Abstract
Purpose
Evaluate safety and determine the recommended phase II dose (RP2D) of ensartinib (X-396), a potent anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor (TKI), and evaluate preliminary pharmacokinetics and antitumor activity in a first-in-human, phase I/II clinical trial primarily in patients with non-small cell lung cancer (NSCLC).
Experimental Design
In dose escalation, ensartinib was administered at doses of 25−250 mg once daily in patients with advanced solid tumors; in dose expansion, patients with advanced ALK-positive NSCLC were administered 225 mg once daily. Patients who had received prior ALK TKI(s) and patients with brain metastases were allowed.
Results
Thirty-seven patients enrolled in dose escalation, and 60 enrolled in dose expansion. The most common treatment-related toxicities were rash (56%), nausea (36%), pruritus (28%), vomiting (26%), and fatigue (22%); 23% of patients experienced a treatment-related Grade 3-4 toxicity (primarily rash and pruritus). The maximum tolerated dose was not reached, but the RP2D was chosen as 225 mg based on the frequency of rash observed at 250 mg without improvement in activity. Among the ALK-positive efficacy evaluable patients treated at ≥200 mg, the response rate (RR) was 60% and median progression-free survival (PFS) was 9.2 months. RR in ALK TKI naïve patients was 80% and median PFS was 26.2 months. In patients with prior crizotinib only, the RR was 69% and median PFS was 9.0 months. Responses were also observed in the central nervous system, with an intracranial RR of 64%.
Conclusions
Ensartinib was active and generally well tolerated in patients with ALK-positive NSCLC.
Keywords: non-small cell lung cancer, ALK inhibitor, ensartinib, X-396, first-in-human study
INTRODUCTION
Chromosomal rearrangements involving the gene encoding the anaplastic lymphoma kinase (ALK) are detected in 3-8% of non-small cell lung cancers (NSCLC).1–5 The resultant ALK fusion proteins are a validated therapeutic target in NSCLC, and testing for ALK is now the accepted standard-of-care in the United States. Crizotinib was the first ALK inhibitor approved to treat patients with locally advanced or metastatic NSCLC whose tumors express ALK fusion proteins. Results from two phase III studies in previously treated or untreated patients with advanced, ALK-positive NSCLC showed that crizotinib, compared to chemotherapy, significantly prolonged progression-free survival (PFS; median treated 7.7 vs. 3.0 months and untreated 10.9 vs. 7.0 months) and increased response rates (RRs [65% vs. 20% treated and 74% vs. 45% untreated]).6,7 Despite experiencing initial responses, the majority of patients eventually had disease progression, typically in less than 12 months, and new strategies to overcome resistance remain an area of active investigation.8,9
Mechanisms of acquired resistance to crizotinib include both ‘on-target’ genomic alterations, including mutations in the ALK tyrosine kinase domain and amplification of the ALK fusion, as well as activation of bypass signaling pathways, including EGFR, IGF-1R, c-KIT, and SRC. Additionally, in a retrospective analysis of two clinical trials, the central nervous system (CNS) was the most common site of progression in patients receiving crizotinib.10 Thus, the development of second-generation ALK inhibitors has primarily focused on improved binding to the ALK kinase domain and improved CNS activity.
Ensartinib (X-396) is a novel, aminopyridazine-based small molecule that potently inhibits ALK. Ensartinib is 10-fold more potent than crizotinib at inhibiting the growth of ALK-positive lung cancer cell lines.11 Additionally, ensartinib potently inhibited ALK fusions engineered to have point mutations, L1196M and C1156Y, that are associated with crizotinib resistance. Ensartinib also demonstrated potent antitumor activity in H3122 lung cancer xenografts that harbored the EML4-ALK E13;A20 fusion, with favorable pharmacokinetic (PK) and safety profiles.11
A phase I/II trial was conducted in patients with ALK-positive NSCLC, where the primary objectives were to evaluate the safety and determine the recommended phase 2 dose (RP2D). Key secondary objectives included characterizing preliminary PK and antitumor activity.
MATERIALS AND METHODS
Biochemical Kinase Activity and Selectivity
Biochemical assays were performed by Reaction Biology Corporation (Malvern, PA) according to the procedures as previously described.12
Distribution Studies
Biodistribution studies were conducted in four groups of Sprague-Dawley rats (3 females and 3 males) treated orally with ensartinib at 50 mg/kg. Mice were sacrificed at 0.5, 4, 12, and 24 hours post-dose to quantify concentration of ensartinib in the plasma and the skin. All animal experiments were reviewed and approved by the animal review board.
Study Population
Eligible patients in dose escalation had advanced solid tumors. Dose expansion was limited to patients with advanced NSCLC whose tumors were positive for ALK as determined by fluorescence in situ hybridization (FISH) or immunohistochemistry (IHC) from local testing. ALK FISH-positive was defined as the FDA cleared recommended threshold of 15% cells showing split signal; a second confirmatory test was required if the positive signal was between 10% and 15%. For ALK positivity by IHC, strong granular cytoplasmic staining (3+) was required. ALK rearrangements were confirmed centrally via FISH for all patients. Additional eligibility criteria included age ≥18 years, an Eastern Cooperative Oncology Group (ECOG) performance status of 0-1, adequate organ function and, in dose expansion, measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST), v1.1. Prior therapy with crizotinib and/or second-generation ALK tyrosine kinase inhibitors (TKIs) was allowed without a limit on prior therapies. A minimum washout period of 10 days was required between termination of treatment and administration of ensartinib. However, in the case of ALK TKIs, a 5-day window was allowed. Patients with asymptomatic CNS lesions were allowed. CNS lesions with evidence of tumor growth at least one month post whole brain radiation therapy (WBRT) can be target lesions as evidenced by gadolinium-enhanced MRI. Target lesions may not have been treated with stereotactic radiosurgery (SRS). Additional eligibility criteria are included in the Supplemental Methods.
This study was approved by the review boards at all participating institutions, and all subjects provided written informed consent. The study was conducted in accordance with good clinical practice and the Declaration of Helsinki and its amendments, and was registered through ClinicalTrials.gov (NCT01625234).
Study Design
Dose escalation used an accelerated titration scheme to determine the maximum tolerated dose (MTD). The starting dose of ensartinib was 25 mg administered orally once daily without food and was continuously doubled until one patient experienced a drug-related Grade ≥2 adverse event (AE). At that point, accelerated titration was stopped and a 3+3 design was used for further dose escalation. In order to collect sufficient PK data, additional patients could be enrolled at lower doses during dose escalation. Once the RP2D was determined, the safety and antitumor activity of ensartinib was further evaluated in dose expansion. Cycle length was 28 days.
A dose limiting toxicity (DLT) was defined as any of the following ensartinib-related events that occurred during the first treatment cycle: Grade 4 neutropenia persisting for >5 days or febrile neutropenia, Grade 4 thrombocytopenia or Grade 3 thrombocytopenia with bleeding, Grade ≥3 non-hematologic toxicity with the exception of Grade 3 rash, diarrhea, nausea, or vomiting if controlled and resolved within 48 hours, or a treatment delay of ≥14 days due to unresolved toxicity.
Dose expansion included five cohorts: 1) patients who were ALK TKI-naïve, 2) patients who progressed on prior crizotinib and had not received other ALK TKIs, 3) patients who had progressed on at least one second-generation ALK TKI and may or may not have had prior crizotinib, 4) patients with CNS metastases, where at least one target lesion was ≥3 mm in diameter, and 5) patients with leptomeningeal disease.
Study Assessments
Safety
AEs were graded according to the National Cancer Institute Common Terminology for Adverse Events, version 4.03. All patients who developed a DLT or received ≥80% of the planned doses during cycle 1 and completed the required safety evaluations were evaluable for the DLT assessment. Patients removed from the study during the first cycle not meeting these criteria were replaced. To test the difference in frequency and severity of specific gastrointestinal toxicities (e.g., nausea and vomiting) between a fed and fasted state, a subset of patients was assigned to take ensartinib with or without food during cycle 1. After the first cycle, patients were allowed to choose how they preferred to take ensartinib.
Pharmacokinetics
On days 1 and 22 of cycle 1, plasma samples were obtained from all patients in dose escalation and a subset of patients in the dose expansion phase before dosing of ensartinib, and at 0.5, 1, 2, 3, 4, 6, and 8 hours after dosing. Plasma samples were also collected prior to dosing on days 2, 8, and 15 of cycle 1. Plasma concentration-time profiles and PK parameters for ensartinib were obtained. To explore the potential effect of food on ensartinib absorption, half of the patients in dose expansion phase were instructed to take the daily dose with food while the other half took the study medication under fasting conditions during cycle 1. After cycle 1, the patients were allowed to choose.
Efficacy
At baseline, all patients underwent tumor imaging with CT and, if appropriate, MRI. Brain imaging was required for patients with known or suspected brain metastases. Restaging scans, both CT and, if applicable, MRI, were obtained at approximately 8-week intervals. Patients entered into the leptomeningeal disease cohort also had a MRI of the brain and spin at Cycle 2 Day 1. Systemic disease was assessed according to RECIST v1.1 by the investigator, although patients with clinical progression were considered to have disease progression in the absence of objective progression.13 Response for CNS metastases was also evaluated based on RECIST criteria, with some modifications (e.g., target lesion may be ≥3 mm).
Statistical Analysis
All patients who received at least one dose of ensartinib were evaluable for safety, and patients who completed at least one cycle of treatment at a dose ≥200 mg and had a post-baseline response assessment were evaluable for efficacy. Confidence intervals were calculated using the Wilson method, and PFS and duration of response (DOR) were estimated using Kaplan-Meier methodology. PFS was calculated from the on-treatment date to the first date disease progression was observed. DOR was calculated from the first date a tumor response was observed per RECIST v1.1 to the first date of disease progression. For those patients that remained on study at the time of data pull, PFS and DOR were censored at the data-cutoff date of February 15, 2017. Enrollment in dose expansion is ongoing.
RESULTS
Biochemical Kinase Activity and Selectivity and Distribution Studies
Ensartinib was tested against wild-type ALK and 17 ALK variants in the Reaction Biology panel. Ensartinib potently inhibited all evaluated ALK variants, with in vitro IC50s <4 nM. The wild-type and F1174, C1156Y, L1196M, S1206R, and T1151 mutants are particularly sensitive to ensartinib, with IC50s of <0.4 nM, while the IC50 for the G1202R mutant is approximately 10-fold higher (3.8 nM). Besides ALK, ensartinib also potently inhibits (IC50 <1 nM) TPM3-TRKA, TRKC, and GOPC-ROS1. Kinases inhibited at higher concentrations (IC50: 1-10 nM) are EphA2, EphA1, EphB1 and c-MET (Supplemental Table 1).
The mean concentration of ensartinib in plasma and skin at multiple time points post-dose is listed in Supplemental Table 2. At 12 hours after a single dose, the concentration of ensartinib was 9.0× higher in the skin than in the plasma.
Patient Characteristics
As of February 15, 2017, 97 patients (37 in dose escalation and 60 in dose expansion) were enrolled across 13 sites in the United States (Figure 1). Baseline demographics are presented in Table 1. The median age was 56 (range: 21–83). Eighty (82%) patients had received at least one prior systemic therapy for advanced disease, including chemotherapy and ALK TKIs, while 58 (60%) patients had ≥2 previous lines of therapy. Thirty-five (36%) patients had brain metastases at baseline. Fourteen patients had not received any prior radiation, 10 patients had prior stereotactic radiosurgery (SRS), and 11 patients had prior WBRT. The majority (92%) of patients had NSCLC; in dose escalation, four patients had head and neck cancer, two had colorectal cancer and one patient each had small cell lung and breast cancer. Note that only one patient with leptomeningeal disease was enrolled as of the cutoff date and that patient discontinued drug due to an unrelated AE and was not evaluable for response. No further efficacy data for that patient will be presented.
Figure 1. CONSORT Diagram.
Clinical trial flow diagram that depicts the number of patients that were consented, received study therapy in both dose escalation and expansion, and evaluable for safety and response. The diagram also depicts the number of pharmacokinetic samples analyzed.
Table 1.
Patient Demographics and Clinical Characteristics
| Patients (%) | ALK-positive Evaluablea Patients (%) | |
|---|---|---|
| Characteristic | n=97 | n=60 |
| Sex − no. (%) | ||
| Male | 48 (49) | 28 (47) |
| Female | 49 (51) | 32 (53) |
| Age − no. (%) | ||
| Median | 56 | 55 |
| Range | 21 - 83 | 21 - 80 |
| Race − no. (%) | ||
| White | 74 (76) | 47 (78) |
| Black/African American | 5 (5) | 1 (2) |
| Asian | 13 (13) | 8 (13) |
| American Indian/Alaskan Native | 1 (1) | 0 |
| Other/Unknown | 4 (4) | 4 (7) |
| Tumor Type − no. (%) | ||
| NSCLC | 89 (92) | 60 (100) |
| Head and Neck | 4 (4) | 0 |
| Colorectal | 2 (2) | 0 |
| Small Cell | 1 (1) | 0 |
| Breast | 1 (1) | 0 |
| ECOG Performance Status − no. (%) | ||
| 0 | 31 (32) | 24 (40) |
| 1 | 66 (68) | 36 (60) |
| Smoking History − no. (%) | ||
| Current | 4 (4) | 2 (3) |
| Former | 38 (39) | 21 (35) |
| Never | 55 (57) | 37 (62) |
| No. of prior treatments − no. (%) | ||
| 0 | 17 (18) | 13 (22) |
| 1 | 22 (23) | 13 (22) |
| 2 | 21 (22) | 13 (22) |
| 3 | 10 (10) | 6 (10) |
| ≥ 4 | 27 (28) | 15 (25) |
| Prior ALK TKI Treatment − no. (%) | ||
| ALK TKI Naïve | 35 (36) | 15 (25) |
| Prior Crizotinib only | 41 (42) | 29 (48) |
| Prior Crizotinib and Ceritinib | 12 (12) | 8 (13) |
| Prior Crizotinib and Alectinib | 1 (1) | 1 (2) |
| Prior Crizotinib, Ceritinib, and Alectinib | 7 (7) | 6 (10) |
| Prior Crizotinib, Ceritinib, and Brigatinib | 1 (1) | 1 (2) |
| Positive for ALK genomic alterations − no. (%) | 79 (81) | 60 (100) |
| Brain Metastases – no. (%) | ||
| Both target and non-target lesions | 11 (11) | 9 (15) |
| Target lesions only | 8 (8) | 5 (8) |
| Non-target lesions only | 16 (16) | 15 (25) |
| Prior Radiation − no. (% CNS Patients) | n=35 | n=29 |
| None | 14 (40) | 12 (41) |
| Prior WBRT | 11 (31) | 9 (31) |
| Prior SRS | 10 (29) | 8 (28) |
Efficacy evaluable: Patients at ≥200 mg who completed 1 cycle of treatment and had a post-baseline response assessment
Adverse Events
Dose escalation proceeded according to Figure 1, where patients received 25-250 mg of ensartinib once daily. Two patients experienced DLTs. One patient at 200 mg had Grade 3 fluid overload and Grade 1 elevated troponin I, and another at 250 mg had Grade 3 erythematous rash. All DLTs resolved after holding treatment, and treatment was resumed in both patients at a lower dose level. Although 250 mg was tolerable, the recommended phase 2 dose of ensartinib was chosen to be 225 mg based on the higher frequency of Grade 3 rash observed at 250 mg without improvement in clinical activity. At the end of dose escalation, six of 10 patients in the 250 mg cohort experience some form of rash (2 had Grade 3 events), whereas two of the three patients in the 225 mg cohort experienced a rash (no Grade 3 events). When this decision was made, four patients had a partial response in the 250 mg cohort, while all three patients in the 225 mg had a partial response. An example of the rash is depicted in Supplemental Figure 1.
Treatment-related AEs, as reported by the investigator, occurred in 83 of 97 (86%) patients. The most common treatment-related AEs were rash (56%), nausea (36%), pruritus (28%), vomiting (26%), and fatigue (22%); the majority of these were Grade 1-2 (Table 2). Treatment-related Grade 3-4 AEs occurred in 22 of 97 patients (Table 2, 23%). The frequency and severity of nausea and vomiting were less when ensartinib was taken with food. In the 47 patients that received either 200 or 225 mg doses and fasted prior to taking ensartinib during cycle 1, 24 (38%) experienced nausea or vomiting during cycle 1 with five events being Grade 2. Of the 27 patients that received either 200 or 225 mg doses and took ensartinib with food during cycle 1, seven (26%) experienced nausea or vomiting and all events were Grade 1. All patients who received 250 mg doses were fasted and thus not included in the above analysis as to not skew the results.
Table 2.
Treatment-related adverse eventsa reported in ≥ 10% of patients (n=97)
| Adverse Event | All grades | Grade ≥3b |
|---|---|---|
| Rash | 54 (56%) | 12 (12%) |
| Nausea | 35 (36%) | 1 (1%) |
| Pruritus | 27 (28%) | 5 (5%) |
| Vomiting | 25 (26%) | 1 (1%) |
| Fatigue | 21 (22%) | 2 (2%) |
| Decreased Appetite | 18 (19%) | 1 (1%) |
| Edema | 15 (15%) | 1 (1%) |
| Dry Skin | 14 (14%) | 1 (1%) |
| Elevated aspartate aminotransferase | 12 (12%) | 1 (1%) |
| Constipation | 11 (11%) | 0 |
| Diarrhea | 11 (11%) | 0 |
As reported by the investigator.
Other related grade 3 events reported were: lymphocytopenia (n=3), dehydration (n=1), anemia (n=1), dizziness (n=1), hyponatremia (n=1), burning sensation (n=1), hypertension (n=1), extremity pain (n=1), urinary tract infection (n=1). One grade 4 event, thrombotic microangiopathy was reported (n=1).
Fourteen patients (14%; 14/97) required at least one dose reduction and fifteen patients (15%; 15/97) required at least one dose interruption due to an ensartinib-related toxicity. Of the 64 patients that received 225 mg doses of ensartinib, 16 (25%) required at least one dose reduction and 13 (20%) required at least one dose interruption due to a treatment-related toxicity. Ensartinib was permanently discontinued in five patients (5.2%) due to a toxicity considered related by the investigator: thrombotic microangiopathy (n=1), hyperbilirubinemia (n=1), and rash (n=3). Five patients died (n=3, respiratory failure; n=1, disease progression; n=1 stroke) while on study, though no deaths were considered by the sponsor to be related to ensartinib.
Pharmacokinetics
PK data were obtained from 36 patients in dose escalation and 28 in dose expansion. Under a fasted state, the mean day 22 Cmax and area under the curve (AUC) increased dose proportionally between 50-200 mg, slightly more than dose proportionally from 200-225 mg, and significantly more than dose proportionally from 225-250 mg (AUC increased by 36% with an 11% increase in dose). Supplemental Figure 2 shows the mean concentration-time curves for patients at 225 mg on days 1 and 22. For fasted patients, the mean Cmax and AUC on day 22 are 2.3- and 3.2-fold higher, respectively, than those on day 1, suggesting significant accumulation. The key PK parameters (Supplemental Table 3) at the RP2D of 225 mg show that food (consumed within 30 minutes after taking ensartinib) has minimal impact on the absorption of ensartinib.
Efficacy
Tumor Response
Ninety-seven patients were enrolled on study, of whom 12 were treated at doses <200 mg, 11 were ALK-negative, eight (two with clinical progression, two were recently enrolled in dose expansion, one requested to discontinue ensartinib, and three unrelated deaths before follow-up scans) had not had their first post-baseline imaging, five discontinued drug prior to 28 days due to unrelated AEs, and one patient was determined ineligible after receiving the first dose. The patients included in the efficacy evaluable group were those patients with at least one post-baseline response assessment and received ≥200 mg doses of ensartinib. A range of doses was chosen to include those patients that were treated at the RP2D (i.e., 225 mg), those who received the maximum evaluated dose of 250 mg, and those who received 200 mg to demonstrate that clinical activity was still observed at the dose level corresponding to the first dose level reduction from the RP2D.
For the 60 evaluable ALK-positive patients, 36 patients had a partial response (PR), a RR of 60% (95% confidence interval [CI], 47.4−71.4); 13 achieved stable disease (SD) after at least 2 cycles of treatment, a disease control rate (DCR) of 81.7%, and 11 had progressive disease (PD) as best response. Figure 2 shows that tumor regression occurred in a majority (80.0%) of patients. Of the 15 ALK TKI-naïve patients, 12 had a PR, a RR of 80.0% (95% CI, 54.8−93.0), and one had SD, a DCR of 86.7%. Interestingly, the two ALK TKI-naïve patients with PD were FISH-positive via local testing, but negative when analyzed using NGS. Among the 29 patients with crizotinib as their only prior ALK TKI, 20 achieved a PR, a RR of 69.0% (95% CI, 50.8−82.7), and eight had SD, a 96.6% DCR. For those with prior crizotinib and at least one second-generation ALK TKI (n=16), four had a PR, a RR of 25% (95% CI, 10.2−49.5), and four had SD, a 50.0% DCR. A waterfall plot showing best tumor response for this cohort is included in Supplemental Figure 3, which is color coded to represent which second-generation ALK TKIs that patient received. The median (range) of washout from prior ALK TKI therapy for the 24 responders that had at least one prior ALK TKI was 25 days (5 – 721 days).
Figure 2. Waterfall plot of best systemic response.
Best percentage change from baseline in sum of target lesions is presented for the ALK-positive evaluable patients at ≥200 mg enrolled on study. Dashed lines are RECIST v1.1 criteria for partial response and progressive disease. Thirty-six patients (of 60) had a partial response and 80% had tumor regression. The navy bars are those patients that were ALK TKI-naïve, while the yellow bars represent those patients that had prior crizotinib therapy only, and the light blue bars represent those patients that had prior crizotinib and a second-generation ALK TKI. *Denotes those patients with progressive disease as the best overall response. >Denotes patients still on study at the time of data cutoff. (Note: Two patients had incomplete follow-up scans, therefore a change in tumor size is not available.)
In the 14 patients with baseline CNS target lesions, two achieved complete intracranial response (both had not received prior radiation), and seven had an intracranial PR (five had not received prior radiation and two had received prior WBRT), a RR of 64.3% (95% CI, 38.8−83.7). Additionally, four patients exhibited intracranial SD (one without prior radiation and three with prior SRS), a 92.9% intracranial DCR. Figure 3 shows that intracranial tumor regression occurred in a majority (78.6%) of these patients.
Figure 3. Waterfall plot of best CNS response.
Best intracranial percentage change from baseline in target CNS lesions is presented for the ALK-positive evaluable patients at doses ≥200 mg enrolled on study. Dashed lines indicate RECIST v1.1 cut-offs for partial response and progressive disease. Of the 14 patients with target CNS lesions, two complete responses were observed, seven had a partial response, and four had stable disease. The navy bars are those patients that were ALK TKI-naïve, while the yellow bars represent those patients that had prior crizotinib therapy only, and the light blue bars represent those patients that had prior crizotinib and a second-generation ALK TKI. *Denotes those patients with progressive disease as the best intracranial response. >Denotes patients still on study at the time of data cutoff.
Progression-free Survival and Duration of Response
The overall median PFS for the ALK-positive evaluable patients was 9.2 months (Figure 4A; 95% CI, 5.6−11.7). In the ALK TKI-naïve patients, the median PFS was 26.2 months (Figure 4B; 95% CI, 9.2−Not Estimable). Of the patients with prior crizotinib only, the median PFS was 9.0 months (Figure 4B; 95% CI, 5.6−11.7). Within the subgroup that received prior crizotinib and a second-generation ALK TKI, the median PFS was 1.9 months (Figure 4B; 95% CI, 1.7−5.7).
Figure 4. Progression-free survival curves.
Kaplan-Meier estimate of progression-free survival (PFS) with 95% confidence intervals for all ALK-positive, evaluable NSCLC patients that received ≥200 mg of ensartinib, where the median PFS was 9.2 months (A). Kaplan-Meier estimates of PFS are also shown for those ALK-positive, evaluable patients who were ALK TKI-naïve (red line), received prior crizotinib only (green line), and received prior crizotinib and a 2nd generation inhibitor (blue line), where the median PFS for those groups was 26.2 months, 9.0 months, and 1.9 months, respectively (B).
The median DOR for ALK-positive evaluable patients (n=35) at data cutoff was 12.8 months (95% CI, 5.6−24.4). Note that one responding patient was not included since the patient had not yet had a confirmatory scan. The median DOR for ALK TKI naïve patients (n=12) was 24.4 months (95% CI, 7.6−Not Estimable). Of those with prior crizotinib only (n=19), the median DOR was 7.4 months (95% CI, 3.7−12.9). In the subgroup treated with crizotinib and a second-generation ALK TKI (n=4), the median DOR was 4.4 months (95% CI, 0.4−Not Estimable). Among the responding ALK-positive evaluable patients at doses ≥200 mg with CNS target lesions at baseline (n=9), the median intracranial DOR was 5.7 months, ranging from 0.9 to 21 months.
DISCUSSION
Ensartinib demonstrated clinical activity with high RR and DCR in patients with ALK-positive NSCLC. Ensartinib was not only effective in patients who were ALK TKI-naïve (RR=80%), but also in patients with prior crizotinib as their only previous ALK TKI (RR=69%). Encouraging efficacy was also observed in half of the patients who received a second-generation ALK TKI post crizotinib (RR=25%, DCR=50%). The CNS activity of ensartinib is also notable, given that 64.3% of NSCLC patients with CNS target lesions at baseline treated at doses ≥200 mg achieved an intracranial response. Moreover, the median DOR in the CNS at data cutoff was 5.7 months (with five of nine patients still responding), which is important considering that the CNS is a common site of disease progression while on crizotinib.14,15
Overall, ensartinib was well tolerated, indicated by the low proportion of patients discontinuing the study due to an unacceptable drug-related toxicity and by most related AEs being Grade 1-2. The most common toxicity associated with ensartinib was rash, which was generally managed with the use of topical medications and, for more severe toxicity, holding the dose until improvement and then resuming treatment at a reduced dose. The mechanism of rash related to ensartinib is unclear. But it has been reported that ALK is expressed in the epidermis of normal skin and that crizotinib inhibits growth of normal human epidermal keratinocytes in vitro.16,17 The distribution study in rodents showed that the concentration of ensartinib in the skin was 9.0× higher than in the plasma 12 hours after a single dose (Supplemental Table 2). In comparison, alectinib was 5.7× higher in the skin than in the plasma.18 Taken together, these could help explain why ensartinib resulted in a higher frequency of rash compared to other ALK TKIs. This hypothesis is preliminary, however, and future studies are needed to fully characterize this mechanism.
Other second- and third-generation ALK inhibitors have entered the clinic and represent treatment options for patients who have progressed on crizotinib. Ceritinib, alectinib, and brigatinib have shown robust activity in ALK-positive NSCLC patients who have progressed or are intolerant to crizotinib, thus leading to approval in several countries, including the United States. The ASCEND-4 trial reported a RR of 73%, intracranial response of 57%, and median PFS of 16.6 months for first line ceritinib.19 Additionally, 38% of patients experienced a SAE, with 10% of patients discontinuing therapy and 66% of patients with a dose interruption.19 The ALEX trial reported an 82% RR, 81% intracranial response, and median PFS of 25.7 months with first line alectinib.20 Twenty-eight percent of patients had a SAE, while AEs leading to dose reduction, interruption, or discontinuation were reported in 16%, 19%, and 11%, respectively.20 In the crizotinib-refractory population, brigatinib achieved a 54% RR, with a median PFS of 12.9 months.21
Currently, there are no randomized studies that compare next generation ALK TKIs in the setting of crizotinib resistance; therefore, the ability to directly compare these agents is limited. However, the preliminary antitumor activity of ensartinib appears to be similar to that reported with the other second-generation ALK TKIs.10,22 Additionally, ensartinib demonstrated in vitro activity against all ALK variants and a number of ALK mutants. Ensartinib may have other potential advantages as well, particularly with respect to toxicity. In terms of drug-related gastrointestinal toxicities, diarrhea was reported in 11% of patients treated with ensartinib, whereas, in some studies, 41% and 75% of patients who received brigatinib or ceritinib, respectively, experienced diarrhea.10,23 Additionally, vomiting occurred in a majority of patients treated with ceritinib, but was observed in only a quarter of the patients with ensartinib, which was less frequent and severe when taken with food (i.e., meal consumed within 30 minutes of taking ensartinib) without affecting PK (see PK parameters in Supplemental Table 3). Furthermore, the frequency and severity of elevated aminotransferases reported as treatment-related AEs was low with ensartinib, and lower than what has been observed to date with other next generation ALK inhibitors.10,23–25 Lastly, the frequency and severity of early pulmonary toxicities that have been reported with brigatinib and ceritinib have not been observed with ensartinib.10,23 Taken together, ensartinib appears to have a different toxicity profile from the other second-generation ALK TKIs, with most Grade 3 events being rash and pruritus.
Although there are other next generation ALK TKIs currently approved or in development, there is a need for multiple agents. While the RRs and CNS activity appear to be similar, these agents have different profiles with respect to toxicity and activity against different ALK mutations. It has been shown that patients can respond to other ALK TKIs, including ensartinib, after progressing on a prior ALK TKI. The best way to sequence these agents has yet to be determined and will be evaluated in upcoming trials.
It should be noted that there are some limitations to the current study. This is an ongoing study, with enrollment continuing and 23 of the 60 efficacy evaluable patients still on study. Additionally, as it was not a comparative trial, caution must be exercised in making comparisons with other ALK TKI trials.
In summary, ensartinib was generally well tolerated and demonstrated good clinical activity in patients with prior crizotinib, in patients who were ALK TKI-naïve, and in patients with CNS target lesions at baseline. Based on the findings from this trial, a randomized phase III study, eXalt3, comparing ensartinib to crizotinib in advanced ALK-positive, TKI-naive NSCLC patients, was started in June 2016 (NCT02767804).
Supplementary Material
Statement of Relevance.
The anaplastic lymphoma kinase (ALK) has become a validated therapeutic target in patients with non-small cell lung cancer (NSCLC), with approved tyrosine kinase inhibitors (TKIs) in both the first- and second-line settings. Despite experiencing initial responses, a majority of patients will become resistant and progress. Mechanisms of resistance include secondary ALK mutations, amplification of ALK, and activation of by-pass signaling networks. Additionally, a common site of disease progression is within the central nervous system (CNS). Thus, ensartinib was developed to improve on the target specificity and binding, as well as improve activity in the CNS. This first-in-human phase I/II study evaluated the safety and efficacy of ensartinib in advanced ALK-positive NSCLC. Ensartinib was generally well tolerated, with rash being the most commonly observed toxicity, and demonstrated good clinical activity in patients who had received a prior ALK TKI, who were ALK TKI-naïve, and those patients with CNS disease.
Acknowledgments
The authors would like to thank the patients and their families for participation in this study, as well as the investigators and study staff at participating sites.
Financial Support: Christine M. Lovly was supported by a V Foundation Scholar-in-Training Award, an AACR-Genentech Career Development Award, a Damon Runyon Clinical Investigator Award, and a LUNGevity Career Development Award.
Footnotes
Conflicts of Interest: HAW is a consultant for Peregrine Pharmaceuticals, Helsinn Therapeutics, ACEA Biosciences, and Pfizer, has received an honorarium or travel accommodations from Peregrine Pharmaceuticals, Biocon, ACEA Biosciences, Helsinn Therapeutics, Genentech/Roche, Pfizer, and Novartis, and has research support from Genentech/Roche, Pfizer, Lilly, Celgene, AstraZeneca/MedImmune, Exelixis, Novartis, Clovis Oncology, Xcovery, Bristol-Myers Squibb, Gilead Sciences, Pharmacyclics, and ACEA Biosciences. KLR is a consultant for Amgen, Boehringer Ingelheim, ARIAD, Astellas Pharma, Nektar, and Euclises. GB is a consultant for Bristol-Myers Squibb, Bayer, Celgene, Clovis Oncology, Abbvie, ARIAD, AstraZeneca, and Merck, has received an honorarium from Abbvie/Genentech, Bayer, Bristol-Myers Squibb, and Celgene, and has research funding from Merck, AstraZeneca, Celgene, Abbvie, Genentech, Xcovery, Novartis, Bayer Schering Pharma, Bristol-Myers Squibb, and GlaxoSmithKline. TAL is a consultant for ARIAD, Genentech/Roche, and Takeda, and has received travel accommodations from Genentech/Roche, Xcovery, and Takeda. BG is a consultant for AstraZeneca, ARIAD, and Genentech, is part of a speakers’ bureau for Genentech and Lilly, and has research funding from Ignyta, AstraZeneca, and Xcovery. RES is a consultant for Amgen, Seattle Genetics, Peregrine Pharmaceuticals, ARIAD, Genentech/Roche, AstraZeneca, and Celldex, has received an honorarium or travel accommodations from AstraZeneca and Five Prime Therapeutics, and has research funding from Merck. JWN is a consultant for Clovis Oncology, Boehringer Ingelheim, ARMO BioSciences, Nektar, ARIAD/Takeda, and CARET, and has research funding from Genentech/Roche, Merck, ArQule, Novartis, Boehringer Ingelheim, Nektar, and Exelixis. JPG is employed at Novella Clinical. GD is a consultant, has stock or other ownership, and has received travel accommodations from Xcovery and Tyrogenex, and is part of an intellectual property agreement albeit without financial interests with Wyeth/Pfizer. KH is employed, has stock or other ownership, and has received travel accommodations from Xcovery and Tyrogenex. CL is employed in a leadership role and has stock or other ownership in Xcovery and Tyrogenex. JJG is employed with Xcovery and has stock or other ownership with Pfizer. AH is employed at Xcovery. CML is a consultant for ARIAD, Clovis Oncology, Genoptix, and Novartis, has research funding from AstraZeneca and Novartis, and has received an honorarium or travel accommodations from Novartis, Sequenom, Qiagen, Pfizer, and NCCN. LH is a consultant for Bristol-Myers Squibb, Xcovery, Genentech, Abbvie, Merck, and AstraZeneca. All remaining authors have no conflicts to disclose.
References
- 1.Soda M, Choi YL, Enomoto M, Takada S, Yamashita Y, Ishikawa S, et al. Identification of the transforming EML4-ALK fusion gene in non-small-cell lung cancer. Nature. 2007;448:561–6. doi: 10.1038/nature05945. [DOI] [PubMed] [Google Scholar]
- 2.Koivunen JP, Mermel C, Zejnullahu K, Murphy C, Lifshits E, Holmes AJ, et al. EML4-ALK fusion gene and efficacy of an ALK kinase inhibitor in lung cancer. Clin Cancer Res. 2008;14:4275–83. doi: 10.1158/1078-0432.CCR-08-0168. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Kris MG, Johnson BE, Berry LD, Kwiatkowski DJ, Iafrate AJ, Wistuba II, et al. Using multiplexed assays of oncogenic drivers in lung cancers to select targeted drugs. JAMA. 2014;311:1998–2006. doi: 10.1001/jama.2014.3741. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Takeuchi K, Choi YL, Togashi Y, Soda M, Hatano S, Inamura K, et al. KIF5B-ALK, a novel fusion oncokinase identified by an immunohistochemistry-based diagnostic system for ALK-positive lung cancer. Clin Cancer Res. 2009;15:3143–9. doi: 10.1158/1078-0432.CCR-08-3248. [DOI] [PubMed] [Google Scholar]
- 5.Lin E, Li L, Guan Y, Soriano R, Rivers CS, Mohan S, et al. Exon array profiling detects EML4-ALK fusion in breast, colorectal, and non-small cell lung cancers. Molecular cancer research: MCR. 2009;7:1466–76. doi: 10.1158/1541-7786.MCR-08-0522. [DOI] [PubMed] [Google Scholar]
- 6.Shaw AT, Kim DW, Nakagawa K, Seto T, Crino L, Ahn MJ, et al. Crizotinib versus chemotherapy in advanced ALK-positive lung cancer. N Engl J Med. 2013;368:2385–94. doi: 10.1056/NEJMoa1214886. [DOI] [PubMed] [Google Scholar]
- 7.Solomon BJ, Mok T, Kim DW, Wu YL, Nakagawa K, Mekhail T, et al. First-line crizotinib versus chemotherapy in ALK-positive lung cancer. N Engl J Med. 2014;371:2167–77. doi: 10.1056/NEJMoa1408440. [DOI] [PubMed] [Google Scholar]
- 8.Lovly CM, McDonald NT, Chen H, Ortiz-Cuaran S, Heukamp LC, Yan Y, et al. Rationale for co-targeting IGF-1R and ALK in ALK fusion-positive lung cancer. Nat Med. 2014;20:1027–34. doi: 10.1038/nm.3667. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Gainor JF, Dardaei L, Yoda S, Friboulet L, Leshchiner I, Katayama R, et al. Molecular Mechanisms of Resistance to First- and Second-Generation ALK Inhibitors in ALK-Rearranged Lung Cancer. Cancer discovery. 2016;6:1118–33. doi: 10.1158/2159-8290.CD-16-0596. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Shaw AT, Kim DW, Mehra R, Tan DSW, Felip E, Chow LQM, et al. Ceritinib in ALK-Rearranged Non-Small-Cell Lung Cancer. New Engl J Med. 2014;370:1189–97. doi: 10.1056/NEJMoa1311107. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Lovly CM, Heuckmann JM, de Stanchina E, Chen H, Thomas RK, Liang C, et al. Insights into ALK-driven cancers revealed through development of novel ALK tyrosine kinase inhibitors. Cancer Res. 2011;71:4920–31. doi: 10.1158/0008-5472.CAN-10-3879. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Anastassiadis T, Deacon SW, Devarajan K, Ma H, Peterson JR. Comprehensive assay of kinase catalytic activity reveals features of kinase inhibitor selectivity. Nat Biotechnol. 2011;29:1039–45. doi: 10.1038/nbt.2017. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Eisenhauer EA, Therasse P, Bogaerts J, Schwartz LH, Sargent D, Ford R, et al. New response evaluation criteria in solid tumours: revised RECIST guideline (version 1.1) Eur J Cancer. 2009;45:228–47. doi: 10.1016/j.ejca.2008.10.026. [DOI] [PubMed] [Google Scholar]
- 14.Costa DB, Kobayashi S, Pandya SS, Yeo W-L, Shen Z, Tan W, et al. CSF Concentration of the Anaplastic Lymphoma Kinase Inhibitor Crizotinib. Journal of Clinical Oncology. 2011;29:e443–e5. doi: 10.1200/JCO.2010.34.1313. [DOI] [PubMed] [Google Scholar]
- 15.Costa DB, Shaw AT, Ou SHI, Solomon BJ, Riely GJ, Ahn MJ, et al. Clinical Experience With Crizotinib in Patients With Advanced ALK-Rearranged Non-Small-Cell Lung Cancer and Brain Metastases. Journal of Clinical Oncology. 2015;33:1881–U41. doi: 10.1200/JCO.2014.59.0539. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Ning H, Mitsui H, Wang CQ, Suarez-Farinas M, Gonzalez J, Shah KR, et al. Identification of anaplastic lymphoma kinase as a potential therapeutic target in Basal Cell Carcinoma. Oncotarget. 2013;4:2237–48. doi: 10.18632/oncotarget.1357. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 17.Ponten F, Jirstrom K, Uhlen M. The Human Protein Atlas–a tool for pathology. The Journal of pathology. 2008;216:387–93. doi: 10.1002/path.2440. [DOI] [PubMed] [Google Scholar]
- 18.Leighton JK. CENTER FOR DRUG EVALUATION AND RESEARCH: Alectinib. FDA; 2015.
- 19.Soria JC, Tan DS, Chiari R, Wu YL, Paz-Ares L, Wolf J, et al. First-line ceritinib versus platinum-based chemotherapy in advanced ALK-rearranged non-small-cell lung cancer (ASCEND-4): a randomised, open-label, phase 3 study. Lancet. 2017;389:917–29. doi: 10.1016/S0140-6736(17)30123-X. [DOI] [PubMed] [Google Scholar]
- 20.Peters S, Camidge DR, Shaw AT, Gadgeel S, Ahn JS, Kim DW, et al. Alectinib versus Crizotinib in Untreated ALK-Positive Non-Small-Cell Lung Cancer. N Engl J Med. 2017 doi: 10.1056/NEJMoa1704795. [DOI] [PubMed] [Google Scholar]
- 21.Kim DW, Tiseo M, Ahn MJ, Reckamp KL, Hansen KH, Kim SW, et al. Brigatinib in Patients With Crizotinib-Refractory Anaplastic Lymphoma Kinase-Positive Non-Small-Cell Lung Cancer: A Randomized, Multicenter Phase II Trial. J Clin Oncol. 2017 doi: 10.1200/JCO.2016.71.5904. JCO2016715904. [DOI] [PubMed] [Google Scholar]
- 22.Kim DW, Mehra R, Tan DS, Felip E, Chow LQ, Camidge DR, et al. Activity and safety of ceritinib in patients with ALK-rearranged non-small-cell lung cancer (ASCEND-1): updated results from the multicentre, open-label, phase 1 trial. Lancet Oncol. 2016;17:452–63. doi: 10.1016/S1470-2045(15)00614-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Gettinger SN, Bazhenova LA, Langer CJ, Salgia R, Gold KA, Rosell R, et al. Activity and safety of brigatinib in ALK-rearranged non-small-cell lung cancer and other malignancies: a single-arm, open-label, phase 1/2 trial. Lancet Oncol. 2016;17:1683–96. doi: 10.1016/S1470-2045(16)30392-8. [DOI] [PubMed] [Google Scholar]
- 24.Ou SH, Ahn JS, De Petris L, Govindan R, Yang JC, Hughes B, et al. Alectinib in Crizotinib-Refractory ALK-Rearranged Non-Small-Cell Lung Cancer: A Phase II Global Study. J Clin Oncol. 2016;34:661–8. doi: 10.1200/jco.2015.63.9443. [DOI] [PubMed] [Google Scholar]
- 25.Seto T, Kiura K, Nishio M, Nakagawa K, Maemondo M, Inoue A, et al. CH5424802 (RO5424802) for patients with ALK-rearranged advanced non-small-cell lung cancer (AF-001JP study): a single-arm, open-label, phase 1-2 study. Lancet Oncol. 2013;14:590–8. doi: 10.1016/S1470-2045(13)70142-6. [DOI] [PubMed] [Google Scholar]
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