Pharmacokinetics of Asciminib When Taken With Imatinib or With Food

Asciminib, a first-in-class, Specifically Targeting the Abelson kinase Myristoyl Pocket (STAMP) inhibitor with the potential to overcome resistance to adenosine triphosphate-competitive tyrosine kinase inhibitors, is being investigated in leukemia as monotherapy and in combination with tyrosine kinase inhibitors including imatinib. This phase 1 study in healthy volunteers assessed the pharmacokinetics of asciminib (40 mg single dose) under 2 conditions: when taken with imatinib (steady state; 400 mg once daily) and a low-fat meal (according to imatinib prescription information), or when taken as single-agent under different food conditions. Asciminib plus imatinib with a low-fat meal increased asciminib area under the plasma concentration-time curve from time 0 to infinity and maximum plasma concentration (geometric mean ratios [90% confidence interval], 2.08 [1.93-2.24] and 1.59 [1.45-1.75], respectively) compared with asciminib alone under the same food conditions. Asciminib plus food decreased asciminib area under the plasma concentration-time curve from time 0 to infinity compared with asciminib taken under fasted conditions (geometric mean ratios: low-fat meal, 0.7 [0.631-0.776]; high-fat meal, 0.377 [0.341-0.417]). Asciminib plus imatinib was well tolerated with no new safety signals. Overall, coadministration of asciminib with imatinib and a low-fat meal results in a moderate increase in asciminib exposure compared with asciminib alone under the same food condition. Food itself decreases asciminib exposure, indicating that single-agent asciminib should be administered in the fasted state to prevent potential suboptimal exposures.

Pharmacokinetics of Asciminib in Individuals With Hepatic or Renal Impairment

Asciminib is an investigational, first-in-class, specifically targeting the ABL myristoyl pocket (STAMP) inhibitor of BCR-ABL1 with a new mechanism of action compared with approved ATP-competitive tyrosine kinase inhibitors. This report describes the findings from 2 phase 1 studies assessing the pharmacokinetic (PK) profile of a single dose of asciminib (40 mg) in individuals with impaired renal function (based on absolute glomerular filtration rate; NCT03605277) or impaired hepatic function (based on Child-Pugh classification; NCT02857868). Individuals with severe renal impairment exhibited 49%-56% higher exposure (area under the curve [AUC]), with similar maximum plasma concentration (C_max ), than matched healthy controls. Based on these findings, as per the protocol, the PK of asciminib in individuals with mild or moderate renal impairment was not assessed. In individuals with mild and severe hepatic impairment, asciminib AUC was 21%-22% and 55%-66% higher, respectively, and C_max was 26% and 29% higher, respectively, compared with individuals with normal hepatic function. Individuals with moderate hepatic impairment had similar asciminib AUC and C_max than matched healthy controls. The increase in asciminib AUC and C_max in the mild hepatic impairment cohort was mainly driven by 1 participant with particularly high exposure. Asciminib was generally well tolerated, and the safety data were consistent with its known safety profile. In summary, these findings indicate that renal or hepatic impairment has no clinically meaningful effect on the exposure or safety profile of asciminib, and support its use in patients with varying degrees of renal or hepatic dysfunction.

Treatment-free remission following frontline nilotinib in patients with chronic phase chronic myeloid leukemia: 5-year update of the ENESTfreedom trial

The ENESTfreedom trial assessed the feasibility of treatment-free remission (TFR) in patients with chronic myeloid leukemia in chronic phase (CML-CP) following frontline nilotinib treatment. Results for long-term outcomes after a 5-year follow-up are presented herein. Patients who had received ≥2 years of frontline nilotinib therapy and achieved MR^4.5 underwent a 1-year nilotinib treatment consolidation phase before attempting TFR. At the 5-year data cut-off, 81/190 patients entering the TFR phase (42.6%) were still in TFR, with 76 (40.0%) in MR^4.5. Patients who lost major molecular response (MMR) entered a treatment re-initiation phase; 90/91 patients entering this phase (98.9%) regained MMR and 84/91 patients (92.3%) regained MR^4.5. The Kaplan–Meier estimated treatment-free survival rate at 5 years was 48.2%. No disease progression or CML-related deaths were reported. Whereas the incidence of adverse events (AEs) declined from 96 weeks following the start of TFR, an increase in AE frequency was observed for patients in the treatment re-initiation phase. Low Sokal risk score, BCR-ABL1^IS levels at 48 weeks of TFR and stable MR^4.5 response for the first year of TFR were associated with higher TFR rates. Overall, these results support the efficacy and safety of attempting TFR following upfront nilotinib therapy of >3 years in patients with CML-CP.

Adjuvant Pazopanib Versus Placebo After Nephrectomy in Patients With Localized or Locally Advanced Renal Cell Carcinoma: Final Overall Survival Analysis of the Phase 3 PROTECT Trial

Most studies indicate no benefit of adjuvant therapy with VEGFR tyrosine kinase inhibitors in advanced renal cell carcinoma (RCC). PROTECT (NCT01235962) was a randomized, double-blind, placebo-controlled phase 3 study to evaluate adjuvant pazopanib in patients with locally advanced RCC at high risk of relapse after nephrectomy (pazopanib, n = 769; placebo, n = 769). The results of the primary analysis showed no difference in disease-free survival between pazopanib 600 mg and placebo. Here we report the final overall survival (OS) analysis (median follow-up: pazopanib, 76 mo, interquartile range [IQR] 66-84; placebo, 77 mo, IQR 69-85). There was no significant difference in OS between the pazopanib and placebo arms (hazard ratio 1.0, 95% confidence interval 0.80-1.26; nominal p > 0.9). OS was worse for patients with T4 disease compared to those with less advanced disease and was better for patients with body mass index (BMI) ≥30 kg/m² compared to those with lower BMI. OS was significantly better for patients who remained diseasefree at 2 yr after treatment compared with those who relapsed within 2 yr. These findings are consistent with the primary outcomes from PROTECT, indicating that adjuvant pazopanib does not confer a benefit in terms of OS for patients following resection of locally advanced RCC. PATIENT SUMMARY: In the randomized, double-blind, placebo-controlled phase 3 PROTECT study, overall survival was similar for patients with locally advanced renal cell carcinoma (RCC) at high risk of relapse after nephrectomy who received adjuvant therapy with pazopanib or placebo. Pazopanib is not recommended as adjuvant therapy following resection of locally advanced RCC. This trial is registered at Clinicaltrials.gov as NCT01235962.

Estimand framework: Are we asking the right questions? A case study in the solid tumor setting

The estimand framework requires a precise definition of the clinical question of interest (the estimand) as different ways of accounting for "intercurrent" events post randomization may result in different scientific questions. The initiation of subsequent therapy is common in oncology clinical trials and is considered an intercurrent event if the start of such therapy occurs prior to a recurrence or progression event. Three possible ways to account for this intercurrent event in the analysis are to censor at initiation, consider recurrence or progression events (including death) that occur before and after the initiation of subsequent therapy, or consider the start of subsequent therapy as an event in and of itself. The new estimand framework clarifies that these analyses address different questions ("does the drug delay recurrence if no patient had received subsequent therapy?" vs "does the drug delay recurrence with or without subsequent therapy?" vs "does the drug delay recurrence or start of subsequent therapy?"). The framework facilitates discussions during clinical trial planning and design to ensure alignment between the key question of interest, the analysis, and interpretation. This article is a result of a cross-industry collaboration to connect the International Council for Harmonisation E9 addendum concepts to applications. Data from previously reported randomized phase 3 studies in the renal cell carcinoma setting are used to consider common intercurrent events in solid tumor studies, and to illustrate different scientific questions and the consequences of the estimand choice for study design, data collection, analysis, and interpretation.

Imatinib in combination with phosphoinositol kinase inhibitor buparlisib in patients with gastrointestinal stromal tumour who failed prior therapy with imatinib and sunitinib: a Phase 1b, multicentre study

Background

The majority of patients with advanced gastrointestinal stromal tumours (GISTs) develop resistance to imatinib and sunitinib, the standard of care for these patients. This study evaluated the combination of buparlisib, an oral phosphoinositide 3-kinase (PI3K) inhibitor, with imatinib in patients with advanced GIST, who have failed prior therapy with imatinib and sunitinib.

Methods

This Phase 1b, multicentre, open-label study aimed to determine the maximum tolerated dose (MTD) and/or a recommended Phase 2 dose of buparlisib in combination with 400 mg of imatinib through a dose-escalation part and a dose-expansion part, and also evaluated the clinical profile of the combination.

Results

Sixty patients were enrolled, including 25 in the dose-escalation part and 35 in the dose-expansion part. In the combination, MTD of buparlisib was established as 80 mg. No partial or complete responses were observed. The estimated median progression-free survival was 3.5 months in the expansion phase. Overall, 98.3% of patients had treatment-related adverse events (AEs), including 45% with grade 3 or 4 AEs.

Conclusions

Buparlisib in combination with imatinib provided no additional benefit compared with currently available therapies. Due to the lack of objective responses, further development of this combination was not pursued for third-line/fourth-line advanced/metastatic GIST.

Trial registration number

NCT01468688.

A multicenter, randomized phase III study of asciminib (ABL001) versus bosutinib in patients (pts) with chronic myeloid leukemia in chronic phase (CML-CP) previously treated with ≥2 tyrosine kinase inhibitors (TKIs)

TPS7070

Background: There is a need for new treatment options for pts with CML who are intolerant/resistant to currently available BCR-ABL1 ATP-binding site targeted TKIs. Asciminib is a potent and specific BCR-ABL1 inhibitor with a novel allosteric mechanism of action targeting the ABL1 myristoyl pocket. This results in a mutation-driven resistance profile different from that of ATP binding-site TKIs, providing potential for both monotherapy and combination therapy with ATP-binding-site TKIs. In a phase 1 study (NCT02081378), asciminib showed clinical activity and good safety/tolerability in CML pts with resistance/intolerance to ≥2 TKIs and in pts with the T315I mutation. The recommended dose for asciminib monotherapy in CML pts without the T315I mutation was established as 40 mg BID. An ongoing phase 3 study (NCT03106779) is evaluating asciminib monotherapy vs bosutinib in pts with CML who have been treated with ≥2 prior ATP-binding-site TKIs. Methods: Eligible pts are adults with CML-CP who previously received ≥2 TKIs, with intolerance or failure to the most recent TKI. Treatment failure is defined per 2013 European LeukemiaNet (ELN) recommendations. Pts harboring T315I or V299L mutations are excluded. Pts are randomized 2:1 – stratified by baseline cytogenetic response status – to receive asciminib 40 mg BID or bosutinib 500 mg QD (planned enrollment: N = 222). Primary and key secondary objectives are to compare the rate of major molecular response ( BCR-ABL1IS≤0.1%) with asciminib vs bosutinib at 24 and 96 weeks, respectively. In a recent protocol amendment, the baseline BCR-ABL1IS threshold for enrollment was lowered from ≥1% to > 0.1% for pts with intolerance to the most recent TKI. This change was implemented to align with clinical practice and satisfy the treatment need to avoid waiting for an increase in BCR-ABL1IS levels to ≥1%. In addition, pts with documented bosutinib treatment failure as per ELN recommendations may switch to receive asciminib therapy at any time, as such pts may have limited treatment options outside of this study. This study is ongoing with 149 participating study sites in 30 countries. Clinical trial information: NCT03106779.

Treatment-free remission (TFR) following frontline (1L) nilotinib (NIL) in patients (pts) with chronic myeloid leukemia in chronic phase (CML-CP): 192-week data from the ENESTfreedom study

7013

Background: In ENESTfreedom (NCT01784068), which evaluated TFR following 1L NIL in CML-CP pts, 51.6% remained in TFR 48 wks after stopping treatment (primary endpoint) and durability of TFR was demonstrated at 144 wks. Data from longer follow-up (192 wks) evaluating maintenance of TFR are reported. Methods: Pts with MR4.5 ( BCR-ABL1IS ≤0.0032%) and ≥2y of 1L NIL entered a 1y consolidation; pts with sustained deep molecular response (MR) were eligible for TFR. NIL was resumed after loss of major MR (MMR; BCR-ABL1IS ≤0.1%). At the latest data cut-off (Sep 17 2018), all pts had completed ≥192 wks of TFR, resumed NIL, or discontinued the study. Results: By the data cut-off, of 190 pts entering TFR, 87 were ongoing, 91 had resumed NIL, and 12 had permanently discontinued. The TFR rate at 192 wks was 44.2% (84/190, 95% CI: 37.0–51.6%). Of 89 pts with successful TFR at 144 wks, 5 were not assessable for TFR at 192 wks as 2 had discontinued by 192 wks due to pt/physician decision, and 3 with MR4.5 previously did not have 192 wk PCR data. Of 91 pts who resumed NIL, 90 (98.9%) regained MMR and 84 (92.3%) regained MR4.5. 75/90 and 73/84 pts, respectively, had stable MMR and MR4.5 at 48 wks later. There were no cases of disease progression or new deaths. 10 deaths were reported in the 144-wk analysis, none due to CML. The 192-wk treatment-free survival rate was 48.7% (95% CI 41.4–55.6%). Of 89 pts remaining in TFR for > 144 wks (including 87 pts for > 192 wks), all-grade AE rates during consolidation and each subsequent 48 wk period of TFR were 84.3%, 77.5%, 70.8%, 48.3%, and 52.8%, respectively. All-grade musculoskeletal pain AE rates were 15.7%, 40.4%, 9.0%, 3.4% and 3.4%, respectively; cardiovascular event rates were low across these periods. Among pts who resumed NIL, most common AEs were nasopharyngitis (18.7%) and pruritus, fatigue, and increased lipase (14.3% each); the majority of AEs were grade 1/2. Conclusions: Results continue to support the long-term durability and safety of TFR at 192 wks after stopping 1L NIL; overall AE rates declined during the TFR phase and musculoskeletal pain AEs were transient. Pts should continue to be regularly monitored during TFR. Clinical trial information: NCT01784068.

Pazopanib Exposure Relationship with Clinical Efficacy and Safety in the Adjuvant Treatment of Advanced Renal Cell Carcinoma

Purpose: PROTECT, a phase III, randomized, placebo-controlled study, evaluated pazopanib efficacy and safety in the adjuvant renal cell carcinoma setting. The relationship between pazopanib exposure (C_trough) and efficacy and safety was evaluated.Patients and Methods: Evaluable steady-state blood trough concentrations were collected from 311 patients at week 3 or 5 (early C_trough) and 250 patients at week 16 or 20 (late C_trough). Pazopanib pharmacokinetic (PK) data were analyzed via a population model approach. Relationship between C_trough or dose intensity and disease-free survival (DFS) was explored via Kaplan-Meier and multivariate analysis. Adverse events (AE) and AE-related treatment discontinuation proportions were summarized by C_trough quartiles.Results: Most (>90%) patients with early or late C_trough data started on 600 mg. Mean early and late C_trough overlapped across dose levels. Patients with higher early C_trough quartiles achieved longer DFS (adjusted HR, 0.58; 95% confidence interval, 0.42-0.82; P = 0.002). Patients achieving early or late C_trough >20.5 μg/mL had significantly longer DFS: not estimable (NE) versus 29.5 months, P = 0.006, and NE versus 29.9 months, P = 0.008, respectively. Dose intensity up to week 8 did not correlate with DFS, consistent with population PK model-based simulations showing overlapping pazopanib exposure with 600 and 800 mg doses. The proportion of AE-related treatment discontinuation and grade 3/4 AEs, with the exception of hypertension, was not correlated to C_troughConclusions: In the adjuvant setting, higher pazopanib C_trough was associated with improved DFS and did not increase treatment discontinuations or grade 3/4 AEs, with the exception of hypertension. Clin Cancer Res; 24(13); 3005-13. ©2018 AACRSee related commentary by Rini, p. 2979.

Randomized Phase III Trial of Adjuvant Pazopanib Versus Placebo After Nephrectomy in Patients With Localized or Locally Advanced Renal Cell Carcinoma

Purpose This phase III trial evaluated the efficacy and safety of pazopanib versus placebo in patients with locally advanced renal cell carcinoma (RCC) at high risk for relapse after nephrectomy. Patients and Methods A total of 1,538 patients with resected pT2 (high grade) or ≥ pT3, including N1, clear cell RCC were randomly assigned to pazopanib or placebo for 1 year; 403 patients received a starting dose of 800 mg or placebo. To address toxicity attrition, the 800-mg starting dose was lowered to 600 mg, and the primary end point analysis was changed to disease-free survival (DFS) for pazopanib 600 mg versus placebo (n = 1,135). Primary analysis was performed after 350 DFS events in the intent-to-treat (ITT) pazopanib 600 mg group (ITT_600mg), and DFS follow-up analysis was performed 12 months later. Secondary end point analyses included DFS with ITT pazopanib 800 mg (ITT_800mg) and safety. Results The primary analysis results of DFS ITT_600mg favored pazopanib but did not show a significant improvement over placebo (hazard ratio [HR], 0.86; 95% CI, 0.70 to 1.06; P = .165). The secondary analysis of DFS in ITT_800mg (n = 403) yielded an HR of 0.69 (95% CI, 0.51 to 0.94). Follow-up analysis in ITT_600mg yielded an HR of 0.94 (95% CI, 0.77 to 1.14). Increased ALT and AST were common adverse events leading to treatment discontinuation in the pazopanib 600 mg (ALT, 16%; AST, 5%) and 800 mg (ALT, 18%; AST, 7%) groups. Conclusion The results of the primary DFS analysis of pazopanib 600 mg showed no benefit over placebo in the adjuvant setting.

Randomized phase III trial of adjuvant pazopanib versus placebo after nephrectomy in patients with locally advanced renal cell carcinoma (RCC) (PROTECT)

4507

Background: PROTECT (NCT01235962) evaluated the efficacy and safety of pazopanib (PAZ) versus placebo in patients (pts) with locally advanced renal cell carcinoma (RCC) post nephrectomy. Methods: 1538 pts with resected pT2 (high grade), pT3 or greater clear cell RCC were randomly assigned to PAZ or placebo for 1 year. The starting dose (800 mg) following treatment of 403 pts was lowered to 600 mg to improve tolerability and primary endpoint was changed to disease-free survival (DFS) with PAZ 600 (N = 1135). Primary analysis was performed after 350 DFS events in intent-to-treat (ITT) PAZ 600, and DFS follow-up analysis was performed after an additional 12 months. Secondary endpoints included DFS with ITT PAZ 800 and ITT ALL, and safety. Results: Disease characteristics were similar between arms. The primary analysis results of DFS ITT 600 were not significant [HR: 0.862; 95% CI, 0.699, 1.063; p = 0.165] (Table). The secondary endpoint of DFS in ITT PAZ 800 and ITT ALL yielded 31% and 20% risk reduction, respectively. Updated DFS analysis in ITT 600 showed a higher HR with longer follow up. Increased ALT and AST were the most common adverse events leading to treatment discontinuation in the PAZ 600 (ALT 16% and AST 5%) and PAZ 800 (ALT 18% and AST 7%) groups. Conclusions: The study did not meet the primary DFS endpoint in ITT 600; however, a 31% decrease in the risk of recurrence was observed in ITT 800. The safety profiles in the 600 mg and 800 mg groups were similar and consistent with PAZ prior experience. Clinical trial information: NCT01235962. [Table: see text]

Pazopanib exposure-response assessment as adjuvant therapy for patients with localized or locally advanced renal cell carcinoma (RCC) following nephrectomy

4564

Background: PROTECT was a Phase 3 randomized placebo-controlled study to evaluate pazopanib efficacy and safety as adjuvant RCC treatment. The starting dose was 800 mg daily, which was reduced to 600 mg in an attempt to improve tolerability. Pazopanib trough concentrations (Ctrough) were collected from 358 patients at the 600-mg starting dose at two timepoints (Week 3/ 5 and Week 16/20). This analysis characterized the relationship between Ctrough and efficacy and safety endpoints. Methods: The relationship between pazopanib Ctrough and disease-free survival (DFS) was explored by Cox regression analysis. DFS of pazopanib Ctrough quartiles was explored using Kaplan-Meier plots. Exposure-safety relationship was explored via summaries of all grade adverse events (AEs), grade 3/4 (G3/4) AEs, and AE-related treatment discontinuation by Ctrough quartiles. Results: The geometric mean (geo-CV%) of Ctrough at 600-mg dose was 31.4 (57%) µg/mL and 25.3 (70%) µg/mL for Week 3/5 and Week 16/20, respectively. At Week 16/20, Ctrough values overlapped among patients receiving 400-, 600-, and 800-mg doses. Cox regression analysis showed pazopanib Ctrough at Week 3/5 as a significant covariate for DFS after adjusting for TNM staging and Fuhrman Nuclear grading (HR: 0.58, 95% CI, 0.42, 0.82; p = 0.002). Longer DFS was observed in higher Week 3/5 Ctrough quartiles (median DFS by quartile—Q1: 41.89 months, Q2-Q4: median DFS not reached). Incidence of all-grade AEs, as well as G3/4 hypertension, increased as Ctrough increased. Treatment discontinuation due to hypertension among pazopanib-treated subjects was low (3.1% vs < 1% in the placebo group). Ctrough was not correlated to G3/4 ALT increase. Incidence of other G3/4 AEs plateaued at higher Ctrough. No relationship was observed between Ctrough and treatment discontinuation due to AEs. Conclusions: Pazopanib Ctrough levels in PROTECT were consistent with levels associated with efficacy in the advanced setting. Higher pazopanib Ctrough correlated with longer DFS. Higher pazopanib exposure did not increase the incidence of G3/4 AEs, with the exception of hypertension, which was adequately controlled and managed. Clinical trial information: NCT01235962.

A phase I/II study to assess the safety and efficacy of pazopanib (PAZ) and pembrolizumab (PEM) in patients (pts) with advanced renal cell carcinoma (aRCC)

4506

Background: PAZ is indicated for the treatment of aRCC. The combination of an anti-angiogenic agent and immunotherapy may improve anti-tumor activity. We report preliminary safety and efficacy results of the phase I part of the study. Methods: Twenty pts were originally enrolled in cohorts A and B assessing PAZ 800 mg and 600 mg, respectively, both with 2mg/kg (Q2W and then Q3W) PEM to determine the maximum tolerated dose. Due to dose limiting liver toxicity, cohort C was opened to assess if the sequential schedule of 9 weeks PAZ run-in followed by PAZ+PEM would improve safety. Strict safety criteria for initiating PAZ+PEM were set. The data from this ongoing study are presented given the limited information available on the combination of TKI + PD-1 inhibitors in RCC. Results: Overall, 35 pts were treated; 5 out of 15 pts in cohort C received PAZ+PEM at the data cut-off. Three dose-limiting toxicities (DLT) occurred in cohort C in pts receiving PAZ+PEM; updated DLTs in all cohorts are reported in Table. G3/4 AEs were observed in 90% of pts in cohorts A and B and in 80% of pts in cohort C receiving PAZ+PEM. No G3/4 ALT/AST elevation was reported in cohort C PAZ+PEM while they were observed in 70% and 60% in cohorts A and B, respectively. Best overall response (CR+PR) was reported in 6, 2 and 1 pts receiving PAZ+PEM in cohorts A, B and C, respectively. Conclusions: Results from cohorts A and B showed significant hepatotoxicity. The sequential schedule PAZ → PAZ+PEM has shown reduced hepatotoxicity and preliminary signs of efficacy but overall limited tolerability. PAZ+PEM is not suitable to test in a larger cohort. Clinical trial information: 2013-003785-14. [Table: see text]

A Phase II Study of BEZ235 in Patients with Everolimus-resistant, Advanced Pancreatic Neuroendocrine Tumours

BACKGROUND

This was a two-stage, phase II trial of the dual phosphatidylinositol 3-kinase/mammalian target of rapamycin inhibitor BEZ235 in patients with everolimus-resistant pancreatic neuroendocrine tumours (pNETs) (NCT01658436).

PATIENTS AND METHODS

In stage 1, 11 patients received 400 mg BEZ235 orally twice daily (bid). Due to tolerability concerns, a further 20 patients received BEZ235 300 mg bid. Stage 2 would be triggered by a 16-week progression-free survival (PFS) rate of ≥60% in stage 1.

RESULTS

As of 30 June, 2014, 29/31 patients had discontinued treatment. Treatment-related grade 3/4 adverse events were reported in eight (72.7%) patients at 400 mg and eight (40.0%) patients at 300 mg, including hyperglycaemia, diarrhoea, nausea, and vomiting. The estimated 16-week PFS rate was 51.6% (90% confidence interval=35.7-67.3%).

CONCLUSION

BEZ235 was poorly tolerated by patients with everolimus-resistant pNETs at 400 and 300 mg bid doses. Although evidence of disease stability was observed, the study did not proceed to stage 2.

PI3K inhibitors as new cancer therapeutics: implications for clinical trial design

The PI3K–AKT–mTOR pathway is frequently activated in cancer. PI3K inhibitors, including the pan-PI3K inhibitor buparlisib (BKM120) and the PI3Kα-selective inhibitor alpelisib (BYL719), currently in clinical development by Novartis Oncology, may therefore be effective as anticancer agents. Early clinical studies with PI3K inhibitors have demonstrated preliminary antitumor activity and acceptable safety profiles. However, a number of unanswered questions regarding PI3K inhibition in cancer remain, including: what is the best approach for different tumor types, and which biomarkers will accurately identify the patient populations most likely to benefit from specific PI3K inhibitors? This review summarizes the strategies being employed by Novartis Oncology to help maximize the benefits of clinical studies with buparlisib and alpelisib, including stratification according to PI3K pathway activation status, selective enrollment/target enrichment (where patients with PI3K pathway-activated tumors are specifically recruited), nonselective enrollment with mandatory tissue collection, and enrollment of patients who have progressed on previous targeted agents, such as mTOR inhibitors or endocrine therapy. An overview of Novartis-sponsored and Novartis-supported trials that are utilizing these approaches in a range of cancer types, including breast cancer, head and neck squamous cell carcinoma, non-small cell lung carcinoma, lymphoma, and glioblastoma multiforme, is also described.

Abstract A26: Detecting PIK3CA mutations in circulating cell-free DNA from patients with metastatic cancer: An exploratory analysis in patients with endometrial and lung cancer

Background: Personalized therapy relies on the ability to characterize the tumor at the time of treatment. Circulating cell-free DNA (cfDNA) may offer the potential for representative mutation analysis in patients with cancer irrespective of tumor tissue availability. Recent publications have started to establish the feasibility of this approach. For example, 72.5% concordance of PIK3CA mutations was reported between temporally unmatched cfDNA and archival tumor tissue from patients with metastatic breast cancer (Higgins et al. Clin Cancer Res 2012). Here, we present a retrospective analysis evaluating the reliability of detecting PIK3CA mutations in plasma samples from patients with endometrial and lung cancer – two malignancies known to harbor alterations in the PI3K pathway.

Methods: Baseline plasma DNA samples were available from 61 patients with advanced endometrial cancer (NCT01289041) and 37 patients with advanced non-small cell lung cancer (NSCLC; NCT01297491). BEAMing technology (Richardson & Iglehart. Clin Cancer Res 2012) and Sanger analysis were used in all samples. Sanger analysis was able to detect any mutation in exons 1, 5, 7, 9, and 20, whereas only selected mutations (14 in total) known to affect PI3K function in exons 1, 4, 7, 9, and 20 could be detected in cfDNA. Plasma samples were all temporally unmatched to the archival tissue specimen. Concordance analysis was performed by comparing the mutation status of samples (i.e. the proportion of samples that were detected as either wildtype or mutant consistently) between Sanger and cfDNA sequencing.

Results: 54 of 61 patients with endometrial cancer had interpretable mutation results by both Sanger and cfDNA analysis. Concordance of PIK3CA mutation was 74% between plasma and tissue. The PIK3CA mutations detected in cfDNA were distributed over exons 1, 7, 9, and 20 (29%, 19%, 33%, and 19%, respectively). Among the 37 patients with NSCLC, overall concordance was 54%. Variant distribution of PIK3CA mutations in this small number of lung tumors appeared to differ from the usual “hotspots” as two-thirds of mutations detected by Sanger analysis were not available on the BEAMing panel.

Conclusion: Concordance for PIK3CA mutation between temporally unmatched archival specimens and blood samples in this endometrial cancer patient population was in line with the published rate for metastatic breast cancer. The different mutations identified in samples from patients with NSCLC indicate a need for better understanding of the potential role of the PI3K pathway in this tumor type.

Overall these results support the feasibility of assessing PIK3CA mutations in plasma samples. The outcomes show a similar trend to multiple recent publications, thus warranting rapid further exploration of the clinical utility of cfDNA in metastatic cancer.

Citation Format: Emmanuelle di Tomaso, Bradley Monk, Grace Dy, Douglas Robinson, Paola Aimone, Lucia Trandafir, Cristian Massacesi, Samit Hirawat. Detecting PIK3CA mutations in circulating cell-free DNA from patients with metastatic cancer: An exploratory analysis in patients with endometrial and lung cancer. [abstract]. In: Proceedings of the AACR Special Conference: Targeting the PI3K-mTOR Network in Cancer; Sep 14-17, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(7 Suppl):Abstract nr A26.