2 Incidence, Clinical and Laboratory Predictors of Adverse Events (AEs) and Outcomes in Patients (Pts) With Breast Cancer Receiving Alpelisib in the Real World: A Single Institution Experience

Background/Aim

The aim was to identify the incidence and predictors of alpelisib (Piqray)-related AEs in clinical practice. Although clinical trials provided data on AEs of alpelisib, there is a need to study AEs in the real world due to differences in patient characteristics and alpelisib use following multiple lines of therapy.

Methods

We reviewed charts of pts with metastatic, hormone receptor (HR)–positive, HER2-negative, PIK3CA-mutated breast cancer who were treated with alpelisib from 2019 to 2021. Laboratory and clinical variables including comorbidities, metastasis site, prior therapy, clinical responses, time from alpelisib initiation to progression, and last follow-up were collected. Association of these factors with AEs and clinical response were evaluated using a logistic regression model. SAS statistical software, version 9.4 (SAS Institute Inc) was used to perform statistical analysis at a significance level of 0.05.

Results

Twenty pts were included. Median age was 67 years
(48-77 years); 80% of pts (1620) had received 2 or more lines of prior treatment, 36.8% (719) had no comorbidities, and 95% (19/20) had more than 1 site of visceral metastases. Eighty-five percent of pts (17/20) experienced AEs; the most common were hyperglycemia (76.5%), nausea (41.2%), diarrhea (35.3%), and fatigue (29.4%). The most common grade 3 (G3) AEs leading to alpelisib interruption/dose reduction/discontinuation were hyperglycemia (60%) and skin rash (30%). No significant difference in clinical characteristics between pts who did or did not experience an AE was observed. Median duration of alpelisib treatment was 2 months (IQR, 0.6-8.5) for pts who developed AEs and 5.5 months (IQR, 1.2-10.4) for pts without AEs (P = .5). As expected, 88.9% of pts (8/9) who experienced grade 3 or greater AEs had a dose reduction and 80% (8/10) interrupted/discontinued the treatment, while only 22.2% (2/9) who did not have grade 3 or greater AEs had a dose reduction and only 12.5% (1/8) discontinued/interrupted the treatment (P = .015 for both); 44.4% of pts (8/18) achieved a partial response (PR). Pts with a PR had a lower likelihood of visceral metastases (38%) compared with those having stable/progressive disease (90%; P = .043). Lower median absolute lymphocyte count (1.23 × 109/L) was associated with a higher likelihood of PR (P = .046).

Conclusion

In this single-institution study, we found a higher incidence of AEs than reported in prior trials with promising responses in a heavily pretreated population. This emphasizes the need for strategies to mitigate toxicities that would allow continuation of alpelisib, given the observed clinical benefit.

Author Affiliations:

Sabah Alaklabi,¹ Arya Mariam Roy,¹ Kristopher Attwood,² Anthony George,² Tracey O’Connor,¹ Ellis G. Levine,¹ Shipra Gandhi¹

¹Department of Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, NY

²Biostatistics & Bioinformatics, Roswell Park Comprehensive Cancer Center, Buffalo, NY