A groundbreaking case report from China has documented the first instance of exceptional immunotherapy response in a patient with advanced lung adenosquamous carcinoma harboring multiple concurrent driver mutations, achieving unprecedented progression-free survival that challenges current understanding of this aggressive malignancy.
Exceptional Clinical Response Defies Conventional Expectations
The case involves a 63-year-old male with a 40-pack-year smoking history who presented with left-sided chest pain and was diagnosed with stage IVA lung adenosquamous carcinoma. Comprehensive molecular profiling revealed an unusual constellation of driver mutations: KRAS p.G12C (VAF 3.30%), BRAF p.G466R (VAF 4.70%), PIK3CA p.H1047R (VAF 3.5%), and FLT1 p.L1232F (VAF 2.1%).
Despite harboring multiple driver mutations—typically associated with poor immunotherapy response—the patient achieved complete remission following first-line treatment with tislelizumab (PD-1 inhibitor) combined with paclitaxel and nedaplatin chemotherapy. Remarkably, the patient has maintained complete response with progression-free survival exceeding 46.5 months as of the latest follow-up in March 2025.
Molecular Characteristics and Biomarker Profile
The tumor demonstrated several key molecular features that may have contributed to the exceptional response. PD-L1 expression was positive at 18.11% (TPS), while tumor mutational burden remained relatively low at 3.7 muts/Mb with microsatellite instability-low status. This biomarker profile suggests that PD-L1 expression, rather than high TMB, may have been the primary driver of immunotherapy sensitivity.
Histopathological analysis confirmed the diagnosis through characteristic morphologic features on H&E staining, with immunohistochemical positivity for both lung adenocarcinoma-specific markers (TTF-1, Napsin A) and squamous cell carcinoma-specific markers (p63, CK5/6). The patient's tumor markers, initially significantly elevated, normalized following treatment and have remained stable throughout the follow-up period.
Treatment Protocol and Clinical Outcomes
The patient received six cycles of combination therapy comprising paclitaxel 220 mg IV, nedaplatin 60 mg IV, and tislelizumab 200 mg IV every three weeks, followed by maintenance tislelizumab monotherapy through April 2023. Treatment was well-tolerated with only grade IV myelosuppression after cycle 6, which resolved with supportive care.
Serial imaging demonstrated progressive reduction in pulmonary lesions, with complete resolution achieved by November 2021. Restaging per RECIST v1.1 criteria confirmed complete remission, evidenced by complete resolution of pulmonary/pleural lesions and normalization of cervical/axillary lymph nodes.
Literature Context and Clinical Significance
A comprehensive literature review revealed that adenosquamous carcinoma patients typically achieve modest outcomes with conventional therapies. During the pre-immunotherapy era, patients achieved progression-free survival of 5.7-14 months and median overall survival of 13.8-34.7 months across all tumor stages. Even with the introduction of immune checkpoint inhibitors, median progression-free survival improved to only 6.0-7.7 months with overall survival extending to 8.8-24.7 months.
The current case's 46.5-month progression-free survival represents a paradigm shift, surpassing all previously published outcomes for this aggressive NSCLC subtype. This exceptional response challenges the conventional notion that "multiple driver mutations equate to immune resistance" and highlights the complexity of tumor heterogeneity and its interplay with immunotherapy efficacy.
Implications for Precision Medicine
The case provides compelling evidence that personalized combination strategies guided by molecular profiling may overcome traditional therapeutic limitations in adenosquamous carcinoma. The patient's response occurred despite the absence of ASC-specific recommendations in current guidelines, suggesting that biomarker-driven approaches may be more predictive than histological subtype alone.
The findings are particularly significant given that adenosquamous carcinoma represents only 0.4%-4% of all pulmonary malignancies but is associated with inherently poor prognosis. Multiple clinical studies have demonstrated that adenosquamous carcinoma is associated with significantly worse 5-year survival rates compared to pure adenocarcinoma or squamous cell carcinoma.
Future Research Directions
This case underscores the urgent need for accumulating multi-omics data from similar cases and establishing a dedicated biomarker framework for pulmonary adenosquamous carcinoma. The exceptional response suggests that certain molecular subsets within this rare malignancy may be highly responsive to immunotherapy, warranting further investigation into predictive biomarkers and optimal treatment sequencing.
The research team emphasizes that future studies should prioritize comprehensive molecular profiling to identify patients most likely to benefit from immunotherapy-based approaches, potentially transforming outcomes for this historically treatment-refractory malignancy.
