Abstract GS5-05: Primary analysis of NRG-BR005, a phase II trial assessing accuracy of tumor bed biopsies in predicting pathologic complete response (pCR) in patients with clinical/radiological complete response after neoadjuvant chemotherapy (NCT) to explore the feasibility of breast-conserving treatment without surgery

4513 Background: Although neoadjuvant combined modality therapy (NACMTX) has become a standard of care in the United States, median overall survival (OS) for patients (PTS) with EA has changed little over the past 25 years. Progression free survival (PFS) and OS after NACMTX depend on extent of primary tumor response. New regimens to increase pathologic complete response (pCR) are needed. Based on phase I data, SWOG designed a phase II trial (S0356) to test OXP with PI5FU and EBRT for PTS with EA. Objectives included pCR rate ≥ 25%, acceptable toxicity (TOX), PFS, OS and exploration of molecular parameters relevant to pCR. Methods: Eligibility: clinical stage II/III EA, ≥ 18 years, Zubrod PS ≤ 2, standard hematologic/non-hematologic values, and tumor < 2 cm into the gastric cardia. OXP 85 mg/m2 was given day (d) 1, 15 and 29; PI5FU 180 mg/m2/d was given d 8-d43. EBRT 180 cGy/d started d 8 x 25 fractions, 5 d/week to total dose 4500 cGy. S was planned 2–4 weeks after NACMTX, with a second cycle of OXP/ PI5FU after S. Central pathology review of surgical specimens was mandated. The trial used a 2-stage design; the trial was halted at 45 PTS to review pCR rate; it reopened to full accrual. Results: 98 PTS enrolled between 9/15/04 and 8/18/08. 6 PTS were ineligible; 2 PTS did not receive therapy (TX). 90 PTS, 84 men (93%), median age 61.7 years, were analyzed. 4 deaths (4.5%) were due to protocol TX; 2 due to NACMTX, 2 to S. 43% and 18% of PTS had grade 3/4 toxicity, respectively: 39% GI, 22% flu-like/fatigue, 17% pulmonary, 16% hematologic, 14% mucositis and 3% neurologic. 77 PTS (86%) underwent S. 30 PTS (33%) had pCR. 9 PTS (10%) had in-situ cancer or T1N0M0. <50% received postoperative CTX. Conclusions: OXP, PI5FU and EBRT for PTS with EA has produced the highest pCR rate reported to date for a cooperative group trial. Significant but manageable non-hematologic TOX was observed. S mortality is acceptable. Future trials built on this platform should plan to complete all TX before S. Tumor molecular profiles (analyses in progress) may predict benefit from this treatment. Data on PFS and OS will follow. [Table: see text]

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Updated results of phase II trial using escalating doses of neoadjuvant atezolizumab for cisplatin-ineligible patients with nonmetastatic urothelial cancer (NCT02451423).

Journal of Clinical Oncology ◽

10.1200/jco.2021.39.15_suppl.e16510 ◽

2021 ◽

Vol 39 (15_suppl) ◽

pp. e16510-e16510

Author(s):

Divya V Natesan ◽

Li Zhang ◽

David Yoonsuk Oh ◽

Sima P. Porten ◽

Maxwell Meng ◽

...

Keyword(s):

Clinical Trial ◽

Hearing Loss ◽

Phase Ii ◽

Phase Ii Trial ◽

Pathologic Complete Response ◽

Complete Response ◽

Treatment Rate ◽

Carcinoma Of The Bladder ◽

Muscle Invasive ◽

To Receive

e16510 Background: Patients (pts) with muscle-invasive bladder cancer (MIBC) ineligible for cisplatin-based chemotherapy have no standard systemic therapy options and are prioritized for radical cystectomy (RC) alone. This prospective clinical trial investigated the safety and efficacy of escalating doses of neoadjuvant atezolizumab (N-ATZ) prior to RC in MIBC pts. Methods: This is a single-institution, phase II trial of escalating doses of N-ATZ (1200 mg IV every 3 weeks) in pts with MIBC. Key inclusion criteria were resectable urothelial carcinoma of the bladder (T2-T4a,N0-1,M0) and inability to receive cisplatin-based treatment (eGFR < 60 mL/min, G≥2 neuropathy/hearing loss, pt decision). Pts with high-risk disease at RC were eligible to receive adjuvant ATZ for up to 16 total doses. Pts were followed for up to 2 years following RC. Primary efficacy endpoint was pathologic complete response (pCR; pT0N0). Secondary endpoints were safety of treatment, rate of pathologic downstaging (≤pT1N0), response based on PD-L1 status, and overall survival (OS) and recurrence-free survival (RFS) at 1 and 2 years from RC. Results: A total of 20 pts were enrolled and sequentially treated with one (n=6), two (n=5), and three (n=9) cycles of N-ATZ prior to RC. Median age was 69 (range 61-81), 75% were male and 85% Caucasian. Pts were cisplatin-ineligible due to low GFR (35%), hearing loss (25%) or neuropathy (10%); the rest refused cisplatin (30%). Most pts had pT2 disease (80%); the remainder, pT3/pT4 (15%/5%), and 10% had cN1. Among 17 pts with available tumor PD-L1 status, 76% had PD-L1 positive (CPS≥10) tumors. pCR was observed in 2 pts (10%) with 1 and 2 ATZ doses, whereas pathologic downstaging was observed in 5 pts (25%) across all 3 doses (Table). All pts completed intended treatment and RC within the trial-defined timeframe. Perioperative TRAEs of any grade occurred in 75%, but only 10% had G3 TRAEs (diarrhea, fecal incontinence). There were no G4/G5 events. Median follow-up from RC was 23.6 months and 75% were still followed at the time of data cutoff in 2/2021. Among evaluable pts, 1-year RFS and OS were 72% and 94% while 2-year RFS and OS were 64% and 69%. PD-L1 positive pts had superior OS (logrank p=0.06) and RFS (p=0.10) relative to PD-L1 negative pts. Conclusions: N-ATZ was well tolerated at all three dose levels and did not delay or prevent surgery. As few as 1 to 2 ATZ doses resulted in pathologic downstaging, including pCR. Although pCR rate in this trial was lower than expected, most pts had a durable recurrence-free period and all evaluable pts with tumor downstaging were alive and recurrence-free at 2 years following RC. Increased tumor PD-L1 expression was suggestive of improved outcomes and further biomarker analyses are ongoing. Clinical trial information: NCT02451423. [Table: see text]

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