Phase 1 multicenter study of the HSP90 inhibitor SNX-5422 plus carboplatin and paclitaxel in patients with lung cancers

Objectives: Single-agent heat shock protein 90 (HSP90) inhibition has demonstrated activity in oncogene-driven non-small cell and small cell lung cancers. SNX-5422 is an oral HSP90 inhibitor with increased activity in vitro with the addition of carboplatin and paclitaxel. Therefore, we conducted a phase 1, open-label, multicenter study to evaluate SNX-5422, carboplatin and paclitaxel followed by SNX-5422 maintenance in patients with advanced lung cancers.

Materials and methods: In part 1 (3 + 3 dose escalation), SNX-5422 (50/75/100-mg/m2) was dosed every other day (qod) for 21 days (28-day cycle) for ≤4 cycles; carboplatin (AUC 5)-paclitaxel (175 mg/m2) was administered once every 3 weeks for ≤6 courses. In part 2 (maintenance), subjects who achieved at least stable disease in part 1 received 100 mg/m2 SNX-5422 monotherapy qod for 21 days (28-day cycle).

Results: Twenty-three patients with advanced non-small cell lung cancer (NSCLC, n = 20) and small cell lung cancer (SCLC, n = 3) were enrolled. The median age was 60 years and 61% (n = 14/23) had ≥1 prior treatment regimens. The maximum tolerated dose of SNX-5422 was 100 mg/m2 qod in combination with carboplatin-paclitaxel. The most common treatment-related grade 3/4 adverse events (part 1/part 2) were diarrhea (26%/15%) and nausea (9%/0%). In response-evaluable patients with NSCLC, 33% (6/18) had a partial response, 56% (10/18) stable disease, and 11% (2/18) progressive disease. Patients who remained on single-agent SNX-5422 maintenance therapy ≥2 months (n = 9) had cancers enriched for oncogenic drivers (n = 3 KRAS mutation, n = 1 EGFR exon 20 mutation, n = 1 HER2 mutation, and n = 1 RET fusion).

Conclusions: The triplet combination of SNX-5422, carboplatin and paclitaxel followed by maintenance SNX-5422 therapy was well-tolerated and showed anti-tumor activity. Cancers for which disease control on single-agent SNX-5422 maintenance was observed were enriched for oncogene-driven NSCLCs.

Related Products

Cat.No. Product Name Information
S2656 PF-04929113 (SNX-5422) PF-04929113 (SNX-5422) is a potent and selective HSP90 inhibitor with Kd of 41 nM and induces Her-2 degradation with IC50 of 37 nM. Phase 1/2.

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