Differential Impact of Consolidative Thoracic Radiotherapy in Extensive-Stage Small Cell Lung Cancer Based on Systemic Therapy Type and Sex

PURPOSE/OBJECTIVE(S)

Consolidative thoracic radiotherapy (cTRT) has been shown in phase III RCTs to improve overall (OS) and progression-free survival (PFS) after initial chemotherapy (chemo) in extensive-stage small cell lung cancer (ES-SCLC). This benefit was particularly pronounced in women compared to men in the 2015 CREST trial (hazard ratio [HR] 0.68 vs. 1.01, respectively). However, it is unknown whether similar findings would apply after chemoimmunotherapy (chemo-IO) became standard of care first-line treatment in 2018. In this analysis, we report national practice patterns and survival outcomes of cTRT versus no cTRT following chemo or chemo-IO, stratified by sex.

MATERIALS/METHODS

Patients from the nationwide Flatiron Health de-identified electronic health record-derived database were included if they completed 4-6 cycles of first-line systemic therapy (platinum-doublet chemo or chemo-IO) for stage IV SCLC diagnosed between 2014 and 2021. Patients who progressed or started cTRT within 14 days or died within 90 days of completing systemic therapy were excluded to account for immortal time bias. We evaluated OS and PFS using multivariable Cox proportional hazards regression with receipt of cTRT as an independent covariate and last date of chemo as index date. As a sensitivity analysis to address potential selection bias, we weighted the models by the inverse probability of receiving cTRT. All OS and PFS analyses were stratified by systemic therapy type and sex.

RESULTS

A total of 1,227 patients were included (850 chemo, 377 chemo-IO). The proportion of patients who received cTRT increased from 11.7% in 2014 to 20.7% in 2017, and then decreased to 16.4% in 2021. There were no statistically significant differences in baseline characteristics between patients who did and did not receive cTRT. In adjusted analyses among women receiving chemo, cTRT was associated with superior OS (HR 0.68; 95% confidence interval [CI] 0.51-0.91) and PFS (HR 0.64; 95% CI 0.47-0.86) [Table 1]. There was a non-statistically significant trend towards improved OS (HR 0.57; 95% CI 0.32-1.02) and PFS (HR 0.59; 95% CI 0.34-1.02) among women receiving chemo-IO. No OS or PFS benefit with cTRT was observed in men receiving either chemo or chemo-IO. Findings were similar in weighted analyses.

CONCLUSION

The survival impact of cTRT may be differentially impacted by sex, with female patients appearing more likely to benefit than male patients regardless of systemic therapy type. While the underpinnings of this association need to be elucidated, stratification by sex should be considered for RCTs studying cTRT in ES-SCLC.

Observation of thermal-induced optical guiding and bistability in a mid-IR continuous-wave, singly resonant optical parametric oscillator

We report the observation of thermal-induced optical guiding and bistability in a mid-IR cw, singly resonant optical parametric oscillator (SRO) at approximately 3.2 microm. The SRO employs a MgO:PPLN crystal as the gain medium and a 1-nm-linewidth Yb-fiber laser at 1.064 microm as the pump source. As soon as the pump power reaches the thermal guiding threshold at 16.5 W, the SRO shows a step increase in the parametric efficiency by a factor of 2.5. At 25 W pump power, the SRO generated 5.3 and 1.2 W at 1.58 and 3.23 microm, respectively, with single-longitudinal-mode performance for the 3.23 microm radiation.

Low-threshold, narrow-line THz-wave parametric oscillator with an intra-cavity grazing-incidence grating

We report a low-threshold, narrow-line THz-wave parametric oscillator with an intra-cavity grazing-incidence grating and a 1-mm thick, 45-mm long lithium-niobate planar waveguide. When pumped by an actively Q-switched Nd:YAG laser, the threshold energy and intensity of the parametric oscillator were about 2.2 mJ and 70 MW/cm(2), respectively. The linewidths of the output THz wave were 12 and 134 GHz with and without the intra-cavity grating, respectively.

Forward and backward terahertz-wave difference-frequency generations from periodically poled lithium niobate

We report terahertz-wave generation in the wavelength range of 190 - 210 and 457 - 507 microm from forward and backward difference frequency generations, respectively, in a 3.2-cm long multi-grating periodically poled lithium niobate (PPLN) crystal. The grating period of the PPLN crystal varies form 63 to 70 microm in 1-microm increments. The extraordinary refractive index of lithium niobate in the THz-wave range was precisely deduced from the quasi-phase-matching condition of the difference frequency generations.

Monolithically integrated laser Bragg Q-switch and wavelength converter in a PPLN crystal

We report a periodically poled lithium niobate (PPLN) crystal for both temperature-insensitive laser Q-switching and temperature-tuned wavelength conversion. The PPLN crystal consists of two sections, a 20.3-mum period section functioning as an electro-optic Bragg grating for Qswitching a diode-pumped Nd:YVO4 laser at 1064 nm and a 31-mum-period section functioning as an optical parametric generator for down converting the generated 1064-nm laser. When driving the PPLN Bragg grating with 170-V voltage pulses, we measured 181 muJ pulse energy at 1064 nm from the Nd:YVO4 laser pumped by 20.4 W diode power. The 181-muJ pulsed laser was further converted into mid-infrared radiation in the monolithic PPLN crystal with 35% parametric efficiency. The wavelengths were broadly tunable in the range of 1.75-1.88 mum (signal) and 2.7-2.44 mum (idler) via temperature without affecting the performance of the PPLN Bragg Qswitch.

Average-power mediated ultrafast laser osteotomy using a mode-locked Nd:YVO4 laser oscillator

By using a novel temporal characterization technique, we determined that a threshold average laser power of 160 mW is required to drill through a 0.75-mm-thick cortical bone for a Nd:YVO(4) mode-locked laser oscillator with a peak intensity of 1.3 GWcm(2). The ablation mechanism is identified as average-power induced carbonization followed by peak-power induced avalanche ionization in the carbonized osseous tissue.

Phase I trial of PTK787/ZK222584 (PTK/ZK) in combination with carboplatin (C) and paclitaxel (T) in platinum-sensitive recurrent epithelial ovarian (EOC), fallopian tube (FT), or primary peritoneal (PPC) cancers

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Background: Targeting vascular endothelial growth factor (VEGF) in patients (pts) with ovarian cancer achieves objective responses. PTK/ZK is an orally active angiogenesis inhibitor which blocks all known VEGF receptor and platelet-derived growth factor receptor tyrosine kinases. A previous study administered PTK/ZK only on days 3–21 of C and T cycle based on pre-clinical data suggesting PTK/ZK increases T levels (PROC ASCO # 5042, 2005), and recent data supports bid dosing (JCO 18:1–10, 2005). Methods: In this open label, single institution phase I study, pts with platinum sensitive recurrent EOC, FT, or PPC were treated with C and T every 21 days with increasing continuous daily doses of PTK/ZK (250 mg to 1,250mg with bid dosing). Primary endpoints were safety and maximum tolerated dose (MTD). Pharmacokinetic (PK) analysis is planned to describe C and T pharmacokinetics when combined with PTK/ZK. Results: To date, 14 pts with median age 61 (range 45–73) have been enrolled on the first 3 dose levels, including 13 EOC and 1 PPC. All patients were evaluable for toxicity and 8 were evaluable for investigator assessed response. MTD has not been reached. Febrile neutropenia was dose limiting toxicity requiring expansion at levels II and III. PK analysis is ongoing. To date, best responses are: 4 (PR), 3 (SD) and 1 (POD). Other G III toxicity included: C hypersensitivity reaction (1, gr 3), hyperglycemia (4, gr 3), hypertension (1, gr 3), diarrhea (1, gr 3), and elevated liver function tests (1, gr 3). Conclusion: PTK/ZK can be administered continuously in combination with standard doses of C and T using bid dosing. MTD is not yet reached and accrual is ongoing. PK data and MTD will be presented. Supported by Novartis and Bayer Schering Pharma.

[Table: see text]

No significant financial relationships to disclose.

Electro-optic periodically poled lithium niobate Bragg modulator as a laser Q-switch

We report an electro-optic Bragg modulator using a periodically poled lithium niobate (PPLN) crystal. We measured a half-wave voltage of 160 V when transmitting a 1064 nm laser through a 14.2 mm long, 780 microm thick, 20.13 microm period PPLN crystal at the Bragg angle. We also demonstrated a Q-switched Nd:YVO(4) laser using such a PPLN Bragg modulator as its Q-switch, producing 7.8 ns, 201 microJ pulses at a 10 kHz repetition rate when pumped by a 19.35 W diode laser at 808 nm.

Light-enhanced electro-optic spectral tuning in annealed proton-exchanged periodically poled lithium niobate channel waveguides

We report the observation of light-enhanced electro-optic spectral tuning in annealed proton-exchanged, asymmetric domain-duty-cycle periodically poled lithium niobate (PPLN) channel waveguides for second-harmonic generation. The spectral tuning rate was increased rapidly from 0.07 nm/(kV/mm) to a saturated value of 0.32 nm/(kV/mm) in a 30%/70% domain-duty-cycle PPLN waveguide when the fundamental pump power near 1534 nm was increased from 0.6 to 46 mW. The second-harmonic laser power at 767 nm was identified to be the source enhancing the spectral tuning.

Single-longitudinal-mode, tunable dual-wavelength,CW Nd:YVO(4) laser

We report a single-longitudinal-mode CW diode-pumped Nd:YVO(4) laser emitting at both 1064 and 1342 nm with 10% optical efficiency at 20-W pump power. The measured spectral widths at 1064 and 1342 nm were less than 450 MHz and 400 MHz, respectively. The two emission wavelengths can be independently tuned over the lasing bandwidths of the dual-wavelength laser.

Enhanced terahertz-wave parametric generation and oscillation in lithium niobate waveguides at terahertz frequencies

We observed parametric-generation efficiency of 1.61% from 1064 to 1071 nm and at 162 microm in a 0.5 mm thick, 45 mm long z-cut congruent lithium niobate waveguide with a pump energy of 2.2 mJ and a pump pulse width of 5.8 ns. We also measured an ultralow-threshold intensity of 70 MW/cm2 for a 1064 nm pumped parametric oscillator resonating at 1071 nm and emitting at 162 microm with a 1 mm thick, 45 mm long lithium niobate waveguide.

Laser-induced damage threshold at chemical vapor deposition-grown diamond surfaces for 200-ps CO(2) laser pulses

We report laser-induced damage thresholds (LIDTs) at chemical vapor deposition (CVD)-grown diamond surfaces for 200-ps CO(2) laser pulses, obtained with photoacoustic diagnostics. The results are compared with those at ZnSe and Ge surfaces under the same experimental condition. For 200-ps laser pulses, CVD diamond, ZnSe, and Ge were measured and found to have damage fluences of 1.2, 0.45, and 0.2 J/cm(2) , respectively, for a laser waist radius of 134 mum. Acoustic measurement indicated a relatively large variation in the LIDT of the CVD-grown diamond because of its polycrystalline structure.

Distributed-feedback optical parametric oscillation by use of a photorefractive grating in periodically poled lithium niobate

We report a demonstration of distributed-feedback (DFB) optical parametric oscillation (OPO) by writing photorefractive gratings in periodically poled lithium niobate (PPLN). The photorefractive DFB structures were fabricated by illumination of PPLN with UV light through a photomask and by writing of PPLN with UV-light gated interfering laser beams at 532 nm. Evidence of OPO was observed from the spectral narrowing at the 1438.8- and the 619.3-nm signal wavelengths from 1064- and 532-nm-pumped PPLN crystals with the DFB grating periods phase matched to the 4084.5- and 3774-nm idler wavelengths, respectively.

Compact, 220-ps visible laser employing single-pass, cascaded frequency conversion in monolithic periodically poled lithium niobate

We report the first demonstration to our knowledge of 220-ps visible laser generation from passively Q-switched-laser pumped periodically poled lithium niobate (PPLN) in a single-pass, cascaded frequency-conversion process. The monolithic PPLN consists of a 1-cm section for frequency doubling the 1064-nm Nd:YAG pump laser to a 532-nm laser and a subsequent 4-cm section for generating the visible laser in a 532-nm-pumped optical parametric generation (OPG) process. In generating the 622.3-nm OPG signal wavelength we measured a 3.0-microJ/pulse pump threshold at the 1064-nm wavelength, 16% overall efficiency, and 35% slope efficiency at two times threshold. At 10(-6) pump duty cycle and 20-mW average power in the visible, photorefractive damage was not observed at the phase-matching temperature of 40.3 degrees C.