Neoplasms

All Conditions

Digestive System Diseases

Carcinoma

Colorectal Neoplasms

Intestinal Neoplasms

Gastrointestinal Neoplasms

Digestive System Neoplasms

Gastrointestinal Diseases

Colonic Diseases

Intestinal Diseases

Rectal Diseases

Antineoplastic Agents

All Drugs and Chemicals

Irinotecan

Oxaliplatin

Panitumumab

Topoisomerase I Inhibitors

Enzyme Inhibitors

Antineoplastic Agents, Immunological

Participants received panitumumab (6 mg/kg starting dose) with irinotecan (starting dose of 180 mg/m²) every 2 weeks (Q2W) during Part 1. Upon radiographically confirmed disease progression, participants proceeded to Part 2 of the study and received treatment with panitumumab (6 mg/kg starting dose) and ganitumab (12 mg/kg starting dose) Q2W.

Panitumumab 6 mg/kg administered via IV infusion over 60 minutes

AMG 479 12 mg/kg adminstered by IV infusion over 60 minutes

Ganitumab

Irinotecan starting dose of 180 mg/m² adminstered via IV infusion

This study is designed to evaluate the mechanism(s) of resistance to the anti-epidermal growth factor receptor (EGFR) antibody panitumumab given in combination with irinotecan in metastatic colorectal carcinoma (mCRC) patients with wild-type Kirsten rat sarcoma-2 virus oncogene (KRAS) tumor status at the time of initial diagnosis.

In Part 1, all participants will undergo a baseline tumor biopsy and will receive panitumumab with irinotecan. Participants who respond or have stable disease will continue to receive treatment until radiographically-confirmed disease progression. These participants will then undergo a second tumor biopsy and blood sampling and then proceed to Part 2 of the study. Participants with radiographically confirmed disease progression at the time of the first tumor measurement will undergo blood sampling and proceed directly to Part 2.

In Part 2, participants will receive panitumumab with ganitumab. In both parts of the study, panitumumab and irinotecan (Part 1) and panitumumab and ganitumab (Part 2) will be administered every 2 weeks until disease progression, intolerability, withdrawal of consent, death, or unless otherwise indicated by the study team.

Study to Evaluate Mechanisms of Acquired Resistance to Panitumumab

Phase 2 Study of Panitumumab Plus Irinotecan Followed by Panitumumab Plus AMG 479 in Subjects With Metastatic Colorectal Carcinoma Expressing Wild Type KRAS and Refractory to Oxaliplatin-or Irinotecan- and Oxaliplatin-containing Regimens to Evaluate Mechanisms of Acquired Resistance to Panitumumab

Mutation in Kirsten rat sarcoma-2 virus oncogene (KRAS) status was determined by examining KRAS exons 2, 3, and 4. The emergence of mutant KRAS was defined as a change in KRAS mutation status from wild-type at Baseline in KRAS exons 2, 3, and 4 to mutant in any of KRAS exons 2, 3, and 4 at the time of the second biopsy following the radiographic evidence of acquired resistance to panitumumab when given in combination with irinotecan.

Objective response rate (ORR) is defined as the percentage of participants with either a confirmed complete response (CR) or partial response (PR) measured by the investigator per modified Response Evaluation Criteria in Solid Tumors (RECIST) version 1.0 criteria during the treatment period. Complete Response (CR): Disappearance of all target and non-target lesions and no new lesions. Partial Response (PR): At least a 30% decrease in size of target lesions and no progression (increase in size) of non-target lesions and no new lesions, or, the disappearance of all target lesions, persistence of one or more non-target lesion(s) not qualifying for either CR or progressive disease (PD) and no new lesions.

Objective response rate is defined as the percentage of participants with either a confirmed complete response (CR) or partial response (PR) measured by the investigator per modified RECIST version 1.0 criteria during the treatment period.

Complete Response (CR): Disappearance of all target and non-target lesions and no new lesions. Partial Response (PR): At least a 30% decrease in size of target lesions and no progression of non-target lesions and no new lesions, or, the disappearance of all target lesions, persistence of one or more non-target lesion(s) not qualifying for either CR or progressive disease and no new lesions.

Progression-free survival was defined as the interval from the first dose of study therapy to the earlier date of disease progression (per modified RECIST version 1.0) or death prior to the analysis data cutoff date, initiating a new line of anti-tumor therapy, and receiving study treatment in Part 2 where applicable. Participants who had not progressed or died during this period were censored at their last evaluable disease assessment date. Progressive Disease (PD): At least a 20% increase in the size of target or non-target lesions, significant increase in pleural effusions, ascites, or other fluid collections with cytologic proof of malignancy, or any new lesions.

Overall survival was defined as the time from the first dose of study therapy in Part 1 or Part 2 to the date of death. Participants who had not died by the analysis data cutoff date were censored at their last contact date.

Time to objective response was defined as the time from first dose of study drug to the first confirmed objective response. An objective response is defined as a confirmed complete response or partial response per modified RECIST v1.0 criteria during the treatment period.

Duration of response is defined as the time from the first confirmed objective response to the earlier date of disease progression or death. An objective response is defined as a confirmed complete response or partial response per modified RECIST v1.0 criteria during the treatment period.

Two screening immunoassays, an acid-dissociation enzyme-linked immunosorbent assay (ELISA) and a Biacore-based biosensor assay, were used to detect antibodies capable of binding to panitumumab. Postive samples were further tested for neutralizing antibodies in a cell-based epidermal growth factor receptor (EGFR) phosphorylation bioassay.

Two validated assays were used to detect the presence of anti-ganitumab antibodies. First, an eletrochemiluminescent bridging immunoassay was used to detect binding antibodies (screening assay) and confirm antibodies (confirmatory assay) capable of binding ganitumab. Second, a cell-based bioassay was used to test positive binding antibody samples for neutralizing activity against ganitumab.

The severity of each adverse event (AE) was graded using the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) version 3.0 (where 1 = Mild \[aware of sign or symptom, but easily tolerated\]; 2 = Moderate \[discomfort enough to cause interference with usual activity\]; 3 = severe \[incapacitating with inability to work or do usual activity\]; 4 = life-threatening; 5 = fatal), with the exception of selected skin toxicities that were graded using a modified version of CTC. Treatment-related adverse events were those events for which the investigator considered there to be a reasonable possibility that the event may have been caused by panitumumab (Part 1) and by panitumumab and/or ganitumab (Part 2). Discontinuation includes AEs leading to discontinuation of panitumumab (Part 1) and panitumumab, ganitumab (Part 2) or removal from the study.

The severity of laboratory toxicities was graded using CTCAE v3.0.

Amgen

Other Adverse Events summarizes the non-serious occurrences of adverse events that exceed the indicated frequency threshold.

Participants received panitumumab (6 mg/kg starting dose) with irinotecan (starting dose of 180 mg/m²) every 2 weeks (Q2W).

Part-1: Panitumumab + Irinotecan

Upon radiographically confirmed disease progression, participants proceeded to Part 2 of the study and received treatment with panitumumab (6 mg/kg starting dose) and ganitumab (12 mg/kg starting dose) Q2W.

Part-2: Panitumumab + Ganitumab

Age, Continuous

Sex: Female, Male

White or Caucasian

Other

Race/Ethnicity, Customized

Colon Cancer

Rectal Cancer

Primary Diagnosis

Study Director

Part 1: Panitumumab + Irinotecan

KRAS analysis set (participants with known wild-type KRAS tumors from archival tumor sample and who received at least 1 dose of panitumumab and/or irinotecan in Part 1 and with known KRAS status at baseline and at acquired disease resistance to panitumumab in combination with irinotecan (i.e., based on the results of the second biopsy on study).

Part 1: Emergence of Mutant KRAS

Part 2: Panitumumab + Ganitumab

Tumor Response Evaluable Analysis Set - Part 2 (participants who had radiographically confirmed disease progression on panitumumab and irinotecan in Part 1 and received at least 1 dose of panitumumab and/or ganitumab in Part 2 and with at least 1 baseline uni-dimensionally measurable lesion per the RECIST v1.0 based on investigators' review.

Part 2: Objective Response Rate (ORR)

Tumor Response Evaluable Analysis Set - Part 1 (participants who had known wild-type KRAS tumors from archival tumor sample and who received at least 1 dose of panitumumab and/or irinotecan in Part 1 and with at least one Baseline uni-dimensionally measurable lesion per the RECIST version 1.0 based on investigators' review).

Part 1: Objective Response Rate

Primary Analysis Set - Part 1: participants who had known wild-type KRAS tumors from archival tumor sample and who received at least 1 dose of panitumumab and/or irinotecan. Part 2: participants who had radiographically confirmed disease progression on treatment in Part 1 and received at least 1 dose of panitumumab and/or ganitumab in Part 2.

Progression-free Survival (PFS)

Overall Survival (OS)

Tumor Response Evaluable Analysis Set - Part 1 and Part 2 participants with an objective response

Time to Objective Response

Duration of Response

Binding antibody positive

Neutralizing antibody positive

Primary Analysis Set - Part 1 participants with at least 1 post-baseline immunoassay result.

Number of Participants Who Developed Antibodies to Panitumumab

Primary Analysis Set - Part 2 particpants with at least 1 post-baseline immunoassay result.

Spots Global Cancer Trial Database for mechanisms of acquired resistance