Statistical considerations in clinical trial design with event-free survival as the primary efficacy endpoint

In late-phase confirmatory clinical trials in the oncology field, time-to-event (TTE) endpoints are commonly used as primary endpoints for establishing the efficacy of investigational therapies. Among these TTE endpoints, overall survival (OS) is always considered as the gold standard. However, OS data can take years to mature, and its use for measurement of efficacy can be confounded by the use of post-treatment rescue therapies or supportive care. Therefore, to accelerate the development process and better characterize the treatment effect of new investigational therapies, other TTE endpoints such as progression-free survival and event-free survival (EFS) are applied as primary efficacy endpoints in some confirmatory trials, either as a surrogate for OS or as a direct measure of clinical benefits. For evaluating novel treatments for acute myeloid leukemia, EFS has been gradually recognized as a direct measure of clinical benefits. However, the application of an EFS endpoint is still controversial mainly due to the debate surrounding definition of treatment failure (TF) events. In this article, we investigate the EFS endpoint with the most conservative definition for the timing of TF, which is Day 1 since randomization. Specifically, the corresponding non-proportional hazard pattern of the EFS endpoint is investigated with both analytical and numerical approaches.

Mutant Isocitrate Dehydrogenase 1 Inhibitor Ivosidenib in Combination With Azacitidine for Newly Diagnosed Acute Myeloid Leukemia

PURPOSE

Ivosidenib is an oral inhibitor of the mutant isocitrate dehydrogenase 1 (IDH1) enzyme, approved for treatment of IDH1-mutant (mIDH1) acute myeloid leukemia (AML). Preclinical work suggested that addition of azacitidine to ivosidenib enhances mIDH1 inhibition-related differentiation and apoptosis.

PATIENTS AND METHODS

This was an open-label, multicenter, phase Ib trial comprising dose-finding and expansion stages to evaluate safety and efficacy of combining oral ivosidenib 500 mg once daily continuously with subcutaneous azacitidine 75 mg/m² on days 1-7 in 28-day cycles in patients with newly diagnosed mIDH1 AML ineligible for intensive induction chemotherapy (ClinicalTrials.gov identifier: NCT02677922).

RESULTS

Twenty-three patients received ivosidenib plus azacitidine (median age, 76 years; range, 61-88 years). Treatment-related grade ≥ 3 adverse events occurring in > 10% of patients were neutropenia (22%), anemia (13%), thrombocytopenia (13%), and electrocardiogram QT prolongation (13%). Adverse events of special interest included all-grade IDH differentiation syndrome (17%), all-grade electrocardiogram QT prolongation (26%), and grade ≥ 3 leukocytosis (9%). Median treatment duration was 15.1 months (range, 0.3-32.2 months); 10 patients remained on treatment as of February 19, 2019. The overall response rate was 78.3% (18/23 patients; 95% CI, 56.3% to 92.5%), and the complete remission rate was 60.9% (14/23 patients; 95% CI, 38.5% to 80.3%). With median follow-up of 16 months, median duration of response in responders had not been reached. The 12-month survival estimate was 82.0% (95% CI, 58.8% to 92.8%). mIDH1 clearance in bone marrow mononuclear cells by BEAMing (beads, emulsion, amplification, magnetics) digital polymerase chain reaction was seen in 10/14 patients (71.4%) achieving complete remission.

CONCLUSION

Ivosidenib plus azacitidine was well tolerated, with an expected safety profile consistent with monotherapy with each agent. Responses were deep and durable, with most complete responders achieving mIDH1 mutation clearance.

Phase 1 Single- and Multiple-Ascending-Dose Randomized Studies of the Safety, Pharmacokinetics, and Pharmacodynamics of AG-348, a First-in-Class Allosteric Activator of Pyruvate Kinase R, in Healthy Volunteers

Pyruvate kinase deficiency is a chronic hemolytic anemia caused by mutations in PK-R, a key glycolytic enzyme in erythrocytes. These 2 phase 1 randomized, placebo-controlled, double-blind healthy-volunteer studies assessed the safety, tolerability, and pharmacokinetics/pharmacodynamics of AG-348, a first-in-class allosteric PK-R activator. Twelve sequential cohorts were randomized 2:6 to receive oral placebo or AG-348, respectively, as a single dose (30-2500 mg) in the single-ascending-dose (SAD) study (ClinicalTrials.gov: NCT02108106) or 15-700 mg every 12 hours or 120 mg every 24 hours, for 14 days in the multiple-ascending-dose (MAD) study (ClinicalTrials.gov: NCT02149966). All 48 subjects completed the fasted SAD part; 44 of 48 completed the MAD (2 discontinued because of adverse events [AEs], 2 withdrew consent). The most common treatment-related AEs in AG-348-treated subjects were headache (16.7% [SAD] and 13.9% [MAD]) and nausea (13.9%, both studies). AE frequency increased at AG-348 doses ≥ 700 mg (SAD) and at 700 mg every 12 hours (MAD); 1 grade ≥ 3 AE occurred in the latter cohort. Pharmacokinetics were favorable with low variability. Dose-dependent changes in blood glycolytic intermediates consistent with glycolytic pathway activation were observed at all MAD doses, supporting future trials investigating the potential of AG-348 for treating PK deficiency or other anemias.

Durable Remissions with Ivosidenib in IDH1-Mutated Relapsed or Refractory AML

BACKGROUND

Mutations in the gene encoding isocitrate dehydrogenase 1 ( IDH1) occur in 6 to 10% of patients with acute myeloid leukemia (AML). Ivosidenib (AG-120) is an oral, targeted, small-molecule inhibitor of mutant IDH1.

METHODS

We conducted a phase 1 dose-escalation and dose-expansion study of ivosidenib monotherapy in IDH1-mutated AML. Safety and efficacy were assessed in all treated patients. The primary efficacy population included patients with relapsed or refractory AML receiving 500 mg of ivosidenib daily with at least 6 months of follow-up.

RESULTS

Overall, 258 patients received ivosidenib and had safety outcomes assessed. Among patients with relapsed or refractory AML (179 patients), treatment-related adverse events of grade 3 or higher that occurred in at least 3 patients were prolongation of the QT interval (in 7.8% of the patients), the IDH differentiation syndrome (in 3.9%), anemia (in 2.2%), thrombocytopenia or a decrease in the platelet count (in 3.4%), and leukocytosis (in 1.7%). In the primary efficacy population (125 patients), the rate of complete remission or complete remission with partial hematologic recovery was 30.4% (95% confidence interval [CI], 22.5 to 39.3), the rate of complete remission was 21.6% (95% CI, 14.7 to 29.8), and the overall response rate was 41.6% (95% CI, 32.9 to 50.8). The median durations of these responses were 8.2 months (95% CI, 5.5 to 12.0), 9.3 months (95% CI, 5.6 to 18.3), and 6.5 months (95% CI, 4.6 to 9.3), respectively. Transfusion independence was attained in 29 of 84 patients (35%), and patients who had a response had fewer infections and febrile neutropenia episodes than those who did not have a response. Among 34 patients who had a complete remission or complete remission with partial hematologic recovery, 7 (21%) had no residual detectable IDH1 mutations on digital polymerase-chain-reaction assay. No preexisting co-occurring single gene mutation predicted clinical response or resistance to treatment.

CONCLUSIONS

In patients with advanced IDH1-mutated relapsed or refractory AML, ivosidenib at a dose of 500 mg daily was associated with a low frequency of grade 3 or higher treatment-related adverse events and with transfusion independence, durable remissions, and molecular remissions in some patients with complete remission. (Funded by Agios Pharmaceuticals; ClinicalTrials.gov number, NCT02074839 .).

Ceritinib in ALK-rearranged non-small-cell lung cancer

BACKGROUND

Non-small-cell lung cancer (NSCLC) harboring the anaplastic lymphoma kinase gene (ALK) rearrangement is sensitive to the ALK inhibitor crizotinib, but resistance invariably develops. Ceritinib (LDK378) is a new ALK inhibitor that has shown greater antitumor potency than crizotinib in preclinical studies.

METHODS

In this phase 1 study, we administered oral ceritinib in doses of 50 to 750 mg once daily to patients with advanced cancers harboring genetic alterations in ALK. In an expansion phase of the study, patients received the maximum tolerated dose. Patients were assessed to determine the safety, pharmacokinetic properties, and antitumor activity of ceritinib. Tumor biopsies were performed before ceritinib treatment to identify resistance mutations in ALK in a group of patients with NSCLC who had had disease progression during treatment with crizotinib.

RESULTS

A total of 59 patients were enrolled in the dose-escalation phase. The maximum tolerated dose of ceritinib was 750 mg once daily; dose-limiting toxic events included diarrhea, vomiting, dehydration, elevated aminotransferase levels, and hypophosphatemia. This phase was followed by an expansion phase, in which an additional 71 patients were treated, for a total of 130 patients overall. Among 114 patients with NSCLC who received at least 400 mg of ceritinib per day, the overall response rate was 58% (95% confidence interval [CI], 48 to 67). Among 80 patients who had received crizotinib previously, the response rate was 56% (95% CI, 45 to 67). Responses were observed in patients with various resistance mutations in ALK and in patients without detectable mutations. Among patients with NSCLC who received at least 400 mg of ceritinib per day, the median progression-free survival was 7.0 months (95% CI, 5.6 to 9.5).

CONCLUSIONS

Ceritinib was highly active in patients with advanced, ALK-rearranged NSCLC, including those who had had disease progression during crizotinib treatment, regardless of the presence of resistance mutations in ALK. (Funded by Novartis Pharmaceuticals and others; ClinicalTrials.gov number, NCT01283516.).

Clinical activity of the ALK inhibitor LDK378 in advanced, ALK-positive NSCLC

8010

Background: Lung cancers harboring anaplastic lymphoma kinase (ALK) gene rearrangements are sensitive to the tyrosine kinase inhibitor (TKI) crizotinib (CRZ), but invariably develop resistance. LDK378 is a novel, more potent ALK TKI than CRZ, with significant antitumor activity in preclinical models. Methods: In this multicenter phase I study, 131 patients (pts) with advanced malignancies harboring a genetic alteration in ALK, including 123 with ALK-rearranged (ALK+) NSCLC (as determined by FISH), were enrolled. LDK378 was administered orally at doses of 50–750 mg once daily. All pts were assessed for PK, response to therapy, and adverse events (AEs). In >20 pts with CRZ-resistant disease, tumor biopsy was performed before LDK378 treatment to identify CRZ resistance mutations. Results: As of November 8, 2012, 131 pts had been enrolled (38% male, median age 53 years), including 59 pts in the dose escalation phase, during which the MTD of 750 mg once daily was established, and 72 pts in an expanded cohort at the MTD. Among 88 evaluable NSCLC pts who received LDK378 at 400–750 mg daily, the overall response rate (ORR) was 70%, with 40 confirmed and 22 unconfirmed responses. In the subset of 64 CRZ-resistant pts, the ORR was 73%, with 31 confirmed and 16 unconfirmed responses. As of November 8, 2012 50% of pts with unconfirmed responses were ongoing. Responses were observed in pts with different CRZ resistance mutations as well as in pts without detectable mutation. Responses were also seen in pts with untreated CNS metastases. Among NSCLC pts with confirmed response, median duration of response (DOR) was 7.4 months (95% CI, 6.7 – NR), and 78% had a DOR of ≥6 months. In all 123 NSCLC pts, median PFS was 8.6 months (95% CI, 4.3 – 19.3). The most common AEs were nausea (72%), diarrhea (69%), vomiting (50%), and fatigue (31%). The most common Grade 3/4 AEs were ALT elevation (12%), diarrhea (7%), and AST elevation (6%). Conclusions: LDK378 induces durable responses in the majority of pts with advanced, ALK+ NSCLC, including CRZ-resistant pts with and without CRZ resistance mutations. These results suggest that more potent ALK inhibition by LDK378 represents a highly efficacious treatment strategy for ALK+ pts, particularly those who relapse on CRZ. Clinical trial information: NCT01283516.

First-in-human phase I study of the ALK inhibitor LDK378 in advanced solid tumors

3007

Background: LDK378 is a novel, potent and selective small molecule anaplastic lymphoma kinase (ALK) inhibitor (IC50 0.00015 μM), that does not inhibit c-MET (IC50 3.2 μM). Tumor regression has been observed in ALK-driven NSCLC xenografts. A first-in-human, Phase I study is being conducted to determine the MTD and safety profile in patients (pts) with tumors with ALK rearrangement, amplification or mutation. Other objectives were safety, PK and antitumor activity in pts with ALK-driven NSCLC, both naïve to ALK inhibitors and relapsed following previous ALK inhibitor treatment, and other ALK-positive cancers. Methods: Adult pts with advanced malignancies harboring a genetic alteration in ALK who progressed on standard therapy or for whom there was no effective therapy, were given once daily oral LDK378 on a continuous 21-day schedule. Dose escalation, starting at 50 mg/day, was guided by a Bayesian logistic regression model (BLRM) to determine the MTD. Results: At a January 5th 2012 cutoff,31 pts (primary site: lung 26 pts; breast 3 pts; other 2 pts; median age 52 years; 87% ECOG PS 0/1) were enrolled and received LDK378 at doses of 50–750 mg/day. Two dose limiting toxicities, Grade (Gr) 3 alanine aminotransferase elevation (1 pt), and Gr 3 hypophosphatemia (1 pt) occurred in 8 pts at a 400 mg dose level. BLRM allowed dose escalation, and there were no DLTs in 4 pts at 500 mg. Median duration of treatment with LDK378 was 7 weeks (range <1–22+). At the cutoff date, 13 (42%) pts discontinued treatment: 1 (3%) due to adverse events (AEs), and 12 (39%) due to disease progression; 18 (58%) pts were still on treatment. The most frequent AEs (all Gr) were nausea (45%), vomiting (36%), and diarrhea (29%). The most frequent Gr 3/4 AEs were diarrhea and dyspnea (2 pts [7%] each). At doses ≥400 mg steady state exposures exceeded efficacious exposures in xenograft models. Of 16 pts with available response data (RECIST, per investigator) there were 4/6 responses in crizotinib (CRZ)-treated pts, and 2/10 responses in CRZ-naïve pts, of whom 7 were treated below 400 mg. All responses were in NSCLC. Conclusions: Daily oral LDK378 is well tolerated up to 500 mg/day, and escalation continues at 750 mg/day. Preliminary responses have been seen in both CRZ-naïve and CRZ-relapsed pts.

108 A CRITICAL-SIZE CRANIOFACIAL BONE DEFECT MODEL IN THE YORKSHIRE PIG

Substantial and innovative developments in the field of bone tissue engineering have prompted increased demand for suitable pre-clinical large animal models. The pig has several advantages over other non-primate species, including availability, rapid growth, large litters, and similar anatomy and physiology to humans. These characteristics make them ideal models for research in diverse applications such as cardiovascular disease, pharmacological activity testing, and organ transplantation. There has been an increased interest in the use of swine as a model for bone healing and grafting techniques. Maxillofacial surgeons strive to develop the best therapy for large bone defects in the face resulting from tumour resection, congenital abnormalities, and traumatic injuries. Creating a model to study a critical-sized bone defect in the mandible, which does not spontaneously heal without clinical intervention, would be a method to test growth factors and synthetic bone graft therapies. However, the size of bone defect required to create this condition has not been ascertained. In the current study, we examined the in vivo healing response for 4, 8, and 16 weeks of surgically created bone defects in the posterior region of the pig mandible. Yorkshire barrows (n = 12) 6–7 months of age were used for the study. All animal experiments conformed to the University of Illinois Institutional Animal Care and Use Committee (IACUC) guidelines. Animals were maintained under general anaesthesia and transcortical, circular defects with diameters of 6, 10, 16, or 25 mm were created on both sides of the mandible. The presence and amount of calcified tissue was assessed using radiographs and dual energy x-ray absorptiometry (DEXA). Tissue morphology was examined using hard-tissue histological methods and a light microscope. Defect diameters of 6, 10, and 16 mm had completed healing or were in the process of healing within the 16-week timeframe of the study. Compared to controls, average percent differences in bone mineral density, in order of increasing defect size, were 0.62%, 28.1%, and 54.5%, respectively. In contrast, 25 mm diameter defects displayed limited collagenous tissue ingrowth, and the presence of calcified tissue was not detected, as indicated by radiographs and histological staining. As the defect size increased, the time required to heal was prolonged until a critical size was determined and normal bone was not completely regenerated. In conclusion, circular defects in the posterior region of the pig mandible with diameters equal or greater than 25 mm will result in limited healing without additional medical intervention and can be termed critical-sized defects. This porcine model will allow for the rapid development and testing of new approaches for the repair of damaged bone, which is especially prevalent in the craniofacial area. This work was partially supported by the Carle Foundation Hospital (#2007-04072) and the Illinois Regenerative Medicine Institute (IDPH #63080017).

Bleeding and perforation after outpatient colonoscopy and their risk factors in usual clinical practice

BACKGROUND & AIMS

The most widely quoted complication rates for colonoscopy are from case series performed by expert endoscopists. Our objectives were to evaluate the rates of bleeding, perforation, and death associated with outpatient colonoscopy and their risk factors in a population-based study.

METHODS

We identified all individuals 50 to 75 years old who underwent an outpatient colonoscopy during April 1, 2002, to March 31, 2003, in British Columbia, Alberta, Ontario, and Nova Scotia, Canada. Using administrative data, we identified all individuals who were admitted to hospital with bleeding or perforation within 30 days following the colonoscopy in each province. We calculated the pooled rates of bleeding and perforation from the 4 provinces. In Ontario, we abstracted the hospital charts of all deaths that occurred within 30 days following the procedure. We used generalized estimating equations models to evaluate factors associated with bleeding and perforation.

RESULTS

We identified 97,091 persons who had an outpatient colonoscopy. The pooled rates of colonoscopy-related bleeding and perforation were 1.64/1000 and 0.85/1000, respectively. The death rate was 0.074/1000 or approximately 1/14,000. Older age, male sex, having a polypectomy, and having the colonoscopy performed by a low-volume endoscopist were associated with increased odds of bleeding or perforation.

CONCLUSIONS

Although colonoscopy has established benefits for the detection of colorectal cancer and adenomatous polyps, the procedure is associated with risks of serious complications, including death. Older age, male sex, having a polypectomy, and having the procedure done by a low-volume endoscopist were independently associated with colonoscopy-related bleeding and perforation.

Anatomic studies of the circulation in the region of the vertebral end-plate in adult Greyhound dogs

In order to study the detailed arrangements of vascular terminations in the region of the vertebral end-plate in adult dogs, infusions of Japanese ink mixed with a suspension of barium sulfate were used to produce filling of the vascular terminations at the vertebral end-plates. Radiographs were made of the decalcified specimens. Photomicrographs were prepared from transparent sections embedded in celloidin. The distribution of the large veins within the vertebral bodies was found to be more complex than described earlier. Over the entire bone-disc interface there is a continuous capillary bed that is most dense in the area related to the nucleus pulposus. These vessels drain either into the subchondral postcapillary venous network or directly into the veins of the marrow spaces in the vertebral bodies.

Analysis of the type of collagen present in osteoarthritic human cartilage

Abnormal synthesis of type I collagen by fibrocartilage has been suggested as a mechanism involved in degenerative arthritis. Samples of normal and osteoarthritic adult femoral head cartilage were thus studied for histology and collagen composition. The electrophoretic analysis of the cyanogen bromide-derived peptides showed the sole presence of type II collagen in all normal and in all osteoarthritic samples, except those in which fibrocartilage was present. The sensitivity of the technique would not permit, however, the detection of a minute amount (less than 3%) of type I collagen in the samples. The results show that massive deposition of type I collagen occurs only when fibrocartilage is formed. It is suggested that this fibrocartilage is formed when the subchondral bone is damaged.