Abstract
Preclinical studies have demonstrated synergy between poly(ADP-ribose) polymerase (PARP) and phosphatidylinositol-3-kinase (PI3K)/AKT pathway inhibitors in BRCA1 and BRCA2 (BRCA1/2)-deficient and BRCA1/2-proficient tumors. We conducted an investigator-initiated phase I trial utilizing a prospective intrapatient dose-escalation design to assess two schedules of capivasertib (AKT inhibitor) with olaparib (PARP inhibitor) in 64 patients with advanced solid tumors. Dose expansions enrolled germline BRCA1/2-mutant tumors, or BRCA1/2-wildtype cancers harboring somatic DNA damage response (DDR) or PI3K/AKT pathway alterations. The combination was well-tolerated. Recommended phase 2 doses for the two schedules were: olaparib 300mg BID with either capivasertib 400mg BID 4- days-on, 3-days-off, or capivasertib 640mg BID 2-days-on, 5-days-off. Pharmacokinetics were dose-proportional. Pharmacodynamic studies confirmed pGSK3β suppression, increased pERK and decreased BRCA1 expression. 25 (44.6%) of 56 evaluable patients achieved clinical benefit (RECIST CR/PR or stable disease ≥4 months), including patients with tumors harboring germline BRCA1/2- mutations and BRCA1/2-wildtype cancers with or without DDR and PI3K/AKT pathway alterations.
Keywords: PARP inhibitors, olaparib, AKT inhibitor, capivasertib, AZD5363, DNA repair, BRCA1 and BRCA2 mutations
Introduction
Poly(ADP-ribose) polymerase (PARP) inhibitors are the first clinically approved drugs designed to exploit synthetic lethality in homologous recombination (HR) deficient cells, demonstrating proof of concept activity in BRCA1/2 mutant cancers (1,2). The PARP inhibitor olaparib (Lynparza, AstraZeneca) was the first-inclass to be approved by the Food and Drug Administration (FDA) in the advanced recurrent ovarian cancer setting for women with BRCA1/2 mutant cancers (3). Olaparib has subsequently received FDA approval in the maintenance setting for recurrent platinum-sensitive ovarian cancers regardless of BRCA1/2 status, and most recently, in the first-line maintenance setting post-platinum-based chemotherapy both in women with germline or somatic BRCA1/2 mutated advanced ovarian cancer and in patients with germline BRCA1/2 mutated pancreatic cancer (4,5). Olaparib is also FDA approved for the treatment of patients with germline BRCA1/2 mutant, HER2- negative metastatic breast cancers (6,7). In addition, there are now early clinical trial data in patients with tumors harboring other DNA repair aberrations (8).
Despite the broader indications, the greatest clinical benefit from PARP inhibitor monotherapy has been observed in the high grade serous germline BRCA1/2 mutant ovarian cancer population (3). However, these patients almost inevitably develop PARP inhibitor resistance and disease progression. The utility of PARP inhibitor monotherapy in patients with different cancers harboring other DNA repair aberrations is also limited by the emergence of drug resistance and generally shortlived antitumor responses (9). Even for patients with advanced solid tumors bearing deleterious BRCA1/2 mutations, response rates are between 30-60% depending on tumor type (3). Hence, there is a major unmet need for novel antitumor strategies to increase both the proportion of patients with clinical benefit, as well as the depth and duration of response for patients treated with PARP inhibitors (10). Such approaches include the development of rational combination strategies. Multiple preclinical studies have demonstrated synergistic antitumor activity with the combination of PARP and phosphatidylinositol-3-kinase (PI3K)/AKT pathway inhibitors in both BRCA-deficient and proficient cancer models (11–14). PI3K pathway inhibition has been shown to lead to suppression of BRCA gene transcription, which is also accompanied by extracellular signal-regulated kinase (ERK) phosphorylation. Overexpression of an active form of MEK1 was shown to cause ERK activation and BRCA1 downregulation (11). In turn, such MEK1 overexpression resulted in HR deficiency and subsequent PARP inhibitor sensitivity; thus, providing a strong rationale for the development of this combination as an antitumor strategy (11). A phase Ib trial of olaparib in combination with the α-specific PI3K inhibitor alpelisib demonstrated RECIST partial responses in 10 (36%) of 28 patients with ovarian cancer, providing early clinical proof-of-concept (15).
Several novel molecularly targeted agents against the PI3K-AKT pathway have now been developed, including the AKT inhibitor capivasertib (AZD5363; AstraZeneca) (16). Capivasertib is a potent and selective ATP competitive inhibitor of all 3 isoforms of AKT (17). This novel AKT inhibitor is safe and well tolerated in patients with advanced solid tumors, but it has shown limited antitumor benefit as a single agent in early phase clinical trials (17–19). It is hypothesized that capivasertib's limited antitumor benefit as a single agent may be due to the development of signaling crosstalk and the disruption of feedback loops that lead to acquired resistance (20). Hence, this hypothesis supports the use of combination strategies, with agents like the PARP inhibitors described above, in molecularly defined patients that are optimal for the development of AKT inhibitors (20,21).
Based on these promising data, we conducted an investigator-initiated phase Ib clinical trial to determine the safety, tolerability, maximum tolerated dose (MTD), recommended phase 2 dose (RP2D), pharmacokinetics (PK), pharmacodynamics (PD) and preliminary antitumor activity of olaparib in combination with capivasertib in patients with advanced solid tumors. We also assessed a prospective intrapatient dose escalation strategy where patients received a fixed olaparib dose while they were permitted to prospectively increase doses of capivasertib after each cycle (if no Grade (G) 2 or worse toxicities were observed). RP2D expansion cohorts were undertaken in patients with (1) germline BRCA1/2 mutant cancers and (2) sporadic cancers with DNA damage response (DDR) aberrations or molecular abnormalities along the PI3K-AKT pathway. Detailed analyses of archived and fresh sequential tumor biopsies, as well as targeted sequencing of serial cell-free DNA (cfDNA) samples were conducted to identify determinants of response and resistance, including genomic factors and protein expression, and pharmacodynamic mechanism-of-action biomarker studies.
Results
Patients
We enrolled 64 patients with advanced solid tumors from four major cancer centres in the United Kingdom into the dose escalation (20 patients) or expansion (44 patients) cohorts of this phase I trial. Characteristics of these patients are provided in Table 1. The most common tumor enrolled was advanced ovarian cancer (39% of patients); these patients received a median of 5 prior therapies (range 1-12). The next most common tumor type was advanced breast cancer (28% of patients); these paitents received a median number of 3 prior therapies (range 2-10).
Table 1. Patient Demographics.
| Characteristic | Olaparib 300mg BID and Capivasertib BID either 4- days-on, 3-days-off or 2-days-on, 5-days-off schedule | Total n=64 (100%) | |
|---|---|---|---|
| 4-days-on, 3-days-off Schedule, n=33 (52%) | 2-days-on, 5-days-off Schedule, n=31 (48%) | ||
| Median age, years (range) | 59 (32–76) | 54 (32–72) | 57 (32–76) |
| Gender No. (%) | |||
| Male | 6 (18) | 5 (16) | 11 (17) |
| Female | 27 (82) | 26 (84) | 53 (83) |
| ECOG PS, No. (%) | |||
| ECOG PS 0 | 13 (39) | 9 (29) | 22 (34) |
| ECOG PS 1 | 20 (61) | 22 (71) | 42 (66) |
| Tumor, No. (%) | |||
| Ovarian | 13 (39)[7 germline BRCA1/2; 4 somatic BRCA1/2] | 12 (39)[4 germline BRCA1/2; 1 somatic BRCA1/2] | 25 (39) |
| Breast | 8 (24)[2 germline BRCA1/2] | 10 (32)[5 germline BRCA1/2; 1 germline PALB2] | 18 (28) |
| Pancreatic | 3 (9) | 2 (7) | 5 (8) |
| CRPC | 2 (6)[1 germline BRCA1/2] | 2 (7)[2 germline BRCA1/2] | 4 (6) |
| Cervical | 2 (6) | - | 2 (3) |
| Endometrial | 1 (3) | 1 (3) | 2 (3) |
| Bladder | 1 (3) | - | 1 (1.5) |
| Colorectal | 1 (3) | - | 1 (1.5) |
| Cholangiocarcinoma | - | 1 (3) | 1 (1.5) |
| GIST | - | 1 (3) | 1 (1.5) |
| Cancer of unknown origin (CUP) | 1 (3) | - | 1 (1.5) |
| Pleural mesothelioma | - | 1 (3) | 1 (1.5) |
| Peritoneal mesothelioma | - | 1 (3) | 1 (1.5) |
| Carcinosarcoma (uterine) | - | 1 (3) | 1 (1.5) |
| Median prior lines of systemic therapy,No. (range) | 3 (1–10) | 5 (1-12) | 4 (1-12) |
| Ovarian (n=25) | 5 (1-9) | 5 (4-12) | 5 (1-12) |
| Breast (n=18) | 3 (2-10) | 4 (3-9) | 3 (2-10) |
Prospective intrapatient dose escalation
The prospective intrapatient dose escalation strategy utilized during each dose schedule allowed rapid, seamless and safe dose escalation, resulting in completion of the dose escalation phases of two combination schedules over 3 dose levels in 7 months (Supplementary Figure 1). Overall, only 10 patients were required to assess 3 different dose levels for each schedule and to establish both RP2Ds respectively.
Safety
During the dose escalation phase of the 4-days-on, 3-days-off (4/3) schedule, doses of capivasertib were increased using the prospective intrapatient dose escalation design from 320mg, 400mg to 480mg BID with a fixed dose of olaparib at 300mg BID (Supplementary Figure 1). Of 10 patients treated in this 4/3 schedule, only 1 DLT of G3 maculopapular rash, which typically arises with capivasertib and other AKT inhibitors, was observed at the highest dose assessed (capivasertib 480mg BID and olaparib 300mg BID) (Table 2). The erythematous rash fully resolved after both capivasertib and olaparib were withheld, and no recurrent rash was observed after both drugs were restarted at a reduced dose of capivasertib 400mg BID with olaparib maintained at 300mg BID. At the highest dose level (capivasertib 480mg BID and olaparib 300mg BID) administered in a 4/3 schedule, other non-DLT G3 toxicities were observed, including anemia (n=1), vomiting (n=1) and diarrhea (n=2). Due to the DLT of G3 rash, non-DLT G3 AEs and chronic low grade adverse events, e.g. fatigue and anemia, observed outside the DLT period of 21 days at the dose of capivasertib 480mg BID with olaparib 300mg BID, the SRC established the dose level of olaparib 300mg BID with capivasertib 400mg BID as the RP2D for the 4/3 schedule.
Table 2. Treatment-Related Adverse Events during dose escalation.
| Olaparib 300mg BID and Capivasertib BID 320mg (n=6) | Olaparib 300mg BID and Capivasertib BID 400mg (n=7) | Olaparib 300mg BID and Capivasertib BID 480mg (n=6) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Grade 1 or 2 | Grade 3 or 4 | Grade 1 or 2 | Grade 3 or 4 | Grade 1 or 2 | Grade 3 or 4 | ||||||||
| Specific Organ Class | Preferred Term | n | % | n | % | n | % | n | % | n | % | n | % |
| Blood and lymphatic system disorders | Anemia | 0 | 0.0 | 0 | 0.0 | 1 | 14.3 | 1 | 14.3 | 2 | 33.3 | 1 | 16.7 |
| Neutropenia | 1 | 16.7 | 0 | 0.0 | 1 | 14.3 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Thrombocytopenia | 1 | 16.7 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | |
| Gastrointestinal disorders | Abdominal pain | 0 | 0.0 | 0 | 0.0 | 1 | 14.3 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 |
| Constipation | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Diarrhea | 2 | 33.3 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 2 | 33.3 | |
| Melena | 0 | 0.0 | 0 | 0.0 | 1 | 14.3 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | |
| Mouth ulceration | 0 | 0.0 | 0 | 0.0 | 1 | 14.3 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | |
| Nausea | 5 | 83.3 | 0 | 0.0 | 1 | 14.3 | 0 | 0.0 | 5 | 83.3 | 0 | 0.0 | |
| Vomiting | 1 | 16.7 | 0 | 0.0 | 3 | 42.9 | 0 | 0.0 | 1 | 16.7 | 1 | 16.7 | |
| General disorders and administration site conditions | Fatigue | 4 | 66.7 | 0 | 0.0 | 2 | 28.6 | 0 | 0.0 | 4 | 66.7 | 0 | 0.0 |
| Mucosal inflammation | 2 | 33.3 | 0 | 0.0 | 2 | 28.6 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Musculoskeletal and connective tissue disorders | Myalgia | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 |
| Nervous system disorders | Dizziness | 1 | 16.7 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 |
| Dysgeusia | 1 | 16.7 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | |
| Renal and urinary disorders | Hematuria | 0 | 0.0 | 0 | 0.0 | 1 | 14.3 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 |
| Skin and subcutaneous tissue disorders | Dry skin | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 |
| Eczema | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Pruritus | 1 | 16.7 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | |
| Rash | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Rash maculo-papular | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | |
| Olaparib 300g BID and Capivasertib BID 480mg (n=8) | Olaparib 300mg BID and Capivasertib BID 560mg (n=6) | Olaparib 300mg BID and Capivasertib BID 640mg (n=6) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Grade 1 or 2 | Grade 3 or 4 | Grade 1 or 2 | Grade 3 or 4 | Grade 1 or 2 | Grade 3 or 4 | ||||||||
| Specific Organ Class | Preferred Term | n | % | n | % | n | % | n | % | n | % | n | % |
| Blood and lymphatic system disorders | Anemia | 0 | 0.0 | 0 | 0.0 | 2 | 33.3 | 0 | 0.0 | 3 | 50.0 | 0 | 0.0 |
| Neutropenia | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | |
| Gastrointestinal disorders | Abdominal distension | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 |
| Abdominal pain | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Diarrhea | 5 | 62.5 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | 3 | 50.0 | 0 | 0.0 | |
| Gastro-esophageal reflux disease | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Nausea | 6 | 75.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Vomiting | 1 | 12.5 | 0 | 0.0 | 2 | 33.3 | 0 | 0.0 | 2 | 33.3 | 0 | 0.0 | |
| General disorders and administration site conditions | Fatigue | 4 | 50.0 | 0 | 0.0 | 2 | 33.3 | 1 | 16.7 | 3 | 50.0 | 0 | 0.0 |
| Mucosal inflammation | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Infections and infestations | Oral candidiasis | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 |
| Investigations | Transaminases increased | 0 | 0.0 | 1 | 12.5 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 |
| Metabolism and nutrition disorders | Decreased appetite | 1 | 12.5 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 |
| Hyperglycemia | 0 | 0.0 | 1 | 12.5 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Hypokalemia | 1 | 12.5 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | |
| Nervous system disorders | Dysgeusia | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 |
| Renal and urinary disorders | Glycosuria | 1 | 12.5 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 |
| Respiratory, thoracic and mediastinal disorders | Cough | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 |
| Dyspnea | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Wheezing | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 1 | 16.7 | 0 | 0.0 | |
| Skin and subcutaneous tissue disorders | Nail ridging | 1 | 12.5 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 |
For the 2-days-on, 5-days-off (2/5) schedule of capivasertib with olaparib 300mg BID, dose escalation proceeded through dose levels of 480mg, 560mg and 640mg BID with olaparib 300mg BID. In the 10 patients treated on the 2/5 schedule, no DLTs were observed for the 2/5 schedule, and the highest dose level of capivasertib at 640mg BID with olaparib 300mg BID was selected as the RP2D. In view of similarities in overall safety, tolerability and DLT rates, the SRC elected to explore both the 4/3 and 2/5 schedules of capivasertib in the dose expansion phase.
The most common all grade treatment-emergent adverse events (TEAE) observed for all patients across both dose schedules were gastrointestinal toxicities, including nausea (67%, [grade 3-4, 4%]), diarrhea (55%, [grade 3-4, 6%]) and vomiting (41%, [grade 3-4, 5%]), as well as fatigue (51%, [grade 3-4, 5%]) (Table 2; Supplementary Tables 1 and 2). Other significant grade 3-4 toxicities included grade 3 anemia (10%) on the 4/3 schedule. Overall, the 4/3 schedule appeared to be less well tolerated than the 2/5 schedule, as exhibited during dose escalation: six grade 3 TEAEs (anemia and diarrhea [n=2 each]; rash and vomiting [n=1 each]) were observed with the 4/3 schedule, and only three grade 3 TEAEs (liver transaminitis, fatigue and hyperglycemia [all n=1]) in the 2/5 schedule. No drug- related grade 4-5 toxicities were observed in either schedule.
Pharmacokinetics
Dose escalation of capivasertib showed dose dependent increases in PK exposures (Figures 1A and 1B; Supplementary Tables 3 and 4). The PK profile and overall concentration-time profile of capivasertib and olaparib were similar to that previously observed in single agent studies, with no significant interactions identified.
Figure 1. Dose proportionality of Capivasertib during intra-patient dose escalation in both the 4-days-on, 3-days-off (Figure 1A) and 2-days-on, 5-days- off (Figure 1B) schedules.
PK modelling was conducted using a non-compartmental extravascular model for plasma using Phoenix™ WinNonLin Software® version 64 (Pharsight). Once the PK parameters were established for each patient, the mean AUC to the last sampled time point at 12 hours were plotted against the capivasertib dose administered.
Pharmacodynamics
PD studies in platelet-rich plasma (PRP) showed significant decrease in Ser9 GSK3ß phosphorylation post-treatment at all doses in the escalation and expansion (Figures 2A and 2B), confirming target modulation by capivasertib. Phosphorylated ERK expression levels assessed with IHC increased in fresh tumor biopsies collected on cycle 1 day 15 compared with baseline samples in six of 8 patients, while remaining unchanged in 1 patient and decreasing in another patient (Figure 2C). At the same time point, BRCA1 expression decreased in paired fresh tumor biopsies obtained from all 8 patients (Figure 2D).
Figure 2.
A: Pharmacodynamic profile of capivasertib and olaparib in serially collected PRP during intra-patient dose escalation on a 4 days on 3 days off schedule.
Platelet rich plasma was collected from patients at baseline and pre-dose on day 4 (4/7) at each escalating dose. The platelet rich plasma was analyzed for the expression of AKT proximal substrate pSer9 GSK3ß and total GSK3ß. Points represent the levels of pSer9 GSK3ß as a percent of the baseline levels normalized to the levels of total GSK3ß for individual patients and orange lines represent mean of all patients at that time point. **p<0.01; ***p<0.001 Paired t-test compared to baseline.
B: Pharmacodynamic profile of capivasertib and olaparib in serially collected PRP during dose expansion on a 2 days on 5 days off schedule.
During the cohort expansion, to enable PD studies on the 2-days-on, 5-days-off schedule, olaparib was administered alone from cycle 0 days -10 to -7, before capivasertib was given alone from cycle 0 days -6 to -3, before both drugs were given in combination from cycle 1 day 1. PRP was collected from patients at baseline (cycle 0 Day -10), cycle 0 day -5 (post capivasertib only) and cycle 1 day 2 (post capivasertib and olaparib combination). PRP was analyzed for the expression of AKT proximal substrate pSer9 GSK3ß and total GSK3ß. Points represent the levels of pSer9 GSK3ß as a percent of the baseline levels normalized to the levels of total GSK3ß for individual patients and orange lines represent mean of all patients at that time point. ***p<0.001, one-way ANOVA.
2C-2D: Pharmacodynamic effects of capivasertib and olaparib in paired tumor biopsies during dose expansion on 640mg BID of capivasertib 2-days- on, 5-days-off and 300mg BID of olaparib.
Tumor biopsies were collected from patients at baseline (Pre) and C1D16 (Post). Tumor biopsies were analyzed for the expression of phosphorylated ERK (Figure 1C) and BRCA1 by IHC (Figure 1D).
Antitumor activity
The antitumor activity of the combination of capivasertib and olaparib is detailed in Table 3, Figures 3A-3C, and Supplementary Table 5. Of the 56 patients who were evaluable for antitumor response, nineteen (34%) patients had RECIST PRs and/or tumor marker response (GCIG (Gynaecologic Cancer InterGroup) CA-125 response or Prostate Cancer Clinical Trials Working Group 2 (PCWG2) PSA response). Fourteen (25%) patients achieved RECIST PRs (12 confirmed and 2 unconfirmed). In addition, eleven (20%) patients had RECIST stable disease for at least 4 months (SD≥4 months), giving a clinical benefit rate (CBR) of 44.6% (95% CI: 31.3, 58.5). Of these 56 evaluable patients, sixteen (29%) patients were treated on study for more than 6 months, while seven (13%) patients were treated on trial for more than 1 year.
Table 3. Characteristics of patients who achieved clinical benefit (RECIST CR/PR or SD≥4 months).
| Responder Patient No. | Tumor | Pathogenic germline mutation | Pathogenic somatic mutation | Platinum status if known | Prior PARP inhibitor | Prior PI3K pathway inhibitor | PTEN IHC | Best response of RECIST CR/PR | Best response of RECIST SD≥4 months | Tumor marker response | Dose Schedule | Escalation (highest dose) or Expansion | Duration on treatment (weeks) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Breast | BRCA2 | BRCA2, PIK3CA | RESISTANT | - | - | - | cPR | Yes | cPR | 2d-on, 5d- off | Escalation (640mg) | 81 |
| 2 | Breast | None detected | ERBB2,PIK3CA | - | - | - | - | SD | Yes | - | 4d-on, 3d- off | Escalation (480mg) | 36 |
| 3 | Breast | BRCA1 | BRCA1,TP53 | - | - | - | - | cPR | Yes | - | 4d-on, 3d- off | Escalation (480mg) | 39 |
| 4 | Breast | BRCA2, RAD51D | BRCA2, RAD51D, ARID1A | RESISTANT | - | - | - | SD | Yes | - | 2d-on, 5d- off | Expansion | 18 |
| 5 | Breast | BRCA1 | BRCA1,TP53 | SENSITIVE | - | - | - | cPR | Yes | - | 2d-on, 5d- off | Expansion | 51 |
| 6 | Breast | PALB2 | PALB2 | - | - | - | - | cPR | Yes | cPR | 2d-on, 5d- off | Expansion | 66 |
| 7 | Breast | BRCA1 | BRCA1,TP53 | - | - | - | - | uPR | Yes | - | 4d-on, 3d- off | Expansion | 15 |
| 8 | Breast | None detected | None detected | SENSITIVE | - | - | - | cPR | Yes | - | 2d-on, 5d- off | Expansion | 36 |
| 9 | Endometrial cancer | ERCC2 | ERCC2, PIK3CA, PTEN,TP53, TSC1 | SENSITIVE | - | - | PTEN loss | cPR | Yes | cPR | 4d-on, 3d- off | Expansion | 29 |
| 10 | Ovarian | BRCA1 | BRCA1,TP53 | RESISTANT | PARP inhibitor resistant | - | - | SD | Yes | - | 2d-on, 5d- off | Escalation (640mg) | 18 |
| 11 | Ovarian | None detected | TP53 | SENSITIVE | - | - | - | cPR | Yes | cPR | 2d-on, 5d- off | Escalation (640mg) | 27 |
| 12 | Ovarian | BRCA2 | BRCA2,TP53 | RESISTANT | PARP inhibitor exposed | - | - | SD | Yes | - | 4d-on, 3d- off | Escalation (400mg) | 24 |
| 13 | Ovarian | BRCA1 | BRCA1,TP53 | RESISTANT | - | - | - | cPR | Yes | cPR | 2d-on, 5d- off | Escalation (480mg) | 33 |
| 14 | Ovarian | BRCA1 | BRCA1,TP53 | RESISTANT | - | - | - | uPR | Yes | - | 2d-on, 5d- off | Expansion | 18 |
| 15 | Ovarian | None detected | BRCA2,TP53 | SENSITIVE | PARP inhibitor resistant | - | PTEN loss | cPR | Yes | cPR | 4d-on, 3d- off | Expansion | 31 |
| 16 | Ovarian | BRCA2 | BRCA2(Plasma only) | RESISTANT | PARP inhibitor resistant | - | - | SD | Yes | cPR | 4d-on, 3d- off | Expansion | 115 |
| 17 | Ovarian | None detected | PTEN,KRAS,SMARCA4 | RESISTANT | - | - | - | cPR | Yes | cPR | 4d-on, 3d- off | Expansion | 83 |
| 18 | Ovarian | None detected | BRCA1,AR, TP53 | RESISTANT | - | - | - | SD | Yes | cPR | 4d-on, 3d- off | Expansion | 18 |
| 19 | Ovarian | BRCA2 | BRCA2,TP53 | RESISTANT | PARP inhibitor resistant | - | - | SD | Yes | cPR | 4d-on, 3d- off | Expansion | 56 |
| 20 | Ovarian | BRCA2 | BRCA2,NF1, TP53 | SENSITIVE | - | - | - | cPR | No | uPR | 4d-on, 3d- off | Expansion | 11 |
| 21 | Peritoneal mesothelioma | None detected | None detected | SENSITIVE | - | PI3K inhibitor resistant | - | SD | Yes | cPR | 4d-on, 3d- off | Escalation(480mg) | 84 |
| 22 | Pleura mesothelioma | None detected | None detected | SENSITIVE | - | - | - | SD | Yes | - | 2d-on, 5d- off | Escalation(640mg) | 16 |
| 23 | Prostate | RAD51D,NTRK1 | RAD51D,NTRK1 | - | - | - | - | SD | Yes | - | 4d-on, 3d- off | Escalation (480mg) | 18 |
| 24 | Prostate | BRCA2 | BRCA2,CDKN1B | - | - | - | - | SD | Yes | cPR | 4d-on, 3d- off | Escalation (400mg) | 98 |
| 25 | Prostate | BRCA2 | BRCA2,TP53 | - | - | - | - | cPR | Yes | cPR | 2d-on, 5d- off | Expansion | 21 |
Figure 3. Antitumor response waterfall and swimmer plots with corresponding patient/tumor characteristics.
A. Waterfall plot showing best target lesion response by RECIST 1.1 for patients where this could be evaluated. Red bars represent patients harboring gerrmline BRCA1/2 mutations, blue bars represent patients with somatic BRCA1/2 mutations, and grey bars indicate patients who did not have any BRCA1/2 mutations detected. Co-occuring genomic alterations are listed above the respective bars in responding patients without BRCA1/2 mutations detected. Hatched bars indicate patients with a tumor marker response (PSA or CA-125) where these data were available.
B. Waterfall plot showing best target lesion response by RECIST 1.1 for patients where this could be evaluated. Mutations used to classify tumors into DDR- or PI3K- mutated, or both, are shown below the bars for each patient, along with abbreviated site of the primary tumor. Hatched bars indicate patients with a tumor marker response (PSA or CA-125) where these data were available. Horizontal dotted lines represent RECIST 1.1 thresholds for progression (+20%) and partial response (-30%). Genes with mutations are shown with colored tiles. Tumor + Plasma denotes mutations observed in all samples, i.e. original Tumor and plasma where this was available. Tumor (only) denotes mutation only observed in original tumor sample and absent from subsequent plasma samples. Plasma (only) denotes a mutation observed only in plasma samples and not the original tumor sample. Germline and reversion mutations, as well as PTEN IHC classifications, are shown by symbols as indicated. The middle panel shows genes used to classify the tumors in the waterfall plot, and the lower panel shows other genes of interest.
C. Swimmer plot showing time on study for patients, categorized as in Figure 3B.
Molecular characteristics of patients with clinical benefit
Among the 25 (44.6%) patients who achieved clinical benefit (RECIST CR/PR or SD≥4 months), 14 (56%) patients had germline BRCA1 or BRCA2 mutations (ovarian cancer (n=7), breast cancer (n=5) and castration-resistant prostate cancer (CRPC; n=2)) (Table 3; Figures 3A-3C; Supplementary Table 5). Seven of the remaining patients had pathogenic DDR or PI3K pathway aberrations detected, while three patients did not, and one patient did not have available tissue for NGS testing.
Antitumor responses in patients with DDR and/or PI3K pathway mutations
Three RECIST-evaluable patients harboring tumors with both DDR-related and PI3K pathway mutations achieved RECIST PRs (Figure 3B). The mutations for these 3 patients were: (1) germline ERCC2 mutation, somatic PIK3CA and PTEN mutations and PTEN IHC loss; (2) somatic BRCA2 mutation and PTEN IHC loss; and (3) germline BRCA2 and PIK3CA mutations, respectively. Eight of 22 (36.4%) patients with tumors harboring only DDR-related mutations achieved RECIST PR, including those with BRCA1 (n=5), BRCA2 (n=2) and PALB2 (n=1) mutations. A further eight patients had a best response of SD≥4 months. Among those patients with tumors harboring only PI3K pathway mutations (n = 5), there was one objective response in a patient with a tumor found to have a PTEN mutation. In patients with tumors harboring neither PI3K pathway nor DDR-related mutations (n=25), there were two RECIST PRs.
Patients with BRCA1/2 mutant cancers
Among 25 patients with BRCA1/2 mutant cancers (20 with germline BRCA1/2 mutations, 5 with somatic BRCA1/2 mutations; breast (n=7), ovarian (n=15) and CRPC (n=3)), 22 patients had RECIST-measurable disease; 16 (72%) of these 22 patients achieved clinical benefit with the combination of olaparib and capivasertib.
Patients with advanced breast cancer
A total of 18 patients with advanced breast cancer were enrolled onto the study, 8 (44%) of whom achieved clinical benefit (Supplementary Table 5). Five (71.4%) out of 7 patients with BRCA1/2 mutant breast cancer had clinical benefit; four had RECIST PR and one had SD of 19.4 weeks, with a median duration of response of 39.1 weeks (range: 14.9 - 80.9). Two of these responders with clinical benefit were platinum-resistant. None of the responding patients with advanced breast cancer had prior therapy with PARP or PI3K pathway inhibitors.
Patients with advanced ovarian cancer
There were a total of 25 patients with advanced ovarian cancer, 11 of whom achieved clinical benefit (Supplementary Table 5). Seven (63.6%) of these 11 patients with germline BRCA1/2 mutant ovarian cancer achieved clinical benefit for a median duration of response of 24 weeks (range 11.3 - 115.0); 6 of these 7 patients were platinum-resistant. Four other patients with advanced ovarian cancer who also achieved clinical benefit included those with tumors harboring (1) somatic BRCA1, TP53 and AR mutations, (2) somatic BRCA2 and TP53 mutations, (3) somatic PTEN, KRAS and SMARCA4 mutations, and (4) somatic TP53 mutation.
Patients with advanced CRPC
Of four patients with advanced CRPC, three had germline BRCA1/2 mutations, of whom two achieved clinical benefit (Supplementary Table 5). None of the 4 patients had received prior platinum-based chemotherapy.
Prior PARP inhibitor or PI3K pathway inhibitor exposed patients
Thirteen patients had prior exposure to PARP inhibitors, five of whom had clinical benefit on this combination study (Supplementary Table 6). One of the patients had high grade serous ovarian cancer (HGSOC) with a somatic BRCA2 mutation, who achieved RECIST PR and GCIG CA-125 response lasting 31 weeks, while another patient with platinum-resistant germline BRCA2 mutant HGSOC with somatic TP53 mutation and somatic BRCA1 VUS achieved a GCIG CA-125 response and RECIST SD lasting 56 weeks. Another patient who had previously received a PARP inhibitor had platinum-resistant HGSOC harboring a germline BRCA2 mutation and achieved a GCIG CA-125 response and RECIST SD on this trial lasting 115 weeks. Only one patient had previously received a PI3K pathway inhibitor prior to this clinical trial; she was a patient with advanced peritoneal mesothelioma who had previously achieved a RECIST PR on a single agent PI3K pathway inhibitor prior to eventually progressing. On this clinical trial, she achieved a CA-125 response by GCIG criteria and durable RECIST SD lasting 84 weeks before progression.
Cell-free DNA analysis
A total of 157 cfDNA samples were serially collected from 41 patients for analysis on a targeted NGS panel. Of these patients, at least one mutation was detected in baseline cfDNA samples from 38 (93%) patients. Of 39 patients where both tumor and cfDNA samples were available for analysis, mutation status at baseline was concordant between tumor and cfDNA samples in 34 (87.2%) patients. All germline and somatic mutations detected through germline and/or tumor testing were detected in cfDNA. The most common mutations detected in cfDNA included TP53 (n=26 [63.4%] patients), BRCA2 (n=11 [26.8%]), BRCA1 (n=7 [17.1%]), KRAS (n=4 [9.8%]), PIK3CA (n=3 [7.3%]), ARID1A (n=3 [7.3%]) and PTEN (n=2 [4.9%]).
The cfDNA allele frequencies of somatic mutations decreased in selected responding patients and increased upon disease progression (Supplementary Figures 2A-2F). In patients with known germline mutations, e.g. BRCA1/2 mutations, falls in the cfDNA allele frequencies of germline mutations toward 50% were observed as they responded to trial therapy (Supplementary Figures 2C-2D). Of 20 patients harboring germline and/or somatic BRCA1/2 mutations with available cfDNA sampling, 5 patients were found to have BRCA1/2 reversion mutations at disease progression in their end of treatment cfDNA samples (Supplementary Table 7). One of these patients with advanced ovarian cancer, who had early disease progression after 4 weeks on trial, had a tumor somatic BRCA1 mutation (c.329insA, p.K110fs*4) in archived tissue, but was found to have a secondary BRCA1 mutation deletion restoring the original reading frame (c.335_338delATAA) in her cfDNA sample collected at baseline on cycle 1 day 1 and at disease progression.
Discussion
In this study, we have shown that the novel combination of olaparib and capivasertib is well tolerated at biologically effective doses that achieve clinical benefit, including durable responses, in patients with a range of treatment-refractory cancers, including both germline BRCA1/2 mutated tumors, and sporadic cancers harboring actionable somatic alterations. Antitumor responses were also observed in patients who had previously developed disease progression on PARP and PI3K pathway inhibitors.
Two different intermittent schedules of capivasertib were assessed to determine differences in safety, tolerability, PK-PD activity and antitumor responses in combination with olaparib, by comparing a high dose of capivasertib given over a shorter 2/5 schedule versus a lower dose of capivasertib over a longer 4/3 schedule. Overall, this combination was generally well tolerated in both schedules; treatment- related toxicities were reversible and mainly GI-related, including diarrhea, mucositis, nausea and anorexia. Such potential overlapping GI toxicities were effectively managed with simple supportive measures when indicated clinically, such as antiemetics and anti-diarrheals. No DLTs were observed on the 2/5 schedule, while 1 DLT of reversible grade 3 rash was observed at the highest tested dose of 480mg BID of capivasertib with 300mg BID of olaparib in the 4/3 schedule. Dose proportional PKs were observed, and proof-of-mechanism PD studies confirmed AKT pathway modulation across dose levels in platelet-rich plasma. Two different combination RP2Ds were established - 400mg BID of capivasertib with 300mg BID of olaparib for the 4/3 schedule, and 640mg BID of capivasertib with 300mg BID of olaparib with for the 2/5 schedule.
This study employed a prospective intrapatient dose escalation trial design, which enabled the rapid completion of dose escalation phases of two different combination schedules, each involving 3 dose levels, within 7 months and only requiring a total of 10 patients in each schedule. Apart from optimizing speed and minimizing patient numbers, this prospective intrapatient dose escalation has benefits over established Phase I escalation strategies including minimization of patient numbers receiving subtherapeutic drug doses, and safe optimization of drug exposures at an individual level to ensure maximal blockade of critical targets for combination strategies.
In preclinical studies, inhibition of the PI3K pathway has been shown to lead to upregulation of poly-ADP-ribosylation (PAR) and phosphorylation of H2AX, indicating increased DNA damage in cells (12). The accumulation of unrepaired DNA double stranded breaks in BRCA-deficient cells, in turn, makes them exquisitely sensitive to PARP inhibition, potentially accounting for the synergistic effects seen in combined olaparib and capivasertib treatment. Apart from germline BRCA mutant breast cancers, preclinical studies have also demonstrated that PI3K inhibition in triple negative breast cancer (TNBC) models drives ERK-dependent activation of the ETS transcription factor, which suppresses BRCA gene transcription, causing a deficiency of HR activity and PARP inhibitor sensitivity (11). Correlative tumor studies from this study have shown increases in tumor phosphorylated ERK expression associated with decreases in BRCA1 expression levels, supporting this hypothesis and rationale for this novel combination (14). Given that ERK phosphorylation may potentially have negative protumor consequences as well, future studies should investigate if this may represent a compensatory response that blunts antitumor efficacy.
The combination of olaparib and capivasertib on both 4/3 and 2/5 schedules have shown evidence of antitumor activity, with clinical benefit observed in 44.6% of evaluable patients on study. Fourteen (56%) of these 25 responding patients harbored germline BRCA1/2 mutations, while 8 (32%) of 25 had relevant somatic aberrations, including BRCA2, PIK3CA, PTEN, and PALB2 mutations (Figure 3A). All three patients with tumors harboring both DDR-related and PI3K pathway related aberrations had RECIST PRs, eight of 23 evaluable patients with tumors harboring only DDR-related tumor mutations achieved RECIST PR, and 1 of 5 patients deficient for PTEN had a RECIST PR (Figures 2B-2C). Importantly, clinical benefit was also observed in patients with neither PI3K pathway nor DDR-related tumor mutations detected, as well as in patients who had previously progressed on PARP or PI3K pathway inhibitors. While based on small numbers, these findings are in keeping with preclinical studies, which indicate that efficacy is not necessarily confined to tumors with actionable mutations such as BRCA1/2 mutations (11,12). Regardless, a suitably-powered randomized trial will be necessary to formally determine if there is synergistic patient benefit in the clinic with this capivasertib and olaparib combination.
In this study, concordance in the detection of selected mutations between cfDNA and tumor was 87.2%, supporting the use of cfDNA for the contemporaneous molecular profiling of patients. This high concordance may be associated with the large proportion of patients with germline mutation cancers included in this trial. Similar to previous studies (22), the cfDNA allele frequencies of somatic mutations decreased in selected responding patients and increased upon disease progression. Falls in the allele frequencies of germline mutations toward 50% were observed as they responded to trial therapy, suggesting elimination of the tumor clone (22). The development of BRCA1/2 reversion mutations was observed at disease progression in cfDNA from five (25%) out of 20 patients with BRCA1/2 mutant cancers with available cfDNA for analysis (Supplementary Table 7). This finding supports BRCA reversion as a likely resistance mechanism in PARP inhibitor-based therapies, including regimens such as this olaparib-capivasertib combination, and advocates the use of serial cfDNA sampling longitudinally in detecting the emergence of such aberrations. The patient with a BRCA1 reversion mutation detected in cfDNA at baseline and again at early disease progression had primary resistance to this combination, suggesting that the detection of such aberrations in cfDNA should also be considered as part of screening tests prior to PARP inhibitor based therapies (22,23).
Five (71.4%) out of 7 patients with germline BRCA1/2 mutant breast cancers achieved clinical benefit. In the phase 3 OlympiAD trial where patients with germline BRCA1/2 mutant HER2-negative metastatic breast cancer were randomized to receive olaparib or single-agent chemotherapy of the physician’s choice, the response rate was 59.9% in the olaparib group and 28.8% in the standard-therapy group (6). Although based on small numbers, our study provides preliminary clinical data that supports the combination of capivasertib with olaparib as a rational strategy to potentially improve patient benefit beyond that of single agent olaparib. The addition of capivasertib to first line paclitaxel chemotherapy for TNBC was also shown to lead to significantly longer progression-free survival (PFS) and overall survival (OS) in a randomized, double-blind, placebo-controlled phase 2 trial, particularly in patients with tumors harboring PIK3CA/AKT1/PTEN alterations (24). In addition, the FAKTION phase 2 trial showed that the addition of capivasertib to fulvestrant in patients with endocrine-resistant, advanced estrogen receptor positive breast cancer also resulted in significantly longer PFS and an observed OS improvement of approximately 6 months, although this was not statistically significant (37% OS data maturity) (25). Phase 3 trials of capivasertib-based combinations are planned or ongoing.
We observed clinical benefit in 7 of 10 patients (median duration of response for these responders was 24 weeks, range 11.3 – 115.0) with germline BRCA1/2 mutant ovarian cancer, of which 6 were platinum-resistant. Overall, 6 (24%) of 25 patients with advanced ovarian cancer achieved RECIST PR, while 5 (20%) had RECIST SD. An ongoing Phase Ib/2 trial of olaparib and capivasertib in patients with advanced ovarian, endometrial and triple negative breast cancer used the combination RP2D established in this trial of 400mg BID of capivasertib with 300mg BID of olaparib in the 4/3 schedule. Preliminary results from this trial have shown a RECIST PR rate of 7 (24%) of 30 patients, including RECIST PRs in four of 8 patients with recurrent endometrial cancer, 2 patients with TNBC and 1 patient with ovarian cancer, as well as RECIST SD≥ 4 months in 6 additional patients (26). This compares with 10 (36%) of 28 patients with ovarian cancer achieving RECIST PR, and 14 (50%) attaining RECIST SD in the phase Ib trial of olaparib in combination with the α-specific PI3K inhibitor alpelisib (15).
In summary, capivasertib in combination with olaparib was well tolerated in both 4/3 and 2/5 schedules. Blockade of AKT led to a downregulation of pSer9 pGSK3β, indicating target modulation, while increased pERK and decreased BRCA1 expression provided translational mechanistic insights into potential synergistic activity between capivasertib and olaparib. Antitumor activity was observed more frequently in patients with either germline BRCA1/2 mutant cancers and sporadic cancers with somatic aberrations along the DDR and PI3K/AKT pathways. There were also preliminary signals of clinical benefit in platinum-resistant HGSOC and in patients who had received prior PARP inhibitors. Our results support the development of the combination of olaparib and capivasertib as a promising strategy that warrants further exploration in future clinical trials.
Methods
This investigator-initiated study (ClinicalTrials.gov: NCT02338622) was designed by TAY and JDB, with support from AstraZeneca, and conducted in accordance with the provision of the Declaration of Helsinki and Good Clinical Practice guidelines. Dose escalation was conducted at the Royal Marsden NHS Foundation Trust (RM), London, UK, while the dose expansion phase also involved University College London Hospital, London, Northern Centre for Cancer Care, Newcastle, and Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK. The Central London Research Ethics Committee (REC) approved the protocol
(REC reference 14/LO/0103). The trial was co-sponsored by the Institute of Cancer Research (ICR) and RM, and centrally managed by the Drug Development Unit (Investigator Initiated Trials Team) at the ICR/RM. Funding was provided by the Experimental Cancer Medicine Centres (ECMC) network, National Institute of Health Research, Cancer Research UK (CR-UK), and AstraZeneca.
Study population
Eligible patients had histologically confirmed advanced solid tumors refractory to standard therapies and Eastern Cooperative Oncology Group performance status (ECOG PS) 0-1. Complete eligibility criteria are available in the Data Supplement. Dose expansion cohorts mandated patients with germline BRCA1/2 mutated tumors (Cohort A) or germline BRCA1/2 wildtype patients with sporadic tumors likely to harbor HR defects or demonstrating somatic aberrations known to result in a hyperactivated PI3K-AKT pathway (or defective DNA repair) (Cohort B). The dose escalation cohort was enriched for patients with characteristics mandated in expansion cohorts A and B, but this was not a requirement. Written informed consent was obtained from all patients.
Trial design
This was an open-label, multicenter phase Ib trial assessing the combination of olaparib and capivasertib in patients with advanced solid tumors. The primary objectives were to determine the safety and tolerability of olaparib in combination with capivasertib, and to establish a MTD and/or RP2D of this combination. Secondary objectives included the characterization of PK and PD profiles of both agents in combination. Exploratory objectives included the assessment of preliminary antitumor activity of the combination and evaluation of putative predictive biomarkers of response and resistance. Study conduct was overseen by a Safety Review Committee (SRC), comprising the Chief Investigator, Principal Investigator or delegate from each investigational site, DDU Pharmacovigilance Officer or delegate, CR-UK’s Drug Development Office medical advisor or delegate, an observer from AstraZeneca, a Clinical Trials Manager or delegate, an independent senior ECMC network clinician and a RMH representative who was independent of the study team.
Prospective intrapatient dose escalation
This phase I trial utilized a prospective intrapatient dose escalation trial design, where doses of capivasertib were prospectively escalated in each patient in combination with a fixed continuous dose of olaparib (Supplementary Figure 1; Supplementary Methods).
Toxicities and laboratory variables were assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Patients had safety evaluations weekly and tumor response assessments after every three treatment cycles, using computer tomography scans evaluated by RECIST version 1.1. As appropriate, different tumor markers were used to assess the effects of study treatment on respective tumor types, e.g. serum CA-125 was assessed in patients with ovarian cancer according to GCIG criteria or serum PSA levels in patients with CRPC according to PCWG2 criteria.
Pharmacokinetics and pharmacodynamics
PK modelling was conducted using a non-compartmental extravascular model for plasma with Phoenix™ WinNonLin Software® version 64 (Pharsight). PD Biomarker analysis of pSer9 GSK3ß was undertaken on PRP where available, using assays validated to Good Clinical Practice standards on the MesoScale Discovery (MSD®) technology platform (Supplementary Methods) (27). ERK expression was assessed using immunohistochemistry conducted on formalin-fixed, paraffin- embedded (FFPE) tissue sections (Supplementary Methods). BRCA1 expression was assessed using a BRCA1 pan-nuclear IHC staining (Supplementary Methods).
Predictive biomarker studies
Targeted next generation sequencing studies were conducted on patients with available tumor tissue at the Institute of Cancer Research (Supplementary Methods); libraries were constructed with the use of GeneRead DNA seq Panel (Qiagen) and run on a MiSeq sequencer (Illumina). Whole exome sequencing was also performed on germline and tumor DNA of responding patients using Illumina HiSeq 2500 in paired-end mode. Variants are annotated as pathogenic if considered ‘pathogenic’ or ‘likely pathogenic’ according to the ClinVar database (28) and/or ACMG classification using VarSome (29). PTEN loss was assessed by immunohistochemistry performed on FFPE tissue sections from archived tumor where available as previously described (30).
Statistical analysis
Analysis was conducted after all patients had received 1 cycle of treatment and had completed their last study visit conducted 28 days after the last dose of combination treatment. Patients were evaluable for antitumor efficacy assessment if they had at a baseline RECIST assessment and at least one post-baseline RECIST assessment. Under the assumption that the true underlying CBR was 20%, with anticipated recruitment of 40 patients in the expansion phase, there would be a <1% chance of seeing no responses, and a >99% chance of observing 2 or more responses.
Supplementary Material
Statement of Significance.
In the first trial to combine poly(ADP-ribose) polymerase and AKT inhibitors, a prospective intrapatient dose-escalation design demonstrated safety, tolerability, pharmacokinetic-pharmacodynamic activity, and assessed predictive biomarkers of response/resistance. Antitumor activity was observed in patients harboring tumors with germline BRCA1/2-mutations and BRCA1/2-wildtype cancers with or without somatic DDR and/or PI3K/AKT pathway alterations.
Acknowledgements
The authors would like to thank and acknowledge all patients for taking part in this study and their caregivers, as well as the trial research nurses, data managers and clinical coordinators. Funding for this academic study was provided by AstraZeneca through the Cancer Research UK Experimental Cancer Medicine Centre (ECMC) Combinations Alliance. The authors acknowledge the ECMC (London - The Institute of Cancer Research, London - University College London, Cambridge and Newcastle Centres), National Health Service (NHS) funding to the National Institute for Health Research (NIHR) Biomedical Research Centres at the Royal Marsden NHS Foundation Trust and The Institute of Cancer Research and University College London, NIHR Cambridge Clinical Research Facility and Cancer Research Technology Limited. Capivasertib (AZD5363) was discovered by AstraZeneca after a collaboration with Astex Therapeutics (and its collaboration with The Institute of Cancer Research and Cancer Research Technology Limited). UB is a recipient of a National Institute of Health Research award (RP-2016-07-028). The authors thank Dr Filip Janku MD PhD (The University of Texas MD Anderson Cancer Center) for helpful discussions on cfDNA studies.
Author contributions
Study design: TAY and JSDB.
Study supervision: TAY, RK, RP, BB, JL, YD and JSDB
Trial Management: TAY, RK, SW, RM, MP, AT, RP, BB, JL, YD and JSDB
Patient recruitment: TAY, RK, VM, JLL, REM, UB, RP, BB, JL, YD and JSDB.
Data acquisition: SC, DR, RR, SM, DNR, SW, RM, MP, AT, NC, HG, NT, RR, FIR, SD, KS, LF and EH.
Data management: MP
Data analysis and interpretation: TAY, RK, VM, SJP, JSJL, SC, DR, REM, RR, SM, IF, DNR, SW, RM, MP, AT, NT, NC, HG, NT, RR, FIR, SD, KS, LF, EH, PR, JPOL, AF, CJL, UB, RP, BB, JL, YD and JSDB.
Preparation of figures: TAY, SJP, SC, MP, RR, FIR, SD, KS and CJL.
Manuscript writing and review: TAY, RK, VM, SJP, JSJL, SC, DR, REM, RR, SM, IF, DNR, SW, RM, MP, AT, NT, NC, HG, NT, RR, FIR, SD, KS, LF, EH, PR, JPOL, AF, CJL, UB, RP, BB, JL, YD and JSDB.
Conflicts of Interest
TAY: Research support (to Institution): Artios, AstraZeneca, Bayer, Clovis, Constellation, Cyteir, Eli Lilly, EMD Serono, Forbius, F-Star, GlaxoSmithKline, Genentech, ImmuneSensor, Ipsen, Jounce, Karyopharm, Kyowa, Merck, Novartis, Pfizer, Ribon Therapeutics, Regeneron, Repare, Sanofi, Scholar Rock, Seattle Genetics, Tesaro, and Vertex Pharmaceuticals. Consultancies: Almac, Aduro, AstraZeneca, Atrin, Axiom, Bayer, Bristol Myers Squibb, Calithera, Clovis, Cybrexa, EMD Serono, F-Star, Guidepoint, Ignyta, I-Mab, Jansen, Merck, Pfizer, Repare, Roche, Rubius, Schrodinger, Seattle Genetics, Varian and Zai Labs. RK: Advisory boards for Clovis Oncology, Roche, and Tesaro. JSL: Honoraria: Pfizer and Novartis; consulting or advisory role: Pfizer and Novartis; research funding: Synthon; travel expenses from AstraZeneca and Novartis. REM: Consultancy and Advisory Board: Merck, Tesaro, Astrazeneca, Roche and Clovis. Speakers bureau: Roche and Tesaro. Travel grants: AstraZeneca and Tesaro. NTunariu: Speakers bureau: Janssen, Sanofi, Bayer, and Astellas. NTurner: Advisory board honoraria: AstraZeneca, Bristol-Myers Squibb, Eli Lilly, Merck Sharp & Dohme, Novartis, Pfizer, Roche/Genentech, Tesaro, and Bicycle Therapeutics; research funding: AstraZeneca, Bio-Rad, Pfizer, Roche/Genentech, Clovis, and Guardant Health. FIR: Employee of The Institute of Cancer Research, which was involved in the development of AZD5363. SD: Employee of The Institute of Cancer Research, which is involved in the development of PI3K, HSP90, HDAC, AKT, ROCK, RAF, CHK1 and HSF1 inhibitors. KS: Employee of The Institute of Cancer Research, which is involved in the development of PI3K, HSP90, HDAC, AKT, ROCK, RAF, CHK1 and HSF1 inhibitors. LF: Former employee of Amgen. Research funding: AstraZeneca. EH: Research funding: Kyowa Hakko UK, Alliance Pharma (was Cambridge Laboratories), Merck Sharpe & Dohme, Bayer, AstraZeneca, Accuray Inc, Aventis Pharma Ltd (Sanofi) and Varian Medical Systems Inc. PR: Employee and shareholder: AstraZeneca JPOL: Employee and shareholder: AstraZeneca. AF: Employee and shareholder: AstraZeneca. CJL: Stock or other ownership interests: Tango, Obvibio; honoraria with Sun Pharma, GLG, Merck KGaA, Vertex, AstraZeneca, Tango, 3rd Rock, Ono Pharma, and Artios; Consulting or advisory role with Sun Pharma, GLG, Merck KGaA, AstraZeneca, Tango, 3rd Rock, Ono Pharma, Ovibio and Artios; Research funding: AstraZeneca, Merck KGaA, and Artios; CJL’s institution has patents, royalties, or other intellectual property interests in the use of DNA repair inhibitors and CJL stands to gain from these as part of the Institute of Cancer Research Rewards to Inventors scheme. UB: Consultancy: Astellas, Novartis, Karus Therapeutics, Phoenix ACT, Eli Lilly, Astex, Novartis, Vernalis, Janssen, Boehringer-Ingelheim. Research funding: Onyx Pharmaceuticals, BTG International, Chugai, AstraZeneca and Verastem. Employee of The Institute of Cancer Research, which is involved in the development of PI3K, HSP90, HDAC, AKT, ROCK, RAF, CHK1 and HSF1 inhibitors. Travel expenses: Sierra Oncology and Bayer. RP: Consultancies: Pierre Faber, Bayer, Octimet, Clovis Oncology, Novartis, Karus Therapeutics, Biosceptre, BMS, Cybrexa, Ellipses, CV6 Therapeutics, Astex Therapeutics and Sanofi Aventis. Educational talks or chairing educational meetings: AstraZeneca, Novartis, Bayer, Tesaro and BMS. Travel funds: BMS and MSD. My Institution has received research funds from AstraZeneca for a Case PhD fellowship. BB: Consulting: Eisai Europe Limited (paid to Institution), Roche (paid to Institution), GenMab consultancy (paid to Institution). Speakers’ Bureau: Eisai Europe Limited. Research funding: GenMab Data Monitoring Committees (paid to Institution), Celgene Ltd (funding for investigator initiated trial).
Travel expenses: Bayer. JL: Research grant funding: Roche-Genentech, Basilea and Genmab. Advisory boards: Basilea and Genmab. YD: Consultancy, Honoraria, Advisory boards: Clovis, AstraZeneca, Merck, Tesaro and Genmab. Institution received research funding from AstraZeneca, Clovis, Oncology, Merck and Tesaro Inc. JSdB: Honoraria, consulting or advisory roles with, and travel, accommodations, or expenses: AstraZeneca, Sanofi, Astellas, Pfizer, Genentech/Roche, Janssen Oncology, Menarini Silicon Biosystems, Daiichi Sankyo, Sierra Oncology, Bayer, Merck Sharp & Dohme, Merck Serono, Boehringer Ingelheim, Celgene, Taiho, Genmab, GSK, Orion, Eisai, and Bioxcel Therapeutics; JSdB’s institution has a commercial interest in abiraterone, PARP inhibition in DNA repair-defective cancers, and PI3K/AKT pathway inhibitors (no personal income).
The authors VM, SJP, SC, DR, RR, SM, IF, DNR, SW, RRM, MP, AT, NC, HG and RR declare no potential conflicts of interest.
References
- 1.Bryant HE, Schultz N, Thomas HD, Parker KM, Flower D, Lopez E, et al. Specific killing of BRCA2-deficient tumours with inhibitors of poly(ADP-ribose) polymerase. Nature. 2005;434(7035):913–7. doi: 10.1038/nature03443. [DOI] [PubMed] [Google Scholar]
- 2.Farmer H, McCabe N, Lord CJ, Tutt AN, Johnson DA, Richardson TB, et al. Targeting the DNA repair defect in BRCA mutant cells as a therapeutic strategy. Nature. 2005;434(7035):917–21. doi: 10.1038/nature03445. [DOI] [PubMed] [Google Scholar]
- 3.Pilie PG, Tang C, Mills GB, Yap TA. State-of-the-art strategies for targeting the DNA damage response in cancer. Nat Rev Clin Oncol. 2019;16(2):81–104. doi: 10.1038/s41571-018-0114-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Moore K, Colombo N, Scambia G, Kim BG, Oaknin A, Friedlander M, et al. Maintenance Olaparib in Patients with Newly Diagnosed Advanced Ovarian Cancer. N Engl J Med. 2018;379(26):2495–505. doi: 10.1056/NEJMoa1810858. [DOI] [PubMed] [Google Scholar]
- 5.Golan T, Hammel P, Reni M, Van Cutsem E, Macarulla T, Hall MJ, et al. Maintenance Olaparib for Germline BRCA-Mutated Metastatic Pancreatic Cancer. N Engl J Med. 20l9;381(4):317–27. doi: 10.1056/NEJMoa1903387. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Robson M, Im SA, Senkus E, Xu B, Domchek SM, Masuda N, et al. Olaparib for Metastatic Breast Cancer in Patients with a Germline BRCA Mutation. N Engl J Med. 20l7;377(6):523–33. doi: 10.1056/NEJMoa1706450. [DOI] [PubMed] [Google Scholar]
- 7.Litton JK, Rugo HS, Ettl J, Hurvitz SA, Goncalves A, Lee KH, et al. Talazoparib in Patients with Advanced Breast Cancer and a Germline BRCA Mutation. N Engl J Med. 20l8;379(8):753–63. doi: 10.1056/NEJMoa1802905. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Mateo J, Carreira S, Sandhu S, Miranda S, Mossop H, Perez-Lopez R, et al. DNA-Repair Defects and Olaparib in Metastatic Prostate Cancer. N Engl J Med. 20l5;373(18):1697–708. doi: 10.1056/NEJMoa1506859. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Pilie PG, Gay CM, Byers LA, O’Connor MJ, Yap TA. PARP Inhibitors: Extending Benefit Beyond BRCA-Mutant Cancers. Clin Cancer Res. 20l9;25(13):3759–71. doi: 10.1158/1078-0432.CCR-18-0968. [DOI] [PubMed] [Google Scholar]
- 10.Brown JS, O’Carrigan B, Jackson SP, Yap TA. Targeting DNA Repair in Cancer: Beyond PARP Inhibitors. Cancer Discov. 20l7;7(1):20–37. doi: 10.1158/2159-8290.CD-16-0860. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Ibrahim YH, Garcia-Garcia C, Serra V, He L, Torres-Lockhart K, Prat A, et al. PI3K Inhibition Impairs BRCA1/2 Expression and Sensitizes BRCA-Proficient TripleNegative Breast Cancer to PARP Inhibition. Cancer Discov. 2012;2(11):1036–47.:2159-8290.CD-11-0348. doi: 10.1158/2159-8290.CD-11-0348. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Juvekar A, Burga LN, Hu H, Lunsford EP, Ibrahim YH, Balmana J, et al. Combining a PI3K Inhibitor with a PARP Inhibitor Provides an Effective Therapy for BRCA1-Related Breast Cancer. Cancer Discov. 2012;2(11):1048–63.:2159-8290.CD-11-0336. doi: 10.1158/2159-8290.CD-11-0336. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Mo W, Liu Q, Lin CC, Dai H, Peng Y, Liang Y, et al. mTOR Inhibitors Suppress Homologous Recombination Repair and Synergize with PARP Inhibitors via Regulating SUV39H1 in BRCA-Proficient Triple-Negative Breast Cancer. Clin Cancer Res. 20l6;22(7):1699–712. doi: 10.1158/1078-0432.CCR-15-1772. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Rehman FL, Lord CJ, Ashworth A. The Promise of Combining Inhibition of PI3K and PARP as Cancer Therapy. Cancer Discov. 2012;2(11):982–4.:2/11/982. doi: 10.1158/2159-8290.CD-12-0433. [DOI] [PubMed] [Google Scholar]
- 15.Konstantinopoulos PA, Barry WT, Birrer M, Westin SN, Cadoo KA, Shapiro GI, et al. Olaparib and alpha-specific PI3K inhibitor alpelisib for patients with epithelial ovarian cancer: a dose-escalation and dose-expansion phase 1b trial. Lancet Oncol. 2Ol9;20(4):570–80. doi: 10.1016/S1470-2045(18)30905-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Davies BR, Greenwood H, Dudley P, Crafter C, Yu DH, Zhang J, et al. Preclinical pharmacology of AZD5363, an inhibitor of AKT: pharmacodynamics, antitumor activity, and correlation of monotherapy activity with genetic background. Mol Cancer Ther. 2Ol2;11(4):873–87. doi: 10.1158/1535-7163.MCT-11-0824-T. [DOI] [PubMed] [Google Scholar]
- 17.Hyman DM, Smyth LM, Donoghue MTA, Westin SN, Bedard PL, Dean EJ, et al. AKT Inhibition in Solid Tumors With AKT1 Mutations. J Clin Oncol. 2Ol7;35(20):2251–9. doi: 10.1200/JCO.2017.73.0143. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Banerji U, Dean EJ, Perez-Fidalgo JA, Batist G, Bedard PL, You B, et al. A Phase I Open-Label Study to Identify a Dosing Regimen of the Pan-AKT Inhibitor AZD5363 for Evaluation in Solid Tumors and in PIK3CA-Mutated Breast and Gynecologic Cancers. Clin Cancer Res. 2Ol8;24(9):2050–9. doi: 10.1158/1078-0432.CCR-17-2260. [DOI] [PubMed] [Google Scholar]
- 19.Tamura K, Hashimoto J, Tanabe Y, Kodaira M, Yonemori K, Seto T, et al. Safety and tolerability of AZD5363 in Japanese patients with advanced solid tumors. Cancer Chemother Pharmacol. 2Ol6;77(4):787–95. doi: 10.1007/s00280-016-2987-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Fruman DA, Chiu H, Hopkins BD, Bagrodia S, Cantley LC, Abraham RT. The PI3K Pathway in Human Disease. Cell. 2Ol7;170(4):605–35. doi: 10.1016/j.cell.2017.07.029. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Yap TA, Bjerke L, Clarke PA, Workman P. Drugging PI3K in cancer: refining targets and therapeutic strategies. Curr Opin Pharmacol. 2Ol5;23:98–107. doi: 10.1016/j.coph.2015.05.016. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Goodall J, Mateo J, Yuan W, Mossop H, Porta N, Miranda S, et al. Circulating Cell-Free DNA to Guide Prostate Cancer Treatment with PARP Inhibition. Cancer Discov. 2Ol7;7(9):1006–17. doi: 10.1158/2159-8290.CD-17-0261. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Lin KK, Harrell MI, Oza AM, Oaknin A, Ray-Coquard I, Tinker AV, et al. BRCA Reversion Mutations in Circulating Tumor DNA Predict Primary and Acquired Resistance to the PARP Inhibitor Rucaparib in High-Grade Ovarian Carcinoma. Cancer Discov. 2Ol9;9(2):210–9. doi: 10.1158/2159-8290.CD-18-0715. [DOI] [PubMed] [Google Scholar]
- 24.Schmid P, Abraham J, Chan S, Wheatley D, Brunt M, Nemsadze G, et al. AZD5363 plus paclitaxel versus placebo plus paclitaxel as first-line therapy for metastatic triple-negative breast cancer (PAKT): A randomised, double-blind, placebo-controlled, phase II trial. J Clin Oncol. 2018;36(suppl):abstr 1007. doi: 10.1200/JCO.19.00368. [DOI] [PubMed] [Google Scholar]
- 25.Jones RH, Carucci M, Casbard AC, Butler R, Alchami F, Bale CJ, et al. Capivasertib (AZD5363) plus fulvestrant versus placebo plus fulvestrant after relapse or progression on an aromatase inhibitor in metastatic ER-positive breast cancer (FAKTION): A randomized, double-blind, placebo-controlled, phase II trial. Journal of Clinical Oncology. 2019 May 20;37(15_suppl):1005. 101200/JCO20193715_suppl1005. [Google Scholar]
- 26.Westin S, Litton J, Williams R, Soliman P, Frumovitz M, Schmeler K, et al. Phase I Expansion of olaparib (PARP inhibitor) and AZD5363 (AKT inhibitor) in recurrent ovarian, endometrial and triple negative breast cancer. Annals of Oncology. 2017;28(suppl_5):v122–v141. 101093/annonc/mdx367. [Google Scholar]
- 27.Gowan SM, Hardcastle A, Hallsworth AE, Valenti MR, Hunter LJ, de Haven Brandon AK, et al. Application of meso scale technology for the measurement of phosphoproteins in human tumor xenografts. Assay Drug Dev Technol. 2007;5(3):391–401. doi: 10.1089/adt.2006.044. [DOI] [PubMed] [Google Scholar]
- 28.Landrum MJ, Lee JM, Benson M, Brown GR, Chao C, Chitipiralla S, et al. ClinVar: improving access to variant interpretations and supporting evidence. Nucleic Acids Res. 20l8;46(D1):D1062–D7. doi: 10.1093/nar/gkx1153. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 29.Kopanos C, Tsiolkas V, Kouris A, Chapple CE, Albarca Aguilera M, Meyer R, et al. VarSome: the human genomic variant search engine. Bioinformatics. 20l9;35(11):1978–80. doi: 10.1093/bioinformatics/bty897. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30.Ferraldeschi R, Nava Rodrigues D, Riisnaes R, Miranda S, Figueiredo I, Rescigno P, et al. PTEN protein loss and clinical outcome from castration-resistant prostate cancer treated with abiraterone acetate. Eur Urol. 20l5;67(4):795–802. doi: 10.1016/j.eururo.2014.10.027. [DOI] [PMC free article] [PubMed] [Google Scholar]
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