Differences in Reversion of Resistance Mutations to Wild-Type under Structured Treatment Interruption and Related Increase in Replication Capacity

The CPCRA 064 study examined the effect of structured treatment interruption (STI) of up to 4 months followed by salvage treatment in patients failing therapy with multi-drug resistant HIV. We examined the relationship between the reversion rate of major reverse transcriptase (RT) resistance-associated mutations and change in viral replication capacity (RC). The dataset included 90 patients with RC and genotypic data from virus samples collected at 0 (baseline), 2 and 4 months of STI.Rapid shift towards wild-type RC was observed during the first 2 months of STI. Median RC increased from 47.5% at baseline to 86.0% at 2 months and to 97.5% at 4 months. Between baseline and 2 months of STI, T215F had the fastest rate of reversion (41%) and the reversion of E44D and T69D was associated with the largest changes in RC. Among the most prevalent RT mutations, M184V had the fastest rate of reversion from baseline to 2 months (40%), and its reversion was associated with the largest increase in RC. Most rates of reversion increased between 2 months and 4 months, but the change in RC was more limited as it was already close to 100%. The highest frequency of concurrent reversion was found for L100I and K103N. Mutagenesis tree models showed that M184V, when present, was overall the first mutation to revert among all the RT mutations reported in the study.Longitudinal analysis of combined phenotypic and genotypic data during STI showed a large amount of variability in prevalence and reversion rates to wild-type codons among the RT resistance-associated mutations. The rate of reversion of these mutations may depend on the extent of RC increase as well as the co-occurring reversion of other mutations belonging to the same mutational pathway

Prognostic impact of HER2 biomarker levels in trastuzumab-treated early HER2-positive breast cancer

Abstract Background Overexpression of human epidermal growth factor receptor 2 (HER2) caused by HER2 gene amplification is a driver in breast cancer tumorigenesis. We aimed to investigate the prognostic significance of manual scoring and digital image analysis (DIA) algorithm assessment of HER2 copy numbers and HER2/CEP17 ratios, along with ERBB2 mRNA levels among early-stage HER2-positive breast cancer patients treated with trastuzumab. Methods This retrospective study comprised 371 early HER2-positive breast cancer patients treated with adjuvant trastuzumab, with HER2 re-testing performed on whole tumor sections. Digitized tumor tissue slides were manually scored and assessed with uPath HER2 Dual ISH image analysis, breast algorithm. Targeted ERBB2 mRNA levels were assessed by the Xpert® Breast Cancer STRAT4 Assay. HER2 copy number and HER2/CEP17 ratio from in situ hybridization assessment, along with ERBB2 mRNA levels, were explored in relation to recurrence-free survival (RFS). Results The analysis showed that patients with tumors with the highest and lowest manually counted HER2 copy number levels had worse RFS than those with intermediate levels (HR = 2.7, CI 1.4–5.3, p = 0.003 and HR = 2.1, CI 1.1–3.9, p = 0.03, respectively). A similar trend was observed for HER2/CEP17 ratio, and the DIA algorithm confirmed the results. Moreover, patients with tumors with the highest and the lowest values of ERBB2 mRNA had a significantly worse prognosis (HR = 2.7, CI 1.4–5.1, p = 0.003 and HR = 2.8, CI 1.4–5.5, p = 0.004, respectively) compared to those with intermediate levels. Conclusions Our findings suggest that the association between any of the three HER2 biomarkers and RFS was nonlinear. Patients with tumors with the highest levels of HER2 gene amplification or ERBB2 mRNA were associated with a worse prognosis than those with intermediate levels, which is of importance to investigate in future clinical trials studying HER2-targeted therapy

p95HER2 Methionine 611 Carboxy-Terminal Fragment is Predictive of Trastuzumab Adjuvant Treatment Benefit in the FinHer Trial

Abstract Purpose: Expression of p95HER2 (p95), a truncated form of the HER2 receptor, which lacks the trastuzumab binding site but retains kinase activity, has been reported as a prognostic biomarker for poor outcomes in patients with trastuzumab-treated HER2-positive metastatic breast cancer. The impact of p95 expression on trastuzumab treatment efficacy in early HER2-positive breast cancer is less clear. In the current study, p95 was tested as a predictive marker of trastuzumab treatment benefit in the HER2-positive subset of the FinHer adjuvant phase III trial. Experimental Design: In the FinHer trial, 232 patients with HER2-positive early breast cancer were randomized to receive chemotherapy plus 9 weeks of trastuzumab or no trastuzumab treatment. Quantitative p95 protein expression was measured in formalin-fixed paraffin-embedded samples using the p95 VeraTag assay (Monogram Biosciences), specific for the M611 form of p95. Quantitative HER2 protein expression was measured using the HERmark assay (Monogram Biosciences). Distant disease-free survival (DDFS) was used as the primary outcome measure. Results: In the arm receiving chemotherapy only, increasing log10(p95) correlated with shorter DDFS (HR, 2.0; P = 0.02). In the arm receiving chemotherapy plus trastuzumab (N = 95), increasing log10(p95) was not correlated with a shorter DDFS. In a combined analysis of both treatment arms, high breast tumor p95 content was significantly correlated with trastuzumab treatment benefit in multivariate models (interaction P = 0.01). Conclusions: A high p95HER2/HER2 ratio identified patients with metastatic breast cancer with poor outcomes on trastuzumab-based therapies. Further investigation of the p95HER2/HER2 ratio as a potential prognostic or predictive biomarker for HER2-targeted therapy is warranted. Clin Cancer Res; 24(13); 3046–52. ©2018 AACR.</jats:p

Correlation of quantitative p95HER2 and HER2 protein expression with pathologic complete response (pCR) in HER2-positive breast cancer patients (pts) treated with neoadjuvant (NEO) trastuzumab-containing therapy

608 Background: Elevated p95 [HER2-M611-CTF (carboxy-terminal-fragment) also known as p110 or p95HER2] expression has been correlated with poor outcomes in HER2+ pts with metastatic breast cancer treated with trastuzumab (T); however, limited data have been presented on the correlation between p95 and pCR to T in the NEO setting, where p95 was measured by immunohistochemistry. In the current study, we sought to determine whether quantitative p95 and HER2 expression correlated with pCR in pts treated with T + chemotherapy in the NEO setting. Methods: HER2 expression (H2T) was quantified by HERmark in 47 breast tumors using formalin-fixed, paraffin-embedded sections. Tissue remained in 40 cases to measure p95 by VeraTag and compare to a previously published cutoff (Clin Cancer Res 16:4226, 2010). pCR data were available for 45 cases. pCR was defined as the absence of invasive disease in the breast. Results: The overall pCR rate was 46.7% (ER+: 14.3% vs. ER-: 75%; Wilcoxon rank p<0.0001) and was significantly associated with higher H2T levels (p=0.02). In ER- subjects (N=24), no difference in H2T levels was observed between pCR vs non-pCR groups [median H2T=111.5 (IQR 63.4-162.2) vs 150.5 (IQR 43 – 226.2), respectively; p=0.721]. However, within the ER+ group (N=21), H2T levels were significantly higher in the pCR group vs non-pCR group [median H2T=254 (IQR 181.5-584.5) vs 37.3 (IQR 16.4-89); p=0.024]. Using multivariate logistic regression, increasing log(H2T) (p = 0.011), ER-negativity (p = 0.027) and low p95 (p = 0.074) were found to correlate or trend with pCR. Conclusions: pCR was significantly associated with high H2T expression in ER+ HER2+ breast cancer pts who received NEO therapy with T + chemotherapy. A trend towards pCR was seen in tumors that had low p95. These data suggest that quantitative H2T and p95 may provide additional information on response to T-based regimens in breast cancer, particularly ER+ breast cancer. Additional investigation into the possible relationship between quantitative levels of HER2 and p95 expression and T response in the NEO setting in larger cohorts is warranted

Correlation of quantitative p95HER2, HER2, and HER3 protein expression with pathologic complete response (pCR) in HER2-positive breast cancer patients (pts) treated with neoadjuvant chemotherapy and trastuzumab.

137 Background: Elevated p95HER2 [HER2-M611-CTF (carboxy-terminal-fragment) also known as p95] expression has been correlated with poor outcomes in HER2+ pts with metastatic breast cancer treated with trastuzumab (T); however, limited data is available on the correlation between p95 and pCR to T in the neoadjuvant (NEO) setting, where p95 was measured by immunohistochemistry. The current study aims to determine whether quantitative p95, HER3 and HER2 expression correlated with pCR in pts treated with T + chemotherapy in the NEO setting. Methods: pCR data and quantitative HER2 (H2T), p95, and HER3 (H3T) results by HERmark/VeraTag assays were available in 45 patient cases with pre-therapy, formalin-fixed, paraffin-embedded breast tumors. pCR was defined as the absence of invasive disease in the breast. Quantitative biomarker data were correlated with pCR according to previously published or presented biomarker cutoffs. Results: The overall pCR rate was 46.7% (ER+: 14.3% vs. ER-: 75%; p<0.0001) and was significantly associated with higher H2T levels (p=0.02) and lower H3T levels (p=0.04). In ER- subjects (N=24), no difference in H2T levels was observed between pCR vs non-pCR groups (median H2T=111.5 vs 150.5, respectively; p=0.721). However, within the ER+ group (N=21), H2T levels were significantly higher in the pCR group vs non-pCR group (median H2T=254 vs 37.3; p=0.024). Using multivariate logistic regression, increasing log(H2T) (p = 0.012), ER-negativity (p = 0.027) and low p95 (p = 0.074) were found to correlate or trend with pCR. Conclusions: pCR was significantly associated with high H2T, particularly in ER+ HER2+ breast cancer pts who received NEO therapy with T + chemotherapy. Lower H3T was also associated with pCR. A trend towards pCR was seen in tumors with low p95. These data suggest that quantitative H2T, H3T and p95 may provide additional information on response to T-based regimens in breast cancer stratified by ER status. Additional investigation into the relationship between quantitative H2T, p95 and H3T expression and T response in the NEO setting in larger cohorts is warranted

Correlation of HER2, p95HER2 and HER3 expression and treatment outcome of lapatinib plus capecitabine in HER2-positive metastatic breast cancer

Background: Lapatinib plus capecitabine is an effective treatment option for trastuzumab-refractory HER2-positive metastatic breast cancer. We have investigated the correlation between quantitative measures of HER2, p95HER2, and HER3 and treatment outcomes using lapatinib and capecitabine. Methods: Total HER2 (H2T), p95HER2 (p95), and total HER3 (H3T) expression were quantified in formalin-fixed paraffinembedded samples using the VeraTag assays. Patients received lapatinib and capecitabine treatment following trastuzumab failure according to the Lapatinib Expanded Access Program. The association between the protein expression levels and clinical outcomes was analyzed. Results: A total of 52 patients were evaluable. H2T level was significantly higher in responders (median 93.49 in partial response, 47.66 in stable disease, and 17.27 in progressive disease; p = 0.020). Longer time-to-progression (TTP) was observed in patients with high H2T [p = 0.018, median 5.2 months in high (> 14.95) vs. 1.8 in low ( 0.605) vs. 2.2 in low (< 0.605)]. Patients having both high H2T and high H3T had significantly longer TTP [adjusted hazard ratio (HR) 0.38 (95% CI 0.20-0.73), p = 0.004] and overall survival [adjusted HR 0.46 (95% CI 0.24-0.89), p = 0.020]. No significant association between p95 and response or survival was observed. Conclusions: These data suggest a correlation between high HER2 and high HER3 expression and treatment outcome, while no significant difference was observed between clinical outcome and p95 expression level in this cohort of HER2-positive, trastuzumab-refractory metastatic breast cancer patients treated with lapatinib and capecitabine

Quantitative HER2 measurement and PI3K mutation profile in matched primary and metastatic breast cancer tissues.

Background: HER2 status of primary breast cancer (PBC) is routinely used to determine systemic treatment for metastatic breast cancer (MBC) patients. Discordance rates of HER2 status between PBC and MBC range from 5.5% to 29% based on published meta-analyses. The clinical benefit of re-assessing HER2 in MBC tissues remains controversial. In this study, we measured quantitative HER2 expression in matched PBC and MBC tissues and correlated changes of HER2 with mutations in the catalytic domain of PI3 kinase(PIK3CA). Methods: Total HER2 protein expression (H2T) was quantified by the HERmark assay in 41 matched PBC and MBC formalin-fixed, paraffin-embedded specimens. PIK3CA mutation status in exons 9 (E545K and E542K) and 20 (H1047R) was determined using a validated pyrosequencing assay. Results: MBC samples included 5 lymph node, 13 viscera, 6 brain, and 17 soft tissue lesions (N=41). 27 (66%) cases showed higher H2T in MBC than in matched PBC; and 14 (34%) cases had higher H2T in PBC than in matched MBC, indicating an overall increase of H2T in matched MBC lesions (fold change 0.25-17.57; p=0.005, paired Wilcoxon rank sum test). HER2 positive conversion (HERmark negative/equivocal in PBC, but positive in matched MBC) was found in 6 (15%) cases, while HER2 negative conversion (HERmark positive in PBC, but negative/equivocal in matched MBC) was seen in 2 (5%) cases. HER2 status was unchanged in 33 (80%) cases. PIK3CA mutations were detected in 13 (32%) of PBC and 19 (46%) of MBC samples. Among the HER2 positive conversion cases, PIK3CA mutation was identified in 50% (3/6) PBC and 67% (4/6) MBC, compared to 0% (0/2, PBC or MBC) in the HER2 negative conversion cases. Among cases with unchanged HER2 status, PIK3CA mutation was observed in 30% (10/33) PBC and 42% (14/33) MBC. Conclusions: Quantitative HER2 assessment revealed a 20% discordance in HER2 status between matched PBC and MBC tissues, with more frequent conversion from low HER2 in PBC to high HER2 in MBC. PIK3CA mutation was observed more frequently in patients who converted from HER2 negative PBC to HER2 positive MBC. These results suggest that re-assessment of biomarkers in MBC tissues may better inform the selection of therapeutic options for patients with MBC