Clinical performance of the therascreen KRAS RGQ PCR Kit

Clinical studies validating the use of the therascreen KRAS RGQ PCR Kit in non-small cell lung cancer (NSCLC) and colorectal cancer (CRC) testing are found below.

Clinical study supporting use with LUMAKRAS (sotorasib) in NSCLC¹

A clinical performance study demonstrated the clinical validity of the therascreen KRAS RGQ PCR Kit as a CDx test to aid the identification of NSCLC patients for treatment with LUMAKRAS (sotorasib). The objective of the study was to assess whether G12C mutation status, as determined by the therascreen KRAS RGQ PCR Kit, can be used to select patients with advanced NSCLC that will benefit from LUMAKRAS (sotorasib) treatment. Clinical trial 20170543 (CodeBreak 100) was an open-label, multicenter, phase 1/2 study designed to evaluate the efficacy and safety of LUMAKRAS (sotorasib) in adult subjects with advanced solid tumors that harbor the KRAS G12C mutation. Data from the primary analysis of the NSCLC phase 2 portion of this study has been used to support the clinical validity of the therascreen KRAS RGQ PCR Kit as a CDx test. Enrollment was restricted to subjects with KRAS G12C-mutated NSCLC as assessed by a local laboratory result, which was confirmed by central testing using the therascreen KRAS RGQ PCR Kit.

The primary endpoint of the NSCLC phase 2 portion of this study was to evaluate tumor objective response rate (ORR) assessed by RECIST 1.1 criteria of LUMAKRAS (sotorasib) as monotherapy in subjects with KRAS G12C-mutated advanced tumors.

Analysis was performed on 124 patients. The primary endpoint of ORR (complete response + partial response) was assessed by blinded independent centralized review (BICR) using RECIST 1.1. For subjects with KRAS G12C-mutated NSCLC, ORR was 35% (45 of 124 subjects; 95% CI: 28-45%); 2% (two subjects) achieved complete response and 35% (43 subjects) achieved partial response.

A 2-year analysis of CodeBreak 100 has shown that oral once-daily sotorasib demonstrated a favorable safety profile and durable efficacy across subgroups in KRAS G12C-mutated NSCLC. A substantial proportion of patients derived long-term clinical benefit, with 1- and 2-year overall survival rates of 51% and 33%, respectively².

Clinical study supporting use with KRAZATI (adagrasib) in NSCLC¹

A bridging study demonstrated the clinical efficacy of the therascreen KRAS RGQ PCR Kit as a CDx test to aid the identification of NSCLC patients for treatment with KRAZATI (adagrasib) based on a KRAS G12C Mutation Detected test result. The results were compared with the clinical efficacy observed in Cohort A of a clinical trial 849-001. Clinical efficacy was evaluated by assessing the ORR for KRAS G12C mutation detected, KRAS G12C mutation non-detected and KRAS G12C mutation non-evaluable subjects separately.

The clinical trial 849-001 (KRYSTAL 1) was a phase 1/2 multiple expansion cohort trial of KRAZATI (adagrasib) in patients with advanced solid tumors with KRAS G12C mutation. The primary objective of the trial was to characterize the safety and tolerability of KRAZATI (adagrasib) in patients having advanced solid tumor malignancies with the KRAS G12C mutation and to evaluate the pharmacokinetics of KRAZATI (adagrasib). Cohort A enrolled patients with advanced NSCLC with KRAS G12C mutation who had previously received treatment with a platinum-based regimen and an immune checkpoint inhibitor. The primary endpoint for evaluation of efficacy was overall response rate (ORR), in accordance with RECIST version 1.1.

In total, FFPE tissue specimens from 218 unique subjects (104 from cohort A and 114 procured) were sent to a central laboratory for KRAS G12C testing with the therascreen KRAS RGQ PCR Kit. Two specimens were from the same procured subject, therefore, in total 219 specimens were tested for KRAS G12C mutation status. Three samples from cohort A had either no tumor or insufficient sample for the testing. Of the 216 testable samples, 210 produced evaluable results. Of the 218 unique subjects, 209 produced evaluable results. None of the procured clinical KRAS G12C-negative specimens tested KRAS G12C positive when testing with the therascreen KRAS RGQ PCR Kit.

Table 1. Concordance between therascreen KRAS RGQ PCR Kit (CDx) and clinical trial enrollment assays (CTA)

* 95% CI is calculated using the Exact (Clopper-Pearson) method.

Based on the clinical bridging study, the positive percent agreement (PPA) and the negative percent agreement (NPA) between the therascreen KRAS RGQ PCR Kit (CDx) and the clinical trial enrollment assays (CTA) were calculated (PPA: 88.78%; NPA: 100%). An NPA of 100% indicated that the final estimated drug efficacy (ORR) for the KRAS G12C mutation-positive patients tested by CDx in the intended use population is the same as the estimated drug efficacy of the CDx-positive patients observed in cohort A primary efficacy population in KRYSTAL 1.

The efficacy of the therascreen KRAS RGQ PCR Kit, in identifying patients as KRAS G12C mutation detected for treatment with KRAZATI (adagrasib) was demonstrated. The primary endpoint of ORR in KRAS G12C mutation-detected patients with measurable disease was 43% (36/83, 95% CI: 33%, 55%) which exceeded the hypothesized response rate of 23% reported with standard care and met the study acceptance criteria.

Clinical study supporting use with LUMAKRAS (sotorasib) in combination with Vectibix (panitumumab) in CRC¹

This study was designed to utilize the therascreen KRAS RGQ PCR Kit as a screening test in the CodeBreak 300 phase 3 clinical trial (Amgen protocol no. 20190172) to identify CRC patients with KRAS G12C mutation-positive tumors.

A total of 219 subjects were screened for enrollment and 160 were randomized to either the sotorasib 240 mg + panitumumab group (53 subjects), sotorasib 960 mg + panitumumab group (53 subjects), or control (trifluridine and tipiracil or regorafenib) group (54 subjects). Of the 219 subjects, 211 were tested with the CDx (eight subjects screen failed prior to CDx testing). All of the 160 enrolled and randomized subjects had a G12C-positive result with the CDx. Of the remaining 51 screen fail subjects, 27 had CDx G12C-positive results, 12 had G12C-negative results and 12 had invalid results.

All samples had a positive local test result prior to testing with the CDx. Positive percent agreement (PPA) between the CDx and local results was 94.0% (187/199). The PPA between the CDx and the local test methodologies used in the study can be seen in Table 2. No local test negative samples from the study were available for testing with the CDx. However, negative percent agreement (NPA) for the CDx in CRC specimens has been established in the clinical study supporting use of KRAZATI (adagrasib) for CRC.

Table 2. Concordance between therascreen KRAS RGQ PCR Kit (CDx) and clinical trial enrollment assays (CTA)

* Calculated using the data from 91 CTA-negative samples from the clinical study supporting use of KRAZATI (adagrasib) in CRC.

** 95% CI calculated using the Exact (Clopper-Pearson) method.

The primary end point was progression-free survival as assessed by blinded independent central review (BICR) according to the Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1. Key secondary end points were overall survival (OS) and objective response (OR)³.

Data cutoff date for the primary analysis of progression-free survival (PFS) was June 19, 2023. A total of 97 PFS events were reported by the data cutoff date. Median PFS was 3.9 months (95% CI: 3.6, 5.8) in the sotorasib 240 mg + panitumumab group, compared with 2.0 months (95% CI: 1.9, 3.9) in the control group. Median PFS was 5.6 months (95% CI: 4.2, 6.3) in the sotorasib 960 mg + panitumumab group, compared with 2.0 months (95% CI: 1.9, 3.9) in the control group. The hazard ratio (HR) for disease progression or death was 0.6 (95% CI: 0.4, 1.0; 2-sided p-value = 0.06) for the sotorasib 240 mg + panitumumab versus the control, and 0.5 (0.3, 0.8; 2-sided p-value = 0.011) for the sotorasib 960 mg + panitumumab versus the control, demonstrating a statistically significant benefit in PFS in the sotorasib 960 mg + panitumumab treatment group.  The PFS results are consistent with those observed in the analysis of the full analysis set. 

In conclusion, for the KRAS population, as in the full analysis set, sotorasib 960 mg + panitumumab showed a statistically significant improvement in PFS, and a trend toward improved OS (when compared to standard of care in a highly pretreated population) for subjects with KRAS p.G12C-mutated mCRC as determined using the therascreen KRAS RGQ PCR Kit.

Clinical study supporting use with KRAZATI (adagrasib) in combination with ERBITUX (cetuximab) in CRC¹

A bridging study was conducted to evaluate the clinical utility of the therascreen KRAS RGQ PCR Kit when used as a CDx to identify patients diagnosed with metastatic CRC (mCRC) for treatment with KRAZATI (adagrasib) with cetuximab based on a positive KRAS G12C result. Results of the bridging study were compared with the clinical efficacy observed in a phase 1/2 clinical trial (849-001; KRYSTAL 1). Clinical efficacy was evaluated by assessing the overall response rate (ORR) of subjects enrolled into the phase 1 sub-study and phase 2 cohort G.

KRYSTAL 1 clinical trial was a phase 1/2 multiple expansion cohort trial of KRAZATI (adagrasib) with cetuximab in patients with advanced solid tumors with KRAS G12C mutation. The primary objective of the trial was to characterize the safety and tolerability of KRAZATI (adagrasib) in patients with advanced solid tumor malignancies and KRAS G12C mutation and to evaluate the pharmacokinetics of KRAZATI (adagrasib). The primary endpoint for evaluating clinical efficacy was ORR based on RECIST version 1.1.

The bridging study was conducted to establish concordance between the therascreen KRAS RGQ PCR Kit (the CDx) and the CTA used in the trial, as determined by a comparison of ORR for KRAS G12C-positive and -negative cohorts.

Samples from 121 KRAS G12C-positive subjects with mCRC tested with a CTA were enrolled into phase 1 sub-study (32 subjects), phase 1b dose optimization (27 subjects) and phase 2 cohort G (62 subjects) of KRYSTAL 1. Of these, 35 samples were not testable, and were not evaluated using the therascreen KRAS RGQ PCR Kit or included in efficacy analysis. The 86 testable samples from phase 1/2 were supplemented with an additional 91 mCRC samples with KRAS G12C mutation not detected results procured from commercial vendors. In total, FFPE tissue specimens from 177 unique subjects (86 from phase 1/2 of KRYSTAL 1 and 91 procured) were sent to a central laboratory for KRAS G12C testing with the therascreen KRAS RGQ PCR Kit. Of the 177 samples, 171 produced evaluable results.

Based on the clinical bridging study, the positive percent agreement (PPA) and the negative percent agreement (NPA) between the therascreen KRAS RGQ PCR Kit (CDx) and the clinical trial assay (CTA) were calculated (PPA: 92.50%; NPA: 100%; Table 3). Concordance between CTA and CDx is based on the CTA as a reference method.

 

Table 3. Concordance between therascreen KRAS RGQ PCR Kit (CDx) and CTA

* 95% CI calculated using the Exact (Clopper-Pearson) method.

Effectiveness of the therascreen KRAS RGQ PCR Kit (CDx) in identifying mCRC patients as KRAS G12C mutation detected for treatment with KRAZATI (adagrasib) and cetuximab was demonstrated using subjects from the primary efficacy population. The primary endpoint of ORR in CDx KRAS G12C mutation detected patients with measurable disease in the bridging study was 34.6% (19/55, 95% CI: 22.2%, 48.6%). This value exceeded the acceptance criteria from KRYSTAL-1 and was comparable to the ORR value seen in KRYSTAL-1 (34.0%).

Clinical study supporting use with ERBITUX (cetuximab) in CRC¹

A clinical performance study generated data supporting the clinical utility of the therascreen KRAS RGQ PCR Kit as a CDx test to enable selection of patients for treatment with ERBITUX (cetuximab). Study CA225025 was a multicenter, open-label, randomized clinical trial conducted in 572 patients with EGFR-expressing, previously treated, metastatic CRC (mCRC). Patients were randomized (1:1) to receive either ERBITUX (cetuximab) plus best supportive care (BSC) or BSC alone. ERBITUX (cetuximab) was administered as a 400 mg/m² initial dose, followed by 250 mg/m² weekly until disease progression or unacceptable toxicity.

KRAS mutation status was available for 453 (79%) patients. 245 (54%) patients had KRAS mutation-negative tumors, and 208 (46%) patients had KRAS mutation-positive tumors as assessed using the therascreen KRAS RGQ PCR Kit.

The main outcome measure of the study was overall survival (OS) (Table 4). For the KRAS mutation-negative (wild-type) population, median survival time was 8.6 months (95% CI: 7.0, 10.3) months in the ERBITUX (cetuximab)+BSC group and 5.0 months (95% CI: 4.3, 5.7) in the BSC alone group. For the KRAS mutation-positive population, median survival time was 4.8 months (95% CI: 3.9, 5.6) in the ERBITUX (cetuximab)+BSC group and 4.6 months (95% CI: 3.6, 4.9) in the BSC alone group.

Table 4. Overall survival in previously treated EGFR-expressing mCRC

BSC = Best supportive care
* Based on the stratified log-rank test.

Overall survival rates based on Kaplan-Meier estimates at months 6 and 12 were higher for the ERBITUX (cetuximab)+BSC group than the BSC group for the KRAS wild-type subset. This advantage was not observed in the KRAS mutant subset.

Clinical study supporting use with Vectibix (panitumumab) in CRC¹

A clinical performance study generated data supporting the clinical utility of the therascreen KRAS RGQ PCR Kit as a CDx test to enable selection of patients for treatment with Vectibix (panitumumab). The objective of the study was to assess whether KRAS mutation status as determined by the therascreen KRAS RGQ PCR Kit can be used to select patients with mCRC who will benefit from Vectibix (panitumumab) treatment. Clinical trial 20050203 was a multicenter, prospective, open‐label, randomized phase 3 study to assess the efficacy of panitumumab in combination with oxaliplatin, 5‐fluorouracil (5 FU) and leucovorin (FOLFOX4) vs. FOLFOX4 alone in patients with previously untreated mCRC.

Banked tumor samples from patients in study 20050203 were tested with the therascreen KRAS RGQ PCR Kit to identify two subgroups: KRAS mutation-positive (mutant KRAS) and KRAS mutation-negative (wild-type KRAS), according to whether at least one or none of seven KRAS mutations in codons 12 and 13 of exon 2 in the KRAS gene was detected. In retrospective analyses, efficacy data from study 20050203 were stratified by KRAS subgroup. The primary objective of the KRAS analysis was to assess whether an overall improvement in progression-free survival (PFS) for Vectibix (panitumumab) plus FOLFOX relative to FOLFOX alone was significantly greater among subjects with KRAS wild‐type tumors compared to subjects with KRAS mutant tumors.

The prespecified primary efficacy endpoint was PFS in the group of patients (n = 656) with wild-type KRAS mCRC as assessed by blinded independent central review (BICR) of imaging (Table 5). Other key efficacy endpoints included overall survival (OS) and objective response rate (ORR).

Table 5. Efficacy results in patients with wild-type KRAS mCRC

*p = 0.02

In patients with KRAS mutant tumors, median PFS was 7.3 months (95% CI: 6.3, 8.0) in the 221 patients receiving Vectibix (panitumumab) plus FOLFOX versus the median PFS of 8.8 months (95% CI: 7.7, 9.4) in the 219 patients who received FOLFOX alone (HR: 1.29, 95% CI: 1.04, 1.62). Median OS was 15.5 months (95% CI: 13.1, 17.6) in patients receiving Vectibix (panitumumab) plus FOLFOX versus median OS of 19.3 months (95% CI: 16.5, 21.8) in patients who received FOLFOX alone (HR: 1.24, 95% CI: 0.98, 1.57).

For more information regarding ERBITUX, Vectibix, LUMAKRAS, and KRAZATI indications, refer to the most recent drug labels at www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm

References

1. therascreen KRAS RGQ PCR Kit Instructions for Use (Handbook). August 2025.
2. Dy GK, et al. Long-term outcomes and molecular correlates of sotorasib efficacy in patients with pretreated KRAS G12C-mutated non-small-cell lung cancer: 2-year analysis of CodeBreaK 100. J Clin Oncol. 2023;41(18):3311–3317.
3. Fakih MG, et al. Sotorasib plus panitumumab in refractory  colorectal cancer with mutated KRAS G12C. N Engl J Med. 2023;389:2125-39.