of RUBRACA due to an adverse reaction occurred in 57% of patients.
Dose reductions of RUBRACA occurred in 41% of patients.
Tables 6 and 7 summarize the adverse reactions and laboratory abnormalities, respectively, in patients with
BRCA-mutated mCRPC in TRITON2.
Table 6. Adverse Reactions in ≥ 20% of Patients with BRCA-mutated mCRPC in TRITON2| aNCI CTCAE version 4.03.
|
| bIncludes platelet count decreased
|
| cIncludes blister, blood blister, dermatitis, dermatitis contact, eczema, genital rash, palmar-plantar erythrodysaesthesia syndrome, photosensitivity reaction, psoriasis, rash, rash maculo-papular, rash pruritic, skin exfoliation, skin lesion, urticaria
|
| Adverse Reaction | Rubraca
N = 115
|
Grades 1-4
a
(%)
| Grades 3-4
(%)
|
| General disorders and administration site conditions |
| Asthenia/Fatigue | 62 | 9 |
| Gastrointestinal disorders |
| Nausea | 52 | 3 |
| Constipation | 27 | 1 |
| Vomiting | 22 | 1 |
| Diarrhea | 20 | 0 |
| Blood and lymphatic system disorders |
| Anemia | 43 | 25 |
| Thrombocytopenia
b
| 25 | 10 |
| Metabolism and nutrition disorders |
| Decreased appetite | 28 | 2 |
| Skin and subcutaneous tissue disorders |
| Rash
c
| 27 | 2 |
Other clinically relevant adverse reactions that occurred in less than 20% of patients included dyspnea, dizziness, bleeding, urinary tract infection, dysgeusia, dyspepsia, hypersensitivity (including flushing, asthma, choking sensation, periorbital swelling, swelling face, and wheezing), pneumonia, sepsis, ischemic cardiovascular events, renal failure, venous thromboembolism, and stomatitis.
Table 7. Laboratory Abnormalities in ≥ 35% (Grades 1-4) and ≥ 2% (Grades 3-4) Worsening from Baseline in Patients with BRCA-mutated mCRPC in TRITON2| aDenominator for each laboratory parameter is based on the number of patients with a baseline and post-treatment laboratory value available for 111 to 115 patients.
|
| bNCI CTCAE version 5.0; decrease in phosphate is graded using NCI CTACE Version 4.03
|
| cGrade 3-4 ALT or AST elevation led to drug interruption in 4 patients, of which 1 had dose reduction upon rechallenge.
|
| Laboratory Parameter | Rubraca
N = 115
a
|
Grades 1-4
b
(%)
| Grades 3-4
(%)
|
| Clinical Chemistry |
| Increase in ALT
c
| 69 | 5 |
| Decrease in phosphate | 68 | 15 |
| Increase in alkaline phosphatase | 44 | 2 |
| Increase in creatinine | 43 | 2 |
| Increase in triglycerides | 42 | 5 |
| Decrease in sodium | 38 | 3 |
| Hematologic |
| Decrease in leukocytes | 69 | 5 |
| Decrease in absolute neutrophil count | 62 | 5 |