Clinical utility of comprehensive circulating tumor DNA genotyping compared with standard of care tissue testing in patients with newly diagnosed metastatic colorectal cancer

BACKGROUND

Comprehensive biomarker testing is essential in selecting optimal treatment for patients with metastatic colorectal cancer (mCRC); however, incomplete genotyping is widespread, with most patients not receiving testing for all guideline-recommended biomarkers, in part due to reliance on burdensome sequential tissue-based single-biomarker tests with long waiting times or availability of only archival tissue samples. We aimed to demonstrate that liquid biopsy, associated with rapid turnaround time (TAT) and lower patient burden, effectively identifies guideline-recommended biomarkers in mCRC relative to standard of care (SOC) tissue testing.

PATIENTS AND METHODS

Prospectively enrolled patients with previously untreated mCRC undergoing physician discretion SOC tissue genotyping submitted pretreatment blood samples for comprehensive circulating tumor DNA (ctDNA) analysis with Guardant360 and targeted RAS and BRAF analysis with OncoBEAM.

RESULTS

Among 155 patients, physician discretion SOC tissue genotyping identified a guideline-recommended biomarker in 82 patients, versus 88 identified with comprehensive ctDNA (52.9% versus 56.8%, noninferiority demonstrated down to α = 0.005) and 69 identified with targeted PCR ctDNA analysis (52.9% versus 44.5%, noninferiority rejected at α = 0.05). Utilizing ctDNA in addition to tissue increased patient identification for a guideline-recommended biomarker by 19.5% by rescuing those without tissue results either due to tissue insufficiency, test failure, or false negatives. ctDNA median TAT was significantly faster than tissue testing when the complete process from sample acquisition to results was considered (median 10 versus 27 days, P < 0.0001), resulting in accelerated biomarker discovery, with 52.0% biomarker-positive patients identified by ctDNA versus 10.2% by SOC tissue 10 days after sample collection (P < 0.0001).

CONCLUSIONS

Comprehensive ctDNA genotyping accurately identifies guideline-recommended biomarkers in patients with mCRC at a rate at least as high as SOC tissue genotyping, in a much shorter time. Based on these findings, the addition of ctDNA genotyping to clinical practice has significant potential to improve the care of patients with mCRC.

Phase I/II Trial to Evaluate the Efficacy and Safety of Nanoparticle Albumin-Bound Paclitaxel in Combination With Gemcitabine in Patients With Pancreatic Cancer and an ECOG Performance Status of 2

Purpose

Gemcitabine plus nanoparticle albumin-bound (NAB) paclitaxel (GA) significantly improved survival compared with gemcitabine alone in patients with metastatic pancreatic ductal adenocarcinoma (PDAC) and a Karnofsky performance status (PS) of 70% or greater. Because of the low number of patients with reduced PS, the efficacy of this regimen in fragile patients remains unclear. This study aimed to evaluate the efficacy and tolerability of different GA dosing regimens in patients with a poor PS.

Patients and Methods

In the phase I part of this study, patients were randomly assigned to one of the following four parallel GA treatment arms (six patients per arm): a biweekly schedule of NAB-paclitaxel (150 mg/m2 [arm A] or 125 mg/m2 [arm C]) plus gemcitabine 1,000 mg/m2 or a standard schedule of 3 weeks on and 1 week off of NAB-paclitaxel (100 mg/m2 [arm B] or 125 mg/m2 [arm D]) plus gemcitabine 1,000 mg/m2. The two regimens with the better tolerability profile on the basis of predefined criteria were evaluated in the phase II part of the study, the primary end point of which was 6-month actuarial survival.

Results

Arms B and D were selected for the phase II part of the study. A total of 221 patients (111 patients in arm B and 110 patients in arm D) were enrolled. Baseline characteristics including median age (71 and 68 years in arms B and D, respectively), sex (51% and 55% men in arms B and D, respectively), and metastatic disease (88% and 84% in arms B and D, respectively) were comparable between arms. The most frequent grade 3 or 4 toxicities in arms B and D were anemia (12% and 7%, respectively), neutropenia (32% and 30%, respectively), thrombocytopenia (7% and 11%, respectively), asthenia (14% and 16%, respectively), and neurotoxicity (11% and 16%, respectively). In arms B and D, there were no significant differences in response rate (24% and 28%, respectively), median progression-free survival (5.7 and 6.7 months, respectively), and 6-month overall survival (63% and 69%, respectively).

Conclusion

NAB-paclitaxel administered at either 100 and 125 mg/m2 in combination with gemcitabine on days 1, 8, and 15 every 28 days is well tolerated and results in acceptable safety and efficacy in patients with metastatic pancreatic ductal adenocarcinoma and a poor PS.

Phase II trial of erlotinib maintenance therapy after platinun-based chemotherapy in advanced non-small cell lung cancer (NSCLC)

e19013

Background: phase II trial-efficacy & toxicity of sequential erlotinib in advanced NSCLC after platinum-based CT Methods: Pts with adv NSCLC, PS 0/1, adequate renal, hepatic and bone marrow function, no PD after CT. Treatment: erlotinib 150 mg/day starting 3–4 weeks after CT until progression. Safety was evaluated monthly and tumor evaluation bimonthly. Results: 47 pts enrrolled:42(89%)stageIV & 5(11%)wet IIIB, all valid for response & toxicity. Median age 62 y(r:39 -77): 39(83%) males and 8(17%) females. Histology: adenocarcinoma 8(61.7%), bronquioloalveolar 3(6.4%), large cell 3(6.4%), squamous12(25.5%). PS 0: 23(49%), PS 1:24(51%). 38(81.9%) completed 6 cycles of CT. Response: CR: 1(2.1%), PR: 2(51.1%), EE: 22 (46%). Sequential erlotinib improved RR in 6 (12.8%), 23 (48.9) prolonged stabilization, 18 (38.3%) had progression. Median TTP and OS were 9.4 m (95% CI, 4.96–13–84), and 19.23 m (95% CI, 8.82–29.64). No significant differences in TTP according to age, sex, PS, histology or previous response to CT, but yes depending on RR to erlotinib: PR: 31.5 m (95% CI 15.37–47.63), EE: 12.8 m (95% CI, 10.58–15.03), PD: 6.3 m (95% CI, 5.36–7.3), p < 0.001; and moreover depending on smoking status: Never: 21.67 m(95% CI, 5.39–37.94), previous smoker > 5 years: 14.03 m(95% CI, 10.77–17.30), previous smoker 1 year: 7.77 m(95% CI, 7.62–7.91), current smoker: 5.9 m(95% CI, 5.12–6.34), p <0.001. In Cox-regression model, smoking status ( p< 0.001), and response to erlotinib (p=0.002) were associated with a significant difference in TTP. Similar results in OS, although in Cox-regression model only never smoker or > 5 years previous smoker pts had a significant better survival. Toxicity: The most frequent was skin rash, grade (g) 1 in 11(23.4%), g 2: 16(34%) and g 3: 3(6.4%). Only 1 p had diarrea g 3, and no other side effects were observed. We found a significant benefit in p with g 2–3 skin toxicity respect g 0–1, in both TTP( p= 0.0003) and OS (p= 0.0014). Conclusions: Erlotinib-maintenance therapy after platinum-based CT had promising results. Pts with the best benefit were those with response to erlotinib, in never or past (> 5 years) smokers and with g 2–3 skin toxicity.

No significant financial relationships to disclose.