The Phase II Study of Panitumumab in Chemotherapy-Naïve Frail or Elderly Patients with RAS Wild-type Colorectal Cancer: OGSG 1602 Final Results.

BACKGROUND: We previously reported the response rate of a phase II OGSG1602 study on panitumumab in chemotherapy-naive frail or elderly patients with RAS wild-type unresectable colorectal cancer (CRC) [Terazawa T, Kato T, Goto M, et al. Oncologist. 2021;26(1):17]. Herein, we report a survival analysis. METHODS: Patients aged ≥65 years and considered unsuitable for intensive chemotherapy or aged ≥76 years were enrolled. Primary tumors located from the cecum to the transverse colon were considered right-sided tumors (RSTs); those located from the splenic flexure to the rectum were considered left-sided tumors (LSTs). RESULTS: Among the 36 enrolled patients, 34 were included in the efficacy analysis, with 26 and 8 having LSTs and RSTs, respectively. The median progression-free survival (PFS) and overall survival (OS) were 6.0 [95% CI, 5.4-10.0] and 17.5 months (95% CI, 13.8-24.3), respectively. Although no significant differences existed in PFS between patients with LST and RST {6.6 (95% CI, 5.4-11.5) vs. 4.9 months [95% CI, 1.9-not available (NA), P = .120]}, there were significant differences in OS [19.3 (95% CI, 14.2-NA) vs.12.3 months (95% CI, 9.9-NA), P = .043]. CONCLUSION: Panitumumab showed favorable OS in frail or elderly patients with RAS wild-type CRC and no prior exposure to chemotherapy. Panitumumab may be optimal for patients with LSTs (UMIN Clinical Trials Registry Number UMIN000024528).

Phase II Study of Panitumumab Monotherapy in Chemotherapy-Naïve Frail or Elderly Patients with Unresectable RAS Wild-Type Colorectal Cancer: OGSG 1602.

LESSONS LEARNED: Panitumumab monotherapy showed favorable efficacy and feasibility in the treatment of frail or elderly patients with RAS wild-type unresectable colorectal cancer. It is especially effective for left-sided tumors; therefore, panitumumab as first-line treatment could be an additional therapeutic option for frail elderly patients, particularly in those who are unsuitable for upfront oxaliplatin-based or irinotecan-based combination regimens. BACKGROUND: First-line panitumumab monotherapy is expected to be well tolerated and improve survival in patients ineligible for intensive chemotherapy. However, its safety and efficacy in chemotherapy-naïve frail or elderly patients with unresectable RAS wild-type (WT) colorectal cancer (CRC) have not been studied. The aim of this phase II trial was to evaluate the efficacy and safety of panitumumab as first-line treatment. METHODS: We conducted a multicenter phase II study on patients aged ≥76 years or ≥65 years considered unsuitable for intensive chemotherapy. Panitumumab 6 mg/kg of intravenous infusion was administered every 2 weeks. The primary endpoint was disease control rate (DCR). Secondary endpoints included progression-free survival (PFS), overall survival (OS), response rate (RR), time to treatment failure (TTF), and incidence of grade 3 or 4 toxicities. RESULTS: Thirty-six patients (median age: 81 [range, 67-88] years) were enrolled between February 2017 and August 2018. Two patients were excluded from the analysis of efficacy: one from lack of image examination at baseline and the other from lack of a measurable lesion. Thirty-three (91.6%) patients had a performance status (PS) of 0 or 1, whereas two (5.6%) patients and one (2.8%) patient had a PS of 2 and 3, respectively. Twenty-eight patients (77.8%) had left-sided CRC, whereas eight (22.2%) had right-sided CRC. The RR was 50.0% (95% confidence interval [CI], 32.4-67.6), including three patients (8.8%) who had complete responses. A total of 26.5% had stable diseases, resulting in a DCR of 76.5% (90% CI, 61.5-87.7). The RR of patients with left- and right-sided tumors was 65.4% (95% CI, 44.3-82.8) and 0.0% (95% CI, 0.0-36.9), respectively. Major grade 3 or 4 nonhematologic toxicities were rash (n = 6, 16.7%), hypomagnesemia (n = 4, 11.1%), fatigue (n = 3, 8.3%), paronychia (n = 2, 5.6%), and hyponatremia (n = 2, 5.6%). The only grade 3 hematologic toxicity was neutropenia (n = 1, 2.8%). CONCLUSION: Panitumumab monotherapy showed favorable efficacy and feasibility in frail or elderly patients with RAS WT unresectable CRC. Survival analysis including OS, PFS, and TTF is currently in progress.

[A Case of Recurrent Colorectal Cancer with Bilateral Ovarian Metastases That Were Reduced with Regorafenib Therapy].

A 63-year-old woman had recurrences of metastatic rectal cancer in the lung, peritoneum, and ovary. Regorafenib was administered at 160mg/day as third-line chemotherapy. The patient developed Grade(Gr)3 hand-foot syndrome(HFS) and Gr 2 rash, but the abdominal distension and pain were relieved by the 1st course. Analgesics could be reduced and regorafenib was administrated at reduced dosage. The patient received keishi-bukuryo-gan(EK-25)and sai-rei-tou(TJ-114) for HFS. At the beginning of therapy, ovarian metastases were not reduced and showed poor contrast enhancement on CT. Serum levels of lactate dehydrogenase(LDH)and tumor markers were increased. During the 4th course of therapy, ovarian metastases tended to shrink and serum levels of LDH and tumor markers were decreased. Ovarian metastases showed a partial response(PR)after the 6th course. Lung metastases showed a progressive disease during the 2nd course, but a PR after the 3rd course, and were not apparent after the 6th course. Reduction of metastases was maintained at 16 months after the start of therapy, and HFS was assessed at Gr 2 or lower. Physical, laboratory, and imaging findings should be carefully evaluated prior to long-term administration of regorafenib.

[A case with multiple liver metastases from rectal cancer responding completely to FOLFOX for a long duration without exacerbation of peripheral neuropathy].

A 61-year-old man had undergone five courses of modified FOLFOX6(mFOLFOX6)chemotherapy with calcium-magnesium(Ca/Mg)infusion for a rectal cancer with multiple liver metastases from October 2008. After this treatment, the primary rectal tumor and metastatic tumors were considered as a partial response(PR), and lower anterior resection was carried out in February 2009. After the operation, mFOLFOX6 chemotherapy with bevacizumab was started in March 2009. After 15 courses of chemotherapy, the patient received 7. 5 g of gosha-jinki-gan(TJ-107)daily from August 2009, and the drug compliance was 69%. From the 18th course of chemotherapy in October 2009, glutathione(GSH)was given at a dose of 200 mg before each oxaliplatin administration. From the 35th course of chemotherapy in November 2010, the patient received 1. 5 g of powdered processed aconite root(TJ-3027)daily. TJ-3027 administration was escalated to 4. 5 g daily, and drug compliance was 73%. Grade 4 neutropenia was observed in December 2010, and we reduced oxaliplatin to 65 mg/m(2) from the 37th course. Fifty chemotherapy courses were administered until October 2011. The patient received a total 3, 970 mg/m(2) of oxaliplatin, however, the neurotoxicity level of the patient remained at grade 2. Ca/Mg infusion and TJ-107 administration have been reported not to reduce the activity of FOLFOX individually, and severe side effects are rare. So one must consider the combination treatment of Ca/Mg and TJ-107 for prevention of oxaliplatin-related neurotoxicity.

[A patient with peritoneal metastasis from gastric cancer who responded to weekly chemotherapy with paclitaxel on the third line and could take meal].

We report a patient with peritoneal metastasis from gastric cancer who responded to weekly chemotherapy with paclitaxel (TXL) as the third line treatment and could take meals for half a year. The patient was a 64-year-old man who underwent total gastrectomy for advanced gastric cancer with peritoneal metastasis. He was first treated with TS-1 as an outpatient treatment; however, tumor markers rose. He could not take meals and had to be hospitalized. CPT-11 was infused on the second line, but due to disease progress, the patient was administered weekly TXL. TXL (70 mg/m2) was infused over 1 hour after short premedication. Administration was continued for 3 weeks followed by 1 week rest. The tumor markers decreased, and he could take meals and was discharged from hospital. The toxic events were leukopenia (grade 2), alopecia (grade 2) and pneumonia (grade 3).